[PATCH] [RESPUN] Support versioned symbols better in GNU/Linux

[Nix]

[This is a resend of an earlier patch sent on 2003-02-01; one silly typo
 has been corrected and the patch has been respun against libtool-1.5.
 Otherwise, it is unchanged.

 I assume the earlier patch dropped completely out of sight and nobody
 noticed it, so I'm resending the explanatory text as well.]


As Ulrich Drepper has commented (in
<http://people.redhat.com/drepper/dsohowto.pdf>), libtool's support for
non-exported symbol visibility on GNU/Linux could do with
improvement. Presently, if you specify an -export-symbols file, libtool
converts it into a -Wl,-retain-symbols-file argument to $CC. This is
hardly ideal, as --retain-symbols-file doesn't actually affect the
visibility of symbols at runtime at all!

The right thing to do is to use a version script. Luckily, the code to
do this is already present for Solaris without GNU ld; all that is
needed is to use a similar construction for GNU/Linux as well.

Therefore, a patch, against CVS HEAD (KCC and Compaq C++ parts
untested). (I'd write a testcase too but I'm not sure how you suppress
running single testcases, and we'd need to suppress this one for the
non-GNU/Linux, non-Solaris case.)


(It may also be a good idea to add this for other platforms,
particularly Solaris with GNU/ld, for which it would be a matter of
deleting one conditional; but I can't test this at all, so I didn't do
it.)


2003-06-09  Nix  <address@hidden>

        * libtool.m4 (AC_LIBTOOL_PROG_LD_SHLIBS): Use version scripts
        under GNU/Linux.
        (AC_LIBTOOL_LANG_CXX_CONFIG): Likewise for KCC and Compaq C++.

Index: 1.5/libtool.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/libtool.m4,v
retrieving revision 1.314
diff -u -r1.314 libtool.m4
--- 1.5/libtool.m4      5 Apr 2003 19:32:58 -0000       1.314
+++ 1.5/libtool.m4      9 Jun 2003 20:32:30 -0000
@@ -3087,7 +3087,8 @@
        # ends with ".so" (or ".sl" for HP-UX), so rename the library
        # to its proper name (with version) after linking.
        _LT_AC_TAGVAR(archive_cmds, $1)='tempext=`echo $shared_ext | $SED -e 
'\''s/\([[^()0-9A-Za-z{}]]\)/\\\\\1/g'\''`; templib=`echo $lib | $SED -e 
"s/\${tempext}\..*/.so/"`; $CC $predep_objects $libobjs $deplibs 
$postdep_objects $compiler_flags --soname $soname -o \$templib; mv \$templib 
$lib'
-       _LT_AC_TAGVAR(archive_expsym_cmds, $1)='tempext=`echo $shared_ext | 
$SED -e '\''s/\([[^()0-9A-Za-z{}]]\)/\\\\\1/g'\''`; templib=`echo $lib | $SED 
-e "s/\${tempext}\..*/.so/"`; $CC $predep_objects $libobjs $deplibs 
$postdep_objects $compiler_flags --soname $soname -o \$templib 
${wl}-retain-symbols-file,$export_symbols; mv \$templib $lib'
+       _LT_AC_TAGVAR(archive_expsym_cmds, $1)='$echo "{ global:" > 
$lib.exp~cat $export_symbols | sed -e "s/\(.*\)/\1;/" >> $lib.exp~$echo "local: 
*; };" >> $lib.exp~
+       tempext=`echo $shared_ext | $SED -e 
'\''s/\([[^()0-9A-Za-z{}]]\)/\\\\\1/g'\''`; templib=`echo $lib | $SED -e 
"s/\${tempext}\..*/.so/"`; $CC $predep_objects $libobjs $deplibs 
$postdep_objects $compiler_flags --soname $soname -o \$templib 
${wl}-retain-symbols-file,$export_symbols; mv \$templib $lib'
        # Commands to make compiler produce verbose output that lists
        # what "hidden" libraries, object files and flags are used when
        # linking a shared library.
@@ -3118,7 +3119,8 @@
       cxx)
        # Compaq C++
        _LT_AC_TAGVAR(archive_cmds, $1)='$CC -shared $predep_objects $libobjs 
$deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname -o $lib'
-       _LT_AC_TAGVAR(archive_expsym_cmds, $1)='$CC -shared $predep_objects 
$libobjs $deplibs $postdep_objects $compiler_flags ${wl}-soname $wl$soname  -o 
$lib ${wl}-retain-symbols-file $wl$export_symbols'
+       _LT_AC_TAGVAR(archive_expsym_cmds, $1)='$echo "{ global:" > 
$lib.exp~cat $export_symbols | sed -e "s/\(.*\)/\1;/" >> $lib.exp~$echo "local: 
*; };" >> $lib.exp~
+       $CC -shared $predep_objects $libobjs $deplibs $postdep_objects 
$compiler_flags ${wl}-soname $wl$soname  -o $lib ${wl}-retain-symbols-file 
$wl$export_symbols ${wl}-version-script ${wl}$lib.exp'
 
        runpath_var=LD_RUN_PATH
        _LT_AC_TAGVAR(hardcode_libdir_flag_spec, $1)='-rpath $libdir'
@@ -5125,6 +5127,12 @@
       wlarc=
       _LT_AC_TAGVAR(hardcode_direct, $1)=yes
       _LT_AC_TAGVAR(hardcode_shlibpath_var, $1)=no
+      ;;
+
+    linux*)
+      _LT_AC_TAGVAR(archive_cmds, $1)='$CC -shared $libobjs $deplibs 
$compiler_flags ${wl}-soname $wl$soname -o $lib'
+      _LT_AC_TAGVAR(archive_expsym_cmds, $1)='$echo "{ global:" > $lib.exp~cat 
$export_symbols | sed -e "s/\(.*\)/\1;/" >> $lib.exp~$echo "local: *; };" >> 
$lib.exp~
+      $CC -shared $libobjs $deplibs $compiler_flags ${wl}-soname $wl$soname 
${wl}-retain-symbols-file $wl$export_symbols ${wl}-version-script ${wl}$lib.exp 
-o $lib'
       ;;
 
     *)

-- 
`It is an unfortunate coincidence that the date locarchive.h was
 written (in hex) matches Ritchie's birthday (in octal).'
               -- Roland McGrath on the libc-alpha list