crunch/crunchgen/crunchgen.1

.\"
.\" 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 6, 2017
.Dt CRUNCHGEN 1
.Os
.Sh NAME
.Nm crunchgen
.Nd generates build environment for a crunched binary
.Sh SYNOPSIS
.Bk -words
.Nm
.Op Fl foql
.Op Fl h Ar makefile-header-name
.Op Fl m Ar makefile-name
.Op Fl p Ar obj-prefix
.Op Fl c Ar c-file-name
.Op Fl e Ar exec-file-name
.Ar conf-file
.Ek
.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
.Va 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
The
.Nm
utility reads in the specifications in
.Ar conf-file
for a crunched binary, and generates a
.Pa Makefile
and accompanying
top-level C source file that when built creates 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
.Pa Makefile .
This information is cached between runs.
The
.Nm
utility uses the companion program
.Xr crunchide 1
to eliminate link-time conflicts between the component programs by
hiding all unnecessary symbols.
.Pp
The
.Nm
utility places specific requirements on package
.Pa Makefile Ns s
which make it unsuitable for use with
.No non- Ns Bx
sources.
In particular, the
.Pa Makefile
must contain the target
.Ic depend ,
and it must define all object files in the variable
.Va OBJS .
In some cases, you can use a fake
.Pa Makefile :
before looking for
.Pa Makefile
in the source directory
.Pa foo ,
.Nm
looks for the file
.Pa Makefile.foo
in the current directory.
.Pp
After
.Nm
is run, the crunched binary can be built by running
.Dq Li make -f <conf-name>.mk .
The component programs' object files must already be built.
An
.Ic objs
target, included in the output makefile, will
run
.Xr make 1
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
.Pa <conf-name>.c .
.It Fl e Ar exec-file-name
Set crunched binary executable file name to
.Ar exec-file-name .
The default name is
.Pa <conf-name> .
.It Fl f
Flush cache.
Forces the recalculation of cached parameters.
.It Fl l
List names.
Lists the names this binary will respond to.
.It Fl h Ar makefile-header-name
Set the name of a file to be included at the beginning of the
.Pa Makefile Ns s
generated by
.Nm .
This is useful to define some make variables which might affect the behavior of
.Xr make 1
and are annoying to pass through environment variables.
.It Fl m Ar makefile-name
Set output
.Pa Makefile
name to
.Ar makefile-name .
The default name is
.Pa <conf-name>.mk .
.It Fl o
Add
.Dq Li make obj
rules to each program make target.
.It Fl p Ar obj-prefix
Set the pathname to be prepended to the
.Ic srcdir
when computing the
.Ic objdir .
If this option is not present, then the prefix used
is the content of the
.Ev MAKEOBJDIRPREFIX
environment variable, or
.Pa /usr/obj .
.It Fl q
Quiet operation.
Status messages are suppressed.
.El
.Sh CRUNCHGEN CONFIGURATION FILE COMMANDS
The
.Nm
utility 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.
The
.Nm
utility 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 Ic 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 Pa <source-dir>/<progname>/
convention.
Multiple
.Ic srcdirs
lines can be specified.
The directories are searched in the order they are given.
.It Ic progs Ar progname ...
A list of programs that make up the crunched binary.
Multiple
.Ic progs
lines can be specified.
.It Ic libs Ar libspec ...
A list of library specifications to be included in the crunched binary link.
Multiple
.Ic libs
lines can be specified.
.It Ic libs_so Ar libspec ...
A list of library specifications to be dynamically linked in the
crunched binary.
These libraries will need to be made available via the run-time link-editor
.Xr rtld 1
when the component program that requires them is executed from
the crunched binary.
Multiple
.Ic libs_so
lines can be specified.
The
.Ic libs_so
directive overrides a library specified gratuitously on a
.Ic libs
line.
.It Ic buildopts Ar buildopts ...
A list of build options to be added to every make target.
.It Ic ln Ar progname linkname
Causes the crunched binary to invoke
.Ar progname
whenever
.Ar linkname
appears in
.Va 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
.Pa Makefile ,
the following
.Ic special
commands can be used to set
.Nm
parameters for a component program.
.Bl -tag -width indent
.It Ic special Ar progname Ic srcdir Ar pathname
Set the source directory for
.Ar progname .
This is normally calculated by searching the specified
.Ic srcdirs
for a directory named
.Ar progname .
.It Ic special Ar progname Ic objdir Ar pathname
Set the
.Pa obj
directory for
.Ar progname .
The
.Pa obj
directory is normally calculated by looking for a directory
whose name is that of the source directory prepended by
one of the following components, in order of priority:
the
.Fl p
argument passed to the command line; or,
the value of the
.Ev MAKEOBJDIRPREFIX
environment variable, or
.Pa /usr/obj .
If the directory is not found, the
.Ic srcdir
itself becomes the
.Ic objdir .
.It Ic special Ar progname Ic buildopts Ar buildopts
Define a set of build options that should be added to
.Xr make 1
targets in addition to those specified using
.Ic buildopts
when processing
.Ar progname .
.It Ic special Ar progname Ic 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 Ic srcdir Ns / Ns Pa Makefile
and outputs the value of
.Va $(OBJS) .
.It Ic special Ar progname Ic 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
.Ic objdir
pathname to each file in the
.Ic objs
list.
.It Ic special Ar progname Ic objvar Ar variable_name
Sets the name of the
.Xr make 1
variable which holds the list of
object files for program
.Ar progname .
This is normally
.Va OBJS
but some
.Pa Makefile Ns s
might like to use other conventions or
prepend the program's name to the variable, e.g.,
.Va SSHD_OBJS .
.It Ic special Ar progname Ic lib Ar library-name ...
Specifies libraries to be linked with object files to produce
.Ar progname Ns Pa .lo .
This can be useful with libraries which redefine routines in
the standard libraries, or poorly written libraries which
reference symbols in the object files.
.It Ic special Ar progname Ic keep Ar symbol-name ...
Add specified list of symbols to the keep list for program
.Ar progname .
An underscore
.Pq Ql _
is prepended to each symbol and it becomes the argument to a
.Fl k
option for the
.Xr crunchide 1
phase.
This option is to be used as a last resort as its use can cause a
symbol conflict, however in certain instances it may be the only way to
have a symbol resolve.
.It Ic special Ar progname Ic ident Ar identifier
Set the
.Pa Makefile Ns / Ns Tn C
identifier for
.Ar progname .
This is normally generated from a
.Ar progname ,
mapping
.Ql -
to
.Ql _
and ignoring all other non-identifier characters.
This leads to programs named
.Qq Li foo.bar
and
.Qq Li foobar
to map to the same identifier.
.El
.Pp
Only the
.Ic objpaths
parameter is actually needed by
.Nm ,
but it is calculated from
.Ic objdir
and
.Ic objs ,
which are in turn calculated from
.Ic 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
.Ic objs
target that will build the object files for each component program by
running
.Xr make 1
inside that program's source directory.
For this to work the
.Ic srcdir
and
.Ic objs
parameters must also be valid.
If they are not valid for a particular program, that
program is skipped in the
.Ic objs
target.
.Sh EXAMPLES
Here is an example
.Nm
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
progs anotherprog
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

special anotherprog -DNO_FOO WITHOUT_BAR=YES

libs -lutil -lcrypt
.Ed
.Pp
This conf file specifies a small crunched binary consisting of some
basic system utilities plus a homegrown install program
.Dq Pa myinstall ,
for which no source directory is specified, but its object file is
specified directly with the
.Ic special
line.
.Pp
Additionally when
.Dq Pa anotherprog
is built the arguments
.Pp
.Dl -DNO_FOO WITHOUT_BAR=YES
.Pp
are added to all build targets.
.Pp
The crunched binary
.Dq Pa 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 Pa kcopy
can be copied onto an install floppy
and hard-linked to the names of the component programs.
.Pp
Note that if the
.Ic libs_so
command had been used, copies of the libraries so named
would also need to be copied to the install floppy.
.Sh SEE ALSO
.Xr crunchide 1 ,
.Xr make 1 ,
.Xr rtld 1
.Sh AUTHORS
.An -nosplit
The
.Nm
utility was written by
.An James da Silva Aq Mt jds@cs.umd.edu .
.Pp
Copyright (c) 1994 University of Maryland.
All Rights Reserved.
.Pp
The
.Ic libs_so
keyword was added in 2005 by
.An Adrian Steinmann Aq Mt ast@marabu.ch
and
.An Ceri Davies Aq Mt ceri@FreeBSD.org .
.Sh CAVEATS
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 Li make objs
must then be used to get those object files built, or
some other arrangements made.