== INFORMATION ==

This module allows for symbolic (i.e. +rx-w) file permissions as well as "ls"
modes (i.e. -r-xr-xr-x).

This is File::chmod v0.31.

PLEASE read the POD, there have been several changes since the last
version.  Nothing that will wreck your programs, but things that you
should be aware of.

To learn more, go to http://www.pobox.com/japhy/perl.
Jeff Pinyan, [email protected], CPAN ID: PINYAN.


== INSTALLATION INSTRUCTIONS ==

Unpack the .tar.gz file.

Run:
       cd File-chmod-0.31
       perl Makefile.PL
       make
       make test
       make install


== MANUAL ==

NAME
   File::chmod - Implements symbolic and ls chmod modes

VERSION
   This is File::chmod v0.31.

SYNOPSIS
     use File::chmod;

     # chmod takes all three types
     # these all do the same thing
     chmod(0666,@files);
     chmod("=rw",@files);
     chmod("-rw-rw-rw-",@files);

     # or

     use File::chmod qw( symchmod lschmod );

     chmod(0666,@files);           # this is the normal chmod
     symchmod("=rw",@files);       # takes symbolic modes only
     lschmod("-rw-rw-rw-",@files); # takes "ls" modes only

     # more functions, read on to understand

DESCRIPTION
   File::chmod is a utility that allows you to bypass system calls
   or bit processing of a file's permissions. It overloads the
   chmod() function with its own that gets an octal mode, a
   symbolic mode (see below), or an "ls" mode (see below). If you
   wish not to overload chmod(), you can export symchmod() and
   lschmod(), which take, respectively, a symbolic mode and an "ls"
   mode.

   Symbolic modes are thoroughly described in your chmod(1) man
   page, but here are a few examples.

     # NEW: if $UMASK is true, symchmod() applies a bit-mask found in $MASK

     chmod("+x","file1","file2");  # overloaded chmod(), that is...
     # turns on the execute bit for all users on those two files

     chmod("o=,g-w","file1","file2");
     # removes 'other' permissions, and the write bit for 'group'

     chmod("=u","file1","file2");
     # sets all bits to those in 'user'

   "ls" modes are the type produced on the left-hand side of an `ls
   -l' on a directory. Examples are:

     chmod("-rwxr-xr-x","file1","file2");
     # the 0755 setting; user has read-write-execute, group and others
     # have read-execute priveleges

     chmod("-rwsrws---","file1","file2");
     # sets read-write-execute for user and group, none for others
     # also sets set-uid and set-gid bits

   The regular chmod() and lschmod() are absolute; that is, they
   are not appending to or subtracting from the current file mode.
   They set it, regardless of what it had been before. symchmod()
   is useful for allowing the modifying of a file's permissions
   without having to run a system call or determining the file's
   permissions, and then combining that with whatever bits are
   appropriate. It also operates separately on each file.

   An added feature to version 0.30 is the $UMASK variable,
   explained below; if symchmod() is called and this variable is
   true, then the function uses the (also new) $MASK variable
   (which defaults to umask()) as a mask against the new mode. This
   is documented below more clearly.

 Functions

   Exported by default:

   chmod(MODE,FILES)
       Takes an octal, symbolic, or "ls" mode, and then chmods each
       file appropriately.

   getchmod(MODE,FILES)
       Returns a list of modified permissions, without chmodding
       files. Accepts any of the three kinds of modes.

         @newmodes = getchmod("+x","file1","file2");
         # @newmodes holds the octal permissons of the files'
         # modes, if they were to be sent through chmod("+x"...)

   Exported by request:

   symchmod(MODE,FILES)
       Takes a symbolic permissions mode, and chmods each file.

   lschmod(MODE,FILES)
       Takes an "ls" permissions mode, and chmods each file.

   getsymchmod(MODE,FILES)
       Returns a list of modified permissions, without chmodding
       files. Accepts only symbolic permisson modes.

   getlschmod(MODE,FILES)
       Returns a list of modified permissions, without chmodding
       files. Accepts only "ls" permisson modes.

   getmod(FILES)
       Returns a list of the current mode of each file.

 Variables

   $File::chmod::DEBUG
       If set to a true value, it will report warnings, similar to
       those produced by chmod() on your system. Otherwise, the
       functions will not report errors. Example: a file can not
       have file-locking and the set-gid bits on at the same time.
       If $File::chmod::DEBUG is true, the function will report an
       error. If not, you are not warned of the conflict. It is set
       to 1 as default.

   $File::chmod::MASK
       Contains the umask to apply to new file modes when using
       getsymchmod(). This defaults to the return value of umask()
       at compile time. Is only applied if $UMASK is true.

   $File::chmod::UMASK
       This is a boolean which tells getsymchmod() whether or not
       to apply the umask found in $MASK. It defaults to true.

REVISIONS
   *Note: this section was started with version 0.30.*

   This is an in-depth look at the changes being made from version
   to version.

 0.30 to 0.31

   fixed getsymchmod() bug
       Whoa. getsymchmod() was doing some crazy ish. That's about
       all I can say. I did a great deal of debugging, and fixed it
       up. It ALL had to do with two things:

         $or = (/+=/ ? 1 : 0); # should have been /[+=]/

         /u/ && $ok ? u_or() : u_not(); # should have been /u/ and $ok

   fixed getmod() bug
       I was using map() incorrectly in getmod(). Fixed that.

   condensed lschmod()
       I shorted it up, getting rid a variable.

 0.21 to 0.30

   added umask() honoring for symchmod()
       The symchmod() function now honors the $UMASK and $MASK
       variables. $UMASK is a boolean which indicates whether or
       not to honor the $MASK variable. $MASK holds a umask, and it
       defaults to umask(). $UMASK defaults to true. These
       variables are NOT exported. They must explictly set (i.e.
       $File::chmod::UMASK = 0).

   function name changes
       Renamed internal function determine_mode() to mode().
       However, if you happen to be using determine_mode()
       somewhere, mode() will be called, but you'll also get a
       warning about deprecation.

       Renamed internal functions {or,not}_{l,s,t} to
       {l,s,t}_{or,not}. This is to keep in standard with the OTHER
       6 pairs of bitwise functions, such as r_or() and g_not(). I
       don't know WHY the others had 'not' or 'or' in the front.

   fixed debugging bugs
       Certain calls to warn() were not guarded by the $DEBUG
       variable, and now they are. Also, for some reason, I left a
       debugging check (that didn't check to see if $DEBUG was
       true) in getsymchmod(), line 118. It printed "ENTERING /g/".
       It's gone now.

   fixed set-uid and set-gid bug
       Heh, it seems that in the previous version of File::chmod,
       the following code went along broken:

         # or_s sub, File/chmod.pm, v0.21, line 330
         ($VAL & 00100) && do {
           $DEBUG && warn("execute bit must be on for set-uid"); 1;
         } && next;

       Aside from me using '&&' more than enough (changed in the
       new code), this is broken. This is now fixed.

   fixed file lock/set-gid bug
       The not_l() function (now renamed to l_not()) used to take
       the file mode and bit-wise NOT it with ~02000. However, it
       did not check if the file was locked vs. set-gid. Now, the
       function is `$VAL &= ~02000 if not $VAL & 00010;'.

   removed useless data structures
       I do not know why I had the $S variable, or %r, %w, and %x
       hashes. In fact, $S was declared in `use vars qw( ... );',
       but never given a value, and the %r, %w, and %x hashes had a
       'full' key which never got used. And the hashes themselves
       weren't really needed anyway. Here is a list of the
       variables no longer in use, and what they have been replaced
       with (if any):

         $S            nothing
         $U, $G, $O    $W
         %r, %w, %x    octal numbers
         @files        @_ (I had @files = @_; in nearly EVERY sub)
         $c            $_

   compacted code
       The first version of File::chmod that was published was
       0.13, and it was written in approximately 10 days, being
       given the off-and-on treatment I end up having to give
       several projects, due to more pressing matters. Well, since
       then, most of the code has stayed the same, although bugs
       were worked out. Well, I got rid of a lot of slow, clunky,
       and redundant sections of code in this version. Sections
       include the processing of each character of the mode in
       getsymchmod(), the getmod() subroutine, um, nearly ALL of
       the getsymchmod() function, now that I look at it.

       Here's part of the getsymchmod() rewrite:

         for ($c){
           if (/u/){
             u_or() if $MODE eq "+" or $MODE eq "=";
             u_not() if $MODE eq "-";
           }
         ...
         }

         # changed to

         /u/ && $or ? u_or() : u_and();
         # note: operating on $_, $c isn't used anymore
         # note: $or holds 1 if the $MODE was + or =, 0 if $MODE was -
         # note: previous was redundant.  didn't need $MODE eq "-" check
         #       because u_or() and u_not() both go to the next character

PORTING
   This is only good on Unix-like boxes. I would like people to
   help me work on File::chmod for any OS that deserves it. If you
   would like to help, please email me (address below) with the OS
   and any information you might have on how chmod() should work on
   it; if you don't have any specific information, but would still
   like to help, hey, that's good too. I have the following
   information (from the perlport entry elsewhere in this document
   ):

   Win32
       Only good for changing "owner" read-write access, "group",
       and "other" bits are meaningless. *NOTE: Win32::File and
       Win32::FileSecurity already do this. I do not currently see
       a need to port File::chmod.*

   MacOS
       Only limited meaning. Disabling/enabling write permission is
       mapped to locking/unlocking the file.

   RISC OS
       Only good for changing "owner" and "other" read-write
       access.

AUTHOR
   Jeff Pinyan, [email protected], CPAN ID: PINYAN

SEE ALSO
     Stat::lsMode (by Mark-James Dominus, CPAN ID: MJD)
     chmod(1) manpage
     perldoc -f chmod
     perldoc -f stat

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