Re: Preloading without .la

[Pierre Ossman]

I've put together a suggestion (against 1.5 branch, but the difference 
shouldn't be that big compared to HEAD) for this.

What it does is strip ${libext} from the name and, if we're on a 
$need_lib_prefix system, applies a command that should reverse the 
effect of $libname_spec. It then appends the '.la' extension.

Example:

On a non-$need_lib_prefix system:

foomodule.a => foomodule => foomodule.la

On a $need_lib_prefix system:

libfoomodule.a => libfoomodule => foomodule => foomodule.la

The effect is that preloading and "normal" loading will work for any 
application that uses the platform independent ways of loading:

 - lt_dlopen("module.la")
 - lt_dlopenext("module")
 - lt_dlopenext("module.la")


Any programs that uses lt_dlopen("module.a") will break with this patch. 
But I would consider such a call unsupported since they've been mucking 
about in libtool internals to figure out that name.


The is another breakage caused by the fact that libtool special cases 
the 'lib' prefix. dlpreopening a module called libfoo on a 
$need_lib_prefix system with a prefix of 'lib' will not work. The reason 
is that the above magic cannot tell the difference between 'libfoo' and 
'foo' (which will be transformed to 'libfoo') on such a system.


Please review and comment. If it looks good I'll make a patch for HEAD 
and try to do some test cases.

--
Pierre Ossman                Telephone: +46-13-21 46 00
Cendio AB                    Web: http://www.cendio.com

Index: libtool.m4
===================================================================
RCS file: /sources/libtool/libtool/Attic/libtool.m4,v
retrieving revision 1.314.2.148
diff -u -r1.314.2.148 libtool.m4
--- libtool.m4  21 Jan 2006 16:46:08 -0000      1.314.2.148
+++ libtool.m4  27 Jan 2006 16:16:49 -0000
@@ -1195,6 +1195,7 @@
 [AC_MSG_CHECKING([dynamic linker characteristics])
 library_names_spec=
 libname_spec='lib$name'
+libname_rev_cmds='echo $name | $Xsed "s/^lib//"'
 soname_spec=
 shrext_cmds=".so"
 postinstall_cmds=
@@ -1669,6 +1670,7 @@
 
 os2*)
   libname_spec='$name'
+  libname_rev_cmds='$name'
   shrext_cmds=".dll"
   need_lib_prefix=no
   library_names_spec='$libname${shared_ext} $libname.a'
@@ -4133,7 +4135,7 @@
   # variables and quote the copies for generation of the libtool script.
   for var in echo old_CC old_CFLAGS AR AR_FLAGS EGREP RANLIB LN_S LTCC 
LTCFLAGS NM \
     SED SHELL STRIP \
-    libname_spec library_names_spec soname_spec extract_expsyms_cmds \
+    libname_spec libname_rev_cmds library_names_spec soname_spec 
extract_expsyms_cmds \
     old_striplib striplib file_magic_cmd finish_cmds finish_eval \
     deplibs_check_method reload_flag reload_cmds need_locks \
     lt_cv_sys_global_symbol_pipe lt_cv_sys_global_symbol_to_cdecl \
Index: ltmain.in
===================================================================
RCS file: /sources/libtool/libtool/Attic/ltmain.in,v
retrieving revision 1.334.2.118
diff -u -r1.334.2.118 ltmain.in
--- ltmain.in   21 Jan 2006 16:46:08 -0000      1.334.2.118
+++ ltmain.in   27 Jan 2006 16:16:49 -0000
@@ -4577,7 +4577,12 @@
 
          for arg in $dlprefiles; do
            $show "extracting global C symbols from \`$arg'"
-           name=`$echo "$arg" | ${SED} -e 's%^.*/%%'`
+           name=`$echo "$arg" | ${SED} -e 's%^.*/%%' | ${SED} -e 
's%\.'${libext}'$%%'`
+           if test "$need_lib_prefix" != no; then
+             eval shared_ext=\"$shrext_cmds\"
+             eval name=\"$libname_rev_cmds\"
+           fi
+           name="${name}.la"
            $run eval '$echo ": $name " >> "$nlist"'
            $run eval "$NM $arg | $global_symbol_pipe >> '$nlist'"
          done