[RFA] Check for dladdr in gdbserver

[RFA] Check for dladdr in gdbserver

[Doug Evans]

Hi.

gdbserver uses dladdr which is glibc-specific which android doesn't have.

Ok to check in?

NOTE: There's similar code in gdb/linux-thread-db.c but it isn't
compiled for android (android is a cross target) so I didn't change it.
I can add a similar patch there if required.

2009-12-21  Doug Evans  <dje@google.com>

	* configure.ac: Check for dladdr.
	* config.in: Regenerate.
	* configure: Regenerate.
	* thread-db.c (dladdr_to_soname): Only define ifdef HAVE_DLADDR.
	(try_thread_db_load): Update.

Index: configure.ac
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/configure.ac,v
retrieving revision 1.30
diff -u -p -r1.30 configure.ac
--- configure.ac	17 Nov 2009 17:58:15 -0000	1.30
+++ configure.ac	21 Dec 2009 18:00:44 -0000
@@ -1,5 +1,5 @@
 dnl Autoconf configure script for GDB server.
-dnl Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+dnl Copyright (C) 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
 dnl Free Software Foundation, Inc.
 dnl
 dnl This file is part of GDB.
@@ -45,6 +45,15 @@ AC_CHECK_HEADERS(sgtty.h termio.h termio
 AC_CHECK_FUNCS(pread pwrite pread64)
 AC_REPLACE_FUNCS(memmem)
 
+dnl dladdr is glibc-specific.  It is used by thread-db.c but only for
+dnl debugging messages.  It lives in -ldl which is handled below so we don't
+dnl use AC_CHECK_LIB (or AC_SEARCH_LIBS) here.  Instead we just temporarily
+dnl augment LIBS.
+old_LIBS="$LIBS"
+LIBS="$LIBS -ldl"
+AC_CHECK_FUNCS(dladdr)
+LIBS="$old_LIBS"
+
 have_errno=no
 AC_MSG_CHECKING(for errno)
 AC_TRY_LINK([
Index: thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/thread-db.c,v
retrieving revision 1.30
diff -u -p -r1.30 thread-db.c
--- thread-db.c	19 Dec 2009 00:29:11 -0000	1.30
+++ thread-db.c	21 Dec 2009 18:00:44 -0000
@@ -596,6 +596,8 @@ try_thread_db_load_1 (void *handle)
   return 1;
 }
 
+#ifdef HAVE_DLADDR
+
 /* Lookup a library in which given symbol resides.
    Note: this is looking in the GDBSERVER process, not in the inferior.
    Returns library name, or NULL.  */
@@ -610,6 +612,8 @@ dladdr_to_soname (const void *addr)
   return NULL;
 }
 
+#endif
+
 static int
 try_thread_db_load (const char *library)
 {
@@ -626,6 +630,7 @@ try_thread_db_load (const char *library)
       return 0;
     }
 
+#ifdef HAVE_DLADDR
   if (debug_threads && strchr (library, '/') == NULL)
     {
       void *td_init;
@@ -640,6 +645,7 @@ try_thread_db_load (const char *library)
 		     library, libpath);
 	}
     }
+#endif
 
   if (try_thread_db_load_1 (handle))
     return 1;

Re: [RFA] Check for dladdr in gdbserver

[Joel Brobecker]

Not enough experience with the gdbserver code, especially on Linux
targets, so can't really review the patch itself, even if it looks OK
to me. However:

> NOTE: There's similar code in gdb/linux-thread-db.c but it isn't
> compiled for android (android is a cross target) so I didn't change it.
> I can add a similar patch there if required.

IMO: I would leave it be until it because a bona fide issue (when
someone tries to port GDB to a Linux system without a glibc).

-- 
Joel

Re: [RFA] Check for dladdr in gdbserver

[Daniel Jacobowitz]

On Mon, Dec 21, 2009 at 10:12:34AM -0800, Doug Evans wrote:
> 2009-12-21  Doug Evans  <dje@google.com>
> 
> 	* configure.ac: Check for dladdr.
> 	* config.in: Regenerate.
> 	* configure: Regenerate.
> 	* thread-db.c (dladdr_to_soname): Only define ifdef HAVE_DLADDR.
> 	(try_thread_db_load): Update.

OK.

-- 
Daniel Jacobowitz
CodeSourcery