commit a969ce464dc23db39725a891d60537f3d3e51b50 Author: Nick Mathewson nickm@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));