Copy in libbacktrace from gcc

This copies in libbacktrace from the gcc repository as it was in the
commit 62e420293a293608f383d9b9c7f2debd666e9fc9.  GDB is going to
start using this library soon.

A dependency between GDB and libbacktrace has already been added to
the top level Makefile, so, after this commit, when building GDB,
libbacktrace will be built first.  However, libbacktrace is not yet
linked into GDB, or used by GDB in any way.

It is possible to stop libbacktrace being built by configuring the
tree with --disable-libbacktrace.

This commit does NOT update src-release.sh, that will be done in the
next commit, this commit ONLY imports libbacktrace from gcc.  This
means that if you try to make a release of GDB from exactly this
commit then the release tar file will not include libbacktrace.
However, as libbacktrace is an optional dependency this is fine.

1 files changed, 136 insertions, 0 deletions

diff --git a/libbacktrace/allocfail.c b/libbacktrace/allocfail.c
new file mode 100644
index 00000000000..bd0fbb658a9
--- /dev/null
+++ b/libbacktrace/allocfail.c
@@ -0,0 +1,136 @@
+/* allocfail.c -- Test for libbacktrace library
+   Copyright (C) 2018-2021 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"
+
+extern uint64_t get_nr_allocs (void);
+extern void set_fail_at_alloc (uint64_t);
+extern int at_fail_alloc_p (void);
+
+static int test1 (void) __attribute__ ((noinline, unused));
+static int f2 (int) __attribute__ ((noinline));
+static int f3 (int, int) __attribute__ ((noinline));
+
+static unsigned callback_errors = 0;
+
+static void
+error_callback_full (void *vdata ATTRIBUTE_UNUSED,
+		     const char *msg ATTRIBUTE_UNUSED,
+		     int errnum ATTRIBUTE_UNUSED)
+{
+  if (at_fail_alloc_p ())
+    {
+      set_fail_at_alloc (0);
+      return;
+    }
+
+  callback_errors++;
+}
+
+static int
+callback_full (void *vdata ATTRIBUTE_UNUSED, uintptr_t pc ATTRIBUTE_UNUSED,
+	      const char *filename ATTRIBUTE_UNUSED,
+	      int lineno ATTRIBUTE_UNUSED,
+	      const char *function ATTRIBUTE_UNUSED)
+{
+
+  return 0;
+}
+
+static int
+test1 (void)
+{
+  return f2 (__LINE__) + 1;
+}
+
+static int
+f2 (int f1line)
+{
+  return f3 (f1line, __LINE__) + 2;
+}
+
+static int
+f3 (int f1line ATTRIBUTE_UNUSED, int f2line ATTRIBUTE_UNUSED)
+{
+  int i;
+
+  i = backtrace_full (state, 0, callback_full, error_callback_full, NULL);
+
+  if (i != 0)
+    {
+      fprintf (stderr, "test1: unexpected return value %d\n", i);
+      ++failures;
+    }
+
+  if (callback_errors)
+      ++failures;
+
+  return failures;
+}
+
+/* Run all the tests.  */
+
+int
+main (int argc, char **argv)
+{
+  uint64_t fail_at = 0;
+
+  if (argc == 2)
+    {
+      fail_at = atoi (argv[1]);
+      set_fail_at_alloc (fail_at);
+    }
+
+  state = backtrace_create_state (argv[0], BACKTRACE_SUPPORTS_THREADS,
+				  error_callback_full, NULL);
+  if (state == NULL)
+    exit (failures ? EXIT_FAILURE : EXIT_SUCCESS);
+
+#if BACKTRACE_SUPPORTED
+  test1 ();
+#endif
+
+  if (argc == 1)
+    fprintf (stderr, "%llu\n", (long long unsigned) get_nr_allocs ());
+
+  exit (failures ? EXIT_FAILURE : EXIT_SUCCESS);
+}