Patch: RFC: make libltdl search for version-specific symlinks first

[Thomas Fitzsimmons <fitzsim at redhat dot com>]

Hi,

This patch makes libltdl search for a version-specific DSO before
searching for the corresponding versionless DSO.  This will allow
multiple ABI-incompatible versions of libgcj to be installed in parallel
in the same prefix.  Currently, this isn't possible because libltdl
finds only the versionless .so symlink, so only the most
recently-installed libgcj will find the correct version of the peer
library.

Currently, libltdl searches for the peer library like this: first it
looks for lib-gnu-java-awt-peer-gtk.la.  Failing that, it looks for
lib-gnu-java-awt-peer-gtk.so.  This patch adds an intermediate search
for lib-gnu-java-awt-peer-gtk.so.n, where n is the ABI version number.

Comments?
Tom


diff -ru -x configure -x config-h.in -x aclocal.m4 -x Makefile.in libltdl.orig/acinclude.m4 libltdl/acinclude.m4
--- libltdl.orig/acinclude.m4	2004-08-20 17:52:29.000000000 -0400
+++ libltdl/acinclude.m4	2004-08-20 21:56:21.000000000 -0400
@@ -6091,6 +6091,9 @@
 if test -n "$libltdl_cv_shlibext"; then
   AC_DEFINE_UNQUOTED(LTDL_SHLIB_EXT, "$libltdl_cv_shlibext",
     [Define to the extension used for shared libraries, say, ".so".])
+  libltdl_cv_shlibversionext=.so.`grep -v '^\#' ${srcdir}/../libtool-version | awk -F: '{ print $'1' }'`
+  AC_DEFINE_UNQUOTED(LTDL_SHLIB_VERSION_EXT, "$libltdl_cv_shlibversionext",
+    [Define to the versioned extension used for shared libraries, say, ".so.5".])
 fi
 ])# AC_LTDL_SHLIBEXT
 
Only in libltdl: autom4te.cache
diff -ru -x configure -x config-h.in -x aclocal.m4 -x Makefile.in libltdl.orig/ltdl.c libltdl/ltdl.c
--- libltdl.orig/ltdl.c	2004-08-20 17:52:29.000000000 -0400
+++ libltdl/ltdl.c	2004-08-21 00:18:50.000000000 -0400
@@ -859,6 +859,7 @@
 static	const char	objdir[]		= LTDL_OBJDIR;
 static	const char	archive_ext[]		= LTDL_ARCHIVE_EXT;
 #ifdef	LTDL_SHLIB_EXT
+static	const char	shlib_version_ext[]	= LTDL_SHLIB_VERSION_EXT;
 static	const char	shlib_ext[]		= LTDL_SHLIB_EXT;
 #endif
 #ifdef	LTDL_SYSSEARCHPATH
@@ -2388,17 +2389,14 @@
   cur = *handle;
   if (filename)
     {
-      /* Comment out the check of file permissions using access.
-	 This call seems to always return -1 with error EACCES.
-      */
       /* We need to catch missing file errors early so that
-	 file_not_found() can detect what happened.
+	 file_not_found() can detect what happened. */
       if (access (filename, R_OK) != 0)
 	{
 	  LT_DLMUTEX_SETERROR (LT_DLSTRERROR (FILE_NOT_FOUND));
 	  ++errors;
 	  goto done;
-	} */
+	}
 
       cur->info.filename = lt_estrdup (filename);
       if (!cur->info.filename)
@@ -3425,10 +3423,11 @@
   return 0;
 }
 
-/* If FILENAME has an ARCHIVE_EXT or SHLIB_EXT extension, try to
-   open the FILENAME as passed.  Otherwise try appending ARCHIVE_EXT,
-   and if a file is still not found try again with SHLIB_EXT appended
-   instead.  */
+/* If FILENAME has an ARCHIVE_EXT, SHLIB_VERSION_EXT or SHLIB_EXT
+   extension, try to open the FILENAME as passed.  Otherwise try
+   appending ARCHIVE_EXT, and if a file is still not found try again
+   with SHLIB_VERSION_EXT appended.  If the file is still not found,
+   try again with SHLIB_EXT appended.  */
 lt_dlhandle
 lt_dlopenext (filename)
      const char *filename;
@@ -3453,6 +3452,7 @@
      to try appending additional extensions.  */
   if (ext && ((strcmp (ext, archive_ext) == 0)
 #ifdef LTDL_SHLIB_EXT
+	      || (strcmp (ext, shlib_version_ext) == 0)
 	      || (strcmp (ext, shlib_ext) == 0)
 #endif
       ))
@@ -3481,8 +3481,34 @@
     }
 
 #ifdef LTDL_SHLIB_EXT
+  /* Try appending SHLIB_VERSION_EXT.   */
+  if (LT_STRLEN (shlib_version_ext) > LT_STRLEN (archive_ext))
+    {
+      LT_DLFREE (tmp);
+      tmp = LT_EMALLOC (char, len + LT_STRLEN (shlib_version_ext) + 1);
+      if (!tmp)
+	return 0;
+
+      strcpy (tmp, filename);
+    }
+  else
+    {
+      tmp[len] = LT_EOS_CHAR;
+    }
+
+  strcat(tmp, shlib_version_ext);
+  errors = try_dlopen (&handle, tmp);
+
+  /* As before, if the file was found but loading failed, return now
+     with the current error message.  */
+  if (handle || ((errors > 0) && !file_not_found ()))
+    {
+      LT_DLFREE (tmp);
+      return handle;
+    }
+
   /* Try appending SHLIB_EXT.   */
-  if (LT_STRLEN (shlib_ext) > LT_STRLEN (archive_ext))
+  if (LT_STRLEN (shlib_ext) > LT_STRLEN (shlib_version_ext))
     {
       LT_DLFREE (tmp);
       tmp = LT_EMALLOC (char, len + LT_STRLEN (shlib_ext) + 1);