[PATCH] PE direct linking to dlls, accept any filename.

[Pedro Alves <pedro_alves at portugalmail dot pt>]

Hi all,

The gdb testsuite in some shared lib tests, builds shared libs with .so 
or .sl extension uncondicionally,
and then tries to do a direct link, even on PE platforms (eg:cygwin).  
That fails to link with current ld.
I sent a patch there to fix a few cases, by introducing a $SOEXT var in 
the testsuite.
But thinking again, I can't see a reason ld doesn't let us do a direct 
link to a dll with an extension
other than ".dll" or ".DLL".  The Windows loader is happy to load the 
dlls, and in fact there are many
examples of dlls without a ".dll" extension in production.

The attached patch makes ld be able to direct link any dll without 
looking at the filename extension.

Built and regtested on i686-pc-cygwin, and confirmed manually that we 
identify dlls as dlls no matter
what the filename is, that we don't mistake exe images with dlls.  Also 
confirmed linking with msvcrt.dll
to be sure we can identify a dll built with MSVC as such.

Please review and commit.

Cheers,
Pedro Alves

----
ld/

2006-12-15  Pedro Alves  <pedro_alves@portugalmail.pt>

	* emultempl/pe.em (gld_${EMULATION_NAME}_recognized_file):
	Detect dlls using bfd not the filename extension.

ld/testsuite/

2006-12-15  Pedro Alves  <pedro_alves@portugalmail.pt>

	* ld-pe/direct.exp: New file.
	* ld-pe/direct_client.c: Likewise.
	* ld-pe/direct_dll.c: Likewise.


Index: emultempl/pe.em
===================================================================
RCS file: /cvs/src/src/ld/emultempl/pe.em,v
retrieving revision 1.121
diff -u -p -r1.121 pe.em
--- emultempl/pe.em	3 Oct 2006 10:06:26 -0000	1.121
+++ emultempl/pe.em	15 Dec 2006 15:17:21 -0000
@@ -1418,15 +1418,13 @@ gld_${EMULATION_NAME}_recognized_file (l
   if (bfd_get_format (entry->the_bfd) == bfd_object)
     {
       char fbuf[LD_PATHMAX + 1];
-      const char *ext;
 
       if (REALPATH (entry->filename, fbuf) == NULL)
 	strncpy (fbuf, entry->filename, sizeof (fbuf));
 
-      ext = fbuf + strlen (fbuf) - 4;
-
-      if (strcmp (ext, ".dll") == 0 || strcmp (ext, ".DLL") == 0)
-	return pe_implied_import_dll (fbuf);
+      if (obj_pe (entry->the_bfd)
+          && pe_data (entry->the_bfd)->dll)
+        return pe_implied_import_dll (fbuf);
     }
 #endif
   return FALSE;
--- /dev/null	2006-12-15 15:20:26.499625000 +0000
+++ testsuite/ld-pe/direct.exp	2006-12-15 15:12:19.062125000 +0000
@@ -0,0 +1,91 @@
+# Expect script for direct linking from dll tests
+#   Copyright 2006
+#   Free Software Foundation, Inc.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+# 
+# This program 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 General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# Written by Pedro Alves <pedro_alves@portugalmail.pt>
+#
+ 
+# Note: 
+# 
+# This test checks the "direct linking to a dll" functionality.
+# 
+# The test has 4 stages: 
+# 
+# 1. compile and link a test dll with ".dll" extension.
+#
+# 2. compile and link a test dll with ".sl" (i.e. != ".dll") extension.
+#
+# 3. compile and link a client application linking directly to the ".dll" dll built in 1. 
+#    This should produce no errors. 
+#
+# 4. compile and link a client application linking directly to the ".sl" dll built in 2. 
+#    This should produce no errors. 
+
+# This test can only be run on PE/COFF platforms.
+if {    ![istarget *-*-cygwin*]
+     && ![istarget *-*-mingw*]
+     && ![istarget *-*-pe] } {
+    return
+}
+
+# No compiler, no test.
+if { [which $CC] == 0 } {
+    untested "Direct linking to dll test"
+    return
+}
+
+set tmpdir tmpdir
+
+proc test_direct_link_dll {} {
+    global CC
+    global CFLAGS
+    global srcdir
+    global subdir
+    global tmpdir
+    
+    # Compile the dll.
+    if ![ld_compile "$CC $CFLAGS" $srcdir/$subdir/direct_dll.c $tmpdir/direct_dll.o ] {
+	fail "compiling shared lib"
+    } elseif ![ld_simple_link "$CC -shared" $tmpdir/direct_dll.dll "$tmpdir/direct_dll.o" ] {
+	fail "linking shared lib (.dll)"
+    } elseif ![ld_simple_link "$CC -shared" $tmpdir/direct_dll.sl "$tmpdir/direct_dll.o" ] {
+	fail "linking shared lib (.sl)"
+    } else {
+	# Compile and link the client program.
+	if ![ld_compile "$CC $CFLAGS" $srcdir/$subdir/direct_client.c $tmpdir/direct_client.o ] {
+	    fail "compiling client"
+	} else {
+	    # Check linking directly to direct_dll.dll.
+	    set msg "linking client (.dll)"
+	    if [ld_simple_link $CC $tmpdir/direct_client.exe "$tmpdir/direct_client.o $tmpdir/direct_dll.dll" ] {
+		pass $msg
+	    } else {
+		fail $msg 
+	    }
+
+	    # Check linking directly to direct_dll.sl.
+	    set msg "linking client (.sl)"
+	    if [ld_simple_link $CC $tmpdir/direct_client.exe "$tmpdir/direct_client.o $tmpdir/direct_dll.sl" ] {
+		pass $msg
+	    } else {
+		fail $msg 
+	    }
+	}
+    }
+}
+
+test_direct_link_dll
--- /dev/null	2006-12-15 15:20:35.921500000 +0000
+++ testsuite/ld-pe/direct_dll.c	2006-12-15 15:10:30.609000000 +0000
@@ -0,0 +1,5 @@
+__declspec(dllexport) int
+dll_func (void)
+{
+  return 10;
+}
--- /dev/null	2006-12-15 15:20:40.265250000 +0000
+++ testsuite/ld-pe/direct_client.c	2006-12-15 15:10:50.640250000 +0000
@@ -0,0 +1,8 @@
+__declspec(dllimport) int dll_func (void);
+
+int
+main()
+{
+  dll_func ();
+  return 0;
+}