#!/usr/bin/perl -w

## Easy GIT (eg), a frontend for git designed for former cvs and svn users
## Version 1.7.5.2
## Copyright 2008-2013 by Elijah Newren and others
## Licensed under GNU GPL, version 2.

## To use eg, simply stick this file in your path.  Then fire off an
## 'eg help' to get oriented.  You may also be interested in
##   http://www.gnome.org/~newren/eg/git-for-svn-users.html
## to get a comparison to svn in terms of capabilities and commands.
## Webpage for eg: http://www.gnome.org/~newren/eg

use strict;
use warnings;

package main;

use Getopt::Long;
use Cwd qw(getcwd abs_path);
use List::Util qw(max);
use File::Temp qw/ tempfile /;

# configurables
my $DEBUG = $ENV{EASYGIT_DEBUG} || 0;
my $GIT_CMD = $ENV{EASYGIT_GIT_CMD} || "git";  # Includes any global args, thus "git --exec-path=..."
my $USE_PAGER = exists($ENV{EASYGIT_USE_PAGER}) ? $ENV{EASYGIT_USE_PAGER} : -1;

# globals :-(
my $OUTFH;
my $VERSION = "1.7.5.2";
my $EG_EXEC = abs_path($0);
my %ALIAS;
my %COMMAND;    # command=>{section, short_description} mapping
my $SECTION = {
 'creation' =>
   { order => 1,
     desc  => 'Creating repositories',
   },
 'discovery' =>
   { order => 2,
     desc  => 'Obtaining information about changes, history, & state',
   },
 'modification' =>
   { order => 3,
     desc  => 'Making, undoing, or recording changes',
   },
 'projects' =>
   { order => 4,
     desc  => 'Managing branches',
   },
 'collaboration' =>
   { order => 5,
     desc  => 'Collaboration'
   },
 'timesavers' =>
   { order => 6,
     desc  => 'Time saving commands'
   },
 'compatibility' =>
   { order => 7,
     extra => 1,
     desc  => 'Commands provided solely for compatibility with other ' .
              'prominent SCMs'
   },
 'misc' =>
   { order => 8,
     extra => 1,
     desc  => 'Miscellaneous'
   },
 };
my ($CURDIR, $TOPDIR, $GITDIR);

## Commands to list in help even though we haven't overridden the git versions
## (yet, in most cases)
INIT {
 %COMMAND = (
   blame => {
     unmodified_help => 1,
     unmodified_behavior => 1,
     extra => 1,
     section => 'discovery',
     about => 'Show what version and author last modified each line of a file'
     },
   bisect => {
     unmodified_help => 1,
     unmodified_behavior => 1,
     section => 'timesavers',
     about => 'Find the change that introduced a bug by binary search'
     },
   grep => {
     unmodified_help => 1,
     unmodified_behavior => 1,
     extra => 1,
     section => 'discovery',
     about => 'Print lines of known files matching a pattern'
     },
   mv => {
     unmodified_help => 1,
     unmodified_behavior => 1,
     section => 'modification',
     about => 'Move or rename files (or directories or symlinks)'
     },
 );
}



#*************************************************************************#
#*************************************************************************#
#*************************************************************************#
#                   CLASSES DEFINING ACTIONS TO PERFORM                   #
#*************************************************************************#
#*************************************************************************#
#*************************************************************************#

###########################################################################
# subcommand, a base class for all eg subcommands                         #
###########################################################################
package subcommand;
sub new {
 my $class = shift;
 my $self = {git_repo_needed => 0, @_};  # Hashref initialized as we're told
 bless($self, $class);

 # Our "see also" section in help usually references the same subsection
 # as our class name.
 $self->{git_equivalent} = ref($self) if !defined $self->{git_equivalent};

 # We allow direct instantiation of the subcommand class only if they
 # provide a command name for us to pass to git.
 if (ref($class) eq "subcommand" && !defined $self->{command}) {
   die "Invalid subcommand usage"
 }

 # Most commands must be run inside a git working directory
 unless (!$self->{git_repo_needed} || (@ARGV > 0 && $ARGV[0] eq "--help")) {
   $self->{git_dir} = RepoUtil::git_dir();
   if (!defined $self->{git_dir}) {
     # Couldn't find git repository.  That could be for any of three reasons:

     # 1) Is 'git' even in the user's PATH?
     my @paths_to_git = grep {-x "$_/git"} split(/:/, $ENV{PATH});
     if (!@paths_to_git) {
       die "Error: Cannot find git in your PATH!\n";
     }

     # 2) Does 'git' even work (possible bad installation)?
     my ($ret, $output) =
       ExecUtil::execute_captured("$GIT_CMD --version", ignore_ret => 1);
     if ($ret != 0 || $output !~ /^git version .*$/) {
         die "Error: Cannot execute git (check your git installation)!\n";
     }

     # 3) They just aren't in a project tracked by git
     die "Error: Must be run inside a git-tracked working directory!\n";
   }
 }

 # Many commands do not work if no commit has yet been made
 if ($self->{initial_commit_error_msg} &&
     RepoUtil::initial_commit() &&
     (@ARGV < 1 || $ARGV[0] ne "--help")) {
   die "$self->{initial_commit_error_msg}\n";
 }

 return $self;
}

sub help {
 my $self = shift;
 my $package_name = ref($self);
 $package_name =~ s/_/-/;  # Packages use underscores, commands use dashes

 my $git_equiv = $self->{git_equivalent};
 $git_equiv =~ s/_/-/;  # Packages use underscores, commands use dashes

 if ($package_name eq "subcommand") {
   exit ExecUtil::execute("$GIT_CMD $self->{command} --help")
 }

 $ENV{"LESS"} = "FRSX" unless defined $ENV{"LESS"};
 my $less = ($USE_PAGER == 1) ? "less" :
            ($USE_PAGER == 0) ? "cat" :
            `$GIT_CMD config core.pager` || "less";
 chomp($less);
 open(OUTPUT, "| $less");
 print OUTPUT "$package_name: $COMMAND{$package_name}{about}\n";
 print OUTPUT $self->{'help'};
 print OUTPUT "\nDifferences from git $package_name:";
 print OUTPUT "\n  None.\n" if !defined $self->{'differences'};
 print OUTPUT $self->{'differences'} if defined $self->{'differences'};
 if ($git_equiv) {
   print OUTPUT "\nSee also\n";
   print OUTPUT <<EOF;
 Run 'git help $git_equiv' for a comprehensive list of options available.
 eg $package_name is designed to accept the same options as git $git_equiv, and
 with the same meanings unless specified otherwise in the above
 "Differences" section.
EOF
 }
 close(OUTPUT);
 exit 0;
}

sub preprocess {
 my $self = shift;

 return if (scalar(@ARGV) > 0 && $ARGV[0] eq "--");
 my $result=main::GetOptions("--help" => sub { $self->help() });
}

sub run {
 my $self = shift;
 my $package_name = ref($self);

 my $subcommand =
   $package_name eq "subcommand" ? $self->{'command'} : $package_name;

 @ARGV = Util::quote_args(@ARGV);
 return ExecUtil::execute("$GIT_CMD $subcommand @ARGV", ignore_ret => 1);
}

###########################################################################
# add                                                                     #
###########################################################################
package add;
@add::ISA = qw(subcommand);
INIT {
 $COMMAND{add} = {
   unmodified_behavior => 1,
   section => 'compatibility',
   about => 'Mark content in files as being ready for commit'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Description:
 eg add is provided for backward compatibility; it has identical usage and
 functionality as 'eg stage'.  See 'eg help stage' for more details.
";
 return $self;
}

###########################################################################
# apply                                                                   #
###########################################################################
package apply;
@apply::ISA = qw(subcommand);
INIT {
 $COMMAND{apply} = {
   about => 'Apply a patch in a git repository'
 };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg apply [--staged] [-R | --reverse] [-pNUM]

Description:
 Applies a patch to a git repository.

Examples:
 Reverse changes in foo.patch
     \$ eg apply -R foo.patch

 (Advanced) Reverse changes since the last commit to the version of foo.c
 in the staging area (equivalent to 'eg revert --staged foo.c'):
     \$ eg diff --staged foo.c | eg apply -R --staged

Options:
 --staged
   Apply the patch to the staged (explicitly marked as ready to be committed)
   versions of files

 --reverse, -R
   Apply the patch in reverse.

 -pNUM
   Remove NUM leading paths from filenames.  For example, with the filename
     /home/user/bla/foo.c
   using -p0 would leave the name unmodified, using -p1 would yield
     home/user/bla/foo.c
   and using -p3 would yield
     bla/foo.c
";
 $self->{'differences'} = '
 eg apply is identical to git apply except that it accepts --staged as a
 synonym for --cached.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my $result = main::GetOptions("--help" => sub { $self->help() });
 foreach my $i (0..$#ARGV) {
   $ARGV[$i] = "--cached" if $ARGV[$i] eq "--staged";
 }
}

###########################################################################
# branch                                                                  #
###########################################################################
package branch;
@branch::ISA = qw(subcommand);
INIT {
 $COMMAND{branch} = {
   section => 'projects',
   about => 'List, create, or delete branches'
   };
 $ALIAS{'br'} = "branch";
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg branch [-r]
 eg branch [-s] NEWBRANCH [STARTPOINT]
 eg branch -d BRANCH

Description:
 List the existing branches that you can switch to, create a new branch,
 or delete an existing branch.  For switching the working copy to a
 different branch, use the eg switch command instead.

 Note that branches are local; creation of branches in a remote repository
 can be accomplished by first creating a local branch and then pushing the
 new branch to the remote repository using eg push.

Examples
 List the available local branches
     \$ eg branch

 Create a new branch named random_stuff, based off the last commit.
     \$ eg branch random_stuff

 Create a new branch named sec-48 based off the 4.8 branch
     \$ eg branch sec-48 4.8

 Delete the branch named bling
     \$ eg branch -d bling

 Create a new branch named my_fixes in the default remote repository
     \$ eg branch my_fixes
     \$ eg push --branch my_fixes

 (Advanced) Create a new branch named bling, based off the remote tracking
 branch of the same name
     \$ eg branch bling origin/bling
 See 'eg remote' for more details about setting up named remotes and
 remote tracking branches, and 'eg help topic storage' for more details on
 differences between branches and remote tracking branches.

Options:
 -d
   Delete specified branch

 -r
   List remote tracking branches (see 'eg help topic storage') for more
   details.  This is useful when using named remote repositories (see 'eg
   help remote')

 -s
   After creating the new branch, switch to it
";
 $self->{'differences'} = '
 eg branch is identical to git branch other than adding a new -s option for
 switching to a branch immediately after creating it.
';
 return $self;
}

sub run {
 my $self = shift;

 my $switch = 0;
 if (scalar(@ARGV) > 1 && $ARGV[0] eq "-s") {
   $switch = 1;
   shift @ARGV;
 }

 @ARGV = Util::quote_args(@ARGV);
 my $ret = ExecUtil::execute("$GIT_CMD branch @ARGV", ignore_ret => 1);
 $ret = ExecUtil::execute("$GIT_CMD checkout $ARGV[0]", ignore_ret => 1)
   if ($switch && $ret == 0);
 return $ret;
}

###########################################################################
# bundle                                                                  #
###########################################################################
package bundle;
@bundle::ISA = qw(subcommand);
INIT {
 $COMMAND{bundle} = {
   extra => 1,
   section => 'collaboration',
   about => 'Pack repository updates (or whole repository) into a file'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   initial_commit_error_msg => "No bundles can be created until a commit " .
                               "has been made.",
   @_
   );
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg bundle create FILENAME [REFERENCES]
 eg bundle create-update NEWFILENAME OLDFILENAME [REFERENCES]
 eg bundle verify FILENAME

Description:
 Bundle creates a file which contains a repository, or a subset thereof.
 This is useful when two machines cannot be directly connected (thus
 preventing use of the standard interactive git protocols -- git, ssh,
 rsync or http), but changes still need to be communicated between the
 machines.

 The remote side can use the resulting file (or the path to it) as the URL
 for the repository they want to clone or pull updates from.

Examples
 Create a bundle in the file repo.bundle which contains the whole repository
     \$ eg bundle create repo.bundle

 After getting the bundle named repo.bundle from a collaborator (which
 must contain \"HEAD\" as one of the references if you explicitly list which
 ones to be included at creation time), clone the repository into the
 directory named project-name
     \$ eg clone /path/to/repo.bundle project-name

 Create a bundle in the file called new-repo containing only updates since
 the bundle old-repo was created.
     \$ eg bundle create-update new-repo old-repo

 Pulls updates from a new bundle we have been sent.
     \$ eg pull /path/to/repo.bundle

 Pull updates from a new bundle we have been sent, if we first overwrite
 the bundle we originally original cloned from with the new bundle
     \$ eg pull

 (Advanced) Create a bundle containing the two branches debug and
 installer, and the tag named v2.3, in the file called my-changes
     \$ eg bundle create my-changes debug installer v2.3

 (Advanced) Create a bundle in the file called new-repo that contains
 updates since the bundle old-bundle was created, but don't include the
 new branch secret-stuff or crazy-idea
     \$ eg bundle create-update new-repo old-bundle ^secret-stuff ^crazy-idea

Options:
 eg bundle create FILENAME [REFERENCES]
 eg bundle create-update NEWFILENAME OLDFILENAME [REFERENCES]
 eg bundle verify FILENAME

 create FILENAME [REFERENCES]
   Create a new bundle in the file FILENAME.  If no REFERENCES are passed,
   all branches and tags (plus \"HEAD\") will be included.  See below for
   a basic explanation of REFERENCES.

 create-update NEWFILENAME OLDFILENAME [REFERENCES]

   Create a new bundle in the file NEWFILENAME, but don't include any
   commits already included in OLDFILENAME.  See below for a basic
   explanation of REFERNCES.  By default, any new branch or tags will be
   included as well; exclude specific branches or tags by passing ^BRANCH
   or ^TAG as a reference; see below for more details.

 verify FILENAME
   Check whether the given bundle in FILENAME will cleanly apply to the
   current repository.

 REFERENCES
   Which commits to include or exclude from the bundle.  Probably best
   explained by example:

     Example            Meaning
     -----------------  --------------------------------------------------
     master             Include the master branch
     master~10..master  Include the last 10 commits on the master branch
     ^baz foo bar       Include commits on the foo or bar branch, except for
                          those that are in the baz branch
";
 $self->{'differences'} = '
 eg bundle differs from git bundle in two ways:
   (1) eg bundle defaults to "--all HEAD" if no revisions are passed to create
   (2) eg bundle provides a create-update subcommand
';
 return $self;
}

sub preprocess {
 my $self = shift;

 #
 # Parse options
 #
 my @args;
 my $result=main::GetOptions("--help" => sub { $self->help() });

 # Get the (sub)subcommand
 $self->{subcommand} = shift @ARGV;
 push(@args, $self->{subcommand});

 if ($self->{subcommand} eq 'create') {
   my $filename = shift @ARGV ||
     die "Error: need a filename to write bundle to.\n";
   push(@args, $filename);  # Handle the filename
   if (!@ARGV) {
     push(@args, ("--all", "HEAD"));
   }
 }
 elsif ($self->{subcommand} eq 'create-update') {
   pop(@args);  # 'create-update' isn't a real git bundle subcommand

   my $newname = shift @ARGV ||
     die "You must specify a new and an old filename.\n";
   my $oldname = shift @ARGV ||
     die "You must also specify an old filename\n";

   die "$oldname does not exist.\n" if ! -f $oldname;

   my ($retval, $output) =
     ExecUtil::execute_captured("$GIT_CMD bundle list-heads $oldname");
   my @lines = split '\n', $output;

   my @refs = map { m#^([0-9a-f]+)# && "^$1" } @lines;
   push(@args, ('create', $newname, "--all", "HEAD", @refs));
 }
 push(@args, @ARGV);

 # Reset @ARGV with the built up list of arguments
 @ARGV = @args;
}

###########################################################################
# cat                                                                     #
###########################################################################
package cat;
@cat::ISA = qw(subcommand);
INIT {
 $COMMAND{cat} = {
   new_command => 1,
   extra => 1,
   section => 'compatibility',
   about => 'Output the current or specified version of files'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   git_equivalent => 'show',
   initial_commit_error_msg => "Error: Cannot show committed versions of " .
                               "files when no commits have occurred.",
   @_
   );
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg cat [REVISION:]FILE...

Description:
 Output the specified file(s) as of the given revisions.

 Note that this basically is just a compatibility alias provided for users
 of other SCMs.  You should consider using 'git show' instead, though with
 core git whenever you specify a REVISION, you will need to specify the
 path to FILE relative to the toplevel project directory, instead of a
 path for FILE relative to the current directory.

Examples
 Output the most recently committed version of foo.c
     \$ eg cat foo.c

 Output the version of bar.h from the 5th to last commit on the
 ugly_fixes branch
     \$ eg cat ugly_fixes~5:bar.h

 Concatenate the version of hello.c from two commits ago and the
 version of world.h from the branch timbuktu, and output the result:
     \$ eg cat HEAD~1:hello.c timbuktu:world.h
";
 $self->{'differences'} = '
 The output of "git show FILE" is probably confusing to users at first,
 as is the need to specify files relative to the top of the git project
 rather than relative to the current directory.  Thus, "eg cat FILE"
 calls "git show HEAD:PATH/TO/FILE".
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my $result=main::GetOptions("--help" => sub { $self->help() });

 # Get important directories
 my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();

 my @args;
 foreach my $arg (@ARGV) {
   if ($arg !~ /:/) {
     my ($path) = Util::reroot_paths__from_to_files($cur_dir, $top_dir, $arg);
     push(@args, "HEAD:$path");
   } else {
     my ($REVISION, $FILE) = split(/:/, $arg, 2);
     my ($path) = Util::reroot_paths__from_to_files($cur_dir, $top_dir, $FILE);
     push(@args, "$REVISION:$path");
   }
 }

 @ARGV = @args;
}

sub run {
 my $self = shift;

 @ARGV = Util::quote_args(@ARGV);
 return ExecUtil::execute("$GIT_CMD show @ARGV", ignore_ret => 1);
}

###########################################################################
# changes                                                                 #
###########################################################################
package changes;
@changes::ISA = qw(subcommand);
INIT {
 $COMMAND{changes} = {
   new_command => 1,
   section => 'misc',
   about => 'Provide an overview of the changes from git to eg'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, git_equivalent => '', @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg changes [--details]

Options
 --details
   In addition to the summary of which commands were changed, list the
   changes to each command.
";
 $self->{'differences'} = '
 eg changes is unique to eg; git does not have a similar command.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 $self->{details} = 0;
 my $result = main::GetOptions(
   "--help"    => sub { $self->help() },
   "--details" => \$self->{details},
   );
 die "Unrecognized arguments: @ARGV\n" if @ARGV;
}

sub run {
 my $self = shift;

 if ($DEBUG == 2) {
   print "    >>(No commands to run, just data to print)<<\n";
   return;
 }

 # Print valid subcommands sorted by section
 my $indent = "  ";
 my $header_indent = "";
 $ENV{"LESS"} = "FRSX" unless defined $ENV{"LESS"};
 my $less = ($USE_PAGER == 1) ? "less" :
            ($USE_PAGER == 0) ? "cat" :
            `$GIT_CMD config core.pager` || "less";
 chomp($less);
 open(OUTPUT, "| $less");

 if ($self->{details}) {
   print OUTPUT "Summary of changes:\n";
   $indent = "    ";
   $header_indent = "  ";
 }
 print OUTPUT "${header_indent}Modified Behavior:\n";
 foreach my $c (sort keys %COMMAND) {
   next if $COMMAND{$c}{unmodified_behavior};
   next if $COMMAND{$c}{new_command};
   print OUTPUT "$indent$c\n";
 }
 print OUTPUT "${header_indent}New commands:\n";
 foreach my $c (sort keys %COMMAND) {
   next if !$COMMAND{$c}{new_command};
   print OUTPUT "$indent$c\n";
 }
 print OUTPUT "${header_indent}Modified Help Only:\n";
 foreach my $c (sort keys %COMMAND) {
   next if $COMMAND{$c}{unmodified_help};
   next if !$COMMAND{$c}{unmodified_behavior};
   next if $COMMAND{$c}{new_command};
   print OUTPUT "$indent$c\n";
 }

 if ($self->{details}) {
   foreach my $c (sort keys %COMMAND) {
     next if $COMMAND{$c}{unmodified_help} || $COMMAND{$c}{unmodified_behavior};

     my $real_c = $c;
     $c =~ s/-/_/;  # Packages use underscores, commands use dashes
     next if !$c->can("new");
     my $obj = $c->new(initial_commit_error_msg => '');

     print OUTPUT "Changes to $real_c:\n";
     if ($obj->{differences}) {
       $obj->{differences} =~ s/^\n//;
       print OUTPUT $obj->{differences};
     } else {
       print OUTPUT "  <Unknown>.\n";
     }
   }
 }
 close(OUTPUT);
}

###########################################################################
# checkout                                                                #
###########################################################################
package checkout;
@checkout::ISA = qw(subcommand);
INIT {
 $COMMAND{checkout} = {
   section => 'compatibility',
   about => 'Compatibility wrapper for clone/switch/revert'
 };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg checkout [-b] BRANCH
 eg checkout [REVISION] PATH...

Description:
 eg checkout mostly exists as a compatibility wrapper for those used to
 other systems (cvs/svn and git).  If you:
   (1) want a new copy of the source code from a remote repository
   OR
   (2) want to switch your working copy to a different branch
   OR
   (3) want to revert the contents of a file to its content from a
       different revision
 Then use:
   (1) eg clone
   (2) eg switch
   (3) eg revert

 eg checkout will accept the same arguments as eg clone (for getting a new
 copy of the source code from a remote repository), but will provide an
 error message and tell the user to use eg clone in such cases.

 The first usage form of eg checkout is used to switch to a different
 branch (optionally also creating it first).  This is something that can
 be done with no network connectivity in git and thus eg.  Users can find
 identical functionality in eg switch.

 The second usage form of eg checkout is used to replace files in the
 working copy with versions from an older commit, i.e. to revert files to
 an older version.  Note that this only works when the specified files
 also existed in the older version (eg checkout will not delete or unstage
 files for you), does not work for the initial commit (since there's no
 older revision to revert back to -- unless you are an advanced user
 interested in just undoing the changes since the most recent staging),
 and cannot be used to undo an incomplete merge (since it only operates on
 a subset of files and not everything since a given commit).  Users can
 find the same functionality (without all the caveats) as well as other
 capabilities in eg revert.

Examples:
 Switch to the stable branch
     \$ eg checkout stable

 Replace foo.c with the third to last version before the most recent
 commit (Note that HEAD always refers to the current branch, and the
 current branch always refers to its most recent commit)
     \$ eg checkout HEAD~3 foo.c
";
 $self->{'differences'} = '
 eg checkout accepts all parameters that git checkout accepts with the
 same meanings and same output (eg checkout merely calls git checkout in
 such cases).

 The only difference between eg and git regarding checkout is that eg
 checkout will also accept all arguments to git clone, and then tell users
 that they must have meant to run eg clone (a much nicer error message for
 users trying to get a copy of source code from a remote repository than
 "fatal: Not a git repository").
';
 return $self;
}

sub _looks_like_git_repo ($) {
 my $path = shift;

 my $clone_protocol = qr#^(?:git|ssh|http|https|rsync)://#;
 my $git_dir = RepoUtil::git_dir();
 my $in_working_copy = defined $git_dir ? 1 : 0;

 # If the path looks like a git, ssh, http, https, or rsync url, then it
 # looks like we're being given a url to a git repo
 if ($path =~ /$clone_protocol/) {
   return 1;
 }

 # If the path isn't a clone_protocol url and isn't a directory, it can't be
 # a git repo
 if (! -d $path) {
   return 0;
 }

 my $path_is_absolute = ($path =~ m#^/#);
 return (!$in_working_copy || ($in_working_copy && $path_is_absolute));
}

sub preprocess {
 my $self = shift;

 if (scalar(@ARGV) > 0 && $ARGV[0] ne "--") {
   main::GetOptions("--help" => sub { $self->help() });
 }

 $self->{command} = 'checkout';
 die "eg checkout requires at least one argument.\n" if !@ARGV;

 #
 # Determine whether this should be a call to git clone or git checkout
 #
 my $clone_protocol = qr#^(?:git|ssh|http|https|rsync)://#;
 if (_looks_like_git_repo($ARGV[-1]) ||
     (! -d $ARGV[-1] && @ARGV > 1 && _looks_like_git_repo($ARGV[-2]))
    ) {
   $self->{command} = 'clone';
 }
}

sub run {
 my $self = shift;

 @ARGV = Util::quote_args(@ARGV);
 if ($self->{command} ne 'clone') {
   # If this operation isn't a clone, then we should have checked for
   # whether we are in a git directory.  But we didn't do that, just in
   # case it was a clone.  So, do it now.
   $self->{git_dir} = RepoUtil::git_dir();
   die "Must be run inside a git repository!\n" if !defined $self->{git_dir};

   return ExecUtil::execute("$GIT_CMD checkout @ARGV", ignore_ret => 1);
 } else {
   die "Did you mean to run\n  eg clone @ARGV\n?\n";
 }
}

###########################################################################
# cherry_pick                                                             #
###########################################################################
package cherry_pick;
@cherry_pick::ISA = qw(subcommand);
INIT {
 $COMMAND{"cherry-pick"} = {
   extra => 1,
   section => 'modification',
   about => 'Apply (or reverse) a commit, usually from another branch'
 };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg cherry-pick [--reverse] [--edit] [-n] [-m parent-number] [-s] [-x] REVISION

Description:
 Given an existing revision, apply the change between its parent and it
 (or reverse apply if the --reverse option is present), and record a new
 revision with this change.  Your working tree must be clean (no local
 unsaved modifications) in order to run eg cherry-pick.

Examples:
 Apply the fix 3 commits behind the tip of the experimental branch
 (i.e. the fix made in experimental~3) to the current branch
     \$ eg cherry-pick experimental~3

 Make a new commit that reverses the changes made in the most recent
 commit of the current branch
     \$ eg cherry-pick -R HEAD

Options:
 --reverse, --revert, -R
   Reverse apply the changes from the specified commit (i.e. revert the
   specified revision with a new commit).

 --edit, -e
   With this option, eg cherry-pick will let you edit the commit message
   prior to committing.

 -x
   When recording the commit, append to the original commit message a note
   that indicates which commit this change was cherry-picked from.  Append
   the note only for cherry picks without conflicts. Do not use this
   option if you are cherry-picking from your private branch because the
   information is useless to the recipient. If on the other hand you are
   cherry-picking between two publicly visible branches (e.g. backporting
   a fix to a maintenance branch for an older release from a development
   branch), adding this information can be useful.

   This option is turned on automatically when -R is specified.

 --mainline parent-number, -m parent-number
   cherry-pick always applies the changes between a revision and its
   parent; thus if a revision represents a merge commit, it is not clear
   which parent cherry-pick should get the changes relative to.  This
   option specifies the parent number (starting from 1) of the mainline
   and allows cherry-pick to replay the change relative to the specified
   parent.

 --no-commit, -n
   Usually cherry-pick automatically creates a commit. This flag applies
   the change necessary to cherry-pick the named revision to your working
   tree and staging area, but does not make the commit. In addition, when
   this option is used, the staging area can contain unsaved changes and
   the cherry-pick will be done against the beginning state of your
   staging area.

   This is useful when cherry-picking more than one commit into a single
   combined change.

 --signoff, -s
   Add Signed-off-by line at the end of the commit message.

 REVISION
   A reference to a recorded version of the repository.  See 'eg help
   topic revisions' for more details.
";
 $self->{'differences'} = '
 eg cherry-pick contains both the functionality of git cherry-pick and git
 revert.  If the -R option is specified, eg cherry-pick calls git revert
 (after removing the -R option); otherwise it calls git cherry-pick.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my ($reverse, $dash_x, $mainline) = (0, 0, -1);
 Getopt::Long::Configure("permute");  # Allow unrecognized options through
 my $result = main::GetOptions(
   "--help"       => sub { $self->help() },
   "mainline|m=i" => \$mainline,
   "reverse|R"    => \$reverse,
   "revert"       => \$reverse,
   "x"            => \$dash_x,
   );
 $self->{reverse} = $reverse;
 unshift(@ARGV, "-x") if (!$reverse && $dash_x);
 unshift(@ARGV, ("-m", $mainline)) if $mainline != -1;
}

sub run {
 my $self = shift;

 @ARGV = Util::quote_args(@ARGV);
 if ($self->{reverse}) {
   return ExecUtil::execute("$GIT_CMD revert @ARGV", ignore_ret => 1);
 } else {
   return ExecUtil::execute("$GIT_CMD cherry-pick @ARGV", ignore_ret => 1);
 }
}

###########################################################################
# clone                                                                   #
###########################################################################
package clone;
@clone::ISA = qw(subcommand);
INIT {
 $COMMAND{clone} = {
   section => 'creation',
   about => 'Clone a repository into a new directory'
 };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg clone [--depth DEPTH] REPOSITORY [DIRECTORY]

Description:
 Obtains a copy of a remote repository, including all history by default.
 A --depth option can be passed to only include a specified number of
 recent commits instead of all history (however, this option exists mostly
 due to the fact that users of other SCMs fail to understand that all
 history can be compressed into a size that is often smaller than the
 working copy).

 See 'eg help topic remote-urls' for a detailed list of the different ways
 to refer to remote repositories.

Examples:
 Get a local clone of cairo
     \$ eg clone git://git.cairographics.org/git/cairo

 Get a clone of a local project in a new directory 'mycopy'
     \$ eg clone /path/to/existing/repo mycopy

 Get a clone of a project hosted on someone's website, asking for only the
 most recent 20 commits instead of all history, and storing it in the
 local directory mydir
     \$ eg clone --depth 20 http://www.random.machine/path/to/git.repo mydir

Options:
 --depth DEPTH
   Only download the DEPTH most recent commits instead of all history
";
 return $self;
}

###########################################################################
# commit                                                                  #
###########################################################################
package commit;
@commit::ISA = qw(subcommand);
INIT {
 $COMMAND{commit} = {
   section => 'modification',
   about => 'Record changes locally'
   };
 $ALIAS{'checkin'} = "commit";
 $ALIAS{'ci'}      = "commit";
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg commit [-a|--all-known] [-b|--bypass-unknown-check]
           [--staged|-d|--dirty] [-F FILE | -m MSG] [--amend] [--]
           [FILE...]

Description:
 Records changes locally along with a log message describing the
 changes you have made.  If no -F or -m option is supplied, an editor
 is opened for you to enter a log message.

 In order to prevent common errors, the commit will abort with a warning
 message if there are no changes to commit, there are conflicts from a
 merge, or if eg detects that the choice of what to commit is ambiguous.
 In particular, if you have any \"newly created\" unknown files present,
 or if you have both staged changes (i.e. changes explicitly marked as
 ready for commit) and unstaged changes, then you will get a warning
 rather than having the commit occur.  You can run 'eg status' to get the
 status of various files and their changes.  These commit checks can be
 bypassed with various options.

Examples:
 Record current changes locally, not changing anything in CVS...OR...get
 a warning message if eg detects that the choice of what to commit is not
 necessarily clear.
     \$ eg commit

 Record current changes, ignoring any unknown files present.  Also
 remember the list of unknown files so that their existence will not
 trigger future \"You have new unknown files present\" warnings when not
 using the -b flag.
     \$ eg commit -b

 Record brand new file and current changes.
     \$ eg stage file.c
     \$ eg commit -a
 Note: Running 'eg stage FILE' explicitly marks FILE as being ready to
 commit.  Since you likely haven't explicitly marked your other changes as
 ready to commit, pass the -a flag to specify that both kinds of changes
 should be recorded.

 (Advanced) Record staged changes, ignoring both unstaged changes and
 unknown files.
     \$ eg commit --staged

Options:
 --all-known, -a
   (Could also be called --act-like-other-vcses).  Commit both staged
   (i.e. explictly marked as ready for commit) changes and unstaged
   changes.

   Incompatible with explicitly specifying files to commit on the command
   line, and incompatible with the --staged option.

 --bypass-unknown-check, -b
   Commit local changes, even if there are unknown files around.  If this
   flag is not used and unknown files are currently present that were not
   present the last time the -b flag was used, then the commit will be
   aborted with a warning message.

 --staged, --dirty, -d
   Commit only staged changes and bypass sanity checks.  (\"dirty\" is kept
   as a synonym in order to provide a short (-d) form.  The term \"dirty\"
   is used to convey the fact that the working area will likely not be
   \"clean\" after a commit since unstaged changes will still be present).

   WARNING: Do not try to use -s as a shorthand for --staged; -s has a
   different meaning (see 'git commit --help')

   Incompatible with explicitly specifying files to commit on the command
   line, and incompatible with the --all-known option.

 -F FILE
   Use the contents of FILE as the commit message

 -m MSG
   Use MSG as the commit message.

 --amend
   Amend the last commit on the current branch.
";
 $self->{'differences'} = '
 The "--staged" (and "-d" and "--dirty" aliases) are unique to eg commit;
 git commit behavior differs from eg commit in that it acts by default
 like the --staged flag was passed UNLESS either the -a option is passed
 or files are explicitly listed on the command line.

 The "--bypass-unknown-check" is unique to eg commit; git commit
 behavior differs by always turning on this functionality -- there is
 no way to have git commit do an unknown files sanity check for you.

 "-a" is not nearly as useful for eg commit as it is for git commit.  "-a"
 has the same behavior in both, but the "smart" behavior of eg commit
 means it is only rarely needed.

 The "--all-known" alias for "-a" is known as "--all" to git-commit; I
 find the latter confusing and misleading and thus renamed to the former
 for eg commit.

 To be precise about the behavior of a plain "eg commit":
    If the working copy is clean                -> warn user: nothing to commit
    else if there are unmerged files            -> warn user: unmerged files
    else if there are new untracked files       -> warn user: new unknown files
    else if both "staged" & unstaged changes[1] -> warn user: mix
    else                                        -> run "git commit -a"
 Actually, I do not pass -a if there are only staged changes present, but
 the result is the same.  Note that this essentially boils down to making
 the user do less work (no need to remember -a in the common case) and
 extending the sanity checks git commit does (which currently only covers
 the clean working copy case) to also prevent a number of other very
 common user pitfalls.

 [1] The reason for putting "staged" in quotes comes from the case of
 running "eg commit --amend" when you have local unstaged changes.  Does
 the user want to merely amend the prior commit message or add their
 changes to the previous commit?  (Even if the index matches HEAD at this
 time, we are committing relative to HEAD^1.)  It is not clear what the
 user wants, so we warn and ask them to use -a or --staged.
';
 return $self;
}

sub preprocess {
 my $self = shift;
 my $package_name = ref($self);

 #
 # Parse options
 #
 $self->{args} = [];
 my $record_arg   = sub { push(@{$self->{args}}, "$_[0]$_[1]"); };
 my $record_args  = sub { push(@{$self->{args}}, "$_[0]$_[1]");
                          push(@{$self->{args}}, splice(@_, 2)); };
 my ($all_known, $bypass_unknown, $staged, $amend,
     $dry_run, $allow_empty, $include) = (0, 0, 0, 0, 0, 0, 0);
 Getopt::Long::Configure("permute");
 my $result = main::GetOptions(
   "--help|h"                    => sub { $self->help() },
   "all-known|a"                 => \$all_known,
   "bypass-unknown-check|b"      => \$bypass_unknown,
   "staged|dirty|d"              => \$staged,
   "dry-run"                     => sub { $dry_run = 1,
                                          &$record_arg("--", @_) },
   "s"                           => sub { &$record_arg("-", @_) },
   "v"                           => sub { &$record_arg("-", @_) },
   "u"                           => sub { &$record_arg("-", @_) },
   "c=s"                         => sub { &$record_args("-", @_) },
   "C=s"                         => sub { &$record_args("-", @_) },
   "F=s"                         => sub { &$record_args("-", @_) },
   "file=s"                      => sub { &$record_args("--", @_) },
   "m=s"                         => sub { &$record_args("-", @_) },
   "amend"                       => sub { $amend = 1; &$record_arg("--", @_) },
   "allow-empty"                 => sub { $allow_empty = 1;
                                          &$record_arg("--", @_) },
   "interactive"                 => sub { $allow_empty = 1;
                                          &$record_arg("--", @_) },
   "no-verify"                   => sub { &$record_arg("--", @_) },
   "e"                           => sub { &$record_arg("-", @_) },
   "author=s"                    => sub { &$record_args("--", @_) },
   "cleanup=s"                   => sub { &$record_args("--", @_) },
   "include|i=s"                 => sub { $include = 1;
                                          &$record_args("--", @_) },
   );
 my ($opts, $revs, $files) = RepoUtil::parse_args([], @ARGV);

 #
 # Set up flags based on options, do sanity checking of options
 #
 my ($check_no_changes, $check_unknown, $check_mixed, $check_unmerged);
 my $skip_all = $include || $dry_run;
 $self->{'commit_flags'} = [];
 die "Cannot specify both --all-known (-a) and --staged (-d)!\n" if
   $all_known && $staged;
 die "Cannot specify --staged when specifying files!\n" if @$files && $staged;
 $check_no_changes = !$amend && !$allow_empty && !$skip_all;
 $check_unknown   = !$bypass_unknown && !$staged && !@$files && !$skip_all;
 $check_mixed     = !$all_known      && !$staged && !@$files && !$skip_all;
 $check_unmerged  = !$skip_all;
 push(@{$self->{'commit_flags'}}, "-a") if $all_known;

 #
 # Lots of sanity checks
 #
 my $status =
   RepoUtil::commit_push_checks($package_name,
                                {no_changes       => $check_no_changes,
                                 unknown          => $check_unknown,
                                 partially_staged => $check_mixed,
                                 unmerged_changes => $check_unmerged});

 if ($amend && !$all_known && !$staged && !$skip_all && !@$files &&
     $status->{has_unstaged_changes} && !$status->{has_staged_changes}) {
   print STDERR <<EOF;
Aborting: It is not clear whether you want to simply amend the commit
message or whether you want to include your local changes in the amended
commit.  Please pass --staged to just amend the previous commit message, or
pass -a to include your current local changes with the previous amended
commit.
EOF
   exit 1;
 }

 die "No staged changes, but --staged given.\n"
     if (!$status->{has_staged_changes} && $staged && !$amend && !$dry_run);

 if (!$all_known && !$include && !$staged &&
     $status->{has_unstaged_changes} && !$status->{has_staged_changes} &&
     !@$files) {
   push(@{$self->{'commit_flags'}}, "-a");
 }

 #
 # Record the set of unknown files we ignored with -b, so the -b flag isn't
 # needed next time.
 #
 if ($bypass_unknown) {
   RepoUtil::record_ignored_unknowns();
 }

 push(@{$self->{args}}, @{$self->{commit_flags}});
 unshift(@ARGV, @{$self->{args}});
}

###########################################################################
# config                                                                  #
###########################################################################
package config;
@config::ISA = qw(subcommand);
INIT {
 $COMMAND{config} = {
   unmodified_behavior => 1,
   extra => 1,
   section => 'misc',
   about => 'Get or set configuration options'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg config OPTION [ VALUE ]
 eg config --unset OPTION
 eg config [ --list ]

Description:
 Gets or sets configuration options.

 See the 'Configuration File' section of 'git help config' for a fairly
 comprehensive list of special options used by eg (and git).

Examples:
 Get the value of the configuration option user.email
     \$ eg config user.email

 Set the value of the configuration option user.email to whizbang\@flashy.org
     \$ eg config user.email whizbang\@flashy.org

 Unset the values of the configuration options branch.master.remote
 and branch.master.merge
     \$ eg config --unset branch.master.remote
     \$ eg config --unset branch.master.merge

 List all options that have been set
     \$ eg config --list
";
 return $self;
}

###########################################################################
# diff                                                                    #
###########################################################################
package diff;
@diff::ISA = qw(subcommand);
INIT {
 $COMMAND{diff} = {
   section => 'discovery',
   about => 'Show changes to file contents'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg diff [--unstaged | --staged] [REVISION] [REVISION] [FILE...]

Description:
 Shows differences between different versions of the project.  By default,
 it shows the differences between the last locally recorded version and the
 version in the working copy.

Examples:
 Show local unrecorded changes
     \$ eg diff

 In a project with the current branch being 'master', show the differences
 between the version before the last recorded commit and the working copy.
     \$ eg diff master~1
 Or do the same using \"HEAD\" which is a synonym for the current branch:
     \$ eg diff HEAD~1

 Show changes to the file myscript.py between 10 versions before last
 recorded commit and the last recorded commit (assumes the current branch
 is 'master').
     \$ eg diff master~10 master myscript.py

 (Advanced) Show changes between staged (ready-to-be-committed) version of
 files and the working copy (use 'eg stage' to stage files).  In other
 words, show the unstaged changes.
     \$ eg diff --unstaged

 (Advanced) Show changes between last recorded copy and the staged (ready-
 to-be-committed) version of files (use 'eg stage' to stage files).  In
 other words, show the staged changes.
     \$ eg diff --staged

 (Advanced) Show changes between 5 versions before the last recorded
 commit and the currently staged (ready-to-be-committed) version of the
 repository.  (Use 'eg stage' to stage files).
     \$ eg diff --staged HEAD~5

Options:
 REVISION
   A reference to a recorded version of the repository, defaulting to HEAD
   (meaning the most recent commit on the current branch).  See 'eg help
   topic revisions' for more details.

 --staged
   Show changes between the last commit and the staged copy of files.
   Cannot be used when two revisions have been specified.

 --unstaged
   Show changes between the staged copy of files and the current working
   directory.  Cannot be used when a revision is specified.
";
 $self->{'differences'} = '
 Changes to eg diff relative to git diff are:
   (1) Different defaults for what to diff relative to
   (2) Providing a more consistent double-dot operator

 Section 1: Different defaults for what to diff relative to

 The following illustrate the two changed defaults of eg diff:
   eg diff            <=> git diff HEAD
   eg diff --unstaged <=> git diff
 (Which is not 100% accurate due to merges; see below.)  In more detail:

 The "--unstaged" option is unique to eg diff; to get the same behavior
 with git diff you simply list no revisions and omit the "--cached" flag.

 When neither --staged nor --unstaged are specified to eg diff and no
 revisions are given, eg diff will pass along the revision "HEAD" to git
 diff.

 The "--staged" option is an alias for "--cached" unique to eg diff; the
 purpose of the alias is to reduce the number of different names in git
 used to refer to the same concept.  (Update: the --staged flag is now
 part of git with the same meaning as in eg.)

 Merges: The above is slightly modified if the user has an incomplete
 merge; if the user has conflicts during a merge (or uses --no-commit when
 calling merge) and then tries "eg diff", it will abort with a message
 telling the user that there is no "last" commit and will provide
 alternative suggestions.

 Section 2: Providing a more consistent double-dot operator

   The .. operator of git diff (e.g. git diff master..devel) means what
   the ... operator of git log means, and vice-versa.  This causes lots of
   confusion.  We fix this by making the .. operator of eg diff
   do exactly what the ... operator of git diff does.  To see why:

   Meanings of git commands, as a reminder (A and B are revisions):
     git diff A..B  <=> git diff A B                      # Endpoint difference
     git diff A...B <=> git diff $(git merge-base A B) B  # Changes from base

   Why this is confusing (compare to above):
     git log A..B  <=> git log ^$(git merge-base A B) B   # Changes from base
     git log A...B <=> git log A B ^$(git merge-base A B) # Endpoint difference

   So, my translation:
     eg diff A B   <=>  git diff A B    <=> git diff A..B
     eg diff A..B  <=>  git diff A...B
     eg diff A...B <=>  git diff A...B

   Reasons for this change:
     * New users automatically get sane behavior, and use either eg diff A B
       or eg diff A..B, each doing what one would expect.  They do not ever
       realize that A...B is a bit weird because they have no need to try to
       use it; eg diff A B covers their needs.
     * Users worried about switching between eg and git without having to
       modify their command lines can always use either diff A B or
       diff A...B, but never any other form; using this subset ensures that
       both eg and git behave identically.
     * Users only access git diff A..B behavior through eg diff A B, which
       is less typing and makes more sense.
     * Since git diff A..B and git diff A B are the same, the latter is far
       more common, and the former is confusing, odds are that if any git
       user suggests someone use git diff A..B they probably really meant
       git diff A...B
';
 return $self;
}

sub preprocess {
 my $self = shift;

 # Avoid Util::git_rev_parse because it fails on t2010-checkout-ambiguous by
 # treating "--quiet" as a revision rather than an option; use our own
 # parse_args implementation instead.
 my ($opts, $revs, $files) = RepoUtil::parse_args(["--extcmd", "-x"], @ARGV);

 # Replace '..' with '...' in revision specifiers.  Use backslash escaping to
 # get actual dots and not just any character.  Use negative lookbehind and
 # lookahead assertions to avoid replacing '...' with '....'.
 my @new_revs = map(m#(.+)(?<!\.)\.\.(?!\.)(.+)# ? "$1...$2" : $_, @$revs);
 $revs = \@new_revs;

 #
 # Parse options
 #
 $self->{'opts'} = "";
 @ARGV = @$opts;
 my ($staged, $unstaged, $no_index, $ours, $theirs) = (0, 0, 0, 0, 0);
 my $extcmd;
 Getopt::Long::Configure("permute");
 my $result = main::GetOptions(
   "--help"         => sub { $self->help() },
   "staged|cached"  => \$staged,
   "unstaged"       => \$unstaged,
   "no-index"       => \$no_index,
   "extcmd=s"       => \$extcmd,
   "ours"           => \$ours,
   "theirs"         => \$theirs,
   );
 die "Cannot specify both --staged and --unstaged!\n" if $staged && $unstaged;
 my @args;
 push(@args, "--cached") if $staged;
 push(@args, "--no-index") if $no_index;
 push(@args, "--extcmd", $extcmd) if $extcmd;
 push(@args, "--theirs") if $theirs;
 push(@args, "--ours") if $ours;
 push(@args, @ARGV);

 #
 # Parse revs
 #
 die "eg diff: Cannot specify '--staged' with more than 1 revision.\n"
   if ($staged && scalar @$revs > 1);
 die "eg diff: Cannot specify '--unstaged' with any revisions.\n"
   if ($unstaged && scalar @$revs > 0);
 # 'eg diff' (without arguments) should act like 'git diff HEAD', unless
 # we are in an aborted merge state
 if (!@$revs && !$unstaged && !$staged && !$no_index && !$ours && !$theirs) {
   if (-f "$self->{git_dir}/MERGE_HEAD") {
     my @merge_branches = RepoUtil::merge_branches();
     my $list = join(", ", @merge_branches);
     print STDERR <<EOF;
Aborting: Cannot show the changes since the last commit, since you are in the
middle of a merge and there are multiple last commits.  Try passing one of
 --unstaged, $list
to eg diff.

For additional conflict resolution help, try eg log --merge or
 eg show BRANCH:FILE
where FILE is any file in your working copy and BRANCH is one of
 $list
EOF
     exit 1;
   }
   if (RepoUtil::initial_commit()) {
     print STDERR <<EOF;
Aborting: Cannot show the changes since the last commit, since you do not
yet have any commits on the current branch.  Try passing --unstaged to diff,
or making a commit first.
EOF
     exit 1;
   }
   push(@$revs, "HEAD")
 }

 push(@args, @$revs);
 push(@args, "--");
 push(@args, @$files);
 @ARGV = @args;
}

###########################################################################
# difftool                                                                #
###########################################################################
package difftool;
@difftool::ISA = qw(diff);
INIT {
 $COMMAND{difftool} = {
   new_command => 1,
   extra => 1,
   section => 'discovery',
   about => 'Show changes to file contents using an external tool'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);

 $self->{'help'} = "
Usage:
 eg difftool [--tool=<tool>] [--unstaged | --staged] [REVISION] [REVISION] [FILE...]

Description:
 Shows differences between different versions of the project using an
 external tool.  By default, it shows the differences between the last
 locally recorded version and the version in the working copy.

 This command behaves just like 'eg diff'; see 'eg help diff' for more
 details.

 You can configure the default external tool with 'eg config'.  You can
 specify the default tool by setting 'diff.tool'; you can configure the
 tool by setting 'difftool.<tool>.cmd'.  See the 'Configuration File'
 section of 'git help config' for more details.

Example:
 Show local unrecorded changes in vimdiff
     \$ eg difftool --tool=vimdiff

 See 'eg help diff' for more diff examples.

";
 $self->{'differences'} = "
 git difftool behaves just like git diff, but launches an external tool
 instead of using git's built-in machinery.  eg diff is quite different from
 git diff (see 'eg help diff' for details); eg difftool behaves just like
 eg diff.
";
 return $self;
}



###########################################################################
# gc                                                                      #
###########################################################################
package gc;
@gc::ISA = qw(subcommand);
INIT {
 $COMMAND{gc} = {
   unmodified_behavior => 1,
   extra => 1,
   section => 'timesavers',
   about => 'Optimize the local repository to make later operations faster',
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg gc

Description:
 Optimizes the local repository; in particular, this command compresses
 file revisions to reduce disk space and increase performance.

 This command is occasionally called during normal git usage, making
 explicit usage of this command unnecessary for many users.  However, the
 automatic calls of this command only do simple and quick optimizations,
 so some users (particularly those with many revisions) may benefit from
 manually invoking this command periodically (such as from nightly or
 weekly cron scripts).
";
 return $self;
}

###########################################################################
# help                                                                    #
###########################################################################
package help;
@help::ISA = qw(subcommand);
INIT {
 $COMMAND{help} = {
   section => 'misc',
   about => 'Get command syntax and examples'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(exit_status => 0,
                               git_equivalent => '',
                               git_repo_needed => 0,
                               @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg help --all
 eg help [COMMAND]
 eg help topic [TOPIC]

Description:
 Shows general help for eg, for one of its subcommands, or for a
 specialized topic.

Examples:
 Show help for eg
     \$ eg help

 Show help for extended list of commands available in eg
     \$ eg help --all

 Show help for the switch command of eg
     \$ eg help switch

 Show which topics have available help
     \$ eg help topic

 Show the help for the staging topic
     \$ eg help topic staging
";
 $self->{'differences'} = "
 eg help uses its own help system, ignoring the one from git help...except
 that eg help will call git help if asked for help on a subcommand it does
 not recognize.

 'git help COMMAND', by default, simply calls 'man git-COMMAND'.  The git
 man pages are really nice for people who are experts with git; they are
 comprehensive and detailed.  However, new users tend to get lost in a sea
 of details and advanced topics (among other problems).  'eg help COMMAND'
 provides much simpler pages of its own and refers to the manpages for
 more details.  The eg help pages also list any differences between the eg
 commands and the git ones, to assist interested users in learning git.

 If you simply want a brief list of available options and descriptions,
 you may also want to try running 'git COMMAND -h' (which differs from
 the two identical commands 'git COMMAND --help' and 'git help COMMAND').
";

 return $self;
}

sub preprocess {
 my $self = shift;

 $self->{all} = 0;
 my $result=main::GetOptions("--help" => sub { $self->help() },
                             "--all"  => \$self->{all});
}

sub run {
 my $self = shift;

 if ($DEBUG == 2) {
   print "    >>(No commands to run, just data to print)<<\n";
   return;
 }

 # Check if we were asked to get help on a subtopic rather than toplevel help
 if (@ARGV > 0) {
   my $orig_subcommand = shift @ARGV;
   my $subcommand = $orig_subcommand;
   $subcommand =~ s/-/_/;  # Packages use underscores, commands use dashes
   if (@ARGV != 0 && ($subcommand ne 'topic' || @ARGV != 1)) {
     die "Too many arguments to help.\n";
   }
   die "Oops, there's a bug.\n" if $self->{exit_status} != 0;
   $subcommand = "help::topic" if $subcommand eq 'topic';

   if (!$subcommand->can("new")) {
     print "$orig_subcommand is not modified by eg (eg $orig_subcommand is" .
           " equivalent to git $orig_subcommand).\nWill try running 'git" .
           " help $orig_subcommand' in 2 seconds...\n";
     sleep 2;
     exit ExecUtil::execute("$GIT_CMD help $orig_subcommand");
   }

   my $subcommand_obj = $subcommand->new(initial_commit_error_msg => '',
                                         git_repo_needed => 0);
   $subcommand_obj->help();
 }

 # Set up a pager, if wanted
 $ENV{"LESS"} = "FRSX" unless defined $ENV{"LESS"};
 my $less = ($USE_PAGER == 1) ? "less" :
            ($USE_PAGER == 0) ? "cat" :
            `$GIT_CMD config core.pager` || "less";
 chomp($less);
 open(OUTPUT, "| $less");

 # Help users know about the --all switch
 if (!$self->{all}) {
   print OUTPUT "(Run 'eg help --all' for a more detailed list.)\n\n";
 }

 # Print valid subcommands sorted by section
 foreach my $name (sort
                   {$SECTION->{$a}{'order'} <=> $SECTION->{$b}{'order'}}
                   keys %$SECTION) {
   next if $SECTION->{$name}{extra} && !$self->{all};
   print OUTPUT "$SECTION->{$name}{desc}\n";
   foreach my $c (sort keys %COMMAND) {
     next if !defined $COMMAND{$c}{section};
     next if $COMMAND{$c}{section} ne $name;
     next if $COMMAND{$c}{extra} && !$self->{all};
     printf OUTPUT "  eg %-11s %s\n", $c, $COMMAND{$c}{about};
   }
   print OUTPUT "\n";
 }

 # Check to see if someone added a command with an invalid section
 my $broken_commands = "";
 foreach my $c (keys %COMMAND) {
   next if !defined $COMMAND{$c}{section};
   next if defined $SECTION->{$COMMAND{$c}{section}};
   my $tmp = sprintf("  eg %-10s %s\n", $c, $COMMAND{$c}{about});
   $broken_commands .= $tmp;
 }
 if ($broken_commands) {
   print OUTPUT "Broken (typo in classification?) commands:\n" .
                "$broken_commands\n";
 }

 # And let them know how to get more detailed help...
 print OUTPUT "Additional help:\n";
 print OUTPUT "  eg help COMMAND      Get more help on COMMAND.\n";
 print OUTPUT "  eg help --all        List more commands (not really all)\n";
 print OUTPUT "  eg help topic        List specialized help topics.\n";

 # And let them know how to compare to git
 if ($self->{all}) {
   print OUTPUT "\n";
   print OUTPUT "Learning or comparing to git\n";
   print OUTPUT "  eg --translate ARGS  Show commands that would be executed for 'eg ARGS'\n";
   print OUTPUT "  eg --debug ARGS      Show & run commands that would be executed by 'eg ARGS'\n";
 }

 close(OUTPUT);

 exit $self->{exit_status};
}

###########################################################################
# help::topic                                                             #
###########################################################################
package help::topic;

sub new {
 my $class = shift;
 my $self = {};
 bless($self, $class);
 return $self;
}

sub middle_of_am {
 my $continue_text = "
1. Standard case

When all conflicts have been resolved, run
 eg am --resolved
Do NOT run \"eg commit\" to continue an interrupted rebase (unless you want
to manually insert a new commit; if you already accidentally ran eg commit,
then run 'eg reset HEAD~1' to undo it).  If you try to continue without
resolving all conflicts, the command will error out and tell you that some
conflicts remain to be resolved.

2. Special case -- skipping a commit

If you do not want this particular commit to be included in the final
result, run
 eg am --skip";
 my $abort_text = "
To abort your rebase operation, simply run
 eg am --abort";

 return _conflict_resolution_message(op => "am",
                                     show_empty_case => 1,
                                     continue_text => $continue_text,
                                     abort_text => $abort_text
                                     );
}

sub middle_of_merge {
 my $completion_text = "
When all conflicts have been resolved, run
 eg commit

The log message will be pre-populated with a sample commit message for you,
noting the merge and any file conflicts.  If you try to run this command
without resolving all conflicts, the command will error out and tell you
that some conflicts remain to be resolved.";
 my $abort_text = "
To abort your merge operation, simply run
 eg merge --abort";
 return _conflict_resolution_message(op => "merge",
                                     show_empty_case => 0,
                                     continue_text => $completion_text,
                                     abort_text => $abort_text);
}

sub middle_of_rebase {
 my $extra_stop_info = "

If you are in the middle of an interactive rebase (i.e. you specified the
--interactive flag), then rebase can also stop if you selected to edit a
commit, even when there are no conflicts.  In such a case where there are
no conflicts, there is something else you may want to do:
 5) Editing during an interactive rebase
Before telling git to continue the operation.";
 my $continue_text = "
1. Standard case

When all conflicts have been resolved, run
 eg rebase --continue
Do NOT run \"eg commit\" to continue an interrupted rebase (unless you want
to manually insert a new commit; if you already accidentally ran eg commit,
then run 'eg reset HEAD~1' to undo it).  If you try to continue without
resolving all conflicts, the command will error out and tell you that some
conflicts remain to be resolved.

2. Special case -- skipping a commit

If you do not want this particular commit to be included in the final
result, run
 eg rebase --skip";
 my $abort_text = "
To abort your rebase operation, simply run
 eg rebase --abort";
 my $interactive_edit_text = "
******************* Editing during an interactive rebase *******************

When an interactive rebase stops to allow you to edit a commit, make any
necessary changes to files, then run
 eg commit --amend
If you do not use the --amend flag, you will be inserting a new commit
after the one you chose to edit.

After you are done amending the previous commit (and/or commit message),
run 'eg rebase --continue' to allow the rebase operation to continue.
";
 return _conflict_resolution_message(op => "rebase",
                                     show_empty_case => 1,
                                     extra_stop_info => $extra_stop_info,
                                     continue_text => $continue_text,
                                     abort_text => $abort_text,
                                     final_text => $interactive_edit_text,
                                     );
}

sub _conflict_resolution_message (%) {
 my $opts = {op              => "!!!FIXME!!!",
             show_empty_case => 0,
             extra_stop_info => '',
             continue_text   => '!!!FIXME!!!',
             abort_text      => '!!!FIXME!!!',
             final_text      => '',
             @_};  # Hashref initialized as we're told
 my $result = "
When conflicting changes are detected, a $opts->{op} operation will stop to
allow a user to resolve the conflicts.  At this stage there is one of four
things a user may want to do:
 1) Find out more about what conflicts occurred
 2) Resolve the conflicts
 3) Tell git to complete the operation
 4) Abort the operation
Each will be discussed below.$opts->{extra_stop_info}

*************** Find out more about what conflicts occurred ***************

1. Standard case

In order to find out which files have conflicts, run
 eg status
and then look for lines that begin with \"unmerged:\".  You can then open
the relevant file in an editor and look for lines with conflict markers,
i.e. lines that start with one of
 <<<<<<<
 =======
 >>>>>>>
Between the <'s and the ='s will be one version of the changed file, while
betwen the ='s and the >'s will be another version.

2. Simple tip

Since git will stage any changes it is able to successfully merge, you can
find the unresolved conflict sections of a file by running
 eg diff --unstaged FILE
";
 if ($opts->{show_empty_case}) {
 $result .= "
3. Special empty commit case

Sometimes, during a $opts->{op}, the changes in a commit will no longer be
necessary since they have already been included in the code which your
commit is being applied on top of.  In such a case, eg status will simply
show that there are no changes at all, and you can continue by telling git
to skip the current unneeded commit (see below).

4. Difficult cases
"
 } else {
 $result .= "
3. Difficult cases
";
 }
 $result .= "
You can run
 eg ls-files --unmerged
to get a list of all files in the unmerged state.  This will list up to
three lines for each file, and look like the following:
 100644 45b983be36b73c0788dc9cbcb76cbb80fc7bb057 1     foo.C
 100644 ce013625030ba8dba906f756967f9e9ca394464a 2     foo.C
 100644 dd7e1c6f0fefe118f0b63d9f10908c460aa317a6 3     foo.C
The first line corresponds to a version of the file at some common point in
history, the second and third lines correspond to different versions of the
file being merged (relative to the common version).  Each line is of the
form
 mode   internal-object-name                     stage filename
The mode represents the permission bits and or type (executable file,
symlink etc.), the internal-object-name is git's internal name for the
contents of the file, the stage is a simple integer, and you should
recognize the filename.

You can make use of this information to detect the following situations:
 A) There's a conflict in mode change (e.g. removed the executable bit on
    one side of history, turned the file into a symlink in another)
 B) The file is deleted in one version and modified in another (when this
    happens either the 2nd or 3rd stage line will be missing)
Further, you can view the different versions of the file easily, by using
either of:
 eg show :STAGE:FILENAME
 eg show INTERNAL-OBJECT-NAME
Some examples using the output above:
 eg show :2:foo.C
 eg show dd7e1c6f0fefe118f0b63d9f10908c460aa317a6

************************** Resolve the conflicts **************************

1. Standard case.

For each file with conflicts, edit the file to remove the conflict markers
and provide just the correct version of the merged file.  Then run
 eg stage FILE
to tell git that you have resolved the conflicts in FILE.

2. Special cases

Nearly all special cases (and even the standard case) boil down to making
sure the file has the correct contents, the correct permission bits and
type, and then running
 eg stage FILE

If the file is a binary, then there will not be any conflict markers.  In
such a case, simply ensure that the contents of the file are what you want
and then run eg stage, as noted above.

If the file is deleted on one side of history and changed in another,
decide what contents the file should have.  If the correct resolution is to
delete the file, run
 eg rm FILE
Otherwise, put the appropriate contents in the file and run eg stage as
noted above.

If the file has a mode conflict, then fix up the mode of the file (run
'man chmod' and 'man ln' for help on how to do so).  Note that the modes
used by git are as follows:
 100644  --  Normal, non-executable file
 100755  --  File with the executable bit set
 120000  --  symlink
 160000  --  A git submodule (run 'git help submodule' for more info)

******************** Tell git to continue the operation ********************
$opts->{continue_text}

*************************** Abort the operation ***************************
$opts->{abort_text}
";
 $result .= $opts->{final_text};
 return $result;
}

sub middle_of_bisect {
 return "
When git is bisecting, it will pick commits that need to be tested, check
them out, and then let you test them.  (Unless, of course, you give git a
script that it can run to automatically test commits.)  At this point you
can test and then:

1) Continue

 eg bisect good    # Mark the current commit as good, give me a new commit
OR
 eg bisect bad     # Mark the current commit as bad, give me a new commit

2) Skip this particular commit

 eg bisect skip    # Can't test the current version; give me a new commit

3) Abort

 eg bisect reset

See 'git help bisect' for more details."
}

sub refspecs {
 return "
Before reading up on refspecs, be sure you understand all the following
help pages:
 eg help merge
 eg help pull
 eg help push
 eg help rebase
 eg help remote
 eg help topic storage
refspecs compress knowledge from pieces of all those things into a short
amount of space.

refspecs are command line parameters to eg push or eg pull, used at the end
of the command line.  refspecs provide fine-grained control of pushing and
pulling changes in the following two areas:
 Since branches, tags, and remote tracking branches are all implemented by
 creating simple files consisting solely of a sha1sum, it is possible to
 push to or pull from different reference names and different reference
 types.

 Pushing and pulling of (possibly remote tracking) branches are typically
 accompanied by sanity checks to make sure the sha1sums on each end are
 related (to make sure that updates don't throw away previous commits, for
 example).  In some cases it is desirable to ignore such checks, such as
 when a branch has been rebased or commits have been amended.

The canonical format of a refspec is
 [+]SRC:DEST
That is, an optional plus character followed by a source reference, then a
colon character, then the destination reference.  There are a couple
special abbreviations, noted in the abbreviations section below.  The
meaning and syntax of the parts of a refspec are discussed next.

General source and destination handling
 Both the source and the destination reference are typically named by
 their path specification under the .git directory.  Examples:
   refs/heads/bob            # branch: bob
   refs/tags/v2.0            # tag: v2.0
   refs/remotes/jill/stable  # remote-tracking branch: jill/stable
 Leading directory paths can be omitted if no ambiguity would result.

 The refspec specifies that the push or pull operation should take the
 sha1sum from SRC in the source repository, and use it to fast-foward DEST
 in the destination repository.  The operation will fail if updating DEST
 would not be a fast-foward, unless the optional plus in the refspec is
 present.

 Pull operations are somewhat unusual.  For a pull, DEST is usually not
 the current branch.  In such cases, the current branch is also updated
 after DEST is.  The method of updating depends on whether --rebase was
 specified, and whether the latest revision of the current branch is an
 ancestor of the revision stored by DEST:
   If --rebase is specified:
     Rebase the current branch against DEST
   If --rebase is not specified, current branch is an ancestor of DEST:
     Fast-forward the current branch to DEST
   If --rebase is not specified, current branch is not an ancestor of DEST:
     Merge DEST into the current branch

Overriding push and pull sanity checks
 For both push and pull operations, the operation will fail if updating
 DEST to SRC is not a fast-forward.  This tends to happen in a few
 different circumstances:
   For pushes:
     * If someone else has pushed updates to the specified location
       already -- in such cases one should resolve the problem by doing a
       pull before attempting a push rather than overriding the safety
       check.
     * If one has rewritten history (e.g. using rebase, commit --amend,
       reset followed by subsequent commits)
   For pulls:
     * If one is pulling to a branch instead of a remote tracking branch
       -- in such a case, one should instead either specify a remote
       tracking branch for DEST or specify an empty DEST rather than
       overriding the safety check.
     * If one has somehow recorded commits directly to a remote tracking
       branch
     * If history has been rewritten on the remote end (e.g. by using
       rebase, commit --amend, reset followed by subsequent commits).
 In all such cases, users can choose to throw away any existing unique
 commits at the DEST end and make DEST record the same sha1sum as SRC, by
 using a plus character at the beginning of the refspec.

Abbreviations of refspecs
 Globbing syntax
   For either pushes or pulls, one can use a globbing syntax, such as
     refs/heads/*:refs/remotes/jim/*
   or
     refs/heads/*:refs/heads/*
   in order to specify pulling or pushing multiple locations at once.

 The following special abbreviations are allowed for both pushes and pulls:
   tag TAG
     This is equivalent to specifying refs/tags/TAG:refs/tags/TAG.

 The following special abbreviations are allowed for pushes:
   :REFERENCE
     This specifies delete the reference at the remote end (think of it as
     \"using nothing to update the remote reference\")

   REFERENCE
     This is the same as REFERENCE:REFERENCE

 The following special abbreviations are allowed for pulls:
   REFERENCE:
     This is used to merge REFERENCE into the current branch directly
     without storing the remote branch in some remote tracking branch.

   REFERENCE
     This is the same as REFERENCE: which is explained above.
";
}


sub remote_urls {
#
# NOTE: The help for remote_urls is basically lifted from the git manpages,
# which are licensed under GPLv2 (as is eg).
#
 return "
Any of the following notations can be used to name a remote repository:
 rsync://host.xz/path/to/repo.git/
 http://host.xz/path/to/repo.git/
 https://host.xz/path/to/repo.git/
 git://host.xz/path/to/repo.git/
 git://host.xz/~user/path/to/repo.git/
 ssh://[user@]host.xz[:port]/path/to/repo.git/
 ssh://[user@]host.xz/path/to/repo.git/
 ssh://[user@]host.xz/~user/path/to/repo.git/
 ssh://[user@]host.xz/~/path/to/repo.git
You can also use any of the following, which are identical to the last
three above, respectively
 [user@]host.xz:/path/to/repo.git/
 [user@]host.xz:~user/path/to/repo.git/
 [user@]host.xz:path/to/repo.git
Finally, you can also use the following notation to name a not-so-remote
repository:
 /path/to/repo.git/
 file:///path/to/repo.git/
These last two are identical other than that the latter disables some local
optimizations (such as hardlinking copies of history when cloning, in order
to save disk space).
";
}

sub revisions {
#
# NOTE: The pictoral example of revision suffixes is taken from the
# git-rev-parse manpage, which is licensed under GPLv2 (as is eg).
#
 return "
There are MANY different ways to refer to revisions (also referred to as
commits) of the repository.  Most are only needed for fine-grained control
in very large projects; the basics should be sufficient for most.

Basics
 The most common ways of referring to revisions (or commits), are:
   - Branch or tag name (e.g. stable, v0.77, master, 2.28branch, version-1-0)
   - Counting back from another revision (e.g. stable~1, stable~2, stable~3)
   - Cryptographic checksum (e.g. dae86e1950b1277e545cee180551750029cfe735)
   - Abbreviated checksum (e.g. dae86e)

 The output of 'eg log' shows (up to) two names for each revision: its
 cryptographic checksum and the count backward relative to the currently
 active branch (if the revision being shown in eg log is not part of the
 currently active branch then only the cryptographic checksum is shown).

 One can always check the validity of a revision name and what revision
 it refers to using 'eg log -1 REVISION' (the -1 to show only one revision).

Branches and Tags
 Users can specify a tag name to refer to the revision marked by that tag.
 Run 'eg tag' to get a list of existing tags.

 Users can specify a branch name to refer to the most recent revision of
 that branch.  Use 'eg branch' to get a list of existing branches.

Cryptographic checksums
 Each revision of a repository has an associated cryptographic checksum
 (in particular, a sha1sum) identifying it.  This cryptographic checksum
 is a sequence of 40 letters and numbers from 0-9 and a-f.  For example,
   dae86e1950b1277e545cee180551750029cfe735
 In addition to using these sha1sums to refer to revisions, one can also
 use an abbreviation of a sha1sum so long as enough characters are used to
 uniquely identify the revision (typically 6-8 characters are enough).

Special Names
 There are a few special revision names.

 Names that always exist:
   HEAD - A reference to the most recent revision of the current branch
          (thus HEAD refers to the same revision as using the branch
          name).  If there is no active branch, such as after running
          'eg switch TAG', then HEAD refers to the revision switched to.

          Note that the files in the working copy are always considered to
          be a (possibly modifed) copy of the revision pointed to by HEAD.

 Names that only exist in special cases:
   ORIG_HEAD -  Some operations (such as merge or reset) change which
                revision the working copy is relative to.  These will
                record the old value of HEAD in ORIG_HEAD.  This allows
                one to undo such operations by running
                  eg reset --working-copy ORIG_HEAD
   FETCH_HEAD - When downloading branches from other repositories (via
                the fetch or pull commands), the tip of the last fetched
                branch is stored in FETCH_HEAD.
   MERGE_HEAD - If a merge operation results in conflicts, then the merge
                will stop and wait for you to manually fix the conflicts.
                In such a case, MERGE_HEAD will store the tip of the
                branch(es) being merged into the current branch.  (The
                current branch can be accessed, as always, through HEAD.)

Suffixes for counting backwards
 There are two suffixes for counting backwards from revisions to other
 revisions: ~ and ^.

 Adding ~N after a revision, with N a non-negative integer, means to count
 backwards N commits before the specified revision.  If any revision along
 the path has more than one parent (i.e. if any revision is a merge
 commit), then the first parent is always followed.  Thus, if stable is a
 branch, then
   stable   means the last revision on the stable branch
   stable~1 means one revision before the last on the stable branch
   stable~2 means two revisions before the last on the stable branch
   stable~3 means three revisions before the last on the stable branch
 In short, ~N goes back N generation of parents, always following the
 first parent.

 Adding ^N after a revision, with N a non-negative integer, means the Nth
 parent of the specified revision.  N can be omitted in which case it is
 assumed to have the value 1.  Thus, if stable is a branch, then
   stable   means the last revision on the stable branch
   stable^1 means the first parent of the last revision on the stable branch
   stable^2 means the second parent of the last revision on the stable branch
   stable^3 means the third parent of the last revision on the stable branch
 In short, ^N picks out one parent from the first generation of parents.

 Revisions with suffixes can themselves have suffixes, thus
   stable~5 = stable~3~2

 Here is an illustration with an unusually high amount of merging.  The
 illustration has 10 revisions each tagged with a different letter of the
 alphabet, with A referring to the most recent revision:
               A
              / \\
             /   \\
            B     C
           /|\\    |
          / | \\   |
         /  |  \\ /
        D   E   F
       / \\     / \\
      G   H   I   J

 From the illustration, the following equalities hold:
      A =      = A^0
      B = A^   = A^1     = A~1
      C = A^2  = A^2
      D = A^^  = A^1^1   = A~2
      E = B^2  = A^^2
      F = B^3  = A^^3
      G = A^^^ = A^1^1^1 = A~3
      H = D^2  = B^^2    = A^^^2  = A~2^2
      I = F^   = B^3^    = A^^3^
      J = F^2  = B^3^2   = A^^3^2

Revisions from logged branch tip history
 By default, all changes to each branch and to the special identifier HEAD
 are recorded in something called a reflog (short for \"reference log\",
 because calling it a \"branch log\" would not have made the glossary of
 special terms long enough).  Each entry of the reflog records the
 previous revision recorded by the branch, the new revision the branch was
 changed to, the command used to make the change (commit, merge, reset,
 pull, checkout, etc.), and when the change was made.  One can get an
 overview of the changes made to a branch (including the special branch
 'HEAD') by running
   eg reflog show BRANCHNAME

 One can make use of the reflog to refer to revisions that a branch used
 to point to.  The format for referring to revisions from the reflog are
   BRANCH\@{HISTORY_REFERENCE}
 Examples follow.

 Revisions that the branch pointed to, in order
   Assuming that ultra-bling is the name of a branch, the following can be
   used to refer to revisions ultra-bling used to point to:
     ultra-bling\@{0} is the same as ultra-bling
     ultra-bling\@{1} is the revision pointed to before the last change
     ultra-bling\@{2} is the revision ultra-bling pointed to two changes ago
     ultra-bling\@{3} is the revision ultra-bling pointed to three changes ago
   Note that any of these beyond the first could easily refer to commits
   that are no longer part of the ultra-bling branch (due to using a
   command like reset or commit --amend).

 Revisions that the branch pointed to at a previous time
   Assuing that fixes is the name of a branch, the following can be used to
   refer to revisions that fixes used to point to:
     fixes\@{yesterday}           - revision fixes pointed to yesterday
     fixes\@{1 day 3 hours ago}   - revision fixes pointed to 1 day 3 hours ago
     fixes\@{2008-02-29 12:34:00} - revision fixes had at 12:34 on Feb 29, 2008
   Again, these could refer to revisions that are no longer part of the
   fixes branch,

 Using the branch log can be used to recover \"lost\" revisions that are
 no longer part of (or have never been part of) any branch reported by 'eg
 branch'.

Commit messages
 One can also refer a revision using the beginning of the commit message
 recorded in it.  This is done using with the two-character prefix :/
 followed by the beginning of the commit message.  Note that quotation marks
 are also often used to avoid having the shell split the commit message into
 different arguments.  Examples:
   :/\"Fix the biggest bug blocking the 1.0 release\"
   :/\"Make the translation from url\"
   :/\"Add a README file\"
 Note that if the commit message starts with an exclamation mark ('!'), then
 you need to type two of them; for example example:
   :/\"!!Commit messages starting with an exclamation mark are retarded\"

Other methods
 There are even more methods of referring to revisions.  Run \"man
 git-rev-parse\", and look for the \"SPECIFYING REVISIONS\" section for
 more details.
";
}

sub staging {
 return "
Marking changes from certain files as ready for commit allows you to split
your changes into two distinct sets (those that are ready for commit, and
those that aren't).  This includes support for limiting diffs to changes in
one of these two sets, and for committing just the changes that are ready.
It's a simple feature that comes in surprisingly handy:

 * When doing conflict resolution from large merges, hunks of changes can
   be categorized into known-to-be-good and still-needs-more-fixing
   subsets.

 * When reviewing a largish patch from someone else, hunks of changes can
   be categorized into known-to-be-good and still-needs-review subsets.

 * By staging your changes, you can go ahead and add temporary debugging
   code and have less fear of forgetting to remove it before committing --
   you will be warned about having both staged and unstaged changes at
   commit time, and you will have an easy way to locate the temporary
   code.

 * It makes it easier to keep \"dirty\" changes in your working copy for a
   long time without committing them.

Staging changes and working with staged changes
 Mark all changes in foo.py and baz.c as ready to be committed
   eg stage foo.py baz.c

 Selectively stage part of the changes
   eg stage -p
 (You will be asked whether to stage each change, listed in diff format;
 the main options to know are \"y\" for yes, \"n\" for no, and \"s\" for
 splitting the selected change into smaller changes; see 'git help add' for
 more details).

 Get all unstaged changes to bar.C and foo.pl
   eg diff --unstaged foo.pl bar.C

 Get all staged changes
   eg diff --staged

 Get all changes
   eg diff

 Revert the staged changes to bar.C, foo.pl and foo.py
   eg unstage bar.C foo.pl foo.py

 Commit just the staged changes
   eg commit --staged
";
}

sub storage {
 return "
Basics
 Each revision is referred to by a cryptographic checksum (in particular,
 a sha1sum) of its contents.  Each revision also knows which revision(s)
 it was derived from, known as the revision's parent(s).

 Each branch records the cryptographic checksum of the most recent commit
 for the branch.  Since each commit records its parent(s), a branch
 consists of its most recent commit plus all ancestors of that commit.
 When a new commit is made on a branch, the branch just replaces the
 cryptographic checksum of the old commit with the new one.

 Remote tracking branches, if used (see 'eg help remote'), differ from
 normal branches only in that they have a slash in their name.  For
 example, the remote tracking branch that tracks the contents of the
 stable branch of the remote named bob would be called bob/stable.  By
 their nature, remote tracking branches only track the contents of a
 branch of a remote repository; one does not switch to and commit to these
 branches.

 Tags simply record a single revision, much like branches, but tags are
 not advanced when additional commits are made.  Tags are not stored as
 part of a branch, though by default tags that point to commits which are
 downloaded (as part of merging changes from a branch) are themselves
 downloaded as well.

 Neither branches nor tags are revision controlled, though there is a log
 of changes made to each branch (known as a reflog, short for \"reference
 log\", because calling it a \"branch log\" wouldn't make the glossary of
 special terms long enough).

Pictorial explanation
 Using the letters A-P as shorthand for different revisions and their
 cryptographic checksums (which we'll assume were created in the order
 A...P for purposes of illustration), an example of the kind of structure
 built up by having commits track their parents is:
       N
       |
       M   P
       |   |
       L   O
       | \\ |
       J   K
       |   |
       H   I
       | /
       G
       |
       F
      / \\
     C   E
     |   |
     B   D
     |
     A
 In this picture, F has two parents (C and E) and is thus a merge commit.
 L is also a merge commit, having parents J and K.  There are two branches
 depicted here, which can be identified by N and P (due to the fact that
 branches simply track their most recent commit).  This history is
 somewhat unusual in that there is no unique start of history; instead
 there are two beginnings of history -- A and D.  Such a history can be
 created by pulling from, and merging with, a branch from another
 repository that shares no common history.  While unusual, it is fully
 supported.

 For further illustration, let's assume that the following branches exist:
     stable: N
     bling:  P
 Then the picture of each branch, side by side (using revision identifiers
 explained in 'eg help topic revisions'), is:
           stable
             |
          stable~1                                     bling
             |                                           |
          stable~2                                    bling~1
             |   \\                                       |
       stable~3  stable~2^2                           bling~2
             |     |                                     |
       stable~4  stable~2^2~1                         bling~3
             |  /                                     /
         stable~6                                bling~4
             |                                     |
         stable~7                                bling~5
           /   \\                                 /   \\
     stable~8  stable~7^2                   bling~6  bling~5^2
         |       |                             |       |
     stable~9  stable~7^2~1                 bling~7  bling~5^2~1
         |                                     |
     stable~10                              bling~8
 Note that there are many commits which are part of both branches,
 including two commits (I and K in the original picture) which were
 probably created after these two branches separated.  This is simply due
 to recording both parents in merge commits.

 Note that this tree-like or graph-like structure of branches is an
 example of something that computer scientists call a Directed Acyclic
 Graph (DAG); referring to it as such provides us the opportunity to
 make the glossary of special terminology longer.

Files and directories in a git repository (stuff under .git)
 You may find the following files and directories in your git repository.
 This document will discuss the highlights; see the repository-layout.html
 page distributed with git for more details.

 COMMIT_EDITMSG
   A leftover file from previous commits; this is the file that commit
   messages are recorded to when when you do not specify a -m or -F option
   to commit (thus causing an editor to be invoked).

 config
   A simple text file recording configuration options; see 'eg help config'.

 description
   A file that is only used by gitweb, currently.  If you use gitweb, this
   files provides a description of the project tracked in the repository.

 HEAD
 ORIG_HEAD
 FETCH_HEAD
 MERGE_HEAD
   See the Special Names section of 'eg help topic revisions'; these files
   record these special revisions.

 git-daemon-export-ok
   This file is only relevant if you are using git-daemon, a server to
   provide access to your repositories via the git:// protocol.
   git-daemon refuses to provide access to any repository that does not
   have a git-daemon-export-ok file.

 hooks
   A directory containing customizations scripts used by various commands.
   These scripts are only used if they are executable.

 index
   A binary file which records the staging area.  See 'eg help topic
   staging' for more information.

 info
   A directory with additional info about the repository

   info/exclude
     An additional place to specify ignored files.  Users typically use
     .gitignore files in the relevant directories to ignore files, but
     ignored files can also be listed here.

   info/ignored-unknown
     A list of unknown files known to exist previously, used to determine
     whether unknown files should cause commit (or push or publish) to
     abort.  See 'eg help commit' for more information; this list is
     updated whenever the -b flag is passed to commit.

   info/refs
     This is a file created by 'eg update-server-info' and is needed for
     repositories accessed over http.

 logs
   History of changes to references (i.e. to branches, tags, or
   remote-tracking branches).  The file logs/PATH/TO/FILE in the
   repository records the changes to the reference PATH/TO/FILE in the
   repository.  See also the 'Revisions from logged branch tip history'
   section of 'eg help topic revisions'.

 objects
   Storage of actual user data (files, directory trees, commit objects).
   Storage is done according to sha1sum of each object (splitting sha1sums
   into a combination of directory name and file name).  There are also
   packs, which compress many objects into one file for tighter storage
   and reduced disk usage.

 packed-refs
   The combination of paths, filenames, and sha1sums from many different
   refs -- one per line; see refs below.

 refs
   Storage of references (branches, heads, or remote tracking branches).
   Each reference is a simple file consisting of a sha1sum (see 'eg help
   topic storage' for more information).  The path provides the type of
   the reference, the file name provides the name for the reference, and
   the sha1sum is the revision the reference refers to.

   Branches are stored under refs/heads/*, tags under refs/tags/*, and
   remote tracking branches under refs/remotes/REMOTENAME/*.  Note that
   some of these references may appear in packed-refs instead of having
   a file somewhere under the refs directory.
";
}

sub help {
 my $self = shift;
 my $help_msg;

 # Get the topic we want more info on (replace dashes, since they can't
 # be in function names)
 my $topic = shift @ARGV;
 my $orig_topic = $topic;
 $topic =~ s/-/_/g if $topic;

 ### FIXME: Add the following topics, plus maybe some others
 # glossary      <Not yet written; this is just a stub>

 my $topics = "
middle-of-am      How to resolve or abort an incomplete am (apply mail)
middle-of-bisect  How to continue or abort a bisection
middle-of-merge   How to resolve or abort an incomplete merge
middle-of-rebase  How to resolve or abort an incomplete rebase

refspecs      Advanced pushing and pulling: detailed control of storage
remote-urls   Format for referring to remote (and not-so-remote) repositories
revisions     Various methods for referring to revisions
staging       Marking a subset of the local changes ready for committing
storage       High level overview of how commits, tags, and branches are stored
";

 if (defined $topic) {
   die "No topic help for '$topic' exists.  Try 'eg help topic'.\n"
     if !$self->can($topic);
   $help_msg = $self->$topic();
   if ($topics =~ m#^(\Q$orig_topic\E.*)#m) {
     $topic = $1;
   }
 } else {
   $topic = "Topics";
   $help_msg = $topics;
 }

 $ENV{"LESS"} = "FRSX" unless defined $ENV{"LESS"};
 my $less = ($USE_PAGER == 1) ? "less" :
            ($USE_PAGER == 0) ? "cat" :
            `$GIT_CMD config core.pager` || "less";
 chomp($less);
 open(OUTPUT, "| $less");
 print OUTPUT "$topic\n";
 print OUTPUT $help_msg;
 close(OUTPUT);

 exit 0;
}

###########################################################################
# info                                                                    #
###########################################################################
package info;
@info::ISA = qw(subcommand);
INIT {
 $COMMAND{info} = {
   new_command => 1,
   section => 'discovery',
   extra => 1,
   about => 'Show some basic information about the current repository'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_equivalent => '', git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg info [/PATH/TO/REPOSITORY]

Description:
 Shows information about the specified repository, or the current
 repository if none is specified.

 Most of the output of eg info is self-explanatory, but some fields
 benefit from extra explanation or pointers about where to find related
 information.  These fields are:

   Total commits
     The total number of commits (or revisions) found in the repository.
     eg log can be used to view revision authors, dates, and commit log
     messages.

   Local repository
     eg has a number of files and directories it uses to track your data,
     including (by default) a copy of the entire history of the project.
     These files and directories are all stored below a single directory,
     referred to as the local repository.  See 'eg help topic storage' for
     more details.

   Named remote repositories
     To make it easier to track changes from multiple remote repositories,
     eg provides the ability to provide nicknames for and work with
     multiple branches from a remote repository and even working with
     multiple remote repositories at once.  See 'eg help remote' for more
     details, though you will want to make sure you understand 'eg help
     pull' and 'eg help push' first.

   Current branch
     All development is done on a branch, though smaller projects may only
     use one branch per repository (thus making the repository effectively
     serve as a branch).  In contrast to cvs and svn which refer to
     mainline development as \"HEAD\" and \"TRUNK\", respectively, eg
     calls the mainline development a branch as well, with the default
     name of \"master\").  See 'eg help branch' and 'eg help topic
     storage' for more details.

   Cryptographic checksum
     Each revision has an associated cryptographic checksum of both its
     contents and the revision(s) it was derived from, providing strong
     data consistency checks and guarantees.  These checksums are shown in
     the output of eg log, and serve as a way to refer to revisions.  See
     also 'eg help topic storage' for more details.

   Default pull/push configuration options:
     The default repository to push to or pull from defaults to 'origin',
     if the 'origin' remote has been set up (see 'eg help remote' for
     setting up remote repository nicknames).

     However, the default repository can be set on a per-branch basis as a
     configuration option (see 'eg help config').  In fact, a number of
     default pull/push actions can be set as per-branch configuration
     options: default merge options to use on a given branch, default
     branch to merge with from the remote repository, and whether to
     rebase (rewrite local commits on top of new remote commits; see 'eg
     help rebase') rather than merge (keep local commits as they are and
     just make a merge commit combining local and remote changes; see 'eg
     help merge').

";
 $self->{'differences'} = '
 eg info is unique to eg; git does not have a similar command.  It
 originally was intended just to do something nice if svn converts happen
 to try this command, but I have found it to be a really nice way of
 helping users get their bearings.  It also provides some nice statistics
 that git users may appreciate (particularly when it comes time to fill
 out the Git User Survey).
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my $path = shift @ARGV;
 die "Aborting: Too many arguments to eg info.\n" if @ARGV;

 if ($path) {
   die "$path does not look like a directory.\n" if ! -d $path;
   my ($ret, $useless_output) =
     ExecUtil::execute_captured("$GIT_CMD ls-remote $path", ignore_ret => 1);
   if ($ret != 0) {
     die "$path does not appear to be a git archive " .
         "(maybe it has no commits yet?).\n";
   }
   chdir($path);
 }

 # Set git_dir
 $self->{git_dir} = RepoUtil::git_dir();
 die "Must be run inside a git repository!\n" if !defined $self->{git_dir};
}

sub run {
 my $self=shift;

 my $branch = RepoUtil::current_branch();

 #
 # Special case the situation of no commits being present
 #
 if (RepoUtil::initial_commit()) {
   if ($DEBUG < 2) {
     print STDERR <<EOF;
Total commits: 0
Local repository: $self->{git_dir}
There are no commits in this repository.  Please use eg stage to mark new
files as being ready to commit, and eg commit to commit them.
EOF
   }
   exit 1;
 }

 #
 # Repository-global information
 #

 # total commits
 my $total_commits = ExecUtil::output("$GIT_CMD rev-list --all | wc -l");
 print "Total commits: $total_commits\n" if $DEBUG < 2;

 # local repo
 print "Local repository: $self->{git_dir}\n" if $DEBUG < 2;

 # named remote repos
 my %remotes;
 my $longest = 0;
 my @abbrev_remotes = split('\n', ExecUtil::output("$GIT_CMD remote"));
 foreach my $remote (@abbrev_remotes) {
   chomp($remote);
   my $url = RepoUtil::get_config("remote.$remote.url");
   $remotes{$remote} = $url;
   $longest = main::max($longest, length($remote));
 }
 if (scalar keys %remotes > 0 && $DEBUG < 2) {
   print "Named remote repositories: (name -> location)\n";
   foreach my $remote (sort keys %remotes) {
     printf "  %${longest}s -> %s\n", $remote, $remotes{$remote};
   }
 }

 #
 # Stats for the current branch...
 #
 return if !defined($branch);

 # File & directory stats only work if we're in the toplevel directory
 my ($orig_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();
 chdir($top_dir);

 # Name
 print "Current branch: $branch\n" if $DEBUG < 2;

 # Sha1sum
 my $current_commit = ExecUtil::output("$GIT_CMD show-ref -s -h | head -n 1");
 print "  Cryptographic checksum (sha1sum): $current_commit\n" if $DEBUG < 2;

 # Default pull/push options
 my $default = "-None-";
 my $print_config_options = 0;
 my ($ret, $options) =
   ExecUtil::execute_captured("$GIT_CMD config --get-regexp " .
                              "^branch\.$branch\.*", ignore_ret => 1);
 chomp($options);
 my @lines;
 if ($ret == 0) {
   @lines = split('\n', $options);
   my $line_count = scalar(@lines);
   $print_config_options = ($line_count > 0);

   if ($options =~ /^branch\.$branch\.remote (.*)$/m) {
     $default = $1;
     $print_config_options = ($line_count > 1);
   } else {
     my @output = `$GIT_CMD config --get-regexp remote.origin.*`;
     $default = "origin" if @output;
   }
 }
 print "  Default pull/push repository: $default\n" if $DEBUG < 2;
 if ($print_config_options && $DEBUG < 2) {
   print "  Default pull/push options:\n";
   foreach my $line (@lines) {
     $line =~ s/\s+/ = /;
     print "    $line\n";
   }
 }

 # No. contributors
 my $contributors  = ExecUtil::output("$GIT_CMD shortlog -s -n HEAD | wc -l");
 print "  Number of contributors: $contributors\n" if $DEBUG < 2;

 # No. files
 my $num_files = ExecUtil::output("$GIT_CMD ls-tree -r HEAD | wc -l");
 print "  Number of files: $num_files\n" if $DEBUG < 2;

 # No. dirs
 my $num_dirs = ExecUtil::output(
                   "$GIT_CMD ls-tree -r -t HEAD " .
                   " | grep -E '[0-9]+ tree'" .
                   " | wc -l");
 print "  Number of directories: $num_dirs\n" if $DEBUG < 2;

 # Some ugly, nasty code to get the biggest file.  Seems to be the only
 # method I could find that would work given the corner case filenames
 # (spaces and unicode chars) in the git.git repo (Try eg info on repo
 # from 'git clone git://git.kernel.org/pub/scm/git/git.git').
 my @files = `$GIT_CMD ls-tree -r -l --full-name HEAD`;
 my %biggest = (name => '', size => 0);
 foreach my $line (@files) {
   if ($line =~ m#^[0-9]+ [a-z]+ [0-9a-f]+[ ]*(\d+)[ \t]*(.*)$#) {
     my ($size, $file) = ($1, $2);
     if ($file =~ m#^\".*\"#) { $file = eval "$file" };  # Unicode fix
     if ($size >= $biggest{size}) {
       $biggest{name} = $file;
       $biggest{size} = $size;
     }
   }
 }
 my $biggest_file = "$biggest{size} ($biggest{name})";
 print "  Biggest file size, in bytes: $biggest_file\n" if $DEBUG < 2;

 # No. commits
 my $branch_depth  = ExecUtil::output("$GIT_CMD rev-list HEAD | wc -l");
 print "  Commits: $branch_depth\n" if $DEBUG < 2;

 # Other possibilities:
 #   Disk space used by respository (du -hs .git, or packfile size?)
 #   Disk space used by working copy (???)
 #   Number of unpacked objects?

 chdir($orig_dir);

 # Well, if we got this far, it must have worked, so...
 return 0;
}

###########################################################################
# init                                                                    #
###########################################################################
package init;
@init::ISA = qw(subcommand);
INIT {
 $COMMAND{init} = {
   unmodified_behavior => 1,
   section => 'creation',
   about => 'Create a new repository'
 };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg init [--shared]

Description:
 Creates a new repository.

 If you want to publish a copy of an existing repository so that others
 can access it, use 'eg publish' instead.

 Note for cvs/svn users: With cvs or svn it is common to create an empty
 repository on \"the server\", then check it out locally and start adding
 files and committing.  With eg, it is more natural to create a repository
 on your local machine and start creating and adding files, then later
 (possibly as soon as one commit later) publishing your work to \"the
 server\".  git (and thus eg) does not currently allow cloning empty
 repositories, so for now you must change habits.

Examples:
 Create a new blank repository, then use it by creating and adding a file
 to it:
     \$ mkdir project
     \$ cd project
     \$ eg init
     Create and edit a file called foo.py
     \$ eg stage foo.py
     \$ eg commit

 Create a repository to track further changes to an existing project.  Then
 start using it right away
     \$ cd cool-program
     \$ eg init
     \$ eg stage .           # Recursively adds all files
     \$ eg commit -m \"Initial import of all files\"
     Make more changes to fix a bug or add a new feature or...
     \$ eg commit

 (Advanced) Create a new blank repository meant to be used in a
 centralized fashion, i.e. a repository for many users to commit to.
     \$ mkdir new-project
     \$ cd new-project
     \$ eg init --shared
     Check repository ownership and user groups to ensure they are right

Options:
 --shared
   Set up a repository that will shared amongst several users; note that
   you are responsible for creating a common group for developers so that
   they can all write to the repository.  Ask your sysadmin or see the
   groupadd(8), usermod(8), chgrp(1), and chmod(1) manpages.
";
 return $self;
}

###########################################################################
# log                                                                     #
###########################################################################
package log;
@log::ISA = qw(subcommand);
INIT {
 $COMMAND{log} = {
   section => 'discovery',
   about => 'Show history of recorded changes'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg log

Description:
 Shows a history of recorded changes.  Displays commit identifiers,
 the authors of the changes, and commit messages.
";
 $self->{'differences'} = '
 eg log output differs from git log output by showing simpler revision
 identifiers that will be easier for new users to understand and use.
 In detail:
   eg log
 is essentially the same as
   git log | git name-rev --stdin --refs=$(git symbolic-ref HEAD) | less
 However, it implements the name-rev behavior internally to provide
 incremental history processing (which avoids slow upfront full-history
 analyses) in common cases.
';
 return $self;
}

sub _get_values ($$) {
 my ($names, $sha1sum) = @_;
 my ($name, $distance);
 if (defined($names->{$sha1sum})) {
   ($name, $distance) = @{$names->{$sha1sum}};
 }
 return ($name, $distance);
}

sub _path_count ($) {
 my ($name) = @_;
 my @matches = ($name =~ m/[~^]/g);
 return scalar @matches;
}

sub _get_revision_name ($$$) {
 my ($sha1sum, $filehandle, $names) = @_;
 my ($name, $distance);

 # If we've already determined teh name of this sha1sum before, just return it
 ($name, $distance) = _get_values($names, $sha1sum);
 return $name if defined $name;

 # Loop over rev-list output, naming the parents of each commit as we walk
 # backward in history (breaking whenever if we hit our sha1sum)
 while (<$filehandle>) {
   # Each line of the rev-list output is of form
   #   sha1sum-of-commit sha1sum-of-parent1 sha1sum-of-parent2...
   my ($child, $parent, @merge_parents) = split;

   next if !$parent;

   # Determine the name of the current commit, and its distance from the head
   # of the current branch
   my ($cur_name, $distance) = _get_values($names, $child);
   die "Yikes!  Your history is b0rken!\n" if (!$cur_name);

   # Determine any name we previously determined for $parent, the name we
   # would give it relative to $child, and determine which should "win"
   my ($orig_parent_name, $orig_parent_distance) = _get_values($names, $parent);
   my $parent_name;
   if ($cur_name =~ /^(.*)~(\d+)$/) {
     my $count = $2 + 1;
     $parent_name = "$1~$count";
   } else {
     $parent_name = "$cur_name~1";
   }
   my $parent_distance = $distance + 1;
   if (!$orig_parent_name ||
       _path_count($orig_parent_name) > _path_count($parent_name)) {
     $names->{$parent} = [$parent_name, $parent_distance];
   }

   # Do the same for other parents, though their naming scheme is slightly
   # different
   my $count=2;
   foreach my $merge_parent (@merge_parents) {
     ($orig_parent_name, $orig_parent_distance) =
       _get_values($names, $merge_parent);
     if (!$orig_parent_name ||
         _path_count($orig_parent_name) > _path_count("$cur_name^$count")) {
       $names->{$merge_parent} = ["$cur_name^$count", $parent_distance];
     }
     $count++;
   }

   # Check if we found the needed sha1sum, and exit early if so
   push(@merge_parents, $parent);
   last if (grep {$_ eq $sha1sum} @merge_parents);
 }

 # Check if we found the needed sha1sum; if so, return it
 ($name, $distance) = _get_values($names, $sha1sum);
 return $name if $name;

 # We didn't find the wanted sha1sum; it has no name relative to the current
 # branch using tildes and hats.
 return "";
}

sub run {
 my $self = shift;
 @ARGV = Util::quote_args(@ARGV);

 my $branch = RepoUtil::current_branch();

 # Check whether to warn if there are no commits.  We don't want to parse
 # all the arguments to determine if there is a valid revision listed on the
 # command line (or, failing that, whether HEAD reference a valid revision);
 # instead, we just check for the simple case of no branches existing yet.
 if (!`$GIT_CMD branch -a`) {
   die "Error: No recorded commits to show yet.\n";
 }

 # We can just run plain git log if there's not current branch
 if (!$branch || !RepoUtil::valid_ref($branch)) {
   return ExecUtil::execute("$GIT_CMD log @ARGV", ignore_ret => 1);
 }

 my ($ret, $revision) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse refs/heads/$branch");
 exit $ret if $ret;
 chomp($revision);

 # Show the user the essential equivalent to what we manually do
 if ($DEBUG) {
   print "    >>Running: $GIT_CMD log @ARGV | \\\n" .
      "               $GIT_CMD name-rev --stdin " .
          "--refs=refs/heads/$branch | \\\n" .
      "               less\n";
   return 0 if $DEBUG == 2;
 }

 # Setup name determination via output from git rev-list
 my %names;
 open(REV_LIST_INPUT, "$GIT_CMD rev-list --parents $branch -- | ");
 $names{$revision} = [$branch, 0];

 # Loop over the output of git log, printing/modifying as we go
 my $old_git_pager_in_use = $ENV{"GIT_PAGER_IN_USE"};
 if (-t STDOUT) {
   # use colors
   $ENV{"GIT_PAGER_IN_USE"} = "1";
 }
 open(INPUT, "$GIT_CMD log @ARGV | ");
 $ENV{"LESS"} = "FRSX" unless defined $ENV{"LESS"};
 my $less = ($USE_PAGER == 1) ? "less" :
            ($USE_PAGER == 0) ? "cat" :
            `$GIT_CMD config core.pager` || "less";
 chomp($less);
 my $pid = open(OUTPUT, "| $less");

 # Make sure that we don't leave the terminal in a weird state if the user
 # hits Ctrl-C during eg log
 local $SIG{INT} =
   sub { kill 'SIGKILL', $pid; close(INPUT); close(OUTPUT); close(REV_LIST_INPUT);
         exit(0); };

 #open(OUTPUT, ">&STDOUT");
 while (<INPUT>) {
   # If it's a commit line, determine the name of the commit and print it too
   # ANSI color escape sequences make this regex kind of ugly...
   if (/^((?:\e\[.*?m)?commit ([0-9a-f]{40}))((?:\e\[m)?)$/) {
     my $name = _get_revision_name($2, *REV_LIST_INPUT, \%names);
     print OUTPUT "$1 ($name)$3\n" if $name;
     print OUTPUT "$1$3\n"         if !$name;
   } else {
     print OUTPUT;
   }
 }
 my ($ret1, $ret2, $ret3);
 close(INPUT);  $ret1 = $? >> 8;
 close(OUTPUT); $ret2 = $? >> 8;
 $ENV{"GIT_PAGER_IN_USE"} = $old_git_pager_in_use;

 # Make sure we close the pipe from rev-list too; We use "$? && $!"
 # instead of "$?" because we don't care about the return value of the
 # rev-list program -- which we prematurely close -- just whether the close
 # succeeded.  We can't just use "$!" because if --pretty="format:%s" is
 # passed to eg log, then $! will be "Bad file descriptor" which translates
 # to a nonzero exit status.
 # (This is my best guess at what to do given the random failures from
 # t1411-reflog-show.sh, and reading 'man perlfunc' under 'close'; it seems
 # to work.)
 close(REV_LIST_INPUT);  $ret3 = ($? >> 8) && $!;

 return $ret1 || $ret2 || $ret3;
}

###########################################################################
# merge                                                                   #
###########################################################################
package merge;
@merge::ISA = qw(subcommand);
INIT {
 $COMMAND{merge} = {
   unmodified_behavior => 1,
   section => 'projects',
   about => 'Join two or more development histories (branches) together'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg merge [-m MESSAGE] BRANCH...

Description:
 Merges another branch (or more than one branch) into the current branch.

 You may want to skip to the examples; the remainder of this description
 section just has boring details about how merges work.

 There are three different ways to handle merges depending on whether the
 current branch or the specified merge branches have commits not found in
 the other.  These cases are:
   1) The current branch contains all commits in the specified branch(es).
        In this case, there is nothing to do.
   2) Both the current branch and the specified merge branch(es) contain
      commits not found in the other:
        In this case, a new commit will be created which (a) includes
        changes from both the current branch and the merge branch(es) and
        (b) records the parents of the new commit as the last revision of
        the current branch and the last revision(s) of the merge
        branch(es).
   3) The specified merge branch has all the commits found in the current
      branch.
        In this case, a new commit is not needed to merge the branches
        together.  Instead, the current branch simply changes the record
        of its last revision to that of the specified merge branch.  This
        is known as a fast-forward update.
 See 'eg help topic storage' for more information.

Examples:
 Merge all changes from the stable branch that are not already in the
 current branch, into the current branch.
     \$ eg merge stable

 Merge all changes from the refactor branch into the current branch (i.e.
 same as the previous example but merging in a different branch)
     \$ eg merge refactor

Options:
 -m MESSAGE
   Use MESSAGE as the commit message for the created merge commit, if
   a merge commit is needed.
";
 return $self;
}

###########################################################################
# publish                                                                 #
###########################################################################
package publish;
@publish::ISA = qw(subcommand);
INIT {
 $COMMAND{publish} = {
   extra => 1,
   new_command => 1,
   section => 'collaboration',
   about => 'Publish a copy of the current repository on a remote machine'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   git_equivalent => '',
   initial_commit_error_msg => "Error: No recorded commits to publish.",
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg publish [-b|--bypass-modification-check] [-g|--group GROUP]
            [REMOTE_ALIAS] SSH_URL

Description:
 Publishes a copy of the current repository on a remote machine.  Note
 that local changes will be ignored; only committed changes will be
 published.  You must have ssh access to the remote machine and must have
 both git and ssh installed on both local and remote machines.

 After publishing the repository, it is accessible via the remote
 REMOTE_ALIAS, thus allowing you to use REMOTE_ALIAS to push and pull
 commands.  If REMOTE_ALIAS is not specified, it defaults to 'origin'.

 If the --group (or -g) option is specified, the given GROUP must be a
 valid unix group on the remote machine, and the user must be a member of
 that group.  When this option is passed, eg publish will ensure that all
 files are readable and writable by members of that group.

 Note that the remote location is specified using a ssh url; see 'eg help
 topic remote_urls' for a full list of valid possibilities, but the
 general case is to use scp(1) syntax: [[USER@]MACHINE]:REMOTE_PATH.  Note
 that if any files or directories exist below the specified remote
 directory, publish will abort.

Examples:
 Publish a copy of the current repository on the machine myserver.com in
 the directory /var/scratch/git-stuff/my-repo.git, and make it readable
 and writable by the unix group 'gitters'.  Then immediately make a clone
 of the remote repository
     \$ eg publish -g gitters myserver.com:/var/scratch/git-stuff/my-repo.git
     \$ cd ..
     \$ eg clone myserver.com:/var/scratch/git-stuff/my-repo.git

 Publish a copy of the current repository on the machine www.gnome.org, in
 the public_html/myproj subdirectory of the home directory of the remote
 user fake, then immediately clone it again into a separate directory
 named another-myproj.
     \$ eg publish fake\@www.gnome.org:public_html/myproj
     \$ cd ..
     \$ eg clone http://www.gnome.org/~fake/myproj another-myproj

Options
 --bypass-modification-check, -b
   To prevent you from publishing an incomplete set of changes, publish
   typically checks whether you have new unknown files or modified files
   present and aborts if so.  You can bypass these checks with this
   option.
";
 $self->{'differences'} = '
 eg publish is unique to eg, designed to condense the multiple necessary
 steps with git into one (or a few) commands.  The steps that eg publish
 performs are essentially:
     if ( git config --get remote.REMOTE_ALIAS.url > /dev/null); then
       echo "REMOTE_ALIAS already defined"; false;
     fi &&
     ssh [USER@]MACHINE "
       test -d REMOTE_PATH && echo "REMOTE_PATH already exists!" && exit 1;
       if (! groups | grep "\bGROUP\b" > /dev/null); then
         echo "Cannot change to group GROUP";  exit 1;
       fi;
       if (! type -p git>/dev/null);then echo "Cannot find git"; exit 1; fi &&
       newgrp GROUP;
       mkdir -p REMOTE_PATH &&
       cd REMOTE_PATH &&
       git init [--shared] --bare &&
       touch git-daemon-export-ok &&
       (mv hooks/post-update.sample hooks/post-update || true) &&
       chmod u+x hooks/post-update" &&
     git remote add REMOTE_ALIAS [USER@]MACHINE:REMOTE_PATH &&
     git push
 Note that the command involving git-daemon-export-ok is only needed if
 you will be cloning/pulling from the repository via the git:// protocol
 (in which case you are responsible for running git-daemon on the remote
 machine), and the post-update hook related stuff is only necessary if you
 are trying to clone/pull via the http:// protocol (in which case you are
 responsible for running a webserver such as httpd on the remote machine);
 neither of these steps are needed if you are cloning/pulling via ssh, but
 they do not cause problems either.

 MULTI-USER NOTE: If you want multiple people to be able to push to the
 resulting repository, you will need to ensure that they all have ssh
 access to the machine, that they are all part of the same unix group, and
 that you use the --group option to ensure that the repository is set up
 to be shared by the relevant group.
';
 return $self;
}

sub preprocess {
 my $self = shift;
 my $package_name = ref($self);

 my $bypass_modification_check = 0;
 my $group;
 my $result = main::GetOptions(
   "--help"           => sub { $self->help() },
   "bypass-modification-check|b" => \$bypass_modification_check,
   "group|g=s"                   => \$group,
   );

 die "Aborting: Need a URL to push to!\n" if @ARGV < 1;
 die "Aborting: Too many args to eg publish: @ARGV\n" if @ARGV > 2;
 my $extra_info = (@ARGV == 2) ? "" : ", please specify a REMOTE_ALIAS";
 $self->{remote} = (@ARGV == 2) ? shift @ARGV : "origin";
 $self->{repository} = shift @ARGV;
 $self->{group} = $group;

 die "Aborting: remote '$self->{remote}' already exists$extra_info!\n"
   if RepoUtil::get_config("remote.$self->{remote}.url");

 if (!$bypass_modification_check) {
   my $status = RepoUtil::commit_push_checks($package_name,
                                             {unknown => 1,
                                              changes => 1,
                                              unmerged_changes => 1});
 } else {
   # Record the set of unknown files we ignored with -b, so the -b flag
   # isn't needed next time.
   RepoUtil::record_ignored_unknowns();
 }
}

sub run {
 my $self = shift;

 my ($user, $machine, $port, $path) =
   Util::split_ssh_repository($self->{repository});
 if (!defined $path) {
   # It may be a local path rather than an ssh path...
   if ($self->{repository} =~ m#^/[^:]*#) {
     $path = $self->{repository};
   } else {
     die "Aborting: Could not parse remote repository URL " .
         "'$self->{repository}'.\n";
   }
 }

 my ($sg, $sge, $check_group, $shared) = ("", "", "", "");
 if (defined $self->{group}) {
   $check_group = "
       if (! groups | grep '\\b$self->{group}\\b' > /dev/null); then
         echo 'Cannot change to group $self->{group}!'; exit 1;
       fi;";
   $sg = "sg $self->{group} -c '";
   $sge = "'";
   $shared = "--shared ";
 }

 my $ret;
 if (defined $machine) {
   print "Setting up remote repository via ssh...\n";
   $ret = ExecUtil::execute("
     ssh $port -q $user$machine \"
       test -d $path && echo '$path already exists!' && exit 1; $check_group
       if (! which git>/dev/null);then echo 'Cannot find git'; exit 1; fi;
       ${sg}mkdir -p $path${sge} &&
       cd $path &&
       ${sg}git init ${shared}--bare${sge} &&
       touch git-daemon-export-ok &&
       (mv hooks/post-update.sample hooks/post-update || true) &&
       chmod u+x hooks/post-update\"",
     ignore_ret => 1);
 } else {
   print "Setting up not-so-remote repository...\n";
   $ret = ExecUtil::execute("
       test -d $path && echo '$path already exists!' && exit 1; $check_group
       if (! which git>/dev/null);then echo 'Cannot find git'; exit 1; fi;
       ${sg}mkdir -p $path${sge} &&
       cd $path &&
       ${sg}$GIT_CMD init ${shared}--bare${sge} &&
       touch git-daemon-export-ok &&
       (mv hooks/post-update.sample hooks/post-update || true) &&
       chmod u+x hooks/post-update",
     ignore_ret => 1);
 }
 die "Remote repository setup failed!\n" if $ret != 0;

 print "Creating new remote $self->{remote}...\n";
 #if ($self->{remote} ne "origin") {
 #  print "If $self->{remote} should be a default push/pull location, run:\n" .
 #        "   eg track [LOCAL_BRANCH] $self->{remote}/REMOTE_BRANCH\n";
 #}
 ExecUtil::execute("$GIT_CMD remote add $self->{remote} $self->{repository}");
 print "Pushing to new remote $self->{remote}...\n";
 $ret = ExecUtil::execute("$GIT_CMD push --mirror $self->{remote}");
 if ($ret) {
   ExecUtil::execute("$GIT_CMD remote rm $self->{remote}");
   return $ret;
 }

 print "Done.\n";

 return 0;
}

###########################################################################
# pull                                                                    #
###########################################################################
package pull;
@pull::ISA = qw(subcommand);
INIT {
 $COMMAND{pull} = {
   section => 'collaboration',
   about => 'Get updates from another repository and merge them'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg pull [--branch BRANCH] [--no-tags] [--all-tags] [--tag TAG]
         [--no-commit] [--rebase] REPOSITORY

Description:
 Pull changes from another repository and merge them into the local
 repository.  If there are no conflicts, the result will be committed.

 See 'eg help topic remote-urls' for valid syntax for remote repositories.
 If you frequently pull from the same repository, you may want to set up a
 nickname for it (see 'eg help remote'), so that you can specify the
 nickname instead of the full repository URL every time.  If you want to
 set a (different) default repository and branch to pull from, see 'eg
 track'.

 By default, tags in the remote repository associated with commits that
 are pulled, will themselves be pulled.  One can specify to pull
 additional or fewer tags with the --all-tags, --no-tags, or --tag TAG
 options.

 If there is more than one branch (on either end):
   If the local repository has more than one branch, the changes are
   always merged into the active branch (use 'eg info' or 'eg branch' to
   determine the active branch).

   If you do not specify which remote branch to pull, and you have not
   previously pulled a remote branch from the given repository, then eg
   will abort and ask you to specify a remote branch (giving you a list to
   choose from).

 Note for users of named remote repositories and remote tracking branches:
   If you set up named remote repositories (using 'eg remote'), you can
   make 'eg pull' obtain changes from several branches at once.  In such a
   case, eg will take the changes and record them in special local
   branches known as \"remote tracking branches\", a step which involves
   no merging.  Most of these branches will not be handled further after
   this step.  eg will then take changes from just the branch(es)
   specified (with the --branch option, or with the
   branch.CURRENTBRANCH.merge configuration variable, or by the last
   branch(es) merged), and merge it/them into the active branch.

   The advantage of pulling changes from branches that you do not
   immediately merge with is that you can then later inspect, review, or
   merge with such changes (using 'eg merge') even if not connected to the
   network.  Naming the remote repositories also allows you to use the
   shorter name instead of the full location of the repository.  (eg
   remote also provides the ability to update from groups of remote
   repositories simultaneously.)  See 'eg help remote' and 'eg help topic
   storage' for more information about named remote repositories and
   remote tracking branches.

Examples:
 Pull changes from myserver.com:git-stuff/my-repo.git
     \$ eg pull myserver.com:git-stuff/my-repo.git

 Pull changes from the stable branch of git://git.foo.org/whizbang into the
 active local branch
     \$ eg pull --branch stable git://git.foo.org/whizbang

 Pull changes from the debug branch in the remote repository nicknamed
 'carl' (see 'eg help remote' for more information about nicknames for
 remote repositories)
     \$ eg pull --branch debug carl

 Pull changes from a remote repository that has multiple branches
     Hmm, we don't know which branches the remote repository has.  Just
     try it.
     \$ eg pull ssh://machine.fake.gov/~user/hack.git
     That gave us an error telling us it didn't know which branch to pull
     from, but it told us that there were 3 branches: 'master', 'stable',
     and 'nasty-hack'.  Let's get changes from the nasty-hack branch!
     \$ eg pull --branch nasty-hack ssh://machine.fake.gov/~user/hack.git

Options
 --branch BRANCH
   Merge the changes from the remote branch BRANCH.  May be used multiple
   times to merge changes from multiple remote branches at once.

 --no-tags
   Do not download any tags from the remote repository

 --all-tags
   Download all tags from the remote repository.

 --tag TAG
   Download TAG from the remote repository

 --no-commit
   Perform the merge but do not commit even if the merge is clean.

 --rebase
   Instead of a merge, perform a rebase; in other words rewrite commit
   history so that your recent local commits become commits on top of the
   changes downloaded from the remote repository.

   NOTE: This is a potentially dangerous operation if you have local
   commits not found in the repository you are pulling from but which are
   found in some other repository (e.g. your local commits have been
   directly pulled from your copy by another developer, or to your copy
   from another developer).  In such a case, unless the other copy of
   these commits are also rebased (or discarded), you will probably get
   into trouble and need to thoroughly understand 'eg help rebase' before
   using this option.
";
 $self->{'differences'} = "
 eg pull and git pull are nearly identical.  eg provides a slightly more
 meaningful name for --tags (\"--all-tags\"), introduces a new option
 named --branch, and tries to assist the user when no branch to
 merge/rebase is specified on the command line or in the config.

 The new --branch option (1) avoids the need to explain refspecs too early
 to users, (2) makes command line examples more self-documenting.  eg
 still accepts refspecs at the end of the commandline the same as git
 pull, however their explanation is deferred to 'eg help topic refspecs'.

 When no branch to merge/rebase is specified, eg pull will provide a list
 of known branches at the remote end.  In the special case that the remote
 has exactly one branch, eg will use that branch for merging/rebasing
 rather than erroring out.
";
 return $self;
}

sub preprocess {
 my $self = shift;

 #
 # Parse options
 #
 $self->{args} = [];
 my $record_arg  =
   sub { my $prefix = "";
         $prefix = "no-" if defined $_[1] && $_[1] == 0;
         push(@{$self->{args}}, "--$prefix$_[0]");
       };
 my $record_args  = sub { $_[0] = "--$_[0]"; push(@{$self->{args}}, @_);  };
 my ($no_tags, $all_tags) = (0, 0);
 my @branches;
 my @tags;
 my $result = main::GetOptions(
   "--help"           => sub { $self->help() },
   "--branch=s"       => sub { push(@branches, $_[1]) },
   "--tag=s"          => sub { push(@tags, $_[1]) },
   "--all-tags"       => \$all_tags,
   "--no-tags"        => \$no_tags,
   "commit!"          => sub { &$record_arg(@_) },
   "summary!"         => sub { &$record_arg(@_) },
   "no-stat|n"        => sub { &$record_arg(@_) },
   "squash!"          => sub { &$record_arg(@_) },
   "ff!"              => sub { &$record_arg(@_) },
   "strategy|s=s"     => sub { &$record_args(@_) },
   "rebase!"          => sub { &$record_arg(@_) },
   "quiet|q"          => sub { &$record_arg(@_) },
   "verbose|v"        => sub { &$record_arg(@_) },
   "append|a"         => sub { &$record_arg(@_) },
   "upload-pack=s"    => sub { &$record_args(@_) },
   "force|f"          => sub { &$record_arg(@_) },
   "tags"             => \$all_tags,
   "keep|k"           => sub { &$record_arg(@_) },
   "update-head-ok|u" => sub { &$record_arg(@_) },
   "--depth=i"        => sub { &$record_args(@_) },
   );
 die "Cannot specify both --all-tags and --no-tags!\n"
   if $all_tags && $no_tags;
 die "Cannot specify individual tags along with --all-tags or --no-tags!\n"
   if @tags && ($all_tags || $no_tags);
 my $repository = shift @ARGV;
 my @git_refspecs = @ARGV;

 # Record the tags or no-tags arguments
 push(@{$self->{args}}, "--tags") if $all_tags;
 push(@{$self->{args}}, "--no-tags") if $no_tags;

 #
 # Get the repository to pull from
 #
 my $repo_is_a_remote = 1;
 my $repo_specified = defined($repository);
 if ($repository) {
   push(@{$self->{args}}, $repository);
   $repo_is_a_remote = 0 if !RepoUtil::get_config("remote.$repository.url");
 } else {
   $repository = RepoUtil::get_default_push_pull_repository();
   if (!$repository) {
     # This line should never be reached
     die "Don't know what to pull!"
   }
   push(@{$self->{args}}, $repository) if (!$repo_specified && @branches);
 }

 #
 # Get the branch(es) to pull from
 #
 push(@branches, @git_refspecs);

 # If we were given explicit branches or tags to pull, then we know what
 # to pull.  Also, for compatibility with git, if the repository specified
 # is a url rather than a remotename, then we should pull from HEAD if
 # no other refspecs are specified.
 #
 # In all other cases...
 if ($repo_is_a_remote && !@branches && !@tags) {
   my $dont_know_what_to_pull = 0;

   # If we don't have a current branch, we can't tell what branch to merge
   my $branch = RepoUtil::current_branch();
   if (!$branch) {
     $dont_know_what_to_pull = 1;
     goto PULL_CHECK;
   }

   # If there's no default remote, we must ignore branch.$branch.merge so
   # we don't know what branch to merge
   my ($merge_branch, $default_remote);
   $default_remote = RepoUtil::get_config("branch.$branch.remote");
   if (!$default_remote) {
     $dont_know_what_to_pull = 1;
     goto PULL_CHECK;
   }

   # If the default remote doesn't match the specified repository, we must
   # ignore branch.$branch.remote so we don't know what branch to merge
   if ($repo_specified and $repository ne $default_remote) {
     $dont_know_what_to_pull = 1;
     goto PULL_CHECK;
   }

   # If branch.$branch.merge is not set we don't know what branch to merge
   $merge_branch = RepoUtil::get_config("branch.$branch.merge");
   if (!$merge_branch) {
     $dont_know_what_to_pull = 1;
     goto PULL_CHECK;
   }

   PULL_CHECK:
   # Even if we don't know what to pull, if the remote repository has exactly
   # one branch, then we can just pull from that.
   if ($dont_know_what_to_pull) {
     my $location = $repository || $default_remote;
     my $only_branch = RepoUtil::get_only_branch($location, "pull");
     push(@{$self->{args}}, $location) if !$repo_specified;
     push(@branches, $only_branch);
   }
 }

 foreach my $branch (@branches) {
   push(@{$self->{args}}, $branch);
 }
 foreach my $tag (@tags) {
   push(@{$self->{args}}, ("tag", $tag));
 }
}

sub run {
 my $self = shift;

 my @args = Util::quote_args(@{$self->{args}});
 return ExecUtil::execute("$GIT_CMD pull @args", ignore_ret => 1);
}

###########################################################################
# push                                                                    #
###########################################################################
package push;
@push::ISA = qw(subcommand);
INIT {
 $COMMAND{push} = {
   section => 'collaboration',
   about => 'Push local commits to a published repository'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   initial_commit_error_msg => "Error: No recorded commits to push.",
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg push [--bypass-modification-check] [--branch BRANCH] [--tag TAG]
         [--all-branches] [--all-tags] [--mirror] REPOSITORY

Description:
 Push committed changes in the current repository to a published remote
 repository.  Note that this command cannot be used to create a new remote
 repository; use 'eg publish' (which both creates a remote repository and
 pushes to it) if you need to do that.

 The push can fail if the remote repository has commits not
 in the current repository; this can be fixed by pulling and merging
 changes from the remote repository (use eg pull for this) and then
 repeating the push.  Note that for getting changes directly to a fellow
 developer's clone, you should have them use 'eg pull' rather than trying
 to use 'eg push' on your end.

 Branches and tags are typically considered private; thus only the current
 branch will be involved by default (no tags will be sent).  The
 --all-branches, --matching-branches, --all-tags, and --mirror options
 exist to extend the list of changes included.  The --branch and --tag
 options can be used to specifically send different changes.

 See 'eg help topic remote-urls' for valid syntax for remote repositories.

 If you frequently push to the same repository, you may want to set up a
 nickname for it (see 'eg help remote'), so that you can specify the
 nickname instead of the full repository URL every time.  Also, if you want
 to change the default repository and branch to push to, see 'eg track'.

Examples:
 Push commits in the current branch
     \$ eg push myserver.com:git-stuff/my-repo.git

 Push commits in all branches that already exist both locally and remotely
     \$ eg push --matching-branches ssh://web.site/path/to/project.git

 Push commits in all branches, including branches that do no already exist
 remotely, and all tags, to the remote nicknamed 'alice'
     \$ eg push --all-branches --all-tags alice

 Push all local branches and tags and delete anything on the remote end
 that is not in the current repository
     \$ eg push --mirror ssh://jim\@host.xz:22/~jim/project/published

 Create a two new tags locally, then push both
     \$ eg tag MY_PROJECT_1_0
     \$ eg tag USELESS_ALIAS_FOR_1_0
     \$ eg push --tag MY_PROJECT_1_0 --tag USELESS_ALIAS_FOR_1_0

 Push the changes in just the stable branch
     \$ eg push --branch stable

Options
 --bypass-modification-check, -b
   To prevent you from pushing an incomplete set of changes, push
   typically checks whether you have new unknown files or modified files
   present and aborts if so.  You can bypass these checks with this
   option.

 --branch BRANCH
   Push commits in the specified branch.  May be reused multiple times to
   push commits in multiple branches.

   As an advanced option, one can use the syntax LOCAL:REMOTE for the
   branch.  For example, \"--branch my_bugfix:stable\" would mean to use
   the my_bugfix branch of the current repository to update the stable
   branch of the remote repository.

 --tag TAG
   Push the specified tag to the remote repository.

 --all-branches
   Push commits from all branches, including branches that do not yet exist
   in the remote repository

 --matching-branches
   Push commits from all branches that exist locally and remotely.  Note that
   this option is ignored if specific branches or tags are specified, or the
   --all-branches or --all-tags options.

 --all-tags
   Push all tags to the remote repository.

 --mirror
   Make the remote repository a mirror of the local one.  This turns on
   both --all-branches and --all-tags, but it also means that tags and
   branches that do not exist in the local repository will be deleted from
   the remote repository.
";
 $self->{'differences'} = "
 eg push is largely the same as git push, despite attempts to simplify in
 a number of areas:

   (1) push.default=tracking is the default if push.default is unset (git
       uses push.default=matching if push.default is unset).  This seems
       to match the intuition of most former cvs/svn users, though it is
       my one dangerous default change for existing git users.  Tough
       call, since the 'safe' defaults for each group are unsafe and/or
       confusing for the other.  A new --matching-branches flag is added
       to get the old behavior (the plain ':' refspec from git does the
       same, but --matching-branches is more self-documenting and also
       predates the ':' refspec).

   (2) eg prevents pushing into a bare repository as a push-side check
       rather than a receive-side check (when it can determine that the
       remote repository is bare -- i.e. if the repository url is for a
       locally mounted filesystem or uses ssh).  eg also allows the check
       to be overridden on the push-side (by specifying a refspec
       containing a ':' character).  This means it can work for users of
       existing repositories (created with git < 1.7), and it provides a
       solution that both avoids working copy inconsistency for new users
       while allowing more advanced users to do what they need on the same
       repository, and without forcing users to twiddle with the
       configuration of the remote repository.  However, this method
       doesn't work for repositories accessed via git://, and only works
       for ssh-accessed repositories if users have ssh setup to not need a
       password (kerberos, ssh-keys, etc.).

   (3) eg performs checks for uncommitted changes and newly created
       unknown files and warns/aborts if such exist when the user pushes
       (most former cvs/svn users are not yet familiar with the fact that
       only committed stuff gets pushed/pulled).  As with eg commit, such
       checks can be overridden with the -b flag.

   (4) eg provides extra --tag and --branch flags to make command lines
       more self-documenting and to avoid excessively early introduction
       of refspecs (a very confusing topic for new users).  However,
       refspecs still work with eg push, and users can learn about them by
       running 'eg help topic refspecs'.
";
 return $self;
}

sub _get_push_repository ($) {
 my ($repository) = @_;

 if (defined $repository) {
   return RepoUtil::get_config("remote.$repository.pushurl") ||
          RepoUtil::get_config("remote.$repository.url") ||
          $repository;
 } else {
   return RepoUtil::get_config("remote.origin.url")
 }
}

# _check_if_bare: Return whether the given repository is bare.  Returns
# undef the repository doesn't specify a valid repository or the repository
# is not of a type where we can determine bare-ness.  Otherwise returns
# either the string "true" or "false".
sub _check_if_bare ($) {
 my $repository = shift;

 # Don't know how to check rsync, http, https, or git repositories to see
 # if they are bare.
 return undef if $repository =~ m#^(rsync|http|https|git)://#;

 #
 # Check local directories
 #
 if ($repository =~ m#^file://(.*)#) {
   $repository = $1;
 }
 if (-d $repository) {
   my $orig_dir = main::getcwd();
   chdir($repository);

   my ($ret, $output) =
     ExecUtil::execute_captured("$GIT_CMD rev-parse --is-bare-repository",
                                ignore_ret => 1);

   chdir($orig_dir);
   return undef if $ret != 0;
   chomp($output);
   return $output;
 }

 #
 # Check ssh systems
 #
 my ($user, $machine, $port, $path) = Util::split_ssh_repository($repository);
 return undef if !defined $machine || !defined $path;

 my ($ret, $output) =
   ExecUtil::execute_captured(
     "ssh $port -q -o BatchMode=yes $user$machine 'cd $path && $GIT_CMD rev-parse --is-bare-repository'",
     ignore_ret => 1);
 return undef if $ret != 0;
 chomp($output);
 my @lines = split('\n', $output);
 my $result = $lines[-1];
 # If ssh or git itself failed, $ret could still be 0 but $result could be
 # something other than "true" or "false"
 return undef if (! grep {$_ eq $result} ["true", "false"]);
 return $result;
}

sub preprocess {
 my $self = shift;
 my $package_name = ref($self);

 #
 # Parse options
 #
 $self->{args} = [];
 my $record_arg   = sub { push(@{$self->{args}}, "--$_[0]"); };
 my $record_args  = sub { $_[0] = "--$_[0]"; push(@{$self->{args}}, @_);  };
 my ($all_branches, $matching_branches, $all_tags, $mirror) = (0, 0, 0, 0);
 my ($thin, $repo) = (0, 0);
 my @branches;
 my @tags;
 my $bypass_modification_check = 0;
 my $result = main::GetOptions(
   "--help"              => sub { $self->help() },
   "--branch=s"          => sub { push(@branches, $_[1]) },
   "--tag=s"             => sub { push(@tags, $_[1]) },
   "--all-branches|all"  => \$all_branches,
   "--matching-branches" => \$matching_branches,
   "--all-tags"          => \$all_tags,
   "tags"                => \$all_tags,
   "--mirror"            => \$mirror,
   "--dry-run"           => sub { &$record_arg(@_) },
   "--porcelain"         => sub { &$record_arg(@_) },
   "--progress"          => sub { &$record_arg(@_) },
   "--receive-pack=s"    => sub { &$record_args(@_) },
   "force|f"             => sub { &$record_arg(@_) },
   "repo=s"              => \$repo,
   "thin"                => sub { &$record_arg(@_) },
   "no-thin"             => sub { &$record_arg(@_) },
   "verbose|v"           => sub { &$record_arg(@_) },
   "set-upstream|u"      => sub { &$record_arg(@_) },
   "bypass-modification-check|b" => \$bypass_modification_check,
   );
 die "Cannot specify individual branches and request all branches too!\n"
   if @branches && ($all_branches || $mirror);
 die "Cannot specify individual tags and request all tags too!\n"
   if @tags && ($all_tags || $mirror);
 my $repository = shift @ARGV;
 my @git_refspecs = @ARGV;

 if (!$bypass_modification_check) {
   my $status = RepoUtil::commit_push_checks($package_name,
                                             {unknown => 1,
                                              changes => 1,
                                              unmerged_changes => 1});
 } else {
   # Record the set of unknown files we ignored with -b, so the -b flag
   # isn't needed next time.
   RepoUtil::record_ignored_unknowns();
 }

 push(@{$self->{args}}, "--all")    if $all_branches;
 push(@{$self->{args}}, "--tags")   if $all_tags;
 push(@{$self->{args}}, "--mirror") if $mirror;

 my $default_specified = 0;
 $default_specified = 1  if $all_branches;
 $default_specified = 1  if $all_tags;
 $default_specified = 1  if $mirror;

 #
 # Get the repository to push to
 #
 if (defined $repository && $repository =~ m#^-#) {
   die "Invalid repository to push to: $repository\n";
 }
 my $remote;
 if ($repository) {
   push(@{$self->{args}}, $repository);
 } elsif (!$repository && (@branches || @tags || !$default_specified)) {
   $repository = RepoUtil::get_default_push_pull_repository();
   push(@{$self->{args}}, $repository);
   $remote = $repository;
 } else {
   # Just drop through to the git push defaults.
 }

 #
 # Prevent pushing to a non-bare repository (on local filesystem or over
 # ssh; I don't know how to detect other cases)...unless user explicitly
 # specifies both source and destination references explicitly
 #
 my $remote_chk = $remote || $repository;
 $repository = _get_push_repository($repository);
 my $push_to_non_bare_repo;
 if ($repository) {

   # If the user uses a refspec including a colon character, assume
   # they know what they are doing and skip the non-bare check
   if (! grep {$_ =~ /:/} @git_refspecs) {

     # Check if we have already determined this repository to be bare
     my $is_bare;
     $is_bare = RepoUtil::get_config("remote.$remote.bare") if $remote;
     if (defined $is_bare) {
       $push_to_non_bare_repo = ($is_bare eq "false");
     } else {
       $is_bare = _check_if_bare($repository);
       if (defined $is_bare && defined $remote) {
         RepoUtil::set_config("remote.$remote.bare", $is_bare);
       }
       $push_to_non_bare_repo = (defined $is_bare && $is_bare eq "false");
     }
   }
 }
 # Throw an error if the user is trying to push to a bare repository
 # (and not using a refspec with a colon character)
 if ($push_to_non_bare_repo) {
   print STDERR <<EOF;
Aborting: You are trying to push to a repository with an associated working
copy, which will leave its working copy out of sync with its repository.
Rather than pushing changes to that repository, you should go to where that
repository is located and pull changes into it (using eg pull).  If you
know what you are doing and know how to deal with the consequences, you can
override this check by explicitly specifying source and destination
references, e.g.
 eg push REMOTE BRANCH:REMOTE_BRANCH
Please refer to
 eg help topic refspecs
to learn what this syntax means and what the consequences of overriding this
check are.
EOF
   exit 1;
 }

 #
 # Get the default branch to push to, if needed
 #
 push(@{$self->{args}}, ":") if $matching_branches;
 $default_specified = 1  if $matching_branches;

 if (!@branches && !@tags && !@git_refspecs && !$default_specified) {
   # User hasn't specified what to push; default choices:
   # 1 - remote.$remote.(push|mirror) options
   my $default_known = 0;
   if (defined(RepoUtil::get_config("remote.$remote_chk.push")) ||
       defined(RepoUtil::get_config("remote.$remote_chk.mirror"))) {
     $default_known = 1;
   }
   # 2 - push.default option
   if (defined(RepoUtil::get_config("push.default"))) {
     $default_known = 1;
   }
   # 3 - branch.$branch.merge option
   if (!$default_known) {
     my $branch = RepoUtil::current_branch();
     my $push_branch = RepoUtil::get_config("branch.$branch.merge");
     if (defined $push_branch) {
       $push_branch =~ s#refs/heads/##;
       push(@{$self->{args}}, "$branch:$push_branch");
       $default_known = 1;
     }
   }
   # 4 - the only branch that exists at the remote end
   if (!$default_known && defined $repository) {
     my $only_branch = RepoUtil::get_only_branch($repository, "push");
     push(@{$self->{args}}, $only_branch);
   }
 }

 #
 # Get the branch(es) to push
 #
 push(@branches, @git_refspecs);
 push(@{$self->{args}}, @branches);
 foreach my $tag (@tags) {
   push(@{$self->{args}}, ("tag", $tag));
 }
}

sub run {
 my $self = shift;

 my @args = Util::quote_args(@{$self->{args}});
 return ExecUtil::execute("$GIT_CMD push @args", ignore_ret => 1);
}

###########################################################################
# rebase                                                                  #
###########################################################################
package rebase;
@rebase::ISA = qw(subcommand);
INIT {
 $COMMAND{rebase} = {
   extra => 1,
   section => 'timesavers',
   about => "Port local commits, making them be based on a different\n" .
            "                repository version"
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   initial_commit_error_msg => "Error: No recorded commits to rewrite.",
   @_);
 bless($self, $class);
 #
 # Note: Parts of help were taken from the git-rebase manpage, which
 # was also available under GPLv2.
 #
 $self->{'help'} = "
Usage:
 eg rebase [-i | --interactive] [ --since SINCE ] [ --onto ONTO ]
           [ --against AGAINST ] [BRANCH_TO_REBASE]
 eg rebase [ --continue | --skip | --abort ]

Description:
 Rewrites commits on a branch, making them be based on a different
 repository version.  Technically, the old commits are not overwritten or
 deleted (only new ones are written), meaning that other branches sharing
 the same commits will be unaffected and users can undo a rebase (until
 the unused commits are cleaned up after a few weeks).

 WARNING:
   Rebasing commits in a branch is an advanced operation which changes
   history in a way that will cause problems for anyone who already has a
   copy of the branch in their repository when they try to pull updates
   from you.  This may cause them to experience many conflicts in their
   merges and require them to resolve those conflicts manually, or rewrite
   their own history, or even toss out their changes and simply accept
   your version.  (The last of those options is common enough that there
   is a special method of pulling and pushing changes in such cases; see
   'eg help topic refspecs' for more details.)

 Non-interactive rebase (running without the --interactive or -i flags):
   Specifying which commits to rewrite and what to rewrite them relative
   to involves specifying up to three branches or revisions: SINCE, ONTO,
   and BRANCH_TO_REBASE.  eg will take all commits in the BRANCH_TO_REBASE
   branch that are not in the SINCE branch, and record them as commits on
   top of the tip of the ONTO branch.  The ONTO and SINCE branches are not
   changed by this operation.  The BRANCH_TO_REBASE branch is changed to
   record the tip of the newly written branch.

   See also the \"If a conflict occurs\" section below.

 Interactive rebase (running with the --interactive or -i flag):
   Interactive rebasing allows you a chance to edit the commits which are
   rebased, including
     * reordering commits
     * removing commits
     * combining multiple commits into one commit
     * amending commits to include different changes or log messages
     * splitting one commit into multiple commits
   When running interactively, eg rebase will begin by making a list of
   the commits which are about to be rebased and allow you to change the
   the list before rebasing.  The list will include one commit per line,
   allowing you to
     * reorder commits by reordering lines
     * removing commits by removing lines
     * combining multiple commits into one, by changing 'pick' to 'squash'
       at the beginning of each line of the commits you want combined
       *except* the first
     * amend a commit by changing the 'pick' at the beginning of the line
       of the relevant commit to 'edit'.  This will make eg rebase stop
       after applying that commit, allowing you to make changes and run
       'eg commit --amend' followed by 'eg rebase --continue'.
     * split one commit into multiple commits by changing 'pick' at the
       beginning of the line of the relevant commit to 'edit'.  This will
       make eg rebase stop *after* applying that commit, allowing you to
       manually undo that commit while keeping the changes in the working
       copy (with 'eg reset HEAD~1') and then make multiple commits (with
       'eg commit') before running 'eg rebase --continue'.  Note that eg
       stash may come in handy for testing the split commits.

 If a conflict occurs:
   Rebase will stop at the first problematic commit and leave conflict
   markers (<<<<<<) in the tree.  You can use eg status and eg diff to
   find the problematic files and locations.  Once you edit the files to
   fix the conflicts, you can run
     eg resolved FILE
   to mark the conflicts in FILE as resolved.  Once you have resolved all
   conflicts, you can run
     eg rebase --continue
   If you simply want to skip the problematic patch (and end up with one
   less commit), you can instead run
     eg rebase --skip
   Alternatively, to abort the rebase and return to your previous state,
   you can run
     eg rebase --abort

Examples:
 Take a branch named topic that was split off of the master branch, and
 update it to be based on the new tip of master.
     \$ eg rebase --since master --onto master topic
   Pictorally, this changes:
                A---B---C topic
               /
          D---E---F---G master
   into
                        A'--B'--C' topic
                       /
          D---E---F---G master

 Same as the the above example, with less typing
     \$ eg rebase --against master topic

 Same as the last two examples, assuming topic is the current branch
     \$ eg rebase --against master

 Take a branch named topic that is based off of a branch named next, which
 is in turn based off master, and rewrite topic so that it appears to be
 based off the most recent version of master.
     \$ eg rebase --since next --onto master topic
   Pictorally, this changes
          o---o---o---o---o  master
               \\
                o---o---o---o---o  next
                                 \\
                                  o---o---o  topic
   into
          o---o---o---o---o  master
              |            \\
              |             o'--o'--o'  topic
               \\
                o---o---o---o---o  next

 Take just the last two commits of the current branch, and rewrite them
 to be relative to the commit just before the most recent on the master
 branch.
     \$ eg rebase --since current~2 --onto master~1 current
   Pictorally, this changes:
                   A---B---C---D---E  current
                  /
          F---G---H---I---J---K master
   into
                           D'---E' current
                          /
          F---G---H---I---J---K master

 Reorder the last two commits on the current branch
     \$ eg rebase --interactive --since HEAD~2
 (Then edit the file you are presented with and change the order of the
 two lines beginning with 'pick')
   Pictorally, this changes:
          A---B---C---D---E---F master
   into
          A---B---C---D---F'---E' master

Options:
 --since SINCE
   Upstream branch to compare against; only commits not found in this
   branch will be rebased.  Note that if --onto is not specified, the
   value of SINCE will be used for that as well.

   The value of SINCE is not restricted to existing branch names; any
   valid revision can be used (due to the fact that all revisions know
   their parents and a revision plus its ancestors can define a branch).

 --onto ONTO
   Starting point at which to create the new commits.  If the --onto
   option is not specified, the starting point is whatever is provided by
   the --since option.  Any valid revision can be used for the value of
   ONTO.

 --against AGAINST
   An alias for --since AGAINST, provided to make command lines clearer
   when the --onto flag is not also used.  (Typically, --against is used
   if --onto is not, and --since is used if --onto is, but --against and
   --since can be used interchangably.)

 --interactive, -i
   Make a list of the revisions which are about to be rebased and let the
   user edit that list before rebasing.  Can be used to split, combine,
   remove, insert, reorder, or edit commits.

 --continue
   Restart the rebasing process after resovling a conflict

 --skip
   Restart the rebasing process by skipping the current patch (resulting
   in a rewritten history with one less commit).

 --abort
   Abort the stopped rebase operation and restore the original branch
";
 $self->{'differences'} = "
 The only differences between eg rebase and git rebase are cosmetic;
 further, eg rebase accepts all options and flags that git rebase accepts.

 eg adds the identically behaved flags --since and --against in
 preference to using the position of the branch/revision name on the
 command line.  Note that
   git rebase master
 is somewhat confusing in that it isn't rebasing master but the current
 branch.  To make this clearer, eg allows (and encourages) the form
   eg rebase --against master
 The reason that both --against and --since flags were added (with
 identical behavior), is that the former makes for clearer command lines
 when the --onto flag is not also used.
";
 return $self;
}

sub preprocess {
 my $self = shift;

 #
 # Parse options
 #
 $self->{args} = [];
 my $record_arg   = sub { push(@{$self->{args}}, "--$_[0]"); };
 my $record_args  = sub { $_[0] = "--$_[0]"; push(@{$self->{args}}, @_);  };
 my $since;
 my $result = main::GetOptions(
   "--help"              => sub { $self->help() },
   "interactive|i"       => sub { &$record_arg(@_) },
   "verbose|v"           => sub { &$record_arg(@_) },
   "merge|m"             => sub { &$record_arg(@_) },
   "C=i"                 => sub { &$record_args(@_) },
   "whitespace=s"        => sub { push(@{$self->{args}},"--whitespace=$_[1]") },
   "preserve-merges|p"   => sub { &$record_arg(@_) },
   "onto=s"              => sub { &$record_args(@_) },
   "against=s"           => sub { $since=$_[1] },
   "since=s"             => sub { $since=$_[1] },
   "continue"            => sub { &$record_arg(@_) },
   "skip"                => sub { &$record_arg(@_) },
   "abort"               => sub { &$record_arg(@_) },
   );
 die "Too many branches/revisions specified\n"
   if @ARGV > 1 && defined $since;
 push(@{$self->{args}}, $since) if defined $since;
 push(@{$self->{args}}, @ARGV);
}

sub run {
 my $self = shift;

 my @args = Util::quote_args(@{$self->{args}});
 return ExecUtil::execute("$GIT_CMD rebase @args", ignore_ret => 1);
}

###########################################################################
# remote                                                                  #
###########################################################################
package remote;
@remote::ISA = qw(subcommand);
INIT {
 $COMMAND{remote} = {
   unmodified_behavior => 1,
   extra => 1,
   section => 'collaboration',
   about => 'Manage named remote repositories',
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg remote
 eg remote add REMOTENAME URL
 eg remote rm REMOTENAME
 eg remote update GROUPNAME

Description:
 eg remote is a convenience utility to make it easy to track changes from
 multiple remote repositories.  It is used to
   1) Set up
        REMOTENAME -> URL
      aliases that can be used in the place of full urls to simplify
      commands such as push or pull
   2) Pulling updates from multiple branches of a remote repository at
      once and storing them in remote tracking branches (which differ from
      normal branches only in that they have a prefix of REMOTENAME/ in
      their name).
   3) Pulling updates from multiple branches of multiple remote
      repositories at once, storing them all in remote tracking branches.

Examples:
 The examples section is split into three categories:
   1) Managing which remotes exist:
   2) Using one or more existing remotes
   3) Using remote tracking branches created through usage of remotes

 Category 1: Managing which remotes exist:

   List which removes exist
     \$ eg remote
   or, list remotes and their urls (among other things)
     \$ eg info

   Add a new remote for the url ssh://some.machine.org//path/to/repo.git,
   giving it the name jim
     \$ eg remote add jim ssh://some.machine.org//path/to/repo.git

   Add a new remote for the url git://composit.org//location/eyecandy.git,
   giving it the name bling
     \$ eg remote add bling git://composit.org//location/eyecandy.git

   Delete the remote named bob, and remove all related remote tracking
   branches (i.e. those branches whose names begin with \"bob/\"), as well
   as any associated configuration settings
     \$ eg remote rm bob

 Category 2: Using one or more existing remotes

   Pull updates for all branches of the remote jill, storing each in a
   remote tracking branch of the local repository named jill/BRANCH.
     \$ eg fetch jill

   Pull changes from the magic branch of the remote merlin and merge it
   into the current branch (i.e. standard pull behavior) AND also update
   all remote tracking branches associated with the remote (i.e. act as if
   'eg fetch merlin' was also run)
     \$ eg pull --branch magic merlin

   Grab updates from all remotes, i.e. run 'eg fetch REMOTE' for each
   remote.
     \$ eg remote update
   (Technically, some remotes could be manually configured to be excluded
   from this update.)

   Grab updates from all remotes in the group named friends (created by
   use of 'eg config remotes.friends \"REMOTE1 REMOTE2...\"'), i.e. run
   'eg fetch REMOTE' for each remote in the friends group
     \$ eg remote update friends

 Category 3: Using remote tracking branches created through usage of remotes

   List all remote tracking branches
     \$ eg branch -r

   Merge the remote tracking branch jill/stable into the current branch
     \$ eg merge jill/stable

   Get a history of the changes on the bling/explode branch
     \$ eg log bling/explode

   Create a new branch named my-testing based off of the remote tracking
   branch jenny/testing
     \$ eg branch my-testing jenny/testing
";
 return $self;
}

###########################################################################
# reset                                                                   #
###########################################################################
package reset;
@reset::ISA = qw(subcommand);
INIT {
 $COMMAND{reset} = {
   extra => 1,
   section => 'modification',
   about => 'Forget local commits and (optionally) undo their changes'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg reset [--working-copy | --no-unstaging] [REVISION]

Description:
 Forgets local commits for the active branch and (optionally) undoes their
 changes in the working copy.  If you have staged changes (changes you
 explictly marked as ready for commit) this function also unstages them by
 default.  See 'eg help topic staging' to learn about the staging area.

 From a computer science point of view, eg reset moves the current branch
 tip to point at an older commit, and also optionally changes the working
 copy and staging area to match the version of the repository recorded in
 the older commit.

 Note that this function should be used with caution; it is often used to
 discard unwanted data or to modify recent local \"history\" of commits.
 You want to be careful to not also discard wanted data, and modifying
 history is a bad idea if someone has already obtained a copy of that
 local history from you (rewriting history makes merging and updating
 problematic).

Examples:
 Throw away all changes since the last commit
     \$ eg reset --working-copy HEAD
 Note that HEAD always refers to the current branch, and the current
 branch always refers to its last commit.

 Throw away the last three commits and all current changes (this is a bad
 idea if someone has gotten a copy of these commits from you; this should
 only be done for truly local changes that you no longer want).
     \$ eg reset --working-copy HEAD~3

 Unrecord the last two commits, but keep the changes corresponding to these
 commits in the working copy.  (This can be used to fix a set of \"broken\"
 commits.)
     \$ eg reset HEAD~2

 While working on the \"stable\" branch, you decide that the last 5 commits
 should have been part of a separate branch.  Here's how you retroactively
 make it so:
     Verify that your working copy is clean...then
     \$ eg branch difficult_bugfix
     \$ eg reset --working-copy HEAD~5
     \$ eg switch difficult_bugfix
 The first step creates a new branch that initially could be considered an
 alias for the stable branch, but does not switch to it.  The second step
 moves the stable branch tip back 5 commits and modifies the working copy
 to match.  The last step switches to the difficult_bugfix branch, which
 updates the working copy with the contents of that branch.  Thus, in the
 end, the working copy will have the same contents as before you executed
 these three steps (unless you had local changes when you started, in
 which case those local changes will be gone).

 Stage files (mark changes in them as good and ready for commit but
 without yet committing them), then change your mind and unstage all
 files.
     \$ eg stage foo.c bla.h
     \$ eg reset HEAD
 Note that using HEAD as the commit means to forget all commits since HEAD
 (always an empty set) and undo any staged changes since that commit.

Options:
 --working-copy
   Also make the working tree match the version of the repository recorded
   in the specified commit.  If this option is not present, the working
   copy will not be modified.

 --no-unstaging
   Do not modify the staging area; only change the current branch tip to
   point to the older commit.

 REVISION
   A reference to a recorded version of the repository, defaulting to HEAD
   (meaning the most recent commit on the current branch).  See 'eg help
   topic revisions' for more details.

";
 $self->{'differences'} = '
 The only differences between eg reset and git reset are cosmetic;
 further, eg reset accepts all options and flags that git reset accepts.

 git reset uses option names of --soft, --mixed, and --hard.  While eg
 reset will accept these option names for compatibility, it provides
 alternative names that are more meaningful:
   --working-copy     <=> --hard
   --no-unstaging     <=> --soft
 There is no alternate name for --mixed, since it is the default and thus
 does not need to appear on the command line at all.

 The modified revert command of eg is encouraged for reverting specific
 files, though eg reset has the same file-specific reverting that git
 reset does.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 #
 # Parse options
 #
 my ($hard, $soft) = (0, 0);
 return if (scalar(@ARGV) > 0 && $ARGV[0] eq "--");

 my $result = main::GetOptions(
   "--help"         => sub { $self->help() },
   "--working-copy" => \$hard,
   "--no-unstaging" => \$soft,
   );
 die "Cannot specify both --working-copy and --no-unstaging!\n"
   if $hard && $soft;
 unshift(@ARGV, "--hard") if $hard;
 unshift(@ARGV, "--soft") if $soft;
}

###########################################################################
# resolved                                                                #
###########################################################################
package resolved;
@resolved::ISA = qw(subcommand);
INIT {
 $COMMAND{resolved} = {
   new_command => 1,
   extra => 1,
   section => 'compatibility',
   about => 'Declare conflicts resolved and mark file as ready for commit'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1,
                               git_equivalent => 'add',
                               @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg resolved PATH...

Description:
 Declare conflicts resolved for the specified paths, and mark contents of
 those files as ready for commit.

Examples
 After fixing any update or merge conflicts in foo.c, declare the fixing to
 be done and the contents ready to commit.
     \$ eg resolved foo.c
";
 $self->{'differences'} = "
 eg resolved is a command new to eg that is not part of git.  It is
 almost synonymous with git add; however, there are two differences:
 (a) eg resolved will work on a locally deleted file in the unmerged
 state (git add will complain that there's 'No such file or
 directory', and some users have had difficulty trying to find out
 that they needed to run git rm on such files), (b) eg resolved only
 works on files in the unmerged state (reporting an error if files
 not in such a state are specified).
";
 return $self;
}

sub run {
 my $self = shift;

 die "Error: Must specify paths to resolve.\n" if !@ARGV;
 @ARGV = Util::quote_args(@ARGV);

 # Determine which files are actually unmerged
 my ($ret, $output) =
   ExecUtil::execute_captured("$GIT_CMD ls-files -u --error-unmatch @ARGV",
     ignore_ret => 1);
 chomp($output);
 my @lines = split('\n', $output);

 # If there are some files that do not have conflicts, scream at the user
 if ($ret != 0) {
   my @not_unmerged_paths;

   foreach my $line (@lines) {
     if ($line =~ m/^error: pathspec '(.*?)' did not match any file/) {
       push(@not_unmerged_paths, $1);
     }
   }
   if (@not_unmerged_paths) {
     die "Error: The following are not unmerged files and thus don't " .
         "need resolving:\n  " . join("\n  ", @not_unmerged_paths) . "\n";
   } else {
     die "$output\n";
   }
 }

 # Determine the unmerged files (users may have passed a directory which
 # has both unmerged files and modified but unstaged ones; we only want
 # to stage the unmerged files from such a directory).
 my %files;
 foreach my $line (@lines) {
   $line =~ m/^\d+ [0-9a-f]+ \d\t(.*)$/;
   $files{$1} = 1;
 }
 my @unmerged_files = keys %files;

 # Run add -u instead of just add, since we want locally deleted files to
 # be picked up as well.
 return ExecUtil::execute("$GIT_CMD add -u @unmerged_files", ignore_ret => 1);
}

###########################################################################
# revert                                                                  #
###########################################################################
package revert;
@revert::ISA = qw(subcommand);
INIT {
 $COMMAND{revert} = {
   section => 'modification',
   about => 'Revert local changes and/or changes from previous commits'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, git_equivalent => '', @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg revert [[-m PARENT_NUMBER] --in REVISION | --since REVISION]
           [--staged | --unstaged] [--] [PATH...]

Description:
 eg revert undoes edits to your files, without changing the commit history
 or changing which commit is active.  (If you are looking for a different
 kind of 'undo'; they are discussed and contrasted below.)  There are many
 options for what to revert; you may want to jump ahead to the examples
 section below and then come back and read the full description.

 The work eg revert does includes discarding local modifications, removing
 recorded conflict states, undoing add or stage operations (i.e. unstaging
 files), and restoring deleted files to the previously recorded version.
 If you revert changes since some revision prior to the most recent,
 revert will also remove any files which were added in a later revision.

 By default, eg revert will revert edits since the last commit(*).  One
 can specify a different revision to revert file contents back to, or
 revert edits made in a single previous commit(**).  (Advanced usage note:
 eg revert will undo both staged and unstaged changes by default; you can
 request only one of these; see 'eg help topic staging' for more details
 on what staged and unstaged changes are.)

 (*) For an initial or root commit, eg revert will simply undo adds.  When
 in an uncompleted merge state, it is an error to not specify which commit
 to revert relative to (with the --since flag).

(**) When reverting the changes made *in* a merge commit, the revert
 command needs to know which parent of the merge the revert should be
 relative to.  This can be specified using the -m option.

 To avoid accidental loss of local changes, nothing will be done when no
 arguments are provided to eg revert.  However, eg revert will check for
 various special cases (from the different types of 'undo' below), and try
 to provide an error message tailored to any special circumstances
 relevant to you.

 === Comparison of different types of 'undo' available ===
 * Back up or switch to an earlier commit (eg switch)
 * Make a new commit to reverse the changes of a previous commit (eg
   cherry-pick -R)
 * Remove commits from history (eg reset OR eg rebase --interactive)
 * Reverting edits, without switching commits or changing commit history
   (eg revert)
 * Abort an incomplete operation
   * Incomplete merge:      eg revert --since HEAD
   * Unfinished rebase:     eg rebase --abort
   * Unfinished apply mail: eg am --abort
   * Unfinished bisect:     eg bisect reset

Examples:
 Undo changes since the last commit on the current branch to bar.h and
 foo.c.  This can be done with either of the following methods:
     \$ eg revert bar.h foo.c                      # Method #1
     \$ eg revert --since HEAD bar.h foo.c         # Method #2, more explicit

 While on the bling branch, revert the changes in the last 3 commits (as
 well as any local changes) to any file under the directory docs.  This
 can be done by:
     \$ eg revert --since bling~3 docs

 While on the stable branch, you determine that the seventh commit prior
 to the most recent had a faulty change to foosubdir and baz.txt and you
 simply want to undo it.  This can be accomplished by:
     \$ eg revert --in stable~7 -- foosubdir baz.txt

 You decide that all changes to foobar.cpp in your working copy and in the
 last 2 commits are bad and want to revert them.  This is done by:
 of:
     \$ eg revert --since HEAD~2 -- foobar.c

 You decide that some of the changes in the merge commit HEAD~4 are bad.
 You would like to revert the changes to baz.py in HEAD~4 relative to its
 second parent.  This can be accomplished as follows:
     \$ eg revert -m 2 --in HEAD~4 baz.py

 (Advanced) Undo a previous stage, marking changes in foo.c as not
 being ready for commit (this is equivalent to eg unstage foo.c):
     \$ eg revert --staged foo.c

 (Advanced) Undo changes since the most recent stage to soopergloo.f77
     \$ eg revert --unstaged soopergloo.f77

 (Advanced) You decide that the changes to abracadabra.xml made in commit
 HEAD~8 are bad.  You want to revert those changes in the version of
 abracadabra.xml but only to your working copy.  This is done by:
     \$ eg revert --unstaged --in HEAD~8 -- abracadabra.xml

Options:
 --since
   Revert the changes made since the specified commit, including any local
   changes.  This takes the difference between the specified commit and
   the current version of the files and reverses these changes.

 --in
   Revert the changes made in the specified commit.  This takes the
   difference between the parent of the specified commit and the specified
   commit and reverse applies it.

 REVISION
   A reference to a recorded version of the repository, defaulting to HEAD
   (meaning the most recent commit on the current branch).  See 'eg help
   topic revisions' for more details.

 -m PARENT_NUMBER
   When reverting the changes made in a merge commit, the revert command
   needs to know which parent of the merge the revert should be relative
   to.  Use this flag with the parent number (1, 2, 3...) to specify which
   parent commit to revert relative to.

   Can only be used with the --in option.

 --staged
   Make changes only to the staged (explicitly marked as ready to be
   committed) version of files.

 --unstaged
   Make changes only to the unstaged version of files, i.e. only to the
   working copy.

 --
   This option can be used to separate command-line options and commits
   from the list of files, (useful when filenames might be mistaken for
   command-line options or be mistaken as a branch or tag name).

 PATH...
   One or more files or directories.  The changes reverted will be limited
   to the listed files or files below the listed directories.
";
 $self->{'differences'} = '
 eg revert is similar to the revert command of svn, hg, bzr, or darcs.  It
 is not provided by any one git command; it overlaps with about five
 different git commands in specific cases.  git users wanting the
 functionality in eg revert will typically be guided by expert git users
 towards whichever git command seems like the most natural fit for the
 particular case the user asks about.  Quite often, such users will
 continue using the command they are given for subsequent situations...and
 will often stumble across multiple cases where the git command no longer
 matches the wanted revert behavior.

 git does provide a command called revert, which is a subset of the
 behavior of eg cherry-pick:
   git revert COMMIT
 is the same as
   eg cherry-pick -R COMMIT
 which is, modulo the automatic commit message provided by git revert, the
 same as
   eg revert --in COMMIT && eg commit
 Note that while eg revert --in may look similar to git revert, the former
 is about undoing changes in just the working copy, is typically
 restricted to a specific subset of files, and is usually just one change
 of many towards testing or creating something new to be committed.  The
 latter is always concerned with reverse applying an entire commit, and is
 almost always used to immediately record that change.

 Note that git revert commands are invalid syntax in eg (since eg revert
 always requires the --since or --in flags to be specified whenever a
 commit is).  This means that eg can catch such cases and notify git
 users to adopt the eg cherry-pick -R command.

 Due to these changes, eg revert should be much more welcoming to users of
 svn, hg, bzr, or darcs.  It also provides a simple discovery mechanism
 for existing git users to allow them to easily work with eg.
 Additionally, these changes also make the reset and checkout/switch
 subcommands of eg easier to understand by limiting their scope instead of
 each having two very different capabilities.  (Technically, eg reset and
 eg checkout still have those capabilities for backwards compatibility, I
 just omit them in the documentation.)

 It seems that perhaps eg revert could be extended further, to accept
 things like
     \$ eg revert --in HEAD~8..HEAD~5 foo.c
 to allow reverting changes made in a range of commits.  The --in could
 even be optional in such a case, since the range makes it clear what is
 wanted.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();
 my $initial_commit = RepoUtil::initial_commit();

 # Parsing opts
 my ($staged, $unstaged, $in) = (0, 0, -1);
 my $m;
 my $rev;
 my $result = main::GetOptions(
   "--help"         => sub { $self->help() },
   "-m=i"           => \$m,
   "--staged"       => \$staged,
   "--unstaged"     => \$unstaged,
   "--in=s"         => sub { $in = 1; $rev = $_[1]; },
   "--since=s"      => sub { $in = 0; $rev = $_[1]; },
   );

 # Parsing revs and files
 my ($opts, $revs, $files) = RepoUtil::parse_args([], @ARGV);
 unshift(@$revs, $rev) if defined($rev);

 #
 # Big ol' safety checks and warnings
 #
 if (!@$revs && !@$files) {
   my $files_modified = RepoUtil::files_modified();
   if (-f "$self->{git_dir}/MERGE_HEAD") {
     print STDERR<<EOF;
Aborting: no revisions or files specified to revert.  If you want to abort
your incomplete merge, try 'eg reset --working-copy HEAD'.
EOF
     exit 1;
   }
   elsif (-d "$self->{git_dir}/rebase-merge" ||
          -d "$self->{git_dir}/rebase-apply") {
     print STDERR<<EOF;
Aborting: no revisions or files specified to revert.  If you want to abort
your incomplete rebase, try:
 eg rebase --abort
EOF
     exit 1;
   }
   elsif (!$files_modified && !$initial_commit) {
     my $active_branch = RepoUtil::current_branch() || 'HEAD';
     print STDERR<<EOF;
There are no local changes to revert and you specified no revisions to revert
(or revert back to).  Please specify a revision with --in or --since.
Alternatively, if you want to modify commits instead of just the working copy
then use reset instead of revert:

If you want to undo a rebase (or a 'pull --rebase'), try:
 eg rebase --abort
If you want to undo a merge (or a plain 'pull'), try:
 eg merge --abort
If you want to undo the last commit (but keep its changes in the working copy),
try:
 eg reset $active_branch~1
If you just want to amend the last commit without undoing it, make the
additional changes you want and run:
 eg commit --amend
If you want to undo previous reset commands, get the appropriate reflog
reference from eg reflog (for example, using HEAD\@{1} for <REF>) and run:
 eg reset --working-copy <REF>
EOF
     exit 1;
   }
   elsif (!$initial_commit) {
     print STDERR<<EOF;
Aborting: no revisions or files specified.  If you want to revert and lose
all changes since the last commit, try adding the arguments
 --since HEAD
to the end of your command.
EOF
     exit 1;
   } else {
     print STDERR<<EOF;
Aborting: no files specified.
EOF
     exit 1;
   }
 }

 # Sanity checks
 die "Cannot specify -m without specifying --in.\n" if !$in && defined($m);
 die "Can only specify one revision\n" if @$revs > 1;
 die "No revision specified after --in\n"    if ($in == 1 && !@$revs);
 die "No revision specified after --since\n" if ($in == 0 && !@$revs);
 if ($in == -1 && @$revs) {
   die "You must specify either --in or --since when specifying a revision.\n".
       "(git users:) If you are used to git revert; try running\n".
       "  eg cherry-pick -R @ARGV\n";
 }
 die "Unrecognized options: @$opts\n" if @$opts;
 $in = 0 if $in == -1;
 if (!$staged && !$unstaged) {
   $staged = 1;
   $unstaged = 1;
 }

 # Special checks in the case of an incomplete merge to make sure we know
 # what to revert back to; if no --since or --in specified then we can only
 # proceed if the user is only reverting unstaged changes
 if (!@$revs && $staged && -f "$self->{git_dir}/MERGE_HEAD") {
   my @merge_branches = RepoUtil::merge_branches();
   my $list = join(", ", @merge_branches);
   print STDERR <<EOF;
Aborting: Cannot revert the changes since the last commit, since you are in
the middle of a merge and there are multiple last commits.  Please add
 --since BRANCH
to your flags to eg revert, where BRANCH is one of
 $list
If you simply want to abort your merge and undo its conflicts, run
 eg merge --abort
EOF
   exit 1;
 }

 if ($initial_commit) {
   die "Cannot revert a previous commit since there are no previous " .
     "commits.\n" if $in;
   die "Cannot revert to a previous commit since there are no previous " .
       "commits.\n" if !$in && @$revs;
 }

 my @quoted_files = Util::quote_args(@$files);
 my @unmerged_files = `$GIT_CMD ls-files --full-name -u -- @quoted_files`;
 if (@unmerged_files && $in) {
   die "Aborting: please clear conflicts from @unmerged_files before " .
       "proceeding.\n";
 }

 # Record needed information
 $self->{staged} = $staged;
 $self->{unstaged} = $unstaged;
 $self->{just_recent_unstaged} = !$in && !$staged && !@$revs;
 $self->{in} = $in;
 $self->{revs} = "@$revs";
 $self->{revs} = "HEAD" if !@$revs;
 $self->{initial_commit} = $initial_commit;
 if ($in) {
   # Get the revision whose changes we want to revert, and its parents
   Util::push_debug(new_value => 0);
   my $links = ExecUtil::output(
                 "$GIT_CMD rev-list --parents --max-count=1 $self->{revs}");
   Util::pop_debug();
   my @list = split(' ', $links);  # commit id + parent ids

   # Get a symbolic name for the parent revision we will diff against
   my $first_rev = $self->{revs};
   my $parent = $m || 1;
   $first_rev .= "^$parent";

   # Reverting changes in merge commits can only be done against one parent
   die "Cannot revert a merge commit without specifying a parent!\n"
     if !defined($m) && @list > 2;

   # Reverting relative to a parent can only be done with existing parents
   if ($parent + 1 > scalar(@list)) {
     die "Cannot revert the changes made in a commit that has no prior " .
       "commit\n" if !defined($m);
     die "The specified commit does not have $m parents; try a lower " .
       "value for -m\n" if defined($m);
   }

   # The combination of revs to diff between
   $self->{revs} = "$first_rev $self->{revs}";
 }

 # Determine some other stuff needed
 $self->{files} = \@quoted_files;
 my ($new_files, $newish_files, $revert_files);
 my ($newly_added_files, $new_since_rev_files, $other_files);
 if (!$in && !$initial_commit) {
   my $revision = (@$revs) ? $revs->[0] : "HEAD";
   ($newly_added_files, $new_since_rev_files, $other_files) =
      RepoUtil::get_revert_info($revision, @quoted_files);
 } elsif ($initial_commit) {
   $newly_added_files = $files;
   $new_since_rev_files = [];
   $other_files = [];
 }
 $self->{newly_added_files} = $newly_added_files;
 $self->{new_since_rev_files} = $new_since_rev_files;
 $self->{other_files} = $other_files;
}

sub run {
 my $self = shift;

 my $git_dir = RepoUtil::git_dir();
 my $paths_specified = scalar(@{$self->{files}}) > 0;
 my $ret = 0;

 if (!$self->{in}) {
   my $revision = $self->{revs};
   my @newly_added_files = @{$self->{newly_added_files}};
   my @new_since_rev_files = @{$self->{new_since_rev_files}};
   my @other_files = @{$self->{other_files}};
   my @all_files = @{$self->{files}};

   #
   # Case: Initial commit
   #
   if ($self->{initial_commit}) {
     $ret = ExecUtil::execute("$GIT_CMD rm --cached --quiet -- " .
                              "@newly_added_files", ignore_ret => 1);
     exit $ret if $ret;
   }

   #
   # Set: Reverting both staged and unstaged changes
   #
   elsif ($self->{staged} && $self->{unstaged}) {
     #
     # Case: ALL staged and unstaged changes since some revision
     #
     if (!$paths_specified) {
       if (@newly_added_files) {
         # git reset is not quiet even when requested and has idiotic return
         # state; if three files have conflicts and I try to reset some
         # file other than those three, the command is successful but it
         # spews warnings and gives a bad exit status
         ExecUtil::execute("$GIT_CMD reset -q $revision --" .
                           " @newly_added_files >/dev/null",
                           ignore_ret => 1);
       }

       my ($revision_sha1, $head_sha1, $temp_ret);
       if ($revision ne "HEAD") {
         Util::push_debug(new_value => 0);
         ($temp_ret, $revision_sha1) =
           ExecUtil::execute_captured("$GIT_CMD rev-parse --verify $revision",
                                      ignore_ret => 1);
         ($temp_ret, $head_sha1) =
           ExecUtil::execute_captured("$GIT_CMD rev-parse --verify HEAD",
                                      ignore_ret => 1);
         Util::pop_debug();
       }

       $ret = ExecUtil::execute("$GIT_CMD reset --hard $revision",
                                ignore_ret => 1);
       exit $ret if $ret;

       if ($revision ne "HEAD" && $revision_sha1 ne $head_sha1) {
         # Note, cannot git reset --soft HEAD, since HEAD has changed in
         # the above reset...
         $ret = ExecUtil::execute("$GIT_CMD reset --soft HEAD\@{1}",
                                  ignore_ret => 1);
         exit $ret if $ret;
       }
     }

     #
     # Case: Selected staged and unstaged changes since some revision
     #
     if ($paths_specified) {
       if (@newly_added_files) {
         # See rant above about 'git reset is not quiet even when requested'
         ExecUtil::execute("$GIT_CMD reset -q $revision --" .
                           " @newly_added_files >/dev/null",
                           ignore_ret => 1);
       }
       if (@new_since_rev_files) {
         # Ugh, when --quiet doesn't actually mean "quiet".
         # (Reproduce with git-1.6.0.6 on incomplete merge handling testcase)
         $ret = ExecUtil::execute("$GIT_CMD rm --quiet --force " .
                                  "--ignore-unmatch -- @new_since_rev_files" .
                                  " > /dev/null",
                                  ignore_ret => 1);
         exit $ret if $ret;
       }
       if (@other_files) {
         $ret = ExecUtil::execute("$GIT_CMD checkout $revision -- " .
                                  "@other_files", ignore_ret => 1);
         exit $ret if $ret;
       }
     }
   }

   #
   # Set: Reverting just staged changes
   #
   elsif ($self->{staged}) {
     if ($paths_specified) {
       $ret = ExecUtil::execute("$GIT_CMD reset -q $revision -- @all_files",
                                ignore_ret => 1);
       exit $ret if $ret;
     } else {
       $ret = ExecUtil::execute("$GIT_CMD read-tree $revision",
                                ignore_ret => 1);
       exit $ret if $ret;
     }
   }

   #
   # Set: Reverting just unstaged changes
   #
   elsif ($self->{unstaged}) {
     if ($self->{just_recent_unstaged}) {
       die "Assertion failed: Paths not specified.\n" if (!$paths_specified);
       $ret = ExecUtil::execute("$GIT_CMD checkout -- @all_files",
                                ignore_ret => 1);
       exit $ret if $ret;
     }
     else {
       if (@newly_added_files) {
         # This results in a no-op essentially, but at least it shows the
         # equivalent commands when no new_since_rev_files and no other_files
         push(@other_files, @newly_added_files);
       }

       if (@new_since_rev_files) {
         $ret = ExecUtil::execute("rm -f @new_since_rev_files",
                                  ignore_ret => 1);
         exit $ret if $ret;
       }

       if (@other_files || !$paths_specified) {
         my $cf = "@other_files";
         if (!$paths_specified) {
           my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();
           ($cf) = Util::reroot_paths__from_to_files($top_dir, $cur_dir, '.');
         }
         my $old_git_index_file = $ENV{"GIT_INDEX_FILE"};
         $ENV{"GIT_INDEX_FILE"} = "$git_dir/tmp_index";
         $ret = ExecUtil::execute("$GIT_CMD checkout $revision " .
                                  "-- $cf", ignore_ret => 1);
         $ENV{"GIT_INDEX_FILE"} = $old_git_index_file;
         exit $ret if $ret;

         my ($tmp_index) = Util::quote_args("$git_dir/tmp_index");
         $ret = ExecUtil::execute("rm $tmp_index");
         exit $ret if $ret;
       }
     }
   }
 }

 if ($self->{in}) {
   # Must do unstaged changes first, or extra unknown files can "appear"
   my $location_flag;
   $location_flag = ""         if $self->{unstaged};
   $location_flag = "--cached" if $self->{staged};
   $location_flag = "--index"  if ($self->{staged} && $self->{unstaged});

   my @files = @{$self->{files}};
   my $marker = "";
   $marker = "-- " if (@files);

   my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();

   my @diff_flags = ("--binary");
   my @apply_flags = ("--whitespace=nowarn", "--reject");
   push(@apply_flags, $location_flag) if $location_flag;

   # Print out the (nearly) equivalent commands if the user asked for
   # debugging information
   if ($DEBUG) {
     print "    >>Running: " .
           "$GIT_CMD diff @diff_flags $self->{revs} ${marker}@files | ";
     print "(cd $top_dir && " if ($top_dir ne $cur_dir);
     print "$GIT_CMD apply @apply_flags -R";
     print ")" if ($top_dir ne $cur_dir);
     print "\n";
   }

   # Sadly, using "git diff... | git apply ... -R" doesn't quite work,
   # because apply complains very loudly if the diff is empty.  So,
   # we have to run diff, slurp in its output, check if its nonempty,
   # and then only pipe that output back out to git apply if we have
   # an actual diff to revert.
   if ($DEBUG < 2) {
     open(DIFF, "$GIT_CMD diff @diff_flags $self->{revs} ${marker}@files |");
     my @output = <DIFF>;
     my $diff = join("", @output);
     # Listing unmerged paths doesn't count as nonempty
     $diff =~ s/\* Unmerged path.*\n//g;
     close(DIFF);
     $ret = $?;
     exit $ret >> 8 if $ret;

     if ($diff) {
       chdir($top_dir) if $top_dir ne $cur_dir;
       open(APPLY, "| $GIT_CMD apply @apply_flags -R");
       print APPLY $diff;
       close(APPLY);
       chdir($cur_dir) if $top_dir ne $cur_dir;
     }
   }
 }

 return 0;
}

###########################################################################
# rm                                                                      #
###########################################################################
package rm;
@rm::ISA = qw(subcommand);
INIT {
 $COMMAND{rm} = {
   extra => 1,
   section => 'modification',
   about => 'Remove files from subsequent commits and the working copy'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg rm [-f] [-r] [--staged] FILE...

Description:
 Marks the contents of the specified files for removal from the next
 commit.  Also removes the given files from the working copy, unless
 otherwise specified with the --staged flag.

 To prevent data loss, the removal will be aborted if the file has
 modifications.  This check can be overriden with the -f flag.

Examples:
 Mark the content of the files foo and bar for removal from the next
 commit, and delete these files from the working copy.
     \$ eg rm foo bar

 Mark the content of the file baz.c for removal from the next commit, but
 keep baz.c in the working copy as an unknown file.
     \$ eg rm --staged baz.c

 (Advanced) Remove all *.txt files under the Documentation directory OR
 any of its subdirectories.  Note that the asterisk must be preceded with
 a backslash to prevent standard shell expansion.  (Google for 'shell
 expansion' if that makes no sense to you.)
     \$ eg rm Documentation/\\*.txt

Options:
 -f
   Override the file-modification check.

 -r
   Allow recursive removal when a directory name is given.  Without this
   option attempted removal of directories will fail.

 --staged
   Only remove the files from the staging area (the area with changes
   marked as ready to be recorded in the next commit; see 'eg help topic
   staging' for more details).  When using this flag, the given files will
   not be removed from the working copy and will instead become
   \"unknown\" files.

 --
   This option can be used to separate command-line options from the list
   of files, (useful when filenames might be mistaken for command-line
   options).
";
 $self->{'differences'} = '
 eg rm is identical to git rm except that it accepts --staged as a synonym
 for --cached.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 return if (scalar(@ARGV) > 0 && $ARGV[0] eq "--");
 my $result = main::GetOptions("--help" => sub { $self->help() });

 foreach my $i (0..$#ARGV) {
   $ARGV[$i] = "--cached" if $ARGV[$i] eq "--staged";
 }
}

###########################################################################
# squash                                                                  #
###########################################################################
package squash;
@squash::ISA = qw(subcommand);
INIT {
 $COMMAND{squash} = {
   new_command => 1,
   extra => 1,
   section => 'modification',
   about => 'Combine all changes since a given revision into a new commit'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, git_equivalent => '', @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg squash [--against REVISION]

Description:
 Combines all commits since REVISION into a single commit, and open an
 editor with the concatenation of log messages for the user to edit to
 create a new log message.

 REVISION must be an ancestor of the current commit.  If REVISION is
 not specified, the remote tracking branch for the current branch is
 assumed.  (If there is no such branch, eg squash will abort with an
 error.)

Examples:
 Combine all commits in the current branch that aren't in origin/master
 into a single commit
     \$ eg squash --against origin/master

Options:
 --against
   An optional command line argument that makes it clearer what is
   happening.  (In the example above, we are not \"squashing origin/master\",
   we are squashing all changes since origin/master on top of origin/master.
";
 $self->{'differences'} = '
 eg squash is a command new to eg that is not part of git.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 my $since;
 my $result = main::GetOptions(
   "--help"    => sub { $self->help() },
   "against=s" => sub { $since=$_[1] },
   );
 $since = shift @ARGV if !defined($since);
 die "Aborting: Too many revisions specified.\n" if @ARGV > 1;
 if (!defined($since)) {
   my $branch = RepoUtil::current_branch();
   die "Aborting: No revision specified.\n" if !defined($branch);
   my $merge_remote = RepoUtil::get_config("branch.$branch.remote");
   my $merge_branch = RepoUtil::get_config("branch.$branch.merge");
   die "Aborting: No revision specified.\n" if !defined($merge_branch);
   $merge_branch =~ s#^refs/heads/##;
   $since = "$merge_remote/$merge_branch";
 }

 $self->{since} = $since;

 Util::push_debug(new_value => 0);
 my ($retval, $orig_head, $since_sha1sum);

 # Get the sha1sum where HEAD points now, make sure HEAD is valid
 ($retval, $orig_head) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse HEAD", ignore_ret => 1);
 die "Aborting: You have no commits on HEAD.\n" if $retval != 0;
 chomp($orig_head);
 $self->{orig_head} = $orig_head;

 # Get the sha1sum where $since points now, make sure it is valid
 ($retval, $since_sha1sum) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse $self->{since}",
                              ignore_ret => 1);
 die "Invalid revision reference: $self->{since}\n" if $retval != 0;
 chomp($since_sha1sum);

 # Make sure user has no staged changes
 my $output = `$GIT_CMD diff --cached --quiet`;
 die "Aborting: You have staged changes; please commit them first.\n" if $?;

 # Ensure $self->{since} is an ancestor of HEAD
 my $command = "$GIT_CMD rev-list HEAD..$self->{since} | wc -l";
 my ($ret, $unique_to_since) = ExecUtil::execute_captured($command);
 die "Couldn't parse '$command' output '$unique_to_since'"
   unless ($unique_to_since =~ /^\s*([0-9]+)$/);
 my $need_commits = $1;
 die "Aborting: $self->{since} is not an ancestor of HEAD.\n" if $need_commits;
 die "Aborting: There are no commits since $self->{since}.\n"
   if $orig_head eq $since_sha1sum;

 Util::pop_debug();
}

sub run {
 my $self = shift;

 # Fill out a basic log message
 my ($fh, $filename) = main::tempfile();
 print $fh <<EOF;
# Please combine the following commit messages into a single commit message.
# Lines starting with a '#' will be ignored.

EOF
 close($fh);
 my $ret = ExecUtil::execute("$GIT_CMD log --reverse --no-merges --pretty=format:" .
           "'#commit %H%n#Author: %an <%ae>%n#Date:   %ad%n%n%s%n%n%b' " .
           " $self->{since}..$self->{orig_head} >> $filename");
 exit $ret if $ret;

 # Now, reset and commit
 $ret = ExecUtil::execute("$GIT_CMD reset --soft $self->{since}");
 exit $ret if $ret;
 $ret = ExecUtil::execute("$GIT_CMD commit -F $filename --edit",
                          ignore_ret => 1);

 # Restore the branch pointer if the commit failed (e.g. empty log message)
 ExecUtil::execute("$GIT_CMD reset --soft $self->{orig_head}") if $ret != 0;

 unlink($filename);
 return 0;
}

###########################################################################
# stage                                                                   #
###########################################################################
package stage;
@stage::ISA = qw(subcommand);
INIT {
 $COMMAND{stage} = {
   new_command => 1,
   section => 'modification',
   about => 'Mark content in files as being ready for commit'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1,
                               git_equivalent => 'add',
                               @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg stage [--] PATH...

Description:
 Marks the contents of the specified files as being ready to commit,
 scheduling them for addition to the repository.  (This is also known as
 staging.)  This step is often not neccessary, since 'eg commit' will fall
 back to unstaged changes if you have not staged anything.  When a
 directory is passed, all files in that directory or any subdirectory are
 recursively added.

 You can use 'eg unstage PATH...' to unstage files.

 See 'eg help topic staging' for more details, including situations where
 you might find staging useful.

Examples:
 Create a new file, and mark it for addition to the repository.
     \$ echo hi > there
     \$ eg stage there

 (Advanced) Mark some changes as good, add some verbose sanity checking code,
 then commit just the good changes.
     Implement some cool new feature in somefile.C
     \$ eg stage somefile.C
     Add some verbose sanity checking code to somefile.C
     Decide to commit the new feature code but not the sanity checking code:
     \$ eg commit --staged

 (Advanced) Show changes in a file, split by those that you have marked as
 good and those that you haven't:
     Make various edits
     \$ eg stage file1 file2
     Make more edits, include some to file1
     \$ eg diff            # Look at all the changes
     \$ eg diff --staged   # Look at the \"ready to be committed\" changes
     \$ eg diff --unstaged # Look at the changes not ready to be commited

Options:
 --
   This option can be used to separate command-line options from the list
   of files, (useful when filenames might be mistaken for command-line
   options).
";
 $self->{'differences'} = '
 eg stage is a command new to eg that is not part of git (update: it is
 part of newer versions of git, with identical meaning to eg).  eg stage
 merely calls git add.
';
 return $self;
}

sub run {
 my $self = shift;

 @ARGV = Util::quote_args(@ARGV);
 return ExecUtil::execute("$GIT_CMD add @ARGV", ignore_ret => 1);
}

###########################################################################
# stash                                                                   #
###########################################################################
package stash;
@stash::ISA = qw(subcommand);
INIT {
 $COMMAND{stash} = {
   section => 'timesavers',
   about => 'Save and revert local changes, or apply stashed changes',
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   initial_commit_error_msg => "Error: Cannot stash away changes when there " .
                               "is no commit yet.",
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg stash list [--details]
 eg stash [save DESCRIPTION]
 eg stash apply [DESCRIPTION]
 eg stash show [OPTIONS] [DESCRIPTION]
 eg stash (drop [DESCRIPTION] | clear)

Description:
 This command can be used to remove any changes since the last commit,
 stashing these changes away so they can be reapplied later.  It can also
 be used to apply any previously stashed away changes.  This command can
 be used multiple times to have multiple sets of changes stashed away.

 Unknown files (files which you have never run 'eg stage' on) are
 unaffected; they will not be stashed away or reverted.

 When no arguments are specified to eg stash, the current changes are
 saved away with a default description.

 WARNING: Using the default description can be a bad idea if you will not
 be reapplying the stash very soon.  The default description provided for
 you is based on the commit message of the most recent commit, which has
 confused some users into believing that they have already incorporated
 changes from a stash and throwing the stash away (something that can be
 recovered from, but which involves some sleuthing and low-level commands
 like git-fsck and git-cat-file).

Examples:
 You have lots of changes that you're working on, then get an important
 but simple bug report.  You can stash away your current changes, fix the
 important bug, and then reapply the stashed changes:
     \$ eg stash
     fix, fix, fix, build, test, etc.
     \$ eg commit
     \$ eg stash apply

 You can provide a description of the changes being stashed away, and
 apply previous stashes by their description (or a unique substring of the
 description).
     make lots of changes
     \$ eg stash save incomplete refactoring work
     work on something else that you think will be a quick fix
     \$ eg stash save longer fix than I thought
     fix some important but one-liner bug
     \$ eg commit
     \$ eg stash list
     \$ eg stash apply incomplete refactoring work
     finish off the refactoring
     \$ eg commit
     \$ eg stash apply fix than I
     etc., etc.

 You want to get some details about an existing stash created above:
     \$ eg stash show incomplete refactoring
     \$ eg stash show -p incomplete refactoring

Options:
 list [--details]
   Show the saved stash descriptions.  If the --details flag is present,
   provide more information about each stash.

 save DESCRIPTION
   Save current changes with the description DESCRIPTION.  The
   description cannot start with \"-\".

 apply [DESCRIPTION]
   Apply the stashed changes with the specified description.  If no
   description is specified, and more than one stash has been saved, an
   error message will be shown.  The description cannot start with \"-\".

 show [OPTIONS] [DESCRIPTION]
   Show the stashed changes with the specified description.  If no
   description is specified, and more than one stash has been saved, an
   error message will be shown.  The description cannot start with \"-\".

   Note that the output shown is the output from diff --stat.  If you
   want the full patch, pass the -p option.  Other options for
   controlling diff output (such as --name-status or --dirstat, see
   'git help diff') are also possible options.

 drop [DESCRIPTION]
   Delete the specified stash.  The description cannot start with
   \"-\".

 clear
   Delete all stashed changes.
";
 $self->{'differences'} = '
 eg stash is only cosmetically different than git stash, and is fully
 backwards compatible.

 eg stash list, by default, only shows the saved description -- not
 the reflog syntax or branch the change was made on.

 eg stash apply and eg stash show also accept any string and will
 apply or show the stash whose description contains that string.
 Although stash and apply accept reflog syntax (like their git stash
 counterparts), i.e. while
     $ eg stash apply stash@{3}
 will work, I think it will be easier for the user to run
     $ eg stash apply rudely interrupted changes
';
 return $self;
}

sub preprocess {
 my $self = shift;
 my $package_name = ref($self);

 #
 # Parse options
 #
 my @args;
 if (scalar(@ARGV) > 0 && $ARGV[0] ne "--") {
   main::GetOptions("--help" => sub { $self->help() });
 }

 # Get the (sub)subcommand
 if (scalar @ARGV == 0) {
   $self->{subcommand} = 'save';
 } elsif ($ARGV[0] =~ /^--/) {
   $self->{subcommand} = "save";
 } else {
   $self->{subcommand} = shift @ARGV;
   if ($self->{subcommand} eq '-k') {
     $self->{subcommand} = "save";
     unshift @ARGV, '-k';
   }
   push(@args, $self->{subcommand});

   # Pass all flags on to git
   while(@ARGV > 0 && $ARGV[0] =~ /^-/ && $ARGV[0] !~ /^--$/) {
     if ($self->{subcommand} eq 'list' && $ARGV[0] eq '--refs') {
       $self->{show_refs} = 1;
       shift @ARGV;
     } elsif ($self->{subcommand} eq 'list' && $ARGV[0] eq '--details') {
       $self->{show_details} = 1;
       shift @ARGV;
     } else {
       push(@args, shift @ARGV);
     }
   }
   if ($self->{subcommand} eq 'branch') {
     push(@args, shift @ARGV);  # Pull off the branch name
   }
 }

 # Show a help message if they picked a bad stash subaction.
 my @valid_commands = qw(list show apply clear save drop pop branch create);
 if (! grep {$_ eq $self->{subcommand}} @valid_commands) {
   print STDERR<<EOF;
Aborting; invalid stash subcommand: $self->{subcommand}
EOF
   exit 1;
 }

 # Translate the description passed to apply or show into a reflog reference
 my @commands_accepting_existing_stash = qw(show drop pop apply branch);
 if ((grep {$_ eq $self->{subcommand}} @commands_accepting_existing_stash) &&
     scalar @ARGV > 0) {
   my $stash_description = "@ARGV";
   my $single_word_desc = (scalar(@ARGV) == 1);
   @ARGV = ();
   if ($stash_description =~ m#^stash\@{[^{]+}$# ||
       ($single_word_desc && RepoUtil::valid_ref($stash_description))) {
     push(@args, $stash_description)
   } else {
     # Will need to compare arguments to existing stash descriptions...
     print "  >>Getting stash descriptions to compare to arguments:\n"
       if $DEBUG;
     my ($retval, $output) =
       ExecUtil::execute_captured("$EG_EXEC stash list --refs");
     my @lines = split('\n', $output);
     my %refs;
     my %bad_refs;
     while (@lines) {
       my $desc = shift @lines;
       my $ref = shift @lines;
       $bad_refs{$desc}++ if defined $refs{$desc};
       $refs{$desc} = $ref;
     }

     # See if the stash description matches zero, one, or more existing
     # stash descriptions; convert it to a reflog entry if only one
     my @matches = grep {$_ =~ m#\Q$stash_description\E#} (keys %refs);
     if (scalar @matches == 0) {
       die "No stash matching '$stash_description' exists!  Aborting.\n";
     } elsif (scalar @matches == 1) {
       # Only one regex match; use it
       $stash_description = $matches[0];
     } else {
       # See if our string matches one stash description exactly; if so,
       # we can use it.
       if (!grep {$_ eq $stash_description} (keys %refs)) {
         die "Stash description '$stash_description' matches multiple " .
             "stashes:\n  " . join("\n  ", @matches) . "\n" .
             "Aborting.\n";
       }
     }
     die "Stash description '$stash_description' matches multiple stashes.\n"
       if $bad_refs{$stash_description};

     push(@args, $refs{$stash_description});
   }
 }

 # Add any unprocessed args to the arguments to use
 push(@args, @ARGV);

 # Reset @ARGV with the built up list of arguments
 @ARGV = @args;
}

sub run {
 my $self = shift;
 my $package_name = ref($self);
 my $ret;

 @ARGV = Util::quote_args(@ARGV);
 if ($self->{subcommand} eq 'list') {
   my $output = "";
   open($OUTFH, '>', \$output) ||
     die "eg $package_name: cannot open \$OUTFH: $!";

   $ret = ExecUtil::execute("$GIT_CMD $package_name @ARGV", ignore_ret => 1);

   my @lines = split('\n', $output);
   my $regex =
     qr#(stash\@{[^}]+}): (?:WIP )?[Oo]n [^:]*: (?:[0-9a-f]+\.\.\. )?#;
   foreach my $line (@lines) {
     if ($self->{show_details}) {
       print "$line\n";
     } else {
       $line =~ s/$regex//;
       print "$line\n";
       print "$1\n" if $self->{show_refs};
     }
   }
 } else {
   $ret = ExecUtil::execute("$GIT_CMD $package_name @ARGV", ignore_ret => 1);
 }
 return $ret;
}

###########################################################################
# status                                                                  #
###########################################################################
package status;
@status::ISA = qw(subcommand);
INIT {
 $COMMAND{status} = {
   section => 'discovery',
   about => 'Summarize current changes'
   };
 $ALIAS{'st'} = "status";
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg status

Description:
 Show the current state of the project.  In addition to showing the
 currently active branch, whether you have unpushed local commits,
 whether you have stashed any sets of changes away (see 'eg help
 stash'), this command will list files with content in any of the
 following states:

    Unknown files
      Files that are not explicitly ignored (i.e. do not appear in an
      ignore list such as a .gitignore file) but whose contents are still
      not tracked by git.

      These files can become known by running 'eg stage FILENAME', or
      ignored by having their name added to a .gitignore file.

    Newly created unknown files
      Same as unknown files; the reason for splitting unknown files into
      two sets is to make it easier to find the files users are more
      likely to want to add.  Also, 'eg commit' will by default error out
      with a warning message if there are any newly created unknown files
      in order to prevent forgetting to add files that should be included
      in a commit.

    Modified submodules:
      subdirectories that are tracked under their own git repository, and
      that are being tracked via use of the 'git submodule' command.

    Changes not staged for commit (\"unstaged\")
      Files whose contents have been modified in the working copy.

      (Advanced usage note) If you explicitly mark all the changes in a
      file as ready to be committed, then the file will not appear in this
      list and will instead appear in the \"staged\" list (see below).
      However, a file can appear in both the unstaged and staged lists if
      only part of the changes in the file are marked as ready for commit.

    Unmerged paths (files with conflicts)
      Files which could not be automatically merged.  If such files are
      text files, they will have the typical conflict markers.  These
      files need to be manually edited to give them the correct contents,
      and then the user should inform git that the conflicts are resolved
      by running 'eg resolved FILENAME'.

    Changes ready to be committed (\"staged\")
      Files with content changes that have explicitly been marked as ready
      to be committed.  This state only typically appears in advanced
      usage.

      Files enter this state through the use of 'eg stage'.  Files can
      return to the unstaged state by running 'eg unstage' See 'eg help
      topic staging' to learn about the staging area.

";
 $self->{'differences'} = "
 eg status output is essentially just a streamlined and cleaned version of
 git status output, with the addition of a new section (newly created
 untracked files) and an extra status message being displayed when in the
 middle of a special state (am, bisect, merge, or rebase).

 The streamlining serves to avoid information overload to new users (which
 is only possible with a less error prone \"commit\" command) and the
 cleaning (removal of leading hash marks) serves to make the system more
 inviting to new users.

 A slight wording change was done to transform \"untracked\" to \"unknown\"
 since, as Havoc pointed out, the word \"tracked\" may not be very self
 explanatory (in addition to the real meaning, users might think of:
 \"tracked in the index?\", \"related to remote tracking branches?\", \"some
 fancy new monitoring scheme unique to git that other vcses do not have?\",
 \"is there some other meaning?\").  I do not know if \"known\" will fully
 solve this, but I suspect it will be more self-explanatory than
 \"tracked\".

 There are also slight changes to the section names to reinforce
 consistent naming when referring to the same concept (staging, in this
 case), but the changes are very slight.

 The extra status message when in the middle of an am, bisect, merge,
 or rebase serves two purposes: to remind users that they are in the
 middle of some operation (some people don't use the special prompt
 from git's bash-completion support), and to provide a command users
 can run to get help resolving such situations.  (Many users were
 confused about or unaware how to resolve incomplete merges and
 rebases; providing them with a specially written help page they
 could access seemed to effectively assist them figure out the
 appropriate steps to take -- especially in tricky or special cases.)
";
 return $self;
}

sub preprocess {
 my $self = shift;

 my @old_argv = @ARGV;
 my $no_filter = 0;
 Getopt::Long::Configure("permute");
 my $result = main::GetOptions(
   "help|h"    => sub { $self->help() },
   "short|s"   => sub { $no_filter = 1 },
   "suno|sunormal|suall" => sub { $no_filter = 1 },  # git status parser allows combining -s and -u options, somewhat weirdly
   "porcelain" => sub { $no_filter = 1 },
   "z"         => sub { $no_filter = 1 },
   );
 @ARGV = @old_argv;
 $self->{no_filter} = $no_filter;
}

sub run {
 my $self = shift;

 -t STDOUT and $ENV{"GIT_PAGER_IN_USE"}=1;
 return $self->SUPER::run() if $self->{no_filter};

 $self->{special_state} = RepoUtil::get_special_state($self->{git_dir});

 @ARGV = Util::quote_args(@ARGV);
 return ExecUtil::execute("$GIT_CMD status @ARGV", ignore_ret => 1);
}

sub postprocess {
 my $self = shift;
 my $output = shift;

 # If we can't parse the git status output, what we tell the user...
 my $workaround_msg =
   "You'll need to use an older git or a newer eg or 'git status'.";

 if ($DEBUG == 2) {
   print "    >>(No commands to run, just data to print)<<\n";
   return;
 }

 if ($self->{no_filter}) {
   print $output;
   return;
 }

 my $branch;
 my $initial_commit = 0;
 my @sections;
 my %files;
 my %section_mapping = (
      'Untracked files:' => 'Unknown files:',
      'Changes to be committed:' => 'Changes ready to be committed ("staged"):',
      'Changed but not updated:' => 'Changes not staged for commit ("unstaged"):',
      'Changes not staged for commit:' => 'Changes not staged for commit ("unstaged"):',
      'Unmerged paths:' => 'Unmerged paths (files with conflicts):'
      );

 my @basic_info;
 my @diff_info;

 # Exit early if git status had an error
 if ($output =~ m/^fatal:/) {
   print STDERR $output;
   exit 128;
 }

 my $status_hints = RepoUtil::get_config("advice.statusHints");
 $status_hints = (!defined($status_hints) || $status_hints eq "true");

 # Parse the output
 my @lines = split('\n', $output);
 my $cur_state = -1;
 while (@lines) {
   my $line = shift @lines;
   my $section = undef;
   my $title;

   if ($line =~ m/^# On branch (.*)$/) {
     $branch = $1;
   } elsif ($line =~ m/^# Initial commit$/) {
     $initial_commit = 1;
   } elsif ($line =~ m/^# ([A-Z].*:)$/) {
     $cur_state = 1;
     $title = $section_mapping{$1} || $1;
     $section = $title;
   } elsif ($cur_state < 0) {
     next if $line !~ m/^# (.+)/;
     push(@basic_info, $1);
   } elsif ($line =~ m/^no changes added to commit/ ||
            $line =~ m/^# Untracked files not listed/) {
     next;  # Skip this line
   } elsif ($line =~ m#^(?:\e\[.*?m)?diff --git a/#) {
     push(@diff_info, $line);
     push(@diff_info, @lines);
     last;
   } else {
     die "ERROR: Cannot parse git status output.\n" .
         "$workaround_msg\n" .
         "Remaining unparsed lines:\n$line\n" . join("\n", @lines) . "\n";
   }

   # If we're inside a section type, parse it
   if ($cur_state > 0) {
     push (@sections, $section);
     my @section_files;
     my $hints;

     # Parse the hints first
     $line = shift @lines;
     if ($status_hints) {
       while ($line =~ m/^#\s+\((?:use "|commit).*/) {
         $hints .= $line;
         $line = shift @lines;
       }
       die("Bug parsing git status output.\n$workaround_msg\n") if $line ne '#';
       $line = shift @lines; # Get rid of blank line
     }

     while (defined $line && $line =~ m/^(?:\e\[.*?m)?#.+$/) {
       if ($line =~ m/^(?:\e\[.*?m)?#(\s+)(.*)/) {
         my $space = $1;
         my $file = $2;

         # Remove leading space character for submodule changes
         # (There's no real reason to do this other than laziness in
         # updating test file results; output looks fine either way.)
         $space =~ s/^[ ]//;
         # Workaround the file not have proper terminating color escape sequence
         if ($file =~ /^\s*\e\[.*?m/ && $file !~ /\e\[m$/) {
           $file .= "\e[m";
         }
         push @section_files, "$space$file";
       }
       $line = shift @lines;
       unshift(@lines, $line) if $line && $line =~ m#^(?:\e\[.*?m)?diff --git a/#;
     }

     if (defined($files{$section})) {
       push(@{$files{$section}{'file_list'}}, @section_files);
     } else {
       $files{$section} = { title     => $title, # may be undef
                            hint      => $hints,
                            file_list => \@section_files };
     }

     # Record that we finished parsing this section
     $cur_state = 0;
   }
 }

 # Split the unknown files into those that are newly created and those that
 # have been around
 if (defined($files{'Unknown files:'})) {
   # Get the list of unknown files that have been around for a while
   my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();
   my %old_unknown;
   if (-f "$git_dir/info/ignored-unknown") {
     my @old_unknown_files = `cat "$git_dir/info/ignored-unknown"`;
     chomp(@old_unknown_files);
     @old_unknown_files =
       Util::reroot_paths__from_to_files($top_dir, $cur_dir, @old_unknown_files);
     map { $old_unknown{$_} = 1 } @old_unknown_files;
   }

   my @new_unknowns;
   my @old_unknowns;
   foreach my $fileline (@{$files{'Unknown files:'}{'file_list'}}) {
     $fileline =~ m#(\s+(?:\e\[.*?m)?)(.*?)((?:\e\[m)?)$# ||
       die "Failed parsing git status output: '$fileline'\n$workaround_msg\n";
     if ($old_unknown{$2}) {
       push(@old_unknowns, $fileline);
     } else {
       push(@new_unknowns, $fileline);
     }
   }

   my ($index) = grep $sections[$_] eq "Unknown files:", 0 .. $#sections;
   splice(@sections, $index, 1);
   if (@new_unknowns) {
     $files{'new_unknowns'} = { title     => 'Newly created unknown files:',
                                file_list => \@new_unknowns };
     splice(@sections, $index++, 0, 'new_unknowns');
   }
   if (@old_unknowns) {
     $files{'old_unknowns'} = { title     => 'Unknown files:',
                                file_list => \@old_unknowns };
     splice(@sections, $index, 0, 'old_unknowns');
   }
 }

 # Print out the branch we are on
 if (defined $branch) {
   print "(On branch $branch";
   print ", no commits yet" if $initial_commit;
   print ")\n";
 }
 foreach my $line (@basic_info) {
   print "($line)\n";
 }
 my ($retval, $num_stashes) =
     ExecUtil::execute_captured("$GIT_CMD stash list | wc -l");
 chomp($num_stashes);
 if ($num_stashes > 0) {
   print "(You have $num_stashes stash(es).  Use 'eg stash list' to see them.)\n";
 }

 # Print out info about any special state we're in
 my $notice = "";
 if (defined $self->{special_state}) {
   my ($highlight, $reset) = ("", "");
   if (-t STDOUT) {
     $highlight=`$GIT_CMD config --get-color color.status.header "red reverse"`;
     $reset=`$GIT_CMD config --get-color "" "reset"`;
   }

   $notice .= "($highlight";
   $notice .= "YOU ARE IN THE MIDDLE OF A $self->{special_state}; ";
   $notice .= "RUN 'eg help topic middle-of-";
   if ($self->{special_state} eq "APPLY MAIL OR REBASE") {
     # FIXME: How do we get into this state anyway, and what should they run?
     # Well, printing nothing will just get them the general topic page, then
     # they can pick between am and rebase
   } elsif ($self->{special_state} =~ /REBASE$/) {
     $notice .= "rebase";
   } elsif ($self->{special_state} eq "APPLY MAIL") {
     $notice .= "am";
   } elsif ($self->{special_state} eq "MERGE") {
     $notice .= "merge";
   } elsif ($self->{special_state} eq "BISECT") {
     $notice .= "bisect";
   }
   $notice .= "' FOR MORE INFO.";
   $notice .= "$reset)\n";
   print $notice;
 }

 # Print out all the various changes
 my $linecount = 0;
 foreach my $section (@sections) {
   if (defined($files{$section})) {
     print "$files{$section}{'title'}\n";
     $linecount += 1;
     foreach my $fileline (@{$files{$section}{'file_list'}}) {
       print "$fileline\n";
       $linecount += 1;
     }
   }
 }

 # Repeat the notice so users will see it
 if (defined $self->{special_state} && $linecount > 0) {
   print $notice;
 }

 # Print the diff if we're running with the -v option
 print join("\n", @diff_info)."\n" if (@diff_info);
}

###########################################################################
# switch                                                                  #
###########################################################################
package switch;
@switch::ISA = qw(subcommand);
INIT {
 $COMMAND{switch} = {
   new_command => 1,
   section => 'projects',
   about => 'Switch the working copy to another branch'
   };
 $ALIAS{'sw'} = "switch";
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   git_equivalent => 'checkout',
   initial_commit_error_msg => "Error: Cannot create or switch branches " .
                               "until a commit has been made.",
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg switch BRANCH
 eg switch REVISION

Description:
 Switches the working copy to another branch, or to another tag or
 revision.  (Switch is an operation that can be done locally, without any
 network connectivity).

 To list, create, or delete branches to switch to, use eg branch.  To
 list, create, or delete tags to switch to, use eg tag.  To list, create,
 or delete revisions, use eg log, eg commit, or eg reset, respectively.
 :-)

Examples:
 Switch to the 4.8 branch
     \$ eg switch 4.8

 Switch the working copy to the v4.3 tag
     \$ eg switch v4.3

";
 $self->{'differences'} = '
 eg switch is a subset of the functionality of git checkout; the abilities
 and flags for creating and switching branches are identical between the
 two, just the name of the function is different.

 The ability of git checkout to get older versions of files is not part of
 eg switch; instead that ability can be found with eg revert.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 if (scalar(@ARGV) == 0) {
   print STDERR<<EOF;
No branch (or revision) to switch to specified!  See the help for eg switch
and eg branch.  The following branches exist, with the current branch marked
with an asterisk:

EOF
   my $branch_obj = "branch"->new();
   $branch_obj->run();
   exit 1;
 }

 # Don't let them try to use eg switch to check out older revisions of files;
 # this is just supposed to be a subset of git checkout
 if (!grep {$_ =~ /^-/} @ARGV) {
   die "Invalid arguments to eg switch: @ARGV\n" if @ARGV > 1;
   Util::push_debug(new_value => 0);
   my $valid_ref = RepoUtil::valid_ref($ARGV[0]);
   Util::pop_debug();
   die "Invalid branch/revision reference: $ARGV[0]\n" if !$valid_ref;
 }

 $self->SUPER::preprocess();
}

sub run {
 my $self = shift;

 @ARGV = Util::quote_args(@ARGV);
 return ExecUtil::execute("$GIT_CMD checkout @ARGV", ignore_ret => 1);
}

###########################################################################
# tag                                                                     #
###########################################################################
package tag;
@tag::ISA = qw(subcommand);
INIT {
 $COMMAND{tag} = {
   unmodified_behavior => 1,
   extra => 1,
   section => 'modification',
   about => 'Provide a name for a specific version of the repository'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg tag TAG [REVISION]
 eg tag -d TAG

Description:
 Create or delete a tag (i.e. a nickname) for a specific version of the
 project.  (Tags can also be annotated or digitally signed; see the 'See
 Also section.)

 Note that tags are local; creation of tags in a remote repository can be
 accomplished by first creating a local tag and then pushing the new tag
 to the remote repository using eg push.

Examples
 List the available local tags
     \$ eg tag

 Create a new tag named good-version for the last commit.
     \$ eg tag good-version

 Create a new tag named version-2.0.3 for 3 versions before the last commit
 (assuming one is on a branch named project-2.0)
     \$ eg tag version-2.0.3 project-2.0~3

 Delete the tag named gooey
     \$ eg tag -d gooey

 Create a new tag named look_at_me in the default remote repository
     \$ eg tag look_at_me
     \$ eg push --tag look_at_me

Options:
 -d
   Delete the specified tag
";
 return $self;
}

###########################################################################
# track                                                                   #
###########################################################################
package track;
@track::ISA = qw(subcommand);
INIT {
 $COMMAND{track} = {
   new_command => 1,
   extra => 1,
   section => 'projects',
   about => 'Set which remote branch a local branch tracks'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, git_equivalent => '', @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg track (--show [LOCAL_BRANCH] | --show-all)
 eg track [LOCAL_BRANCH] REMOTE_TRACKING_BRANCH
 eg track --unset [LOCAL_BRANCH]

Description:
 eg track helps manage which remote branches your local branches
 track.  Having a local branch track a remote branch means that when
 the local branch is the active branch, that the corresponding remote
 branch is the default push or pull location for eg push or eg pull.

 There are three different things eg track can do, each corresponding to
 one of the usage forms listed above: list which remote branch a local
 branch tracks, make a local branch track some remote branch, or make a
 local branch no longer track any remote branch.

 If LOCAL_BRANCH is not specified, the currently active branch is
 assumed.

Examples:
 Show which remote branches all local branches are tracking
    \$ eg track --show-all

 Show which remote branch the local branch 'stable' tracks
    \$ eg track --show stable

 Make your currently active branch track the 'magic' branch of the 'jim'
 repository (see 'eg help remote' for setting up nicknames like 'jim' for
 remote repositories)
     \$ eg track jim/magic

 Make your branch 'bugfix' track the 'master' branch of the 'origin'
 repository (note that 'origin' is the repository you cloned from, unless
 you've explicitly changed that using the eg remote command or some other
 low-level means):
     \$ eg track bugfix origin/master

 Have your 'random-changes' branch stop tracking any remote branch:
     \$ eg track --unset random-changes
";
 $self->{'differences'} = '
 eg track is unique to eg; git does not have a similar command.
';
 return $self;
}

sub preprocess {
 my $self = shift;

 # Check for the --help arg
 my $mode = "set";
 my ($local_branch, $remote_branch, $remote);
 Getopt::Long::Configure("permute");
 my $result = main::GetOptions(
   "--help"    => sub { $self->help() },
   "show"      => sub { $mode = "show"; },
   "show-all"  => sub { $mode = "show-all"; },
   "unset"     => sub { $mode = "unset"; });

 # Get the remote branch to track, if we're setting up tracking info
 if ($mode eq "set") {
   my ($ret, $remote_tracking_branch);

   # Sanity checks
   die "Error: Too many arguments.  Run 'eg help track'.\n" if (@ARGV > 2);
   die "Error: Insufficient arguments.  Run 'eg help track'.\n" if (@ARGV < 1);

   # Get the remote tracking branch, and sanity check it
   $remote_tracking_branch = pop @ARGV;
   die "Error: Invalid remote tracking branch '$remote_tracking_branch'\n" .
       "Correct format for remote tracking branches is:\n" .
       "  REMOTENAME/REMOTEBRANCHNAME\n" if $remote_tracking_branch !~ '/';

   # Split remote tracking branch into remote name and remote branch name
   ($remote, $remote_branch) = split('/', $remote_tracking_branch, 2);

   # Make sure the remote is a valid name
   Util::push_debug(new_value => 0);
   $ret = ExecUtil::execute("$GIT_CMD remote | grep '^$remote\$' > /dev/null",
                             ignore_ret => 1);
   die "Error: '$remote' is not a valid remote name.\n" .
       "(Use 'eg remote' to find valid remote names).\n" if $ret;
   Util::pop_debug();
 }

 # Get the local branch to operate on
 $local_branch = shift @ARGV;
 if (!$local_branch && $mode ne "show-all") {
   $local_branch = RepoUtil::current_branch();
 }
 # Make sure $local_branch is defined and has a valid value
 Util::push_debug(new_value => 0);
 if (!$local_branch) {
   die "Error: There is no active branch, so it cannot track anything.\n";
 } elsif (!RepoUtil::valid_ref("refs/heads/$local_branch")) {
   die "Error: The branch '$local_branch' is not (yet) a valid local branch.\n";
 }
 Util::pop_debug();

 $self->{mode} = $mode;
 $self->{branch} = $local_branch;
 if ($mode eq "set") {
   $self->{remote_branch} = "refs/heads/$remote_branch";
   $self->{remote} = $remote
 }
}

sub run {
 my $self = shift;

 my ($ret, $output);
 my ($mode, $branch, $remote_branch, $remote) =
    ($self->{mode}, $self->{branch}, $self->{remote_branch}, $self->{remote});

 if ($mode eq "show-all") {
   $branch = ".*";
   $mode = "show";
 }

 if ($mode eq "show") {
   my %tracking;

   # Get the remote tracking flags
   ($ret, $output) = ExecUtil::execute_captured(
     "$GIT_CMD config --get-regexp '^branch\.$branch\.(remote|merge)'",
     ignore_ret => 1);
   chomp($output);

   # Exit early if we're in --translate mode
   if ($DEBUG == 2) {
     print "    >>(No more commands to run, " .
           "just output to parse and print)<<\n";
   }

   # Check if there are no matches
   if ($ret) {
     my $message = "Branch $branch is not";
     $message = "No branches are" if $branch eq ".*";
     print "$message set to track anything.\n";
     return 0;
   }

   # Fill the %tracking hash
   my @lines = split('\n', $output);
   foreach my $line (@lines) {
     $line =~ /^branch\.(.*)\.(remote|merge) (.*)$/
       or die "Bad output '$line'!\n";

     $tracking{$1}{$2} = $3;
   }

   # Show all the tracking information
   foreach my $bname (sort keys %tracking) {
     my $remote = $tracking{$bname}{'remote'} || "''";
     my $remote_branch = $tracking{$bname}{'merge'} || "''";
     print "Branch $bname tracks $remote_branch of remote $remote.\n";
   }
   return 0;

 } elsif ($mode eq "set") {
   $ret =  ExecUtil::execute(
      "$GIT_CMD config branch.$branch.remote $remote", ignore_ret => 1);
   $ret |= ExecUtil::execute(
      "$GIT_CMD config branch.$branch.merge $remote_branch", ignore_ret => 1);

   if (!$ret && $DEBUG < 2) {
     print "$branch now set to track " .
           "branch $remote_branch of remote $remote.\n";
   }
   return $ret;
 } elsif ($mode eq "unset") {
   ExecUtil::execute(
      "$GIT_CMD config --unset branch.$branch.remote", ignore_ret => 1);
   ExecUtil::execute(
      "$GIT_CMD config --unset branch.$branch.merge", ignore_ret => 1);

   if ($DEBUG < 2) {
     print "$branch no longer tracks any remote branch.\n";
   }
   return 0;
 }
}

###########################################################################
# unstage                                                                 #
###########################################################################
package unstage;
@unstage::ISA = qw(revert);
INIT {
 $COMMAND{unstage} = {
   new_command => 1,
   extra => 1,
   section => 'modification',
   about => 'Mark changes in files as no longer ready for commit'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 1, git_equivalent => '', @_);
 bless($self, $class);

 unshift(@ARGV, "--") if scalar(@ARGV) > 0 && $ARGV[0] ne "--";
 unshift(@ARGV, "--staged");

 $self->{'help'} = "
Usage:
 eg unstage [--] PATH...

Description:
 Marks the changes in the specified files as not being ready to commit.
 When a directory is passed, all files in that directory or any
 subdirectory are recursively unstaged.

 Note that this command is equivalent to 'eg revert --staged PATH...'

 See 'eg help topic staging' for more details, including situations where
 you might find staging useful.

Examples:
 Create a new file, and mark it for addition to the repository, then change
 your mind
     \$ echo hi > there
     \$ eg stage there
     \$ eg unstage there

 Modify an existing file, mark the modified version as being ready for commit,
 then change your mind
     \$ echo some extra info at end of file >> foo
     \$ eg stage foo
     \$ eg unstage foo
";
 $self->{'differences'} = '
 eg unstage is a command new to eg that is not part of git; it is implemented
 on top of eg revert --staged, though it could as easily simply call through
 to git reset.
';
 return $self;
}

# unstage inherits from revert, and simply modifies @ARGV in new(), so that
# revert will get run with the right arguments

###########################################################################
# update                                                                  #
###########################################################################
package update;
@update::ISA = qw(subcommand);
INIT {
 $COMMAND{update} = {
   new_command => 1,
   extra => 1,
   section => 'compatibility',
   about => 'Use antiquated workflow for refreshing working copy, if safe'
   };
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(
   git_repo_needed => 1,
   git_equivalent => 'pull',
   @_);
 bless($self, $class);
 $self->{'help'} = "
Usage:
 eg update

Description:
 Gets updates from the default remote repository if updating is safe, and
 provides suggestions on proceeding otherwise.

 eg update does not accept any options...other than --help.

Examples:
 Get any updates from the remote repository
     \$ eg update
";
 $self->{'differences'} = '
 eg update is unique to eg; it exists primarily to ease the transition for
 cvs/svn users and to do something useful for them.  In particular, eg
 update is used just to do fast-forward updates when there are no local
 changes; if anything more than this is needed, eg advises users to run
 other commands.

 Here are the special cases eg update detects and provides tailored
 messages for:
   * User has local commits           => ask user to use eg pull instead
   * User provides argument to update => tell user to use eg switch for
                                         checking out an older revision or
                                         eg revert to undo changes to a file
   * User has locally deleted files   => tell user to use eg revert to
                                         undo local changes (and that they do
                                         not need to delete the file first as
                                         they did with cvs)
   * User has local modifications     => Tell user to stash or commit their
                                         changes before pulling updates
   * No default repository to contact => Tell user to run "eg remote add
                                         origin REPOSITORY_URL"
   * branch.BRANCH.merge not set and  => Warn user that we do not know which
     more than one remote branch         branch to pull from and suggest eg
     present                             pull or setting branch.BRANCH.merge
';
 return $self;
}

sub preprocess {
 my $self = shift;

 # Check for the --help arg
 my $result=main::GetOptions("--help" => sub { $self->help() });

 # Abort if the user specified any args other than --help
 if (@ARGV) {
   print STDERR <<EOF;
Aborting: No arguments to update are allowed.  If you are trying to switch
to a different revision, use eg switch.  If you are trying to undo the changes
to a particular file, use eg revert.
EOF
   exit 1;
 }

 # Check if there are local changes
 my $status = RepoUtil::commit_push_checks();
 my $has_changes = $status->{has_staged_changes} ||
   $status->{has_unstaged_changes} || $status->{has_unmerged_changes};
 if ($has_changes) {
   print STDERR <<EOF;
Aborting: You have local changes, and pulling updates could put your
working copy in a nonworking state.  Consider committing your changes
before updating, or using eg stash to stash the changes away and reapply
them after the update.
EOF

   if ($status->{output} =~ /^\s+deleted:/m) {
     print STDERR "\n";
     print STDERR <<EOF;
NOTE: If you are trying to undo the changes in a file, just run
 eg revert FILE
This works whether or not the file has been deleted.
EOF
   }

   exit 1;
 }

 if ($DEBUG) {
   print "  >>Commands to determine where to update from:\n";
 }

 # Check if there is a default repository to pull from
 # <This code mostly taken from pull, but "origin" serves as extra backup>
 my $branch = RepoUtil::current_branch() || "HEAD";
 my $repo = RepoUtil::get_default_push_pull_repository();
 $self->{repository} = $repo;
 $self->{local_branch} = $branch;

 # Check if there is a default branch to pull
 my $merge_branch = RepoUtil::get_config("branch.$branch.merge");
 if (!$merge_branch) {
   # Check if the remote repository has exactly 1 branch...if so, return it,
   # otherwise throw an error
   my ($quoted_repo) = Util::quote_args("$self->{repository}");
   my ($ret, $output) =
     ExecUtil::execute_captured("$GIT_CMD ls-remote -h $quoted_repo");
   if ($ret == 0) {
     my @remote_refs = split('\n', $output);
     if (@remote_refs == 1) {
       # git ls-remote -h output changed at some point to include the sha1sum;
       # we only want the refspec
       if ($remote_refs[0] =~ /^[0-9a-f]+\s+(.*)/) {
         $merge_branch = $1;
       } else {
         $merge_branch = $remote_refs[0];
       }
     }
   }
 }
 if (!$merge_branch) {
   print STDERR <<EOF;
Error: It is not clear which remote branch to update from.
You can either use eg pull instead, or run
 eg config branch.$branch.merge BRANCHANME
EOF
   exit 1;
 }
 $self->{merge_branch} = $merge_branch;
}

sub run {
 my $self = shift;
 my $package_name = ref($self);

 # Get value to set ORIG_HEAD to (unless we are on the initial commit)
 Util::push_debug(new_value => 0);
 my ($retval, $orig_sha1sum) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse HEAD", ignore_ret => 1);
 my $has_orig_head = ($retval == 0);
 Util::pop_debug();

 # Do the fetch && reset, making sure to set ORIG_HEAD
 my ($ret, $output) =
   ExecUtil::execute_captured("$GIT_CMD fetch $self->{repository} " .
                              "$self->{merge_branch}:$self->{local_branch}",
                              ignore_ret => 1);
 if ($output =~ /\[rejected\].*\(non fast forward\)/) {
   die "fatal: Cannot update because you have local commits; " .
       "try 'eg pull' instead.\n";
 } elsif ($ret != 0) {
   die "Error updating (output = $output); please report the bug, and\n" .
       "try using 'eg pull' instead.\n";
 } else {
   $ret = ExecUtil::execute_captured("$GIT_CMD reset --hard " .
                                     "$self->{local_branch}");
   if ($has_orig_head && $DEBUG < 2) {
     open(ORIG_HEAD, "> $self->{git_dir}/ORIG_HEAD");
     print ORIG_HEAD $output;
     close(ORIG_HEAD);
   }
   print "Updated the current branch.\n" if ($DEBUG < 2);
 }
 return $ret;
}

###########################################################################
# version                                                                 #
###########################################################################
package version;
@version::ISA = qw(subcommand);

BEGIN {
 undef *version::new unless $] < 5.010; # avoid name clashing
}

sub new {
 my $class = shift;
 my $self = $class->SUPER::new(git_repo_needed => 0, @_);
 bless($self, $class);
}

# Override help because we don't want to both definining $COMMAND{help}
sub help {
 my $self = shift;

 $self->{'help'} = "
Usage:
 eg version

Description:
 Show the current version of eg.
";

 open(OUTPUT, ">&STDOUT");
 print OUTPUT $self->{'help'};
 close(OUTPUT);
 exit 0;
}

sub run {
 my $self = shift;

 print "eg version $VERSION\n" if $DEBUG < 2;
 print "    >>(We can print the eg version directly)<<\n" if $DEBUG == 2;
 return $self->SUPER::run();
}



#*************************************************************************#
#*************************************************************************#
#*************************************************************************#
#                             UTILITY CLASSES                             #
#*************************************************************************#
#*************************************************************************#
#*************************************************************************#

###########################################################################
# ExecUtil                                                                #
###########################################################################
package ExecUtil;

# _execute_impl is the guts for execute() and execute_captured()
sub _execute_impl ($@) {
 my ($command, @opts) = @_;
 my ($ret, $output);
 my %options = ( ignore_ret => 0, capture_output => 0, @opts );

 if ($DEBUG) {
   print "    >>Running: '$command'<<\n";
   return $options{capture_output} ? (0, "") : 0 if $DEBUG == 2;
 }

 #
 # Execute the relevant command, in a subdirectory if needed, and capturing
 # stdout and stderr if wanted
 #
 if ($options{capture_output}) {
   if ($options{capture_stdout_only}) {
     $output = `$command`;
   } else {
     $output = `$command 2>&1`;
   }
   $ret = $?;
 } elsif (defined $OUTFH) {
   open(OUTPUT, "$command 2>&1 |");
   while (<OUTPUT>) {
     print $OUTFH $_;
   }
   close(OUTPUT);
   $ret = $?;
 } else {
   system($command);
   $ret = $?;
 }

 #
 # Determine retval
 #
 if ($ret != 0) {
   if (($? & 127) == 2) {
     print STDERR "eg: interrupted\n";
   }
   elsif ($? & 127) {
     print STDERR "eg: received signal ".($? & 127)."\n";
   }
   else {
     $ret = ($ret >> 8);
     if (! $options{ignore_ret}) {
       print STDERR "eg: failed ($ret)\n" if $DEBUG;
       if ($ret >> 8 != 0) {
         print STDERR "eg: command ($command) failed\n";
       }
       elsif ($ret != 0) {
         print STDERR "eg: command ($command) died (retval=$ret)\n";
       }
     }
   }
 }

 return $options{capture_output} ? ($ret, $output) : $ret;
}

# executes a command, capturing its output (both STDOUT and STDERR),
# returning both the return value and the output
sub execute_captured ($@) {
 my ($command, @options) = @_;
 return _execute_impl($command, capture_output => 1, @options);
}

# executes a command, returning its chomped output
sub output ($@) {
 my ($command, @options) = @_;
 my ($ret, $output) = execute_captured($command, @options);
 die "Failed executing '$command'!\n" if $ret != 0;
 chomp($output);
 return $output
}

# executes a command (output not captured), returning its return value
sub execute ($@) {
 my ($command, @options) = @_;
 return _execute_impl($command, @options);
}

###########################################################################
# RepoUtil                                                                #
###########################################################################
package RepoUtil;

# current_branch: Get the currently active branch
sub current_branch () {
 Util::push_debug(new_value => $DEBUG ? 1 : 0);
 my ($ret, $output) = ExecUtil::execute_captured("$GIT_CMD symbolic-ref HEAD",
                                                 ignore_ret => 1);
 Util::pop_debug();

 return undef if $ret != 0;
 chomp($output);
 $output =~ s#refs/heads/## || die "Current branch ($output) is funky.\n";
 return $output;
}

sub git_dir (%) {
 my $options = {force => 0, @_};  # Hashref initialized as we're told
 if (!$options->{force}) {
   return $GITDIR if ($GITDIR);
 }

 Util::push_debug(new_value => 0);
 my ($ret, $output) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse --git-dir", ignore_ret => 1);
 Util::pop_debug();

 return undef if $ret != 0;
 chomp($output);
 return $output;
}

sub get_dirs () {
 my $options = {force => 0, @_};  # Hashref initialized as we're told

 if ($CURDIR && !$options->{force}) {
   return ($CURDIR, $TOPDIR, $GITDIR);
 }

 Util::push_debug(new_value => 0);

 $CURDIR = main::getcwd();

 # Get the toplevel repository directory
 $TOPDIR = $CURDIR;
 my ($ret, $rel_dir) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse --show-prefix",
                              ignore_ret => 1);
 chomp($rel_dir);
 if ($ret != 0) {
   $TOPDIR = undef;
 } elsif ($rel_dir) {
   $rel_dir =~ s#/$##;  # Remove trailing slash
   $TOPDIR =~ s#\Q$rel_dir\E$##;
   $TOPDIR =~ s#/$##;  # Remove trailing slash
 }

 $GITDIR = git_dir(force => $options->{force});

 Util::pop_debug();

 return ($CURDIR, $TOPDIR, $GITDIR);
}

sub initial_commit () {
 my @output = `$GIT_CMD rev-parse --verify -q HEAD`;
 return $?;
}

sub valid_ref ($) {
 my ($ref) = @_;
 my ($ret, $sha1sum) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse --verify -q $ref",
                              ignore_ret => 1);
 return $ret == 0;
}

sub files_modified () {
 my @output = `$GIT_CMD commit --dry-run -a`;
 return $? == 0;
}

sub merge_branches () {
 my $git_dir = RepoUtil::git_dir();
 my $active_branch = RepoUtil::current_branch() || 'HEAD';
 my @merge_branches =
   `cat "$git_dir/MERGE_HEAD" | $GIT_CMD name-rev --stdin`;
 @merge_branches = map { /^[0-9a-f]* \((.*)\)$/ && $1 } @merge_branches;
 my @all_merge_branches = ($active_branch, @merge_branches);
 return @all_merge_branches;
}

sub get_special_state ($) {
 my $git_dir = shift;

 my $special_state;
 if ( -d "$git_dir/rebase-apply" ) {
   if ( -f "$git_dir/rebase-apply/rebasing" ) {
     return "REBASE";
   } elsif ( -f "$git_dir/rebase-apply/applying" ) {
     return "APPLY MAIL";
   } else {
     return "APPLY MAIL OR REBASE";
   }
 } elsif ( -f "$git_dir/rebase-merge/interactive" ) {
   return "INTERACTIVE REBASE";
 } elsif ( -d "$git_dir/rebase-merge" ) {
   return "MERGE REBASE";
 } elsif ( -f "$git_dir/MERGE_HEAD" ) {
   return "MERGE";
 } elsif ( -f "$git_dir/BISECT_LOG" ) {
   return "BISECT";
 }
 return $special_state;
}

sub get_config ($) {
 my $key = shift;
 my ($ret, $output) = ExecUtil::execute_captured("$GIT_CMD config --get $key",
                                                 ignore_ret => 1);
 return undef if $ret != 0;
 chomp($output);
 return $output;
}

sub set_config ($$) {
 my $key = shift;
 my $value = shift;
 ExecUtil::execute("$GIT_CMD config $key \"$value\"");
}

# XXX unused?
sub unset_config ($) {
 my $key = shift;
 ExecUtil::execute("$GIT_CMD config --unset $key", ignore_ret => 1);
}

sub get_only_branch ($$) {
 my $repository = shift;
 my $check_type = shift;

 if ($DEBUG == 2) {
   print "    >>Running: '$GIT_CMD ls-remote -h $repository'<<\n";
   return;
 }

 # Check if the remote repository has exactly 1 branch...if so, return it,
 # otherwise throw an error
 my ($quoted_repo) = Util::quote_args("$repository");
 my ($ret, $output) =
   ExecUtil::execute_captured("$GIT_CMD ls-remote -h $quoted_repo",
                              capture_stdout_only => 1, ignore_ret => 1);
 die "Aborting: Could not determine remote branches " .
     "from repository '$repository'\n" if $ret != 0;
 my @remote_refs = split('\n', $output);

 die "'$repository' has no branches to $check_type!\n" if @remote_refs == 0;
 my @remote_branches = map { m#[0-9a-f]+.*/(.*)$# && $1 } @remote_refs;

 if (@remote_branches > 1) {
   if ($check_type && $check_type eq "push") {
     print STDERR <<EOF;
Aborting: It is not clear which remote branch to push changes to.  Please
retry, specifying which branch(es) you want to push into from your current
EOF
   } else {
   print STDERR <<EOF;
Aborting: It is not clear which remote branch to pull changes from.  Please
retry, specifying which branch(es) you want to be merged into your current
EOF
   }
   print STDERR <<EOF;
branch.  Existing remote branches of
 $repository
are
 @remote_branches
EOF
   exit 1;
 }

 return $remote_branches[0];
}

sub get_default_push_pull_repository () {
 my $branch = current_branch();

 if ($branch) {
   my $default_remote = `$GIT_CMD config --get branch.$branch.remote`;
   if ($default_remote) {
     chomp($default_remote);
     return $default_remote;
   }
 }

 my @output = `$GIT_CMD config --get-regexp remote\.origin\.*`;
 if (@output) {
   return "origin";
 } else {
   print STDERR <<EOF;
Aborting: No repository specified, and "origin" is not set up as a remote
repository.  Please specify a repository or setup "origin" by running
 eg remote add origin URL
EOF
   exit 1;
 }
}

sub print_new_unknowns ($) {
 my ($new_unknowns) = @_;
 my $num = scalar(@$new_unknowns);
 print STDERR "New unknown files";
 print STDERR " include" if $num > 5;
 print STDERR ":\n";
 my $i = 0;
 foreach my $file (@$new_unknowns) {
   print STDERR "  $file\n";
   last if (++$i >= 5);
 }
 if ($num > 5) {
   print STDERR "Run 'eg status' to see a full list of new unknown files.\n";
 }
 exit 1;
}

# Error messages spewed by commit with non-clean working copies
sub commit_error_message_checks ($$$$) {
 my ($commit_type, $check_for, $status, $new_unknown) = @_;

 if ($check_for->{unmerged_changes} && $status->{has_unmerged_changes}) {
   print STDERR <<EOF;
Aborting: You have unresolved conflicts from your merge (run 'eg status' to get
the list of files with conflicts).  You must first resolve any conflicts and
then mark the relevant files as being ready for commit (see 'eg help stage' to
learn how to do so) before proceeding.
EOF
   exit 1;
 }

 if ($check_for->{no_changes} && $status->{has_no_changes}) {
   # There doesn't need to be any changes for a commit if we're trying to
   # make a merge commit.
   my $gitdir = git_dir();
   if ( ! -f "$gitdir/MERGE_HEAD" ) {
     die "Aborting: Nothing to commit (run 'eg status' for details).\n";
   }
 }
 elsif ($check_for->{unknown} && $check_for->{partially_staged} &&
        $status->{has_new_unknown_files} &&
        $status->{has_unstaged_changes} && $status->{has_staged_changes}) {
   print STDERR <<EOF;
Aborting: It is not clear which changes should be committed; you have new
unknown files, staged (explictly marked as ready for commit) changes, and
unstaged changes all present.  Run 'eg help $commit_type' for details (in
particular, the -b option and either the -a or --staged options).
EOF
   print_new_unknowns($new_unknown);
 }
 elsif ($check_for->{unknown} && $status->{has_new_unknown_files}) {
   print STDERR <<EOF;
Aborting: You have new unknown files present and it is not clear whether
they should be committed.  Run 'eg help $commit_type' for details (in
particular the -b option).
EOF
   print_new_unknowns($new_unknown);
 }
 elsif ($check_for->{partially_staged} &&
        $status->{has_unstaged_changes} && $status->{has_staged_changes}) {
   print STDERR <<EOF;
Aborting: It is not clear which changes should be committed; you have both
staged (explictly marked as ready for commit) changes and unstaged changes
present.  Run 'eg help $commit_type' for details (in particular, the -a and
--staged options).
EOF
   exit 1;
 }
}

# Error messages spewed by push, publish for non-clean working copies
sub push_error_message_checks ($$$$) {
 my ($clean_check_type, $check_for, $status, $new_unknown) = @_;

 if ($check_for->{unmerged_changes} && $status->{has_unmerged_changes}) {
   print STDERR <<EOF;
Aborting: You have unresolved conflicts from your merge (run 'eg status' to get
the list of files with conflicts).  You should first resolve any conflicts
before trying to $clean_check_type your work elsewhere.
EOF
   exit 1;
 }

 if ($check_for->{unknown} && $check_for->{changes} &&
     $status->{has_new_unknown_files} &&
     ($status->{has_unstaged_changes} || $status->{has_staged_changes})) {
   print STDERR <<EOF;
Aborting: You have new unknown files and changed files present.  You should
first commit any such changes (and/or use the -b flag to bypass this check)
before trying to $clean_check_type your work elsewhere.
EOF
   print_new_unknowns($new_unknown);
 }
 elsif ($check_for->{unknown} && $status->{has_new_unknown_files}) {
   print STDERR <<EOF;
Aborting: You have new unknown files present.  You should either commit these
new files before trying to $clean_check_type your work elsewhere, or use the
-b flag to bypass this check.
EOF
   print_new_unknowns($new_unknown);
 }
 elsif ($check_for->{changes} &&
        ($status->{has_unstaged_changes} || $status->{has_staged_changes})) {
   print STDERR <<EOF;
Aborting: You have modified your files since the last commit.  You should
first commit any such changes before trying to $clean_check_type your work
elsewhere, or use the -b flag to bypass this check.
EOF
   exit 1;
 }
}

# XXX called with 0 args or 2 args
sub commit_push_checks (;$$) {
 my $clean_check_type = shift;
 my $check_for = shift || {};
 my %status;

 # Determine some useful directories
 my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();

 # Save debug mode, print out commands used up front
 if ($DEBUG) {
   Util::push_debug(new_value => 0);
   if ($clean_check_type) {
     print "    >>Commands to gather data for pre-$clean_check_type sanity checks:\n";
   } else {
     print "    >>Commands to gather data for sanity checks:\n";
   }
   print "        $GIT_CMD status\n";
   print "        $GIT_CMD ls-files --unmerged\n";
   print "        $GIT_CMD symbolic-ref HEAD\n" if $check_for->{no_branch};
   print "        cd $top_dir && $GIT_CMD ls-files --exclude-standard --others --directory --no-empty-directory\n";
 } else {
   Util::push_debug(new_value => 0);
 }

 #
 # Determine which types of changes are present
 #
 my ($ret, $output) = ExecUtil::execute_captured("$EG_EXEC status",
                                                 ignore_ret => 1);
 my @unmerged_files = `$GIT_CMD ls-files --unmerged`;
 $status{has_new_unknown_files} = ($output =~ /^Newly created unknown files:$/m);
 $status{has_unstaged_changes}  = ($output =~ /^Changes not staged for commit/m);
 $status{has_staged_changes}    = ($output =~ /^Changes ready to be commit/m);
 $status{has_unmerged_changes}  = (scalar @unmerged_files > 0);
 $status{has_no_changes}        = !$status{has_unstaged_changes} &&
                                  !$status{has_staged_changes} &&
                                  !$status{has_unmerged_changes};
 $status{output} = $output;

 #
 # Determine which unknown files are "newly created"
 #
 my @new_unknown = `(cd "$top_dir" && $GIT_CMD ls-files --exclude-standard --others --directory --no-empty-directory)`;
 chomp(@new_unknown);
 if ($check_for->{unknown} && $status{has_new_unknown_files} &&
     -f "$git_dir/info/ignored-unknown") {
   my @old_unknown_files = `cat "$git_dir/info/ignored-unknown"`;
   chomp(@old_unknown_files);
   @new_unknown = Util::difference(\@new_unknown, \@old_unknown_files);
   $status{has_new_unknown_files} = (scalar(@new_unknown) > 0);
 }
 @new_unknown =
   Util::reroot_paths__from_to_files($top_dir, $cur_dir, @new_unknown);

 Util::pop_debug();

 if ($check_for->{no_branch}) {
   my $rc = system('$GIT_CMD symbolic-ref -q HEAD >/dev/null');
   $status{has_no_branch} = $rc >> 8;
 }

 return \%status if !defined $clean_check_type;

 if ($clean_check_type =~ /commit/) {
   commit_error_message_checks($clean_check_type,
                               $check_for,
                               \%status,
                               \@new_unknown);
 } elsif ($clean_check_type eq "push" || $clean_check_type eq "publish") {
   push_error_message_checks($clean_check_type,
                             $check_for,
                             \%status,
                             \@new_unknown);
 } else {
   die "Unrecognized clean_check_type: $clean_check_type";
 }

 return \%status;
}

sub record_ignored_unknowns () {
 # Determine some useful directories
 my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();

 mkdir "$git_dir/info" unless -d "$git_dir/info";
 open(OUTPUT, "> $git_dir/info/ignored-unknown");
 my @unknown_files = `cd "$top_dir" && $GIT_CMD ls-files --exclude-standard --others --directory --no-empty-directory`;
 foreach my $file (@unknown_files) {
   print OUTPUT $file;
 }
 close(OUTPUT);
}

sub parse_args ($@) {
 my $multi_args = shift;
 my (@args) = @_;

 Util::push_debug(new_value => 0);

 my (@opts, @revs, @files);
 my $stop_marker_found;

 # Get the opts
 while (@args) {
   my $arg = shift @args;
   if ($arg eq "--") {
     $stop_marker_found = 1;
     last;
   }

   if ($arg =~ /^-/) {
     push(@opts, $arg);
     push(@opts, shift @args) if (grep {$arg eq $_} @$multi_args);
   } else {
     unshift(@args, $arg);
     last;
   }
 }

 # Get the revisions
 if (!$stop_marker_found) {
   while (@args) {
     my $arg = shift @args;
     if ($arg eq "--") {
       $stop_marker_found = 1;
       last;
     }

     my @revs_to_check = split('\.\.\.?', $arg);
     my $found_invalid_ref = 0;
     foreach my $ref (@revs_to_check) {
       if (!RepoUtil::valid_ref($ref)) {
         $found_invalid_ref = 1;
         last;
       }
     }
     if ($found_invalid_ref) {
       unshift(@args, $arg);
       last;
     } else {
       push(@revs, $arg);
     }
   }
 }

 # Get the files
 @files = @args;
 if (!$stop_marker_found && @files && $files[0] eq "--") {
   shift @files;
 } else {
   # If "--" appears in argument list and not at front, then some bad
   # revisions specified by the user showed up in our @files list since
   # they didn't validate as existing revisions.
   my $i = -1;
   foreach my $file (@files) {
     if ($file eq "--") {
       die "Bad revision(s): @files[0..$i]\n";
     }
     ++$i;
   }
 }

 ## FIXME: I should add sanity checking: whether there are too many revs
 ## specified (or too few), whether any of @revs are also valid filenames,
 ## and maybe whether all @files refer to valid paths (maybe including
 ## only allowing files instead of also directories)

 Util::pop_debug();

 return (\@opts, \@revs, \@files);
}

sub get_revert_info ($@) {
 my ($revision, @quoted_files) = @_;

 my $marker = "";
 $marker = "--" if (@quoted_files);

 my @newly_added_files;
 my @new_since_rev_files;
 my @other_files = @quoted_files;

 # If this is a merge commit...
 my ($cur_dir, $top_dir, $git_dir) = RepoUtil::get_dirs();
 my @merge_branches;
 if (-f "$git_dir/MERGE_HEAD") {
   @merge_branches = `cat "$git_dir/MERGE_HEAD"`;
   chomp(@merge_branches);
 }

 # Define how to get newly added files since a commit, or new files added
 # between two commits
 my $get_newish_files = sub {
   my $ref1 = shift;
   my $ref2 = shift;
   my (@files, @lines);
   if (defined $ref2) {
     @lines = `$GIT_CMD diff-tree -r $ref1 $ref2 $marker @quoted_files`;
   } else {
     @lines = `$GIT_CMD diff-index --cached $ref1 $marker @quoted_files`;
   }
   foreach my $line (@lines) {
     # Check for newly added files (not previously tracked but now staged)
     if ($line =~ /:000000 [0-9]+ 0{40} [0-9a-f]{40} A\t(.*)/) {
       push(@files, $1);
     }
   }

   # git diff-tree and diff-index return files relative to $top_dir, but
   # we want filenames relative to $cur_dir
   if ($top_dir ne $cur_dir) {
     return Util::reroot_paths__from_to_files($top_dir, $cur_dir, @files);
   } else {
     return @files;
   }
 };

 # Now, get the files added to the index since the "last commit"
 @newly_added_files = &$get_newish_files("HEAD");
 for my $branch (@merge_branches) {
   my @files = &$get_newish_files($branch);
   @newly_added_files = Util::intersect(\@newly_added_files, \@files);
 }
 if (@newly_added_files) {
   @newly_added_files = Util::quote_args(@newly_added_files);
   @other_files = Util::difference(\@quoted_files, \@newly_added_files);
 }

 # Now, get the files that exist in the "last commit" but not the specified
 # revision.
 if ($revision ne "HEAD" || @merge_branches) {
   my @branches;
   push(@branches, "HEAD");
   push(@branches, @merge_branches);
   foreach my $branch (@branches) {
     my @files = &$get_newish_files($revision, $branch);
     @new_since_rev_files = Util::union(\@new_since_rev_files, \@files);
   }
   if (@new_since_rev_files) {
     @new_since_rev_files = Util::quote_args(@new_since_rev_files);
     @other_files = Util::difference(\@other_files, \@new_since_rev_files);
   }
 }

 return (\@newly_added_files, \@new_since_rev_files, \@other_files);
}

###########################################################################
# Util                                                                    #
###########################################################################
package Util;

# Return items in @$lista but not in @$listb
sub difference ($$) {
 my ($lista, $listb) = @_;
 my %count;

 foreach my $item (@$lista) { $count{$item}++ };
 foreach my $item (@$listb) { $count{$item}-- };

 my @ret = grep { $count{$_} == 1 } keys %count;
}

# Return items in both @$lista and in @$listb
sub intersect ($$) {
 my ($lista, $listb) = @_;
 my %original;
 my @both = ();

 map { $original{$_} = 1 } @$lista;
 @both = grep { $original{$_} } @$listb;

 return @both;
}

# Return items in either @$lista or @$listb
sub union ($$) {
 my ($lista, $listb) = @_;
 my %either;

 map { $either{$_} = 1 } @$lista;
 map { $either{$_} = 1 } @$listb;

 return keys %either;
}

# Returns whether @$list contains $item
sub contains ($$) {
 my ($list, $item) = @_;
 my $found = 0;
 foreach my $elem (@$list) {
   if ($item eq $elem) {
     $found = 1;
     last;
   }
 }

 return $found;
}

sub uniquify_list (@) {
 my @list = @_;
 my %unique;
 @unique{@list} = @list;
 return keys %unique;
}

sub split_ssh_repository ($) {
 my ($repository) = @_;
 my ($user, $machine, $port, $path);
 if ($repository =~ m#^ssh://((?:.*?@)?)([^/:]*)(?::(\d+))?(.*)$#) {
   $user = $1;
   $machine = $2;
   $port = defined $3 ? "-p $3" : "";
   $path = $4;
   $path =~ s#^/~#~#;  # Change leading /~ into plain ~
 } elsif ($repository =~ m#^((?:.*?@)?)([^:]*):(.*)$#) {
   $user = $1;
   $machine = $2;
   $port = "";
   $path = $3;
 }
 return ($user, $machine, $port, $path);
}

sub quote_args (@) {
 my @args = @_;

 # Quote arguments with special characters so that when we
 # do something like
 #   system("$command hardcoded_arg1 @args")
 # that the @args will get passed correctly to the shell command $command
 my @newargs;
 foreach my $arg (@args) {
   my $quotes_needed = 0;
   if (!$arg || $arg =~ /[;'"<>()\[\]|`*       \n\$\\~]/) {
     $quotes_needed = 1;
   }

   $arg =~ s#\\#\\\\#g;    # Backslash escape backslashes
   $arg =~ s#"#\\"#g;      # Backslash escape quotes
   $arg =~ s#`#\\`#g;      # Backslash escape backticks
   $arg =~ s#\$#\\\$#g;    # Backslash escape dollar signs

   $arg = '"'.$arg.'"' if $quotes_needed;

   push(@newargs, $arg);
 }
 return @newargs;
}

# Have git's rev-parse command parse @args and decide which part is files,
# which is options, and which are revisions.  Further, have git translate
# revisions into full 40-character hexadecimal commit ids.
sub git_rev_parse (@) {
 my @args = @_;

 Util::push_debug(new_value => 0);

 my @quoted_args = Util::quote_args(@args);
 my ($ret, $output) =
   ExecUtil::execute_captured("$GIT_CMD rev-parse @quoted_args",
                              ignore_ret => 1);
 if ($ret != 0) {
   $output =~ /^(fatal:.*)$/m   && print STDERR "$1\n";
   $output =~ /^(Use '--'.*)$/m && print STDERR "$1\n";
   exit 1;
 }
 my @opts  =
   split('\n', `$GIT_CMD rev-parse --no-revs --flags    @quoted_args`);
 my @revs  =
   split('\n', `$GIT_CMD rev-parse --revs-only          @quoted_args`);
 my @files =
   split('\n', `$GIT_CMD rev-parse --no-revs --no-flags @quoted_args`);

 # Translate sha1sums back to human specified version of revisions.  Note that
 # something like "REV1...REV2" is translated into "SHA1 SHA2 ^SHA3", so one
 # argument may have become 3 revisions.  options and files should translate
 # one to one, though, so we can back out the original revision names.
 @revs = @args[scalar(@opts)..scalar(@args)-scalar(@files)-1];

 Util::pop_debug();

 return (\@opts, \@revs, \@files);
}

# reroot_paths__from_to_files
#   Given
#     $from   absolute path of directory files were originally relative to
#     $to     absolute path of directory you want files relative to
#     @files  list of files with paths relative to $from
#   returns a list of files with paths relative to $to
#   For example:
#     reroot_paths__from_to_files("/home", "/home/newren", ('bar', '../foo'))
#   would return
#     ('../bar', '../../foo')
#   Another example:
#     reroot_paths__from_to_files("/tmp/junk", "/tmp", ('bar', '../foo'))
#   would return
#     ('junk/bar', 'foo')
sub reroot_paths__from_to_files ($$@) {
 my ($from, $to, @files) = @_;
 $from =~ s#/*$#/#;   # Make sure $from ends with exactly 1 slash
 $to   =~ s#/*$#/#;   # Make sure $to   ends with exactly 1 slash

 my @new_paths;
 foreach my $file (@files) {
   # Get the old path for the file, removing any "PATH/.." sequences
   my $oldpath = "$from$file";
   $oldpath =~ s#/+#/#;               # Remove duplicate slashes in path
   $oldpath = "$1$2" while $oldpath =~ m#^(.*?)(?!\.\./)[^/]+/\.\./(.*)$#;

   # Find what $oldpath and $to have in common
   my $common_leading_path = "";
   my $combined = "$oldpath\n$to";
   if ($combined =~ m#^(.*/).*\n\1.*$#) {
     $common_leading_path = $1;
   }

   # Now get the unique parts of $oldpath and $to
   my $remainder_old_path = substr($oldpath, length($common_leading_path));
   my $remainder_to       = substr($to,      length($common_leading_path));

   # Do an s/DIRECTORY_NAME/../ on remainder_to, since we want to know
   # the relative path for getting from $to to $from.
   $remainder_to =~ s#[^/]+#..#g;

   push(@new_paths, "$remainder_to$remainder_old_path");
 }

 return @new_paths;
}

{
my @debug_values;
sub push_debug (@) {
 my @opts = @_;
 my %options = ( @opts );
 die "Called without new_value!" if !defined($options{new_value});

 my $old_value = $DEBUG;
 push(@debug_values, $DEBUG);
 $DEBUG = $options{new_value};
 return $old_value;
}

sub pop_debug () {
 $DEBUG = pop @debug_values;
}
}


#*************************************************************************#
#*************************************************************************#
#*************************************************************************#
#                              MAIN PROGRAM                               #
#*************************************************************************#
#*************************************************************************#
#*************************************************************************#

package main;

sub launch ($) {
 my $job=shift;
 $job = $ALIAS{$job} || $job;
 my $orig_job = $job;
 $job =~ s/-/_/;  # Packages must have underscores, commands often have dashes

 # Create the action to execute
 my $action;
 $action = $job->new()                           if  $job->can("new");
 $action = subcommand->new(command => $orig_job) if !$job->can("new");
 my $ret;

 # preprocess
 if ($action->can("preprocess")) {
   # Do not skip commands normally executed during the preprocess stage,
   # since they just gather data.
   Util::push_debug(new_value => $DEBUG ? 1 : 0);

   print ">>Stage: Preprocess<<\n" if $DEBUG;
   $action->preprocess();

   Util::pop_debug();
 }

 # run & postprocess
 if (!$action->can("postprocess")) {
   print ">>Stage: Run<<\n" if $DEBUG;
   $ret = $action->run();
 } else {
   my $output = "";
   open($OUTFH, '>', \$output) || die "eg $job: cannot open \$OUTFH: $!";
   print ">>Stage: Run<<\n" if $DEBUG;
   $ret = $action->run();
   print ">>Stage: Postprocess<<\n" if $DEBUG;
   $action->postprocess($output);
 }

 # wrapup
 if ($action->can("wrapup")) {
   print ">>Stage: Wrapup<<\n" if $DEBUG;
   $action->wrapup();
 }

 $ret = 0 unless ($ret);
 exit $ret;
}

sub version () {
 my $version_obj = "version"->new();
 $version_obj->run();
 exit 0;
}

# User gave invalid input; print an error_message, then show command usage
sub help (;$) {
 my $error_message = shift;
 my %extra_args;

 # Clear out any arguments so that help object doesn't think we asked for
 # a specific help topic.
 @ARGV = ();

 # Print any error message we were given
 if (defined $error_message) {
   print STDERR "$error_message\n\n";
   $extra_args{exit_status} = 1;
 }

 # Now show help.
 my $help_obj = "help"->new(%extra_args);
 $help_obj->run();
}

sub main () {
 #
 # Get any global options
 #
 Getopt::Long::Configure("no_bundling", "no_permute",
                         "pass_through", "no_auto_abbrev", "no_ignore_case");
 my @global_args  = ();
 my $record_arg   = sub { push(@global_args, "--$_[0]"); };
 my $record_args  = sub { push(@global_args, "--$_[0]=$_[1]"); };
 my $result=GetOptions(
              "--debug"     => sub { $DEBUG = 1 },
              "--help"      => sub { help()     },
              "--translate" => sub { $DEBUG = 2 },
              "--version"   => sub { version()  },
              "exec-path:s" => sub { $_[1] ? &$record_args(@_)
                                           : &$record_arg(@_); },
              "c:s"         => sub { push(@global_args, "-c", $_[1]); },
              "paginate|p"  => sub { $USE_PAGER = 1; &$record_arg(@_)  },
              "no-pager"    => sub { $USE_PAGER = 0; &$record_arg(@_)  },
              "bare"        => sub { &$record_arg(@_)  },
              "git-dir=s"   => sub { &$record_args(@_) },
              "work-tree=s" => sub { &$record_args(@_) },
              "no-replace-objects" => sub { &$record_arg(@_) },
                       );
 # Make sure all global args are passed to eg subprocesses as well...
 @global_args = Util::quote_args(@global_args);
 $GIT_CMD .= " @global_args";
 $EG_EXEC .= " @global_args" if @global_args;

 #
 # Fix the environment, if needed (eg testsuite invokes eg via 'git', but
 # eg needs to be able to call the real git).
 # WARNING: This does not handle mutual recursion (eg in PATH twice as 'git')
 #
 if ($0 =~ m#(.*)/git$#) {
   my $baddir = $1;
   my @newpaths = grep {$_ ne $baddir} split(/:/, $ENV{PATH});
   $ENV{PATH} = join(':', @newpaths);
 }

 # Sanity check the arguments
 exit ExecUtil::execute($GIT_CMD) if $GIT_CMD =~ m#--exec-path$#;
 die "eg: Error parsing arguments. (Try 'eg help')\n" if !$result;
 die "eg: No subcommand specified. (Try 'eg help')\n" if @ARGV < 1;
 die "eg: Invalid argument '$ARGV[0]'. (Try 'eg help')\n"
   if ($ARGV[0] !~ m#^[a-z]#);

 #
 # Now execute the action
 #
 my $action = shift @ARGV;
 launch($action);
}

main();