extra/libstrip/libstrip

   1 #!/usr/bin/perl -w
   2 # vi: set ts=4:
   3
   4 # Libstrip - A utility to optimize libraries for specific executables
   5 # Copyright (C) 2001  David A. Schleef <ds@schleef.org>
   6 #
   7 # This program is free software; you can redistribute it and/or modify
   8 # it under the terms of version 2 of the GNU General Public License as
   9 # published by the Free Software Foundation.
  10 #
  11 # This is a surprisingly simple script that gets a list of
  12 # unresolved symbols in a list of executables specified on the
  13 # command line, and then relinks the uClibc shared object file
  14 # with only the those symbols and their dependencies.  This
  15 # results in a shared object that is optimized for the executables
  16 # listed, and thus may not work with other executables.
  17 #
  18 # Example: optimizing uClibc for BusyBox
  19 #  Compile uClibc and BusyBox as normal.  Then, in this
  20 #  directory, run:
  21 #    libstrip path/to/busybox
  22 #  After the script completes, there should be a new
  23 #  libuClibc-0.9.5.so in the current directory, which
  24 #  is optimized for busybox.
  25 #
  26 # How it works:
  27 #  The uClibc Makefiles create libuClibc.so by first creating
  28 #  the ar archive libc.a with all the object files, then links
  29 #  the final libuClibc.so by using 'ld --shared --whole-archive'.
  30 #  We take advantage of the linker command line option --undefined,
  31 #  which pulls in a symbol and all its dependencies, and so relink
  32 #  the library using --undefined for each symbol in place of
  33 #  --whole-archive.  The linker script is used only to avoid
  34 #  having very long command lines.
  35
  36 $topdir="../..";
  37
  38 # This is the name of the default ldscript for shared libs.  The
  39 # file name will be different for other architectures.
  40 $ldscript="/usr/lib/ldscripts/elf_i386.xs";
  41
  42 my @syms;
  43 my @allsyms;
  44 my $s;
  45
  46 while($exec = shift @ARGV){
  47         #print "$exec\n";
  48         @syms=`nm --dynamic $exec`;
  49         for $s (@syms){
  50                 chomp $s;
  51                 if($s =~ m/^.{8} [BUV] (.+)/){
  52                         my $x = $1;
  53                         if(!grep { m/^$x$/; } @allsyms){
  54                                 unshift @allsyms, $x;
  55                         }
  56                 }
  57         }
  58 }
  59
  60 open(LDSCRIPT, ">ldscript");
  61 print LDSCRIPT "INCLUDE $ldscript\n";
  62 for $s (@allsyms) {
  63         print LDSCRIPT "EXTERN($s)\n";
  64 }
  65
  66
  67 `gcc -s -nostdlib -Wl,-warn-common -shared \\
  68         -o libuClibc-0.9.5.so \\
  69         -Wl,-soname,libc.so.0 -Wl,--script=ldscript \\
  70         $topdir/libc/libc.a \\
  71         $topdir/libc/tmp/libgcc-need.a`
  72