make libltdl work on platforms without loader

[Ralf Wildenhues]

Dearest libtool-patches audience,

I'd very much like the approval of the following patches, which
finally make libltdl work again on static platforms! :-)

OK to apply to HEAD and branch-2-0?

Cheers,
Ralf


patch #1:
This cute typo (leftover from some incomplete renaming?) was almost
responsible for physical damage.

        * config/ltmain.m4sh (func_mode_link): $dlsymsobj is really
        $symfileobj, bug exposed only in the static preloading case
        (symfileobj is created, but not linked into output).

Index: config/ltmain.m4sh
===================================================================
RCS file: /cvsroot/libtool/libtool/config/ltmain.m4sh,v
retrieving revision 1.1.2.21
diff -u -r1.1.2.21 ltmain.m4sh
--- config/ltmain.m4sh  22 Nov 2004 22:28:48 -0000      1.1.2.21
+++ config/ltmain.m4sh  28 Nov 2004 09:48:18 -0000
@@ -6182,7 +6182,7 @@
          build_libtool_libs=no
        else
          oldobjs="$old_deplibs $non_pic_objects"
-         if test "$preload" = yes && test -f "$dlsymsobj"; then
+         if test "$preload" = yes && test -f "$symfileobj"; then
            oldobjs="$oldobjs $symfileobj"
          fi
        fi




patch #2:
On a platform with only the preopen loader, the symfileobj for
libltdl*.la will not be created, simply because there is no lalib
to be dlpreopened.  However, the ltdl code requires the symbol
lt_$(LIBLTDL)_LTX_preloaded_symbols to be present (program link time
failure).  I guess the proper fix would probably adding a switch to
`libtool --mode=link' which would force output of the symfileobj.
The quickest solution I could come up with was just adding a dummy
loader in case there is no other loader.  We can still do it right
sometime later.

I hate bootstrapping corner cases.

        * libltdl/loaders/dummy.c: new file, dummy loader that doesn't
        do anything and always fails.
        * m4/ltdl.m4 (LT_LIB_DLLOAD), libltdl/loaders/Makefile.am:
        In case of no other loader, use the dummy loader to force
        symfileobj creation.

Index: m4/ltdl.m4
===================================================================
RCS file: /cvsroot/libtool/libtool/m4/ltdl.m4,v
retrieving revision 1.20.2.2
diff -u -r1.20.2.2 ltdl.m4
--- m4/ltdl.m4  10 Nov 2004 13:20:52 -0000      1.20.2.2
+++ m4/ltdl.m4  28 Nov 2004 09:48:27 -0000
@@ -413,7 +413,8 @@
                [AC_DEFINE([HAVE_LIBDL], [1],
                         [Define if you have the libdl library or equivalent.])
                LIBADD_DLOPEN="-lsvld" libltdl_cv_func_dlopen="yes"
-               LT_DLLOADERS="$LT_DLLOADERS dlopen.la"])])])
+               LT_DLLOADERS="$LT_DLLOADERS dlopen.la"],
+               LT_DLLOADERS="$LT_DLLOADERS dummy.la")])])
 if test x"$libltdl_cv_func_dlopen" = xyes || test x"$libltdl_cv_lib_dl_dlopen" 
= xyes
 then
   lt_save_LIBS="$LIBS"
Index: libltdl/loaders/Makefile.am
===================================================================
RCS file: /cvsroot/libtool/libtool/libltdl/loaders/Makefile.am,v
retrieving revision 1.3.2.3
diff -u -r1.3.2.3 Makefile.am
--- libltdl/loaders/Makefile.am 23 Nov 2004 12:47:19 -0000      1.3.2.3
+++ libltdl/loaders/Makefile.am 28 Nov 2004 09:48:20 -0000
@@ -37,7 +37,7 @@
 ## use convenience libraries for that purpose:
 noinst_LTLIBRARIES     = $(LT_DLLOADERS)
 EXTRA_LTLIBRARIES      = dlopen.la dld_link.la dyld.la load_add_on.la \
-                         loadlibrary.la shl_load.la
+                         loadlibrary.la shl_load.la dummy.la
 
 ## Build loaders (other than preopen) as modules:
 dlopen_la_LIBADD       = ../libdlloader.la $(LIBADD_DLOPEN)
@@ -52,7 +52,7 @@
 ## libtoolize --ltdl can find them later:
 ltdldatadir            = $(pkgdatadir)/libltdl/loaders
 ltdldata_DATA          = Makefile.am dld_link.c dlopen.c dyld.c \
-                         load_add_on.c loadlibrary.c shl_load.c
+                         load_add_on.c loadlibrary.c shl_load.c dummy.c
 
 ../libdlloader.la:
        cd ..; $(MAKE) $(AM_MAKEFLAGS) libdlloader.la
--- /dev/null   2004-09-14 22:52:52.000000000 +0200
+++ libltdl/loaders/dummy.c     2004-11-28 10:01:11.000000000 +0100
@@ -0,0 +1,114 @@
+/* dummy.c -- the dummy loader that always fails
+   Copyright (C) 2004 Free Software Foundation, Inc.
+
+   NOTE: The canonical source of this file is maintained with the
+   GNU Libtool package.  Report bugs to address@hidden
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+As a special exception to the GNU Lesser General Public License,
+if you distribute this file as part of a program or library that
+is built using GNU libtool, you may include it under the same
+distribution terms that you use for the rest of that program.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with this library; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307  USA
+
+*/
+
+#include "lt__private.h"
+
+/* Use the preprocessor to rename non-static symbols to avoid namespace
+   collisions when the loader code is statically linked into libltdl.
+   Use the "<module_name>_LTX_" prefix so that the symbol addresses can
+   be fetched from the preloaded symbol list by lt_dlsym():  */
+#define get_vtable     dummy_LTX_get_vtable
+
+LT_SCOPE lt_dlvtable *get_vtable (lt_user_data loader_data);
+
+
+/* Boilerplate code to set up the vtable for hooking this loader into
+   libltdl's loader list:  */
+static lt_module vm_open  (lt_user_data loader_data, const char *filename);
+static int      vm_close (lt_user_data loader_data, lt_module module);
+static void *   vm_sym   (lt_user_data loader_data, lt_module module,
+                         const char *symbolname);
+
+/* Return the vtable for this loader, only the name and sym_prefix
+   attributes (plus the virtual function implementations, obviously)
+   change between loaders.  */
+lt_dlvtable *
+get_vtable (lt_user_data loader_data)
+{
+  static lt_dlvtable *vtable = 0;
+
+  if (!vtable)
+    {
+      vtable = lt__zalloc (sizeof *vtable);
+    }
+
+  if (vtable && !vtable->name)
+    {
+      vtable->name             = "lt_dummy";
+#if defined(DLSYM_USCORE)
+      vtable->sym_prefix       = "_";
+#endif
+      vtable->module_open      = vm_open;
+      vtable->module_close     = vm_close;
+      vtable->find_sym         = vm_sym;
+      vtable->dlloader_data    = loader_data;
+      vtable->priority         = LT_DLLOADER_PREPEND;
+    }
+
+  if (vtable && (vtable->dlloader_data != loader_data))
+    {
+      LT__SETERROR (INIT_LOADER);
+      return 0;
+    }
+
+  return vtable;
+}
+
+
+
+/* --- IMPLEMENTATION --- */
+
+
+/* A function called through the vtable to open a module with this
+   loader.  Returns an opaque representation of the newly opened
+   module for processing with this loader's other vtable functions.  */
+static lt_module
+vm_open (lt_user_data loader_data, const char *filename)
+{
+  LT__SETERROR (CANNOT_OPEN);
+  return NULL;
+}
+
+
+/* A function called through the vtable when a particular module
+   should be unloaded.  */
+static int
+vm_close (lt_user_data loader_data, lt_module module)
+{
+  return 0;
+}
+
+
+/* A function called through the vtable to get the address of
+   a symbol loaded from a particular module.  */
+static void *
+vm_sym (lt_user_data loader_data, lt_module module, const char *name)
+{
+  LT__SETERROR (SYMBOL_NOT_FOUND);
+  return NULL;
+}