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

[Christopher Faylor]

On Fri, Dec 15, 2006 at 03:45:03PM +0000, Pedro Alves wrote:
>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.

Wow.  I'm giddy.  I like patches which generalize things like this and
you even included a test case!

Unless someone (Danny?) objects in the next few days, I'll check this
in.

Thank you, Pedro.

cgf

>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;
>+}