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CRUNCHGEN(1)                General Commands Manual               CRUNCHGEN(1)

     crunchgen - generates build environment for a crunched binary

     crunchgen [-FfOoq] [-c c-file-name] [-D src-root] [-e exec-file-name]
               [-L lib-dir] [-m makefile-name] [-v var-spec] [-V var-spec]

     A crunched binary is a program made up of many other programs linked
     together into a single executable.  The crunched binary 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.

     crunchgen reads in the specifications in 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, crunchgen 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.
     crunchgen uses the companion program crunchide to eliminate link-time
     conflicts between the component programs by hiding all unnecessary

     After crunchgen is run, the crunched binary can be built by running "make
     -f <conf-name>.mk".  The component programs' object files must already be
     built.  An "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.

     The options are as follows:

     -c c-file-name
             Set output C file name to c-file-name.  The default name is

     -D src-root
             Assume that relative source directory specifications begin with

     -e exec-file-name
             Set crunched binary executable file name to exec-file-name.  The
             default name is "<conf-name>".

     -F      Enable fortify.

     -f      Flush cache.  Forces the recalculation of cached parameters.

     -L lib-dir
             Try to obtain libraries from lib-dir.

     -m makefile-name
             Set output Makefile name to makefile-name.  The default name is

     -O      Force crunchgen to parse the program's Makefile in determine the
             list of .o files.  Without this option crunchgen expects the
             program's Makefile to have a program.ro target that links all the
             program objects into a single relocatable.

     -o      Use existing object files.  Rather than rebuilding object files
             via reach-over makefiles, instead search for and use existing
             object files.

     -q      Quiet operation.  Status messages are suppressed.

     -v varspec
             Append a variable specification to the on-the fly generated
             Makefiles for the individual programs.

     -V 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.

     crunchgen reads specifications from the 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.  crunchgen 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 crunchgen needs.

     The conf-file commands are as follows:

     srcdirs dirname ...
             A list of source trees in which the source directories of the
             component programs can be found.  These dirs are searched using
             the BSD "<source-dir>/<progname>/" convention.  Multiple srcdirs
             lines can be specified.  The directories are searched in the
             order they are given.

     progs progname ...
             A list of programs that make up the crunched binary.  Multiple
             progs lines can be specified.

     libs libspec ...
             A list of library specifications to be included in the crunched
             binary link.  Multiple libs lines can be specified.

     ln progname linkname
             Causes the crunched binary to invoke progname whenever linkname
             appears in argv[0].  This allows programs that change their
             behavior when run under different names to operate correctly.

     To handle specialized situations, such as when the source is not
     available or not built via a conventional Makefile, the following special
     commands can be used to set crunchgen parameters for a component program.

     special progname keepsymbols symbols ...
             Don't hide the specified symbols for progname.  Normally all
             externally visible symbols for a program is hidden to avoid
             interference.  Multiple keepsymbols lines can be specified for
             given progname.

     special progname srcdir pathname
             Set the source directory for progname.  This is normally
             calculated by searching the specified srcdirs for a directory
             named progname.

     special progname objdir pathname
             Set the obj directory for progname.  This is normally calculated
             by looking for a directory named "obj" under the srcdir, and if
             that is not found, the srcdir itself becomes the objdir.

             Note: This option only takes effect if the -o option to use
             existing object files is also specified.

     special progname objs object-file-name ...
             Set the list of object files for program progname.  This is
             normally calculated by constructing a temporary makefile that
             includes "srcdir / Makefile" and outputs the value of $(OBJS).
             Multiple objs lines can be specified for given progname.

     special progname objpaths full-pathname-to-object-file ...
             Sets the pathnames of the object files for program progname.
             This is normally calculated by prepending the objdir pathname to
             each file in the objs list.  Multiple objpaths lines can be
             specified for given progname.

     Only the objpaths parameter is actually needed by crunchgen but it is
     calculated from objdir and objs, which are in turn calculated from
     srcdir, so is sometimes convenient to specify the earlier parameters and
     let crunchgen calculate forward from there if it can.

     The makefile produced by crunchgen contains an optional 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 srcdir and
     objs parameters must also be valid.  If they are not valid for a
     particular program, that program is skipped in the objs target.

     The makefile produced by crunchgen strips certain sections from the final
     binary to reduce its size.  This includes:

     .eh_frame          Unwinding tables for exceptions and backtraces.

     .eh_frame_hdr      Index of the .eh_frame section.

     .note              Optional data for the kernel and/or runtime linker.

     .comment           Comments in the binary.

     .ident             Embedded source revisions used by ident(1).

     .copyright         Embedded copyright notes.

     MAKEOBJDIRPREFIX  If the environment variable MAKEOBJDIRPREFIX is set,
                       the object directory will be prefixed with the path
                       contained in this environment variable.

                       Note: This variable is only used if the -o option to
                       use existing object files is also specified.

     MACHINE           If the environment variable 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 uname(3).

                       Note: This option is only used if the -o option to use
                       existing object files is also specified.

     MAKE              If the environment variable MAKE is set, it is used as
                       the name of the make(1) executable to be called.  If
                       this environment variable is not set, crunchgen
                       defaults to "make".

     Here is an example crunchgen input conf file, named "kcopy.conf":

           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

     This conf file specifies a small crunched binary consisting of some basic
     system utilities plus a home-grown install program "myinstall", for which
     no source directory is specified, but its object file is specified
     directly with the special line.

     The crunched binary "kcopy" can be built as follows:

           % 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!

     At this point the binary "kcopy" can be copied onto an install floppy and
     hard-linked to the names of the component programs.

     crunchgen used to have builtin entries for some Makefile variables,
     namely it set by default:


     To set those defaults again, use:

           -V DBG=-Os \
           -V LDSTATIC=-static -V NOPIE= \
           -V NOMAN= \

     The -p flag that set pic mode internally set:

           LDSTATIC="-static -pie"

     and did not set:


     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:

           -F  NOFORT

           -P  NOSSP


           -s  NOSANITIZER

     crunchide(1), make(1)

     crunchgen was written by James da Silva <jds@cs.umd.edu>.

     Copyright (c) 1994 University of Maryland.  All Rights Reserved.

     While crunchgen 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.

     Some versions of the BSD build environment do not by default build the
     intermediate object file for single-source file programs.  The "make
     objs" target must then be used to get those object files built, or some
     other arrangements made.

     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:

           srcdirs /usr/src/usr.bin /usr/src/usr.bin/less
           progs less gzip

     as the /usr/src/usr.bin/less directory will be found with the
     /usr/src/usr.bin srcdirs entry, and as it does not contain the require
     objects, crunchgen fails to find objects for the less program.  To avoid
     this problem, list specific srcdirs first, and the more general ones
     later, for e.g.:

           srcdirs /usr/src/usr.bin/less /usr/src/usr.bin
           progs less gzip

     will not have the above problem.

NetBSD 10.99                    January 2, 2020                   NetBSD 10.99