NOTE: This patch has been forwardported from RHEL-6.7.

URL: <https://sourceware.org/ml/gdb-patches/2013-05/msg00364.html>

Message-ID: <1368136582.30058.7.camel@soleil>

  From: Philippe Waroquiers <philippe dot waroquiers at skynet dot be>

  To: gdb-patches at sourceware dot org

  Subject: RFA: fix gdb_assert caused by 'catch signal ...' and fork

  Date: Thu, 09 May 2013 23:56:22 +0200

  The attached patch fixes a gdb_assert caused by the combination of catch

  signal and fork:

    break-catch-sig.c:152: internal-error: signal_catchpoint_remove_location: Assertion `signal_catch_counts[iter] > 0' failed.

  The problem is that the signal_catch_counts is decremented by detach_breakpoints.

  The fix consists in not detaching breakpoint locations of type bp_loc_other.

  The patch introduces a new test.

Comments by Sergio Durigan Junior:

  I addded a specific testcase for this patch, which tests exactly the

  issue that the customer is facing.  This patch does not solve the

  whole problem of catching a syscall and forking (for more details,

  see <https://sourceware.org/bugzilla/show_bug.cgi?id=13457>,

  specifically comment #3), but it solves the issue reported by the

  customer.

  I also removed the original testcase of this patch, because it

  relied on "catch signal", which is a command that is not implemented

  in this version of GDB.

commit bd9673a4ded96ea5c108601501c8e59003ea1be6

Author: Philippe Waroquiers <philippe@sourceware.org>

Date:   Tue May 21 18:47:05 2013 +0000

    Fix internal error caused by interaction between catch signal and fork

Index: gdb-7.6.1/gdb/breakpoint.c

===================================================================

--- gdb-7.6.1.orig/gdb/breakpoint.c

+++ gdb-7.6.1/gdb/breakpoint.c

@@ -3542,6 +3542,15 @@ detach_breakpoints (ptid_t ptid)

     if (bl->pspace != inf->pspace)

       continue;

+    /* This function must physically remove breakpoints locations

+       from the specified ptid, without modifying the breakpoint

+       package's state.  Locations of type bp_loc_other are only

+       maintained at GDB side.  So, there is no need to remove

+       these bp_loc_other locations.  Moreover, removing these

+       would modify the breakpoint package's state.  */

+    if (bl->loc_type == bp_loc_other)

+      continue;

+

     if (bl->inserted)

       val |= remove_breakpoint_1 (bl, mark_inserted);

   }

Index: gdb-7.6.1/gdb/testsuite/gdb.base/gdb-rhbz1149207-catch-syscall-fork.c

===================================================================

--- /dev/null

+++ gdb-7.6.1/gdb/testsuite/gdb.base/gdb-rhbz1149207-catch-syscall-fork.c

@@ -0,0 +1,11 @@

+#include <stdio.h>

+#include <unistd.h>

+

+int

+main (int argc, char **argv)

+{

+  if (fork () == 0)

+    sleep (1);

+  chdir (".");

+  return 0;

+}

Index: gdb-7.6.1/gdb/testsuite/gdb.base/gdb-rhbz1149207-catch-syscall-fork.exp

===================================================================

--- /dev/null

+++ gdb-7.6.1/gdb/testsuite/gdb.base/gdb-rhbz1149207-catch-syscall-fork.exp

@@ -0,0 +1,58 @@

+# Copyright 2015 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/>.

+

+if { [is_remote target] || ![isnative] } then {

+    continue

+}

+

+set testfile "gdb-rhbz1149207-catch-syscall-fork"

+set srcfile ${testfile}.c

+set binfile ${objdir}/${subdir}/${testfile}

+

+# Until "catch syscall" is implemented on other targets...

+if {![istarget "hppa*-hp-hpux*"] && ![istarget "*-linux*"]} then {

+    continue

+}

+

+# This shall be updated whenever 'catch syscall' is implemented

+# on some architecture.

+#if { ![istarget "i\[34567\]86-*-linux*"]

+if { ![istarget "x86_64-*-linux*"] && ![istarget "i\[34567\]86-*-linux*"]

+     && ![istarget "powerpc-*-linux*"] && ![istarget "powerpc64-*-linux*"]

+     && ![istarget "sparc-*-linux*"] && ![istarget "sparc64-*-linux*"] } {

+     continue

+}

+

+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {

+    untested ${testfile}.exp

+    return -1

+}

+

+gdb_exit

+gdb_start

+gdb_reinitialize_dir $srcdir/$subdir

+gdb_load $binfile

+

+if { ![runto_main] } {

+    return -1

+}

+

+gdb_test "catch syscall chdir" \

+  "Catchpoint $decimal \\\(syscall (.)?chdir(.)? \\\[$decimal\\\]\\\)" \

+  "catch syscall chdir"

+

+gdb_test "continue" \

+  "Continuing\.\r\n.*\r\nCatchpoint $decimal \\\(call to syscall .?chdir.?.*" \

+  "continue from catch syscall after fork"