CRUNCHGEN(1) | General Commands Manual | CRUNCHGEN(1) |
crunchgen
—
crunchgen |
[-fOopqSs ] [-c
c-file-name] [-D
src-root] [-d
build-options] [-e
exec-file-name] [-L
lib-dir] [-m
makefile-name] [-v
var-spec] conf-file |
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 symbols.
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-D
src-root-d
build-options-e
exec-file-name-f
-L
lib-dir-m
makefile-name-O
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
-p
-q
-S
-s
-v
varspeccrunchgen
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 ...progs
progname ...libs
libspec ...ln
progname linknameTo 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 ...special
progname
srcdir
pathnamespecial
progname
objdir
pathnameNote
: This option only takes effect if
the -o option to use existing object files is also specified.
special
progname
objs
object-file-name ...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 ...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
.eh_frame_hdr
.eh_frame
section..note
.comment
.ident
.copyright
MAKEOBJDIRPREFIX
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
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
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”.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
was written by James da
Silva
<jds@cs.umd.edu>.
Copyright (c) 1994 University of Maryland. All Rights Reserved.
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.
June 21, 2018 | NetBSD 9.0 |