[tor-commits] [tor/master] Remove log dependency from backtrace.[ch]
nickm at torproject.org
nickm at torproject.org
Wed Jun 20 20:17:15 UTC 2018
commit a969ce464dc23db39725a891d60537f3d3e51b50
Author: Nick Mathewson <nickm at torproject.org>
Date: Wed Jun 20 13:51:49 2018 -0400
Remove log dependency from backtrace.[ch]
---
src/common/backtrace.c | 78 +++++++++++++++++++++++++++++---------------------
src/common/backtrace.h | 11 +++++--
src/or/main.c | 8 +++++-
3 files changed, 62 insertions(+), 35 deletions(-)
diff --git a/src/common/backtrace.c b/src/common/backtrace.c
index 56cefdf93..af939b0a8 100644
--- a/src/common/backtrace.c
+++ b/src/common/backtrace.c
@@ -14,9 +14,6 @@
*/
#include "orconfig.h"
-#include "common/compat.h"
-#include "common/util.h"
-#include "common/torlog.h"
#include "common/torerr.h"
#ifdef HAVE_EXECINFO_H
@@ -31,6 +28,9 @@
#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
#ifdef HAVE_CYGWIN_SIGNAL_H
#include <cygwin/signal.h>
@@ -40,8 +40,13 @@
#include <ucontext.h>
#endif /* defined(HAVE_CYGWIN_SIGNAL_H) || ... */
+#ifdef HAVE_PTHREAD_H
+#include <pthread.h>
+#endif
+
#define EXPOSE_CLEAN_BACKTRACE
#include "common/backtrace.h"
+#include "common/torerr.h"
#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION)
@@ -52,17 +57,21 @@
#define NO_BACKTRACE_IMPL
#endif
-/** Version of Tor to report in backtrace messages. */
-static char *bt_version = NULL;
+// Redundant with util.h, but doing it here so we can avoid that dependency.
+#define raw_free free
#ifdef USE_BACKTRACE
+/** Version of Tor to report in backtrace messages. */
+static char bt_version[128] = "";
+
/** Largest stack depth to try to dump. */
#define MAX_DEPTH 256
/** Static allocation of stack to dump. This is static so we avoid stack
* pressure. */
static void *cb_buf[MAX_DEPTH];
-/** Protects cb_buf from concurrent access */
-static tor_mutex_t cb_buf_mutex;
+/** Protects cb_buf from concurrent access. Pthreads, since this code
+ * is Unix-only, and since this code needs to be lowest-level. */
+static pthread_mutex_t cb_buf_mutex = PTHREAD_MUTEX_INITIALIZER;
/** Change a stacktrace in <b>stack</b> of depth <b>depth</b> so that it will
* log the correct function from which a signal was received with context
@@ -95,33 +104,35 @@ clean_backtrace(void **stack, size_t depth, const ucontext_t *ctx)
}
/** Log a message <b>msg</b> at <b>severity</b> in <b>domain</b>, and follow
- * that with a backtrace log. */
+ * that with a backtrace log. Send messages via the tor_log function at
+ * logger". */
void
-log_backtrace(int severity, int domain, const char *msg)
+log_backtrace_impl(int severity, int domain, const char *msg,
+ tor_log_fn logger)
{
size_t depth;
char **symbols;
size_t i;
- tor_mutex_acquire(&cb_buf_mutex);
+ pthread_mutex_lock(&cb_buf_mutex);
depth = backtrace(cb_buf, MAX_DEPTH);
symbols = backtrace_symbols(cb_buf, (int)depth);
- tor_log(severity, domain, "%s. Stack trace:", msg);
+ logger(severity, domain, "%s. Stack trace:", msg);
if (!symbols) {
/* LCOV_EXCL_START -- we can't provoke this. */
- tor_log(severity, domain, " Unable to generate backtrace.");
+ logger(severity, domain, " Unable to generate backtrace.");
goto done;
/* LCOV_EXCL_STOP */
}
for (i=0; i < depth; ++i) {
- tor_log(severity, domain, " %s", symbols[i]);
+ logger(severity, domain, " %s", symbols[i]);
}
raw_free(symbols);
done:
- tor_mutex_release(&cb_buf_mutex);
+ pthread_mutex_unlock(&cb_buf_mutex);
}
static void crash_handler(int sig, siginfo_t *si, void *ctx_)
@@ -157,17 +168,18 @@ crash_handler(int sig, siginfo_t *si, void *ctx_)
}
/** Install signal handlers as needed so that when we crash, we produce a
- * useful stack trace. Return 0 on success, -1 on failure. */
+ * useful stack trace. Return 0 on success, -errno on failure. */
static int
-install_bt_handler(void)
+install_bt_handler(const char *software)
{
int trap_signals[] = { SIGSEGV, SIGILL, SIGFPE, SIGBUS, SIGSYS,
SIGIO, -1 };
int i, rv=0;
- struct sigaction sa;
+ strncpy(bt_version, software, sizeof(bt_version) - 1);
+ bt_version[sizeof(bt_version) - 1] = 0;
- tor_mutex_init(&cb_buf_mutex);
+ struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = crash_handler;
@@ -177,8 +189,7 @@ install_bt_handler(void)
for (i = 0; trap_signals[i] >= 0; ++i) {
if (sigaction(trap_signals[i], &sa, NULL) == -1) {
/* LCOV_EXCL_START */
- log_warn(LD_BUG, "Sigaction failed: %s", strerror(errno));
- rv = -1;
+ rv = -errno;
/* LCOV_EXCL_STOP */
}
}
@@ -201,20 +212,21 @@ install_bt_handler(void)
static void
remove_bt_handler(void)
{
- tor_mutex_uninit(&cb_buf_mutex);
}
#endif /* defined(USE_BACKTRACE) */
#ifdef NO_BACKTRACE_IMPL
void
-log_backtrace(int severity, int domain, const char *msg)
+log_backtrace_impl(int severity, int domain, const char *msg,
+ tor_log_fn logger)
{
- tor_log(severity, domain, "%s. (Stack trace not available)", msg);
+ logger(severity, domain, "%s. (Stack trace not available)", msg);
}
static int
-install_bt_handler(void)
+install_bt_handler(const char *software)
{
+ (void) software;
return 0;
}
@@ -228,13 +240,17 @@ remove_bt_handler(void)
int
configure_backtrace_handler(const char *tor_version)
{
- tor_free(bt_version);
- if (tor_version)
- tor_asprintf(&bt_version, "Tor %s", tor_version);
- else
- tor_asprintf(&bt_version, "Tor");
+ char version[128];
+ strncpy(version, "Tor", sizeof(version)-1);
+
+ if (tor_version) {
+ strncat(version, " ", sizeof(version)-1);
+ strncat(version, tor_version, sizeof(version)-1);
+ }
+
+ version[sizeof(version) - 1] = 0;
- return install_bt_handler();
+ return install_bt_handler(version);
}
/** Perform end-of-process cleanup for code that generates error messages on
@@ -243,6 +259,4 @@ void
clean_up_backtrace_handler(void)
{
remove_bt_handler();
-
- tor_free(bt_version);
}
diff --git a/src/common/backtrace.h b/src/common/backtrace.h
index 8c4390e98..7182aeb07 100644
--- a/src/common/backtrace.h
+++ b/src/common/backtrace.h
@@ -5,11 +5,19 @@
#define TOR_BACKTRACE_H
#include "orconfig.h"
+#include "common/compat_compiler.h"
-void log_backtrace(int severity, int domain, const char *msg);
+typedef void (*tor_log_fn)(int, unsigned, const char *fmt, ...)
+ CHECK_PRINTF(3,4);
+
+void log_backtrace_impl(int severity, int domain, const char *msg,
+ tor_log_fn logger);
int configure_backtrace_handler(const char *tor_version);
void clean_up_backtrace_handler(void);
+#define log_backtrace(sev, dom, msg) \
+ log_backtrace_impl((sev), (dom), (msg), tor_log)
+
#ifdef EXPOSE_CLEAN_BACKTRACE
#if defined(HAVE_EXECINFO_H) && defined(HAVE_BACKTRACE) && \
defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_SIGACTION)
@@ -18,4 +26,3 @@ void clean_backtrace(void **stack, size_t depth, const ucontext_t *ctx);
#endif /* defined(EXPOSE_CLEAN_BACKTRACE) */
#endif /* !defined(TOR_BACKTRACE_H) */
-
diff --git a/src/or/main.c b/src/or/main.c
index 55ff41fd9..b2856d3f8 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -4214,7 +4214,13 @@ tor_run_main(const tor_main_configuration_t *tor_cfg)
}
#endif /* defined(_WIN32) */
- configure_backtrace_handler(get_version());
+ {
+ int bt_err = configure_backtrace_handler(get_version());
+ if (bt_err < 0) {
+ log_warn(LD_BUG, "Unable to install backtrace handler: %s",
+ strerror(-bt_err));
+ }
+ }
init_protocol_warning_severity_level();
update_approx_time(time(NULL));
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