[libbacktrace] Avoid realloc with size == 0 in backtrace_vector_release

As of C17, realloc with size 0 is marked as an obsolescent feature.

Fix this in backtrace_vector_release by using free instead.

Bootstrapped and reg-tested on x86_64.

2018-11-27  Tom de Vries  <tdevries@suse.de>

	* alloc.c (backtrace_vector_release): Handle vec->size == 0 using free
	instead of realloc.
	* Makefile.am (check_PROGRAMS): Add unittest.
	* Makefile.in: Regenerate.
	* unittest.c: New file.

From-SVN: r266504

1 files changed, 92 insertions, 0 deletions

diff --git a/libbacktrace/unittest.c b/libbacktrace/unittest.c
new file mode 100644
index 0000000..576aa08
--- /dev/null
+++ b/libbacktrace/unittest.c
@@ -0,0 +1,92 @@
+/* unittest.c -- Test for libbacktrace library
+   Copyright (C) 2018 Free Software Foundation, Inc.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    (1) Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+    (2) Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+    (3) The name of the author may not be used to
+    endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.  */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "filenames.h"
+
+#include "backtrace.h"
+#include "backtrace-supported.h"
+
+#include "testlib.h"
+
+#include "internal.h"
+
+static unsigned count;
+
+static void
+error_callback (void *vdata ATTRIBUTE_UNUSED, const char *msg ATTRIBUTE_UNUSED,
+		int errnum ATTRIBUTE_UNUSED)
+{
+  ++count;
+}
+
+static int
+test1 (void)
+{
+  int res;
+  int failed;
+
+  struct backtrace_vector vec;
+
+  memset (&vec, 0, sizeof vec);
+
+  backtrace_vector_grow (state, 100, error_callback, NULL, &vec);
+  vec.alc += vec.size;
+  vec.size = 0;
+
+  count = 0;
+  res = backtrace_vector_release (state, &vec, error_callback, NULL);
+  failed = res != 1 || count != 0;
+
+  printf ("%s: unittest backtrace_vector_release size == 0\n",
+	  failed ? "FAIL": "PASS");
+
+  if (failed)
+    ++failures;
+
+  return failures;
+}
+
+int
+main (int argc ATTRIBUTE_UNUSED, char **argv)
+{
+  state = backtrace_create_state (argv[0], BACKTRACE_SUPPORTS_THREADS,
+				  error_callback_create, NULL);
+
+  test1 ();
+
+  exit (failures ? EXIT_FAILURE : EXIT_SUCCESS);
+}