1 files changed, 157 insertions, 0 deletions
diff --git a/src/common/backtrace.c b/src/common/backtrace.c
new file mode 100644
index 000000000..d3f59b2c7
--- /dev/null
+++ b/src/common/backtrace.c
@@ -0,0 +1,157 @@
+/* Copyright (c) 2013, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "orconfig.h"
+#include "backtrace.h"
+#include "compat.h"
+#include "util.h"
+
+#ifdef HAVE_EXECINFO_H
+#include <execinfo.h>
+#endif
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
+  defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION)
+#define USE_BACKTRACE
+#endif
+
+#if !defined(USE_BACKTRACE)
+#define NO_BACKTRACE_IMPL
+#endif
+
+static char *bt_filename = NULL;
+static char *bt_version = NULL;
+
+#ifndef NO_BACKTRACE_IMPL
+/**DOCDOC*/
+static int
+open_bt_target(void)
+{
+  int fd = -1;
+  if (bt_filename)
+    fd = open(bt_filename, O_WRONLY|O_CREAT|O_APPEND, 0700);
+  return fd;
+}
+#endif
+
+/**DOCDOC*/
+static void
+bt_write(int fd, const char *s, ssize_t n)
+{
+  int r;
+  if (n < 0) n = strlen(s);
+
+  r = write(STDERR_FILENO, s, n);
+  if (fd >= 0)
+    r = write(fd, s, n);
+  (void)r; 
+}
+
+#ifdef USE_BACKTRACE
+#define MAX_DEPTH 256
+static void *cb_buf[MAX_DEPTH];
+
+/**DOCDOC*/
+void
+dump_backtrace(const char *msg)
+{
+  char timebuf[32];
+  time_t t = time(NULL);
+  int timebuf_len;
+  int depth;
+  int fd;
+  if (!msg) msg = "unspecified crash";
+
+  depth = backtrace(cb_buf, MAX_DEPTH);
+
+  t /= 900; t *= 900; /* Round to the previous 15 minutes */
+  timebuf[0] = '\0';
+  timebuf_len = format_dec_number_sigsafe(t, timebuf, sizeof(timebuf));
+
+  fd = open_bt_target();
+  bt_write(fd, "========================================"
+               "====================================\n", -1);
+  bt_write(fd, bt_version, -1);
+  bt_write(fd, " died around T=", -1);
+  bt_write(fd, timebuf, timebuf_len);
+  bt_write(fd, ": ", 2);
+  bt_write(fd, msg, -1);
+  bt_write(fd, "\n", 1);
+  backtrace_symbols_fd(cb_buf, depth, STDERR_FILENO);
+  if (fd >= 0)
+    backtrace_symbols_fd(cb_buf, depth, fd);
+
+  close(fd);
+}
+
+/**DOCDOC*/
+static int
+install_bt_handler(void)
+{
+  /*XXXX add signal handlers */
+  /*XXXX make this idempotent */
+  return 0;
+}
+/**DOCDOC*/
+static void
+remove_bt_handler(void)
+{
+}
+#endif
+
+#ifdef NO_BACKTRACE_IMPL
+/**DOCDOC*/
+void
+dump_backtrace(const char *msg)
+{
+  bt_write(-1, bt_version, -1);
+  bt_write(-1, " died: ", -1);
+  bt_write(-1, msg, -1);
+  bt_write(-1, "\n", -1);
+}
+
+/**DOCDOC*/
+static int
+install_bt_handler(void)
+{
+  return 0;
+}
+
+/**DOCDOC*/
+static void
+remove_bt_handler(void)
+{
+}
+#endif
+
+/**DOCDOC*/
+int
+configure_backtrace_handler(const char *filename, const char *tor_version)
+{
+  tor_free(bt_filename);
+  if (filename)
+    bt_filename = tor_strdup(filename);
+  tor_free(bt_version);
+  if (!tor_version)
+    tor_version = "Tor";
+  bt_version = tor_strdup(tor_version);
+
+  return install_bt_handler();
+}
+
+/**DOCDOC*/
+void
+clean_up_backtrace_handler(void)
+{
+  remove_bt_handler();
+
+  tor_free(bt_filename);
+  tor_free(bt_version);
+}
+