\"      $NetBSD: crunchgen.1,v 1.42 2021/08/01 15:52:11 andvar Exp $
\"
\" Copyright (c) 1994 University of Maryland
\" All Rights Reserved.
\"
\" Permission to use, copy, modify, distribute, and sell this software and its
\" documentation for any purpose is hereby granted without fee, provided that
\" the above copyright notice appear in all copies and that both that
\" copyright notice and this permission notice appear in supporting
\" documentation, and that the name of U.M. not be used in advertising or
\" publicity pertaining to distribution of the software without specific,
\" written prior permission.  U.M. makes no representations about the
\" suitability of this software for any purpose.  It is provided "as is"
\" without express or implied warranty.
\"
\" U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
\" BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
\" IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
\"
\" Author: James da Silva, Systems Design and Analysis Group
\"                         Computer Science Department
\"                         University of Maryland at College Park
\"
Dd January 2, 2020
Dt CRUNCHGEN 1
Os
Sh NAME
Nm crunchgen
Nd generates build environment for a crunched binary
Sh SYNOPSIS
Nm
Op Fl FfOoq
Op Fl c Ar c-file-name
Op Fl D Ar src-root
Op Fl e Ar exec-file-name
Op Fl L Ar lib-dir
Op Fl m Ar makefile-name
Op Fl v Ar var-spec
Op Fl V Ar var-spec
Ar conf-file
Sh DESCRIPTION
A crunched binary is a program made up of many other programs linked
together into a single executable.
The crunched binary
Fn main
function determines which component program to run by the contents of
argv[0].
The main reason to crunch programs together is for fitting as many
programs as possible onto an installation or system recovery floppy.
Pp
Nm
reads in the specifications in
Ar conf-file
for a crunched binary, and generates a Makefile and accompanying
top-level C source file that when built create the crunched executable
file from the component programs.
For each component program,
Nm
can optionally attempt to determine the object (.o) files that make up
the program from its source directory Makefile.
This information is cached between runs.
Nm
uses the companion program
Em crunchide
to eliminate link-time conflicts between the component programs by
hiding all unnecessary symbols.
Pp
After
Nm
is run, the crunched binary can be built by running
Dq make -f Ao conf-name Ac Ns .mk .
The component programs' object files must already be built.
An
Dq objs
target, included in the output makefile, will
run make in each component program's source dir to build the object
files for the user.
This is not done automatically since in release
engineering circumstances it is generally not desirable to be
modifying objects in other directories.
Pp
The options are as follows:
Bl -tag -width indent
It Fl c Ar c-file-name
Set output C file name to
Ar c-file-name .
The default name is
Dq Ao confname Ac Ns .c .
It Fl D Ar src-root
Assume that relative source directory specifications begin with
Ar src-root .
It Fl e Ar exec-file-name
Set crunched binary executable file name to
Ar exec-file-name .
The default name is
Dq Aq Mt conf-name .
It Fl F
Enable fortify.
It Fl f
Flush cache.
Forces the recalculation of cached parameters.
It Fl L Ar lib-dir
Try to obtain libraries from
Ar lib-dir .
It Fl m Ar makefile-name
Set output Makefile name to
Ar makefile-name .
The default name is
Dq Ao conf-name Ac Ns .mk .
It Fl O
Force
Nm
to parse the program's Makefile in determine the list of .o files.
Without this option
Nm
expects the program's Makefile to have a program.ro target that links all
the program objects into a single relocatable.
It Fl o
Use existing object files.
Rather than rebuilding object files via reach-over
makefiles, instead search for and use existing object files.
It Fl q
Quiet operation.
Status messages are suppressed.
It Fl v Ar varspec
Append a variable specification to the on-the fly generated Makefiles
for the individual programs.
It Fl V Ar varspec
Set the variable in the top level Makefile, and pass it in the command
line of all sub-makes, so that it cannot be overwritten.
El
Sh CRUNCHGEN CONFIGURATION FILE COMMANDS
Nm
reads specifications from the
Ar conf-file
that describe the components of the crunched binary.
In its simplest
use, the component program names are merely listed along with the
top-level source directories in which their sources can be found.
Nm
then calculates (via the source makefiles) and caches the
list of object files and their locations.
For more specialized
situations, the user can specify by hand all the parameters that
Nm
needs.
Pp
The
Ar conf-file
commands are as follows:
Bl -tag -width indent
It Nm srcdirs Ar dirname ...
A list of source trees in which the source directories of the
component programs can be found.
These dirs are searched using the
Bx
Dq Ao source-dir Ac Ns / Ns Ao progname Ac Ns /
convention.
Multiple
Em srcdirs
lines can be specified.
The directories are searched in the order they are given.
It Nm progs Ar progname ...
A list of programs that make up the crunched binary.
Multiple
Em progs
lines can be specified.
It Nm libs Ar libspec ...
A list of library specifications to be included in the crunched binary link.
Multiple
Em libs
lines can be specified.
It Nm ln Ar progname linkname
Causes the crunched binary to invoke
Ar progname
whenever
Ar linkname
appears in argv[0].
This allows programs that change their behavior when
run under different names to operate correctly.
El
Pp
To handle specialized situations, such as when the source is not
available or not built via a conventional Makefile, the following
Em special
commands can be used to set
Nm
parameters for a component program.
Bl -tag -width indent
It Nm special Ar progname Nm keepsymbols Ar symbols ...
Don't hide the specified symbols for
Ar progname .
Normally all externally visible symbols for
a program is hidden to avoid interference.
Multiple
Em keepsymbols
lines can be specified for given
Ar progname .
It Nm special Ar progname Nm srcdir Ar pathname
Set the source directory for
Ar progname .
This is normally calculated by searching the specified
Em srcdirs
for a directory named
Ar progname .
It Nm special Ar progname Nm objdir Ar pathname
Set the obj directory for
Ar progname .
This is normally calculated by looking for a directory named
Dq Pa obj
under the
Ar srcdir ,
and if that is not found, the
Ar srcdir
itself becomes the
Ar objdir .
Pp
Nm Note :
This option only takes effect if the -o option to use existing object files is also
specified.
It Nm special Ar progname Nm objs Ar object-file-name ...
Set the list of object files for program
Ar progname .
This is normally calculated by constructing a temporary makefile that includes
Dq Nm srcdir / Pa Makefile
and outputs the value of $(OBJS).
Multiple
Em objs
lines can be specified for given
Ar progname .
It Nm special Ar progname Nm objpaths Ar full-pathname-to-object-file ...
Sets the pathnames of the object files for program
Ar progname .
This is normally calculated by prepending the
Em objdir
pathname to each file in the
Nm objs
list.
Multiple
Em objpaths
lines can be specified for given
Ar progname .
El
Pp
Only the
Em objpaths
parameter is actually needed by
Nm
but it is calculated from
Em objdir
and
Em objs ,
which are in turn calculated from
Em srcdir ,
so is sometimes convenient to specify the earlier parameters and let
Nm
calculate forward from there if it can.
Pp
The makefile produced by
Nm
contains an optional
Ar objs
target that will build the object files for each component program by
running make inside that program's source directory.
For this to work the
Em srcdir
and
Em objs
parameters must also be valid.
If they are not valid for a particular program, that
program is skipped in the
Ar objs
target.
Pp
The makefile produced by
Nm
strips certain sections from the final binary to reduce its size.
This includes:
Bl -tag -width ".Li .eh_frame_hdr"
It Li .eh_frame
Unwinding tables for exceptions and backtraces.
It Li .eh_frame_hdr
Index of the
Li .eh_frame
section.
It Li .note
Optional data for the kernel and/or runtime linker.
It Li .comment
Comments in the binary.
It Li .ident
Embedded source revisions used by
Xr ident 1 .
It Li .copyright
Embedded copyright notes.
El
Sh ENVIRONMENT
Bl -tag -width MAKEOBJDIRPREFIX
It Ev MAKEOBJDIRPREFIX
If the environment variable
Ev MAKEOBJDIRPREFIX
is set, the object directory will be prefixed with the path contained in this
environment variable.
Pp
Nm Note :
This variable is only used if the -o option to use existing object files is also
specified.
It Ev MACHINE
If the environment variable
Ev MACHINE
is set, it is used as the name of the machine type, when accessing object
directories of the form obj.MACHINE.
If it is not set, it defaults to the machine type returned by
Xr uname 3 .
Pp
Nm Note :
This option is only used if the -o option to use existing object files is also
specified.
It Ev MAKE
If the environment variable
Ev MAKE
is set, it is used as the name of the
Xr make 1
executable to be called.
If this environment variable is not set,
Nm
defaults to
Dq make .
El
Sh EXAMPLES
Here is an example
Em crunchgen
input conf file, named
Dq Pa kcopy.conf :
Bd -literal -offset indent
srcdirs /usr/src/bin /usr/src/sbin

progs test cp echo sh fsck halt init mount umount myinstall
ln test [       # test can be invoked via [
ln sh -sh       # init invokes the shell with "-sh" in argv[0]

special myprog objpaths /homes/leroy/src/myinstall.o # no sources

libs -lutil -lcrypt
Ed
Pp
This conf file specifies a small crunched binary consisting of some
basic system utilities plus a home-grown install program
Dq myinstall ,
for which no source directory is specified, but its object file is
specified directly with the
Em special
line.
Pp
The crunched binary
Dq kcopy
can be built as follows:
Bd -literal -offset indent
% crunchgen -m Makefile kcopy.conf    # gen Makefile and kcopy.c
% make objs             # build the component programs' .o files
% make                  # build the crunched binary kcopy
% kcopy sh              # test that this invokes a sh shell
$                       # it works!
Ed
Pp
At this point the binary
Dq kcopy
can be copied onto an install floppy
and hard-linked to the names of the component programs.
Sh MIGRATION GUIDE
Nm
used to have builtin entries for some Makefile variables, namely it
set by default:
Bd -literal -offset indent
DBG=-Os
LDSTATIC=-static
NOPIE=
NOMAN=
NOFORT=
NOLIBCSANITIZER=
NOSANITIZER=
NOSSP=
Ed
Pp
To set those defaults again, use:
Bd -literal -offset indent
-V DBG=-Os \e
-V LDSTATIC=-static -V NOPIE= \e
-V NOMAN= \e
-V NOFORT= -V NOLIBCSANITIZER= -V NOSANITIZER= -V NOSSP=
Ed
Pp
The
Fl p
flag that set pic mode internally set:
Bd -literal -offset indent
LDSTATIC="-static -pie"
Ed
Pp
and did not set:
Bd -literal -offset indent
NOPIE=
Ed
Pp
The remaining flags just disabled setting the variables that turned off various
sanitizers, fortify, and stack protector.
The mapping of those variables to the old options is:
Bl -tag -width XX -offset indent
It Fl F
Dv NOFORT
It Fl P
Dv NOSSP
It Fl S
Dv NOLIBCSANITIZER
It Fl s
Dv NOSANITIZER
El
Sh SEE ALSO
Xr crunchide 1 ,
Xr make 1
Sh AUTHORS
Nm
was written by
An James da Silva Aq Mt [email protected] .
Pp
Copyright (c) 1994 University of Maryland.
All Rights Reserved.
Sh BUGS
While
Nm
takes care to eliminate link conflicts between the component programs
of a crunched binary, conflicts are still possible between the
libraries that are linked in.
Some shuffling in the order of
libraries may be required, and in some rare cases two libraries may
have an unresolvable conflict and thus cannot be crunched together.
Pp
Some versions of the
Bx
build environment do not by default build the
intermediate object file for single-source file programs.
The
Dq make objs
target must then be used to get those object files built, or
some other arrangements made.
Pp
If a program directory being searched for is found, but contains
no objects, other directories are not searched.
This causes the following directive to fail:
Bd -literal -offset indent
srcdirs /usr/src/usr.bin /usr/src/usr.bin/less
progs less gzip
Ed
Pp
as the
Pa /usr/src/usr.bin/less
directory will be found with the
Pa /usr/src/usr.bin
Em srcdirs
entry, and as it does not contain the require objects,
Nm
fails to find objects for the
Em less
program.
To avoid this problem, list specific srcdirs first, and
the more general ones later, for e.g.:
Bd -literal -offset indent
srcdirs /usr/src/usr.bin/less /usr/src/usr.bin
progs less gzip
Ed
Pp
will not have the above problem.

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