Commit 063bea58 authored by Nick Mathewson's avatar Nick Mathewson 🎨
Browse files

Basic backtrace ability

On platforms with the backtrace/backtrace_symbols_fd interface, Tor
can now dump stack traces on assertion failure.  By default, I log
them to DataDir/stack_dump and to stderr.
parent f6d8bc93
o Major features:
- On some platforms (currently, recent OSX versions, and glibc-based
platforms that support the ELF format), Tor can now dump
stack traces when an assertion fails. By default, traces are dumped
to stderr, and to a stack_dump file in the DataDirectory.
......@@ -302,6 +302,8 @@ dnl exports strlcpy without defining it in a header.
AC_CHECK_FUNCS(
_NSGetEnviron \
accept4 \
backtrace \
backtrace_symbols_fd \
clock_gettime \
flock \
ftime \
......@@ -319,6 +321,7 @@ AC_CHECK_FUNCS(
memmem \
prctl \
rint \
sigaction \
socketpair \
strlcat \
strlcpy \
......@@ -802,6 +805,7 @@ dnl These headers are not essential
AC_CHECK_HEADERS(
arpa/inet.h \
crt_externs.h \
execinfo.h \
grp.h \
ifaddrs.h \
inttypes.h \
......
/* 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);
}
/* Copyright (c) 2013, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef TOR_BACKTRACE_H
#define TOR_BACKTRACE_H
void dump_backtrace(const char *msg);
int configure_backtrace_handler(const char *filename, const char *tor_version);
void clean_up_backtrace_handler(void);
#endif
......@@ -50,6 +50,7 @@ endif
LIBOR_A_SOURCES = \
src/common/address.c \
src/common/backtrace.c \
src/common/compat.c \
src/common/container.c \
src/common/di_ops.c \
......@@ -90,6 +91,7 @@ src_common_libor_event_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
COMMONHEADERS = \
src/common/address.h \
src/common/backtrace.h \
src/common/aes.h \
src/common/ciphers.inc \
src/common/compat.h \
......
......@@ -24,6 +24,7 @@
#include "torint.h"
#include "container.h"
#include "address.h"
#include "backtrace.h"
#ifdef _WIN32
#include <io.h>
......@@ -101,8 +102,13 @@ void
tor_assertion_failed_(const char *fname, unsigned int line,
const char *func, const char *expr)
{
char buf[256];
log_err(LD_BUG, "%s:%u: %s: Assertion %s failed; aborting.",
fname, line, func, expr);
tor_snprintf(buf, sizeof(buf),
"Assertion %s failed in %s at %s:%u",
expr, func, fname, line);
dump_backtrace(buf);
fprintf(stderr,"%s:%u: %s: Assertion %s failed; aborting.\n",
fname, line, func, expr);
}
......
......@@ -12,6 +12,7 @@
#define CONFIG_PRIVATE
#include "or.h"
#include "addressmap.h"
#include "backtrace.h"
#include "channel.h"
#include "circuitbuild.h"
#include "circuitlist.h"
......@@ -1113,6 +1114,19 @@ options_act_reversible(const or_options_t *old_options, char **msg)
/* No need to roll back, since you can't change the value. */
}
/* Enable crash logging to files */
{
/* XXXX we might want to set this up earlier, if possible! */
char *backtrace_fname = NULL;
char *progname = NULL;
tor_asprintf(&backtrace_fname, "%s"PATH_SEPARATOR"stack_dump",
options->DataDirectory);
tor_asprintf(&progname, "Tor %s", get_version());
configure_backtrace_handler(backtrace_fname, progname);
tor_free(backtrace_fname);
tor_free(progname);
}
/* Write control ports to disk as appropriate */
control_ports_write_to_file();
......
......@@ -12,6 +12,7 @@
#include "or.h"
#include "addressmap.h"
#include "backtrace.h"
#include "buffers.h"
#include "channel.h"
#include "channeltls.h"
......@@ -2304,7 +2305,7 @@ handle_signals(int is_parent)
int
tor_init(int argc, char *argv[])
{
char buf[256];
char progname[256];
int i, quiet = 0;
time_of_process_start = time(NULL);
if (!connection_array)
......@@ -2314,8 +2315,8 @@ tor_init(int argc, char *argv[])
if (!active_linked_connection_lst)
active_linked_connection_lst = smartlist_new();
/* Have the log set up with our application name. */
tor_snprintf(buf, sizeof(buf), "Tor %s", get_version());
log_set_application_name(buf);
tor_snprintf(progname, sizeof(progname), "Tor %s", get_version());
log_set_application_name(progname);
/* Initialize the history structures. */
rep_hist_init();
/* Initialize the service cache. */
......@@ -2684,6 +2685,8 @@ tor_main(int argc, char *argv[])
}
#endif
configure_backtrace_handler(NULL, get_version());
update_approx_time(time(NULL));
tor_threads_init();
init_logging();
......
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