2 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include "fatal-signal.h"
26 #include "ovs-thread.h"
27 #include "poll-loop.h"
31 #include "socket-util.h"
35 #include "type-props.h"
37 #ifndef SIG_ATOMIC_MAX
38 #define SIG_ATOMIC_MAX TYPE_MAXIMUM(sig_atomic_t)
41 VLOG_DEFINE_THIS_MODULE(fatal_signal
);
43 /* Signals to catch. */
45 static const int fatal_signals
[] = { SIGTERM
, SIGINT
, SIGHUP
, SIGALRM
};
47 static const int fatal_signals
[] = { SIGTERM
};
50 /* Hooks to call upon catching a signal */
52 void (*hook_cb
)(void *aux
);
53 void (*cancel_cb
)(void *aux
);
58 static struct hook hooks
[MAX_HOOKS
];
59 static size_t n_hooks
;
61 static int signal_fds
[2];
62 static volatile sig_atomic_t stored_sig_nr
= SIG_ATOMIC_MAX
;
68 static struct ovs_mutex mutex
;
70 static void call_hooks(int sig_nr
);
72 static BOOL WINAPI
ConsoleHandlerRoutine(DWORD dwCtrlType
);
75 /* Initializes the fatal signal handling module. Calling this function is
76 * optional, because calling any other function in the module will also
77 * initialize it. However, in a multithreaded program, the module must be
78 * initialized while the process is still single-threaded. */
80 fatal_signal_init(void)
82 static bool inited
= false;
87 assert_single_threaded();
90 ovs_mutex_init_recursive(&mutex
);
92 xpipe_nonblocking(signal_fds
);
94 wevent
= CreateEvent(NULL
, TRUE
, FALSE
, NULL
);
96 char *msg_buf
= ovs_lasterror_to_string();
97 VLOG_FATAL("Failed to create a event (%s).", msg_buf
);
100 /* Register a function to handle Ctrl+C. */
101 SetConsoleCtrlHandler(ConsoleHandlerRoutine
, true);
104 for (i
= 0; i
< ARRAY_SIZE(fatal_signals
); i
++) {
105 int sig_nr
= fatal_signals
[i
];
107 struct sigaction old_sa
;
109 xsigaction(sig_nr
, NULL
, &old_sa
);
110 if (old_sa
.sa_handler
== SIG_DFL
111 && signal(sig_nr
, fatal_signal_handler
) == SIG_ERR
) {
112 VLOG_FATAL("signal failed (%s)", ovs_strerror(errno
));
115 if (signal(sig_nr
, fatal_signal_handler
) == SIG_ERR
) {
116 VLOG_FATAL("signal failed (%s)", ovs_strerror(errno
));
120 atexit(fatal_signal_atexit_handler
);
124 /* Registers 'hook_cb' to be called from inside poll_block() following a fatal
125 * signal. 'hook_cb' does not need to be async-signal-safe. In a
126 * multithreaded program 'hook_cb' might be called from any thread, with
127 * threads other than the one running 'hook_cb' in unknown states.
129 * If 'run_at_exit' is true, 'hook_cb' is also called during normal process
130 * termination, e.g. when exit() is called or when main() returns.
132 * If the current process forks, fatal_signal_fork() may be called to clear the
133 * parent process's fatal signal hooks, so that 'hook_cb' is only called when
134 * the child terminates, not when the parent does. When fatal_signal_fork() is
135 * called, it calls the 'cancel_cb' function if it is nonnull, passing 'aux',
136 * to notify that the hook has been canceled. This allows the hook to free
139 fatal_signal_add_hook(void (*hook_cb
)(void *aux
), void (*cancel_cb
)(void *aux
),
140 void *aux
, bool run_at_exit
)
144 ovs_mutex_lock(&mutex
);
145 ovs_assert(n_hooks
< MAX_HOOKS
);
146 hooks
[n_hooks
].hook_cb
= hook_cb
;
147 hooks
[n_hooks
].cancel_cb
= cancel_cb
;
148 hooks
[n_hooks
].aux
= aux
;
149 hooks
[n_hooks
].run_at_exit
= run_at_exit
;
151 ovs_mutex_unlock(&mutex
);
154 /* Handles fatal signal number 'sig_nr'.
156 * Ordinarily this is the actual signal handler. When other code needs to
157 * handle one of our signals, however, it can register for that signal and, if
158 * and when necessary, call this function to do fatal signal processing for it
159 * and terminate the process. Currently only timeval.c does this, for SIGALRM.
160 * (It is not important whether the other code sets up its signal handler
161 * before or after this file, because this file will only set up a signal
162 * handler in the case where the signal has its default handling.) */
164 fatal_signal_handler(int sig_nr
)
167 ignore(write(signal_fds
[1], "", 1));
171 stored_sig_nr
= sig_nr
;
174 /* Check whether a fatal signal has occurred and, if so, call the fatal signal
177 * This function is called automatically by poll_block(), but specialized
178 * programs that may not always call poll_block() on a regular basis should
179 * also call it periodically. (Therefore, any function with "block" in its
180 * name should call fatal_signal_run() each time it is called, either directly
181 * or through poll_block(), because such functions can only used by specialized
182 * programs that can afford to block outside their main loop around
186 fatal_signal_run(void)
192 sig_nr
= stored_sig_nr
;
193 if (sig_nr
!= SIG_ATOMIC_MAX
) {
194 char namebuf
[SIGNAL_NAME_BUFSIZE
];
196 ovs_mutex_lock(&mutex
);
199 VLOG_WARN("terminating with signal %d (%s)",
200 (int)sig_nr
, signal_name(sig_nr
, namebuf
, sizeof namebuf
));
202 VLOG_WARN("terminating with signal %d", (int)sig_nr
);
207 /* Re-raise the signal with the default handling so that the program
208 * termination status reflects that we were killed by this signal */
209 signal(sig_nr
, SIG_DFL
);
212 ovs_mutex_unlock(&mutex
);
218 fatal_signal_wait(void)
222 poll_wevent_wait(wevent
);
224 poll_fd_wait(signal_fds
[0], POLLIN
);
229 fatal_ignore_sigpipe(void)
232 signal(SIGPIPE
, SIG_IGN
);
237 fatal_signal_atexit_handler(void)
243 call_hooks(int sig_nr
)
245 static volatile sig_atomic_t recurse
= 0;
251 for (i
= 0; i
< n_hooks
; i
++) {
252 struct hook
*h
= &hooks
[i
];
253 if (sig_nr
|| h
->run_at_exit
) {
261 BOOL WINAPI
ConsoleHandlerRoutine(DWORD dwCtrlType
)
263 stored_sig_nr
= SIGINT
;
269 /* Files to delete on exit. */
270 static struct sset files
= SSET_INITIALIZER(&files
);
272 /* Has a hook function been registered with fatal_signal_add_hook() (and not
273 * cleared by fatal_signal_fork())? */
274 static bool added_hook
;
276 static void unlink_files(void *aux
);
277 static void cancel_files(void *aux
);
278 static void do_unlink_files(void);
280 /* Registers 'file' to be unlinked when the program terminates via exit() or a
283 fatal_signal_add_file_to_unlink(const char *file
)
287 ovs_mutex_lock(&mutex
);
290 fatal_signal_add_hook(unlink_files
, cancel_files
, NULL
, true);
293 sset_add(&files
, file
);
294 ovs_mutex_unlock(&mutex
);
297 /* Unregisters 'file' from being unlinked when the program terminates via
298 * exit() or a fatal signal. */
300 fatal_signal_remove_file_to_unlink(const char *file
)
304 ovs_mutex_lock(&mutex
);
305 sset_find_and_delete(&files
, file
);
306 ovs_mutex_unlock(&mutex
);
309 /* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
310 * Returns 0 if successful, otherwise a positive errno value. */
312 fatal_signal_unlink_file_now(const char *file
)
318 ovs_mutex_lock(&mutex
);
320 error
= unlink(file
) ? errno
: 0;
322 VLOG_WARN("could not unlink \"%s\" (%s)", file
, ovs_strerror(error
));
325 fatal_signal_remove_file_to_unlink(file
);
327 ovs_mutex_unlock(&mutex
);
333 unlink_files(void *aux OVS_UNUSED
)
339 cancel_files(void *aux OVS_UNUSED
)
346 do_unlink_files(void)
350 SSET_FOR_EACH (file
, &files
) {
355 /* Clears all of the fatal signal hooks without executing them. If any of the
356 * hooks passed a 'cancel_cb' function to fatal_signal_add_hook(), then those
357 * functions will be called, allowing them to free resources, etc.
359 * Following a fork, one of the resulting processes can call this function to
360 * allow it to terminate without calling the hooks registered before calling
361 * this function. New hooks registered after calling this function will take
362 * effect normally. */
364 fatal_signal_fork(void)
368 assert_single_threaded();
370 for (i
= 0; i
< n_hooks
; i
++) {
371 struct hook
*h
= &hooks
[i
];
373 h
->cancel_cb(h
->aux
);
378 /* Raise any signals that we have already received with the default
380 if (stored_sig_nr
!= SIG_ATOMIC_MAX
) {
381 raise(stored_sig_nr
);
386 /* Blocks all fatal signals and returns previous signal mask into
389 fatal_signal_block(sigset_t
*prev_mask
)
394 sigemptyset(&block_mask
);
395 for (i
= 0; i
< ARRAY_SIZE(fatal_signals
); i
++) {
396 int sig_nr
= fatal_signals
[i
];
397 sigaddset(&block_mask
, sig_nr
);
399 xpthread_sigmask(SIG_BLOCK
, &block_mask
, prev_mask
);