btrace: do not return out of TRY/CATCH

In btrace_pt_readmem_callback, we read memory inside TRY/CATCH and return in
case of an error return value.  This corrupts the cleanup chain, which
eventually results in a SEGV when doing or discarding cleanups later on.

gdb/
	* btrace.c (btrace_pt_readmem_callback): Do not return in TRY/CATCH.

testsuite/
	* gdb.btrace/dlopen.exp: New.
	* gdb.btrace/dlopen.c: New.
	* gdb.btrace/dlopen-dso.c: New.

1 files changed, 50 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.btrace/dlopen.c b/gdb/testsuite/gdb.btrace/dlopen.c
new file mode 100644
index 0000000..7e01f79
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/dlopen.c
@@ -0,0 +1,50 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015-2016 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/>.  */
+
+#include <dlfcn.h>
+#include <assert.h>
+#include <stdlib.h>
+
+static int
+test (void)
+{
+  void *dso;
+  int (*fun) (void);
+  int answer;
+
+  dso = dlopen (DSO_NAME, RTLD_NOW | RTLD_GLOBAL);
+  assert (dso != NULL);
+
+  fun = (int (*) (void)) dlsym (dso, "answer");
+  assert (fun != NULL);
+
+  answer = fun ();
+
+  dlclose (dso);
+
+  return answer;
+}
+
+int
+main (void)
+{
+  int answer;
+
+  answer = test ();
+
+  return answer;
+}