/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
#include <config.h>
+#include "backtrace.h"
#include "fatal-signal.h"
-#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdbool.h>
#include <stdio.h>
+#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
-#include "shash.h"
+#include "ovs-thread.h"
+#include "openvswitch/poll-loop.h"
+#include "openvswitch/shash.h"
+#include "sset.h"
+#include "signals.h"
+#include "socket-util.h"
#include "util.h"
+#include "openvswitch/vlog.h"
-#define THIS_MODULE VLM_fatal_signal
-#include "vlog.h"
+#include "openvswitch/type-props.h"
-/* Signals to catch. */
-static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM };
+#ifdef HAVE_UNWIND
+#include "daemon-private.h"
+#endif
+
+#ifndef SIG_ATOMIC_MAX
+#define SIG_ATOMIC_MAX TYPE_MAXIMUM(sig_atomic_t)
+#endif
-/* Signals to catch as a sigset_t. */
-static sigset_t fatal_signal_set;
+VLOG_DEFINE_THIS_MODULE(fatal_signal);
+
+/* Signals to catch. */
+#ifndef _WIN32
+static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM,
+ SIGSEGV };
+#else
+static const int fatal_signals[] = { SIGTERM };
+#endif
/* Hooks to call upon catching a signal */
struct hook {
- void (*func)(void *aux);
+ void (*hook_cb)(void *aux);
+ void (*cancel_cb)(void *aux);
void *aux;
bool run_at_exit;
};
static struct hook hooks[MAX_HOOKS];
static size_t n_hooks;
-/* Number of nesting signal blockers. */
-static int block_level = 0;
+static int signal_fds[2];
+static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX;
-/* Signal mask saved by outermost signal blocker. */
-static sigset_t saved_signal_mask;
+#ifdef _WIN32
+static HANDLE wevent;
+#endif
-/* Disabled by fatal_signal_fork()? */
-static bool disabled;
+static struct ovs_mutex mutex;
-static void call_sigprocmask(int how, sigset_t* new_set, sigset_t* old_set);
-static void atexit_handler(void);
static void call_hooks(int sig_nr);
-
-/* Registers 'hook' to be called when a process termination signal is raised.
- * If 'run_at_exit' is true, 'hook' is also called during normal process
- * termination, e.g. when exit() is called or when main() returns.
- *
- * 'func' will be invoked from an asynchronous signal handler, so it must be
- * written appropriately. For example, it must not call most C library
- * functions, including malloc() or free(). */
-void
-fatal_signal_add_hook(void (*func)(void *aux), void *aux, bool run_at_exit)
-{
- fatal_signal_block();
- assert(n_hooks < MAX_HOOKS);
- hooks[n_hooks].func = func;
- hooks[n_hooks].aux = aux;
- hooks[n_hooks].run_at_exit = run_at_exit;
- n_hooks++;
- fatal_signal_unblock();
-}
-
-/* Blocks program termination signals until fatal_signal_unblock() is called.
- * May be called multiple times with nesting; if so, fatal_signal_unblock()
- * must be called the same number of times to unblock signals.
- *
- * This is needed while adjusting a data structure that will be accessed by a
- * fatal signal hook, so that the hook is not invoked while the data structure
- * is in an inconsistent state. */
+#ifdef _WIN32
+static BOOL WINAPI ConsoleHandlerRoutine(DWORD dwCtrlType);
+#endif
+
+/* Initializes the fatal signal handling module. Calling this function is
+ * optional, because calling any other function in the module will also
+ * initialize it. However, in a multithreaded program, the module must be
+ * initialized while the process is still single-threaded. */
void
-fatal_signal_block(void)
+fatal_signal_init(void)
{
static bool inited = false;
+
if (!inited) {
size_t i;
+ assert_single_threaded();
inited = true;
- sigemptyset(&fatal_signal_set);
+
+ ovs_mutex_init_recursive(&mutex);
+#ifndef _WIN32
+ xpipe_nonblocking(signal_fds);
+#else
+ wevent = CreateEvent(NULL, TRUE, FALSE, NULL);
+ if (!wevent) {
+ char *msg_buf = ovs_lasterror_to_string();
+ VLOG_FATAL("Failed to create a event (%s).", msg_buf);
+ }
+
+ /* Register a function to handle Ctrl+C. */
+ SetConsoleCtrlHandler(ConsoleHandlerRoutine, true);
+#endif
+
for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
int sig_nr = fatal_signals[i];
+#ifndef _WIN32
struct sigaction old_sa;
- sigaddset(&fatal_signal_set, sig_nr);
- if (sigaction(sig_nr, NULL, &old_sa)) {
- ovs_fatal(errno, "sigaction");
- }
+ xsigaction(sig_nr, NULL, &old_sa);
if (old_sa.sa_handler == SIG_DFL
&& signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
- ovs_fatal(errno, "signal");
+ VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
+ }
+#else
+ if (signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
+ VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
}
+#endif
}
- atexit(atexit_handler);
- }
-
- if (++block_level == 1) {
- call_sigprocmask(SIG_BLOCK, &fatal_signal_set, &saved_signal_mask);
+ atexit(fatal_signal_atexit_handler);
}
}
-/* Unblocks program termination signals blocked by fatal_signal_block() is
- * called. If multiple calls to fatal_signal_block() are nested,
- * fatal_signal_unblock() must be called the same number of times to unblock
- * signals. */
+/* Registers 'hook_cb' to be called from inside poll_block() following a fatal
+ * signal. 'hook_cb' does not need to be async-signal-safe. In a
+ * multithreaded program 'hook_cb' might be called from any thread, with
+ * threads other than the one running 'hook_cb' in unknown states.
+ *
+ * If 'run_at_exit' is true, 'hook_cb' is also called during normal process
+ * termination, e.g. when exit() is called or when main() returns.
+ *
+ * If the current process forks, fatal_signal_fork() may be called to clear the
+ * parent process's fatal signal hooks, so that 'hook_cb' is only called when
+ * the child terminates, not when the parent does. When fatal_signal_fork() is
+ * called, it calls the 'cancel_cb' function if it is nonnull, passing 'aux',
+ * to notify that the hook has been canceled. This allows the hook to free
+ * memory, etc. */
void
-fatal_signal_unblock(void)
+fatal_signal_add_hook(void (*hook_cb)(void *aux), void (*cancel_cb)(void *aux),
+ void *aux, bool run_at_exit)
{
- assert(block_level > 0);
- if (--block_level == 0) {
- call_sigprocmask(SIG_SETMASK, &saved_signal_mask, NULL);
+ fatal_signal_init();
+
+ ovs_mutex_lock(&mutex);
+ ovs_assert(n_hooks < MAX_HOOKS);
+ hooks[n_hooks].hook_cb = hook_cb;
+ hooks[n_hooks].cancel_cb = cancel_cb;
+ hooks[n_hooks].aux = aux;
+ hooks[n_hooks].run_at_exit = run_at_exit;
+ n_hooks++;
+ ovs_mutex_unlock(&mutex);
+}
+
+#ifdef HAVE_UNWIND
+/* Convert unsigned long long to string. This is needed because
+ * using snprintf() is not async signal safe. */
+static inline int
+llong_to_hex_str(unsigned long long value, char *str)
+{
+ int i = 0, res;
+
+ if (value / 16 > 0) {
+ i = llong_to_hex_str(value / 16, str);
}
+
+ res = value % 16;
+ str[i] = "0123456789abcdef"[res];
+
+ return i + 1;
}
+/* Send the backtrace buffer to monitor thread.
+ *
+ * Note that this runs in the signal handling context, any system
+ * library functions used here must be async-signal-safe.
+ */
+static inline void
+send_backtrace_to_monitor(void) {
+ /* volatile added to prevent a "clobbered" error on ppc64le with gcc */
+ volatile int dep;
+ struct unw_backtrace unw_bt[UNW_MAX_DEPTH];
+ unw_cursor_t cursor;
+ unw_context_t uc;
+
+ if (daemonize_fd == -1) {
+ return;
+ }
+
+ dep = 0;
+ unw_getcontext(&uc);
+ unw_init_local(&cursor, &uc);
+
+ while (dep < UNW_MAX_DEPTH && unw_step(&cursor)) {
+ memset(unw_bt[dep].func, 0, UNW_MAX_FUNCN);
+ unw_get_reg(&cursor, UNW_REG_IP, &unw_bt[dep].ip);
+ unw_get_proc_name(&cursor, unw_bt[dep].func, UNW_MAX_FUNCN,
+ &unw_bt[dep].offset);
+ dep++;
+ }
+
+ if (monitor) {
+ ignore(write(daemonize_fd, unw_bt,
+ dep * sizeof(struct unw_backtrace)));
+ } else {
+ /* Since there is no monitor daemon running, write backtrace
+ * in current process.
+ */
+ char str[] = "SIGSEGV detected, backtrace:\n";
+ char ip_str[16], offset_str[6];
+ char line[64], fn_name[UNW_MAX_FUNCN];
+
+ vlog_direct_write_to_log_file_unsafe(str);
+
+ for (int i = 0; i < dep; i++) {
+ memset(line, 0, sizeof line);
+ memset(fn_name, 0, sizeof fn_name);
+ memset(offset_str, 0, sizeof offset_str);
+ memset(ip_str, ' ', sizeof ip_str);
+ ip_str[sizeof(ip_str) - 1] = 0;
+
+ llong_to_hex_str(unw_bt[i].ip, ip_str);
+ llong_to_hex_str(unw_bt[i].offset, offset_str);
+
+ strcat(line, "0x");
+ strcat(line, ip_str);
+ strcat(line, "<");
+ memcpy(fn_name, unw_bt[i].func, UNW_MAX_FUNCN - 1);
+ strcat(line, fn_name);
+ strcat(line, "+0x");
+ strcat(line, offset_str);
+ strcat(line, ">\n");
+ vlog_direct_write_to_log_file_unsafe(line);
+ }
+ }
+}
+#else
+static inline void
+send_backtrace_to_monitor(void) {
+ /* Nothing. */
+}
+#endif
+
/* Handles fatal signal number 'sig_nr'.
*
* Ordinarily this is the actual signal handler. When other code needs to
void
fatal_signal_handler(int sig_nr)
{
- call_hooks(sig_nr);
-
- /* Re-raise the signal with the default handling so that the program
- * termination status reflects that we were killed by this signal */
- signal(sig_nr, SIG_DFL);
- raise(sig_nr);
+#ifndef _WIN32
+ if (sig_nr == SIGSEGV) {
+ signal(sig_nr, SIG_DFL); /* Set it back immediately. */
+ send_backtrace_to_monitor();
+ raise(sig_nr);
+ }
+ ignore(write(signal_fds[1], "", 1));
+#else
+ SetEvent(wevent);
+#endif
+ stored_sig_nr = sig_nr;
}
-static void
-atexit_handler(void)
+/* Check whether a fatal signal has occurred and, if so, call the fatal signal
+ * hooks and exit.
+ *
+ * This function is called automatically by poll_block(), but specialized
+ * programs that may not always call poll_block() on a regular basis should
+ * also call it periodically. (Therefore, any function with "block" in its
+ * name should call fatal_signal_run() each time it is called, either directly
+ * or through poll_block(), because such functions can only used by specialized
+ * programs that can afford to block outside their main loop around
+ * poll_block().)
+ */
+void
+fatal_signal_run(void)
{
- if (!disabled) {
- call_hooks(0);
+ sig_atomic_t sig_nr;
+
+ fatal_signal_init();
+
+ sig_nr = stored_sig_nr;
+ if (sig_nr != SIG_ATOMIC_MAX) {
+ char namebuf[SIGNAL_NAME_BUFSIZE];
+
+ ovs_mutex_lock(&mutex);
+
+#ifndef _WIN32
+ VLOG_WARN("terminating with signal %d (%s)",
+ (int)sig_nr, signal_name(sig_nr, namebuf, sizeof namebuf));
+#else
+ VLOG_WARN("terminating with signal %d", (int)sig_nr);
+#endif
+ call_hooks(sig_nr);
+ fflush(stderr);
+
+ /* Re-raise the signal with the default handling so that the program
+ * termination status reflects that we were killed by this signal */
+ signal(sig_nr, SIG_DFL);
+ raise(sig_nr);
+
+ ovs_mutex_unlock(&mutex);
+ OVS_NOT_REACHED();
}
}
+void
+fatal_signal_wait(void)
+{
+ fatal_signal_init();
+#ifdef _WIN32
+ poll_wevent_wait(wevent);
+#else
+ poll_fd_wait(signal_fds[0], POLLIN);
+#endif
+}
+
+void
+fatal_ignore_sigpipe(void)
+{
+#ifndef _WIN32
+ signal(SIGPIPE, SIG_IGN);
+#endif
+}
+
+void
+fatal_signal_atexit_handler(void)
+{
+ call_hooks(0);
+}
+
static void
call_hooks(int sig_nr)
{
for (i = 0; i < n_hooks; i++) {
struct hook *h = &hooks[i];
if (sig_nr || h->run_at_exit) {
- h->func(h->aux);
+ h->hook_cb(h->aux);
}
}
}
}
+
+#ifdef _WIN32
+BOOL WINAPI ConsoleHandlerRoutine(DWORD dwCtrlType)
+{
+ stored_sig_nr = SIGINT;
+ SetEvent(wevent);
+ return true;
+}
+#endif
\f
-static struct shash files = SHASH_INITIALIZER(&files);
+/* Files to delete on exit. */
+static struct sset files = SSET_INITIALIZER(&files);
+
+/* Has a hook function been registered with fatal_signal_add_hook() (and not
+ * cleared by fatal_signal_fork())? */
+static bool added_hook;
static void unlink_files(void *aux);
+static void cancel_files(void *aux);
static void do_unlink_files(void);
/* Registers 'file' to be unlinked when the program terminates via exit() or a
void
fatal_signal_add_file_to_unlink(const char *file)
{
- static bool added_hook = false;
+ fatal_signal_init();
+
+ ovs_mutex_lock(&mutex);
if (!added_hook) {
added_hook = true;
- fatal_signal_add_hook(unlink_files, NULL, true);
+ fatal_signal_add_hook(unlink_files, cancel_files, NULL, true);
}
- fatal_signal_block();
- if (!shash_find(&files, file)) {
- shash_add(&files, file, NULL);
- }
- fatal_signal_unblock();
+ sset_add(&files, file);
+ ovs_mutex_unlock(&mutex);
}
/* Unregisters 'file' from being unlinked when the program terminates via
void
fatal_signal_remove_file_to_unlink(const char *file)
{
- struct shash_node *node;
+ fatal_signal_init();
- fatal_signal_block();
- node = shash_find(&files, file);
- if (node) {
- shash_delete(&files, node);
- }
- fatal_signal_unblock();
+ ovs_mutex_lock(&mutex);
+ sset_find_and_delete(&files, file);
+ ovs_mutex_unlock(&mutex);
}
/* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
int
fatal_signal_unlink_file_now(const char *file)
{
- int error = unlink(file) ? errno : 0;
+ int error;
+
+ fatal_signal_init();
+
+ ovs_mutex_lock(&mutex);
+
+ error = unlink(file) ? errno : 0;
if (error) {
- VLOG_WARN("could not unlink \"%s\" (%s)", file, strerror(error));
+ VLOG_WARN("could not unlink \"%s\" (%s)", file, ovs_strerror(error));
}
fatal_signal_remove_file_to_unlink(file);
+ ovs_mutex_unlock(&mutex);
+
return error;
}
static void
-unlink_files(void *aux UNUSED)
+unlink_files(void *aux OVS_UNUSED)
+{
+ do_unlink_files();
+}
+
+static void
+cancel_files(void *aux OVS_UNUSED)
{
- do_unlink_files();
+ sset_clear(&files);
+ added_hook = false;
}
-/* This is a fatal_signal_add_hook() callback (via unlink_files()). It will be
- * invoked from an asynchronous signal handler, so it cannot call most C
- * library functions (unlink() is an explicit exception, see
- * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html).
- * That includes free(), so it doesn't try to free the 'files' data
- * structure. */
static void
do_unlink_files(void)
{
- struct shash_node *node;
+ const char *file;
- SHASH_FOR_EACH (node, &files) {
- unlink(node->name);
+ SSET_FOR_EACH (file, &files) {
+ unlink(file);
}
}
\f
-/* Disables the fatal signal hook mechanism. Following a fork, one of the
- * resulting processes can call this function to allow it to terminate without
- * triggering fatal signal processing or removing files. Fatal signal
- * processing is still enabled in the other process. */
+/* Clears all of the fatal signal hooks without executing them. If any of the
+ * hooks passed a 'cancel_cb' function to fatal_signal_add_hook(), then those
+ * functions will be called, allowing them to free resources, etc.
+ *
+ * Following a fork, one of the resulting processes can call this function to
+ * allow it to terminate without calling the hooks registered before calling
+ * this function. New hooks registered after calling this function will take
+ * effect normally. */
void
fatal_signal_fork(void)
{
size_t i;
- disabled = true;
+ assert_single_threaded();
- for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
- int sig_nr = fatal_signals[i];
- if (signal(sig_nr, SIG_DFL) == SIG_IGN) {
- signal(sig_nr, SIG_IGN);
+ for (i = 0; i < n_hooks; i++) {
+ struct hook *h = &hooks[i];
+ if (h->cancel_cb) {
+ h->cancel_cb(h->aux);
}
}
+ n_hooks = 0;
+
+ /* Raise any signals that we have already received with the default
+ * handler. */
+ if (stored_sig_nr != SIG_ATOMIC_MAX) {
+ raise(stored_sig_nr);
+ }
}
-\f
-static void
-call_sigprocmask(int how, sigset_t* new_set, sigset_t* old_set)
+
+#ifndef _WIN32
+/* Blocks all fatal signals and returns previous signal mask into
+ * 'prev_mask'. */
+void
+fatal_signal_block(sigset_t *prev_mask)
{
- int error = sigprocmask(how, new_set, old_set);
- if (error) {
- fprintf(stderr, "sigprocmask: %s\n", strerror(errno));
+ int i;
+ sigset_t block_mask;
+
+ sigemptyset(&block_mask);
+ for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
+ int sig_nr = fatal_signals[i];
+ sigaddset(&block_mask, sig_nr);
}
+ xpthread_sigmask(SIG_BLOCK, &block_mask, prev_mask);
}
+#endif
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