[patch] Fix separate-debug with non-unique section names (PR 11409)

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi,

gdb-7.1 is now broken for example for debugging /usr/bin/emacs due to:
http://sourceware.org/bugzilla/show_bug.cgi?id=11409
  [22] .data   PROGBITS 00000000007fe8a0 1fe8a0 215068 00  WA  0   0 32
  [23] .data   PROGBITS 0000000000a13920 413920 68c6e0 00  WA  0   0 32

It is in fact a regression against gdb-7.0 by me due to:

commit 71d0069a9f238a11f7f455bf6ad2adfc25683521
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Tue Jan 5 15:51:01 2010 +0000

gdb/
        * symfile.c (syms_from_objfile): Remove the !MAINLINE conditional.

as while the code was broken even before the broken relocation was not applied
to mainline binary (before PIE+OSX patches went in).


No regressions on {x86_64,x86_64-m32,i686}-fedora12-linux-gnu.

OK to check-in also for gdb-7.1 (7.1.1)?


Thanks,
Jan


gdb/
2010-03-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* symfile.c (addr_info_make_relative): Move sect declaration to the
	outer block.  Initialize it to NULL.  Prefer SECT->next more than
	bfd_get_section_by_name.

gdb/testsuite/
2010-03-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.base/dup-sect.exp, gdb.base/dup-sect.S: New.

--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -529,6 +529,7 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
   asection *lower_sect;
   CORE_ADDR lower_offset;
   int i;
+  asection *sect;
 
   /* Find lowest loadable section to be used as starting point for
      continguous sections.  */
@@ -553,11 +554,23 @@ addr_info_make_relative (struct section_addr_info *addrs, bfd *abfd)
      (the loadable section directly below it in memory).
      this_offset = lower_offset = lower_addr - lower_orig_addr */
 
+  sect = NULL;
   for (i = 0; i < addrs->num_sections && addrs->other[i].name; i++)
     {
       const char *sect_name = addrs->other[i].name;
-      asection *sect = bfd_get_section_by_name (abfd, sect_name);
 
+      /* Prefer the next section of that we have found last.  The separate
+	 debug info files have either the same section layout or just a few
+	 sections are missing there.  On the other hand the section name is not
+	 unique and we could find an inappropraite section by its name.  */
+
+      if (sect)
+	sect = sect->next;
+      if (sect && strcmp (sect_name, bfd_get_section_name (abfd, sect)) != 0)
+	sect = NULL;
+
+      if (sect == NULL)
+	sect = bfd_get_section_by_name (abfd, sect_name);
       if (sect)
 	{
 	  /* This is the index used by BFD. */
--- /dev/null
+++ b/gdb/testsuite/gdb.base/dup-sect.S
@@ -0,0 +1,22 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2010 Free Software Foundation, Inc.
+
+   This program 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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+	.section	sect1, "a"
+var1:	.byte	1
+
+	.section	sect2, "a"
+var2:	.byte	2
--- /dev/null
+++ b/gdb/testsuite/gdb.base/dup-sect.exp
@@ -0,0 +1,79 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2010 Free Software Foundation, Inc.
+
+# This program 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 3 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, see <http://www.gnu.org/licenses/>.
+
+# Test inappropriate offseting of multiple sections with the same name.
+# When kept in object file (before final executable link) it still works.
+# When separate debug info file is not used it still works.
+# When the ELF symbol table is kept in the main binary it still works.
+# Used .S file as in .c file we would need __attriute__((section)) which is
+# a GCC extension.
+
+# This test can only be run on targets which support ELF and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+    && ![istarget *-*-gnu*]
+    && ![istarget *-*-elf*]
+    && ![istarget arm-*-eabi*]
+    && ![istarget powerpc-*-eabi*]} {
+    return 0
+}
+
+set testfile dup-sect
+set srcfile ${testfile}.S
+set srcmainfile start.c
+set executable ${testfile}
+set binfile ${objdir}/${subdir}/${executable}
+
+if {[build_executable ${testfile}.exp $executable [list ${srcfile} ${srcmainfile}] {}] == -1} {
+    return -1
+}
+
+set test "rename section"
+set objcopy_program [transform objcopy]
+set result [catch "exec $objcopy_program --rename-section sect2=sect1 $binfile" output]
+verbose "result is $result"
+verbose "output is $output"
+if {$result != 0} {
+    fail $test
+    return
+}
+pass $test
+
+set test "split"
+if {[gdb_gnu_strip_debug $binfile] != 0} {
+    fail $test
+} else {
+    pass $test
+}
+
+# gdb_gnu_strip_debug uses only --strip-debug and keeps the ELF symbol table
+# in $binfile.
+set test "strip"
+set strip_program [transform strip]
+set result [catch "exec $strip_program $binfile" output]
+verbose "result is $result"
+verbose "output is $output"
+if {$result != 0} {
+    fail $test
+    return
+}
+pass $test
+
+clean_restart $executable
+
+gdb_test "p/d *(const char *) &var1" " = 1" "var1 after strip"
+gdb_test "p/d *(const char *) &var2" " = 2" "var2 after strip"