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* Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
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* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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/* Signals to catch. */
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static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP, SIGALRM };
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/* Signals to catch as a sigset_t. */
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static sigset_t fatal_signal_set;
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/* Hooks to call upon catching a signal */
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void (*hook_cb)(void *aux);
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static int signal_fds[2];
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static volatile sig_atomic_t stored_sig_nr = SIG_ATOMIC_MAX;
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static void fatal_signal_init(void);
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static struct ovs_mutex mutex;
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static void atexit_handler(void);
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static void call_hooks(int sig_nr);
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/* Initializes the fatal signal handling module. Calling this function is
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* optional, because calling any other function in the module will also
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* initialize it. However, in a multithreaded program, the module must be
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* initialized while the process is still single-threaded. */
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fatal_signal_init(void)
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static bool inited = false;
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assert_single_threaded();
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ovs_mutex_init(&mutex, PTHREAD_MUTEX_RECURSIVE);
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xpipe_nonblocking(signal_fds);
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sigemptyset(&fatal_signal_set);
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for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
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int sig_nr = fatal_signals[i];
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struct sigaction old_sa;
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sigaddset(&fatal_signal_set, sig_nr);
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xsigaction(sig_nr, NULL, &old_sa);
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if (old_sa.sa_handler == SIG_DFL
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&& signal(sig_nr, fatal_signal_handler) == SIG_ERR) {
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VLOG_FATAL("signal failed (%s)", strerror(errno));
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VLOG_FATAL("signal failed (%s)", ovs_strerror(errno));
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atexit(atexit_handler);
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/* Registers 'hook_cb' to be called when a process termination signal is
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* raised. If 'run_at_exit' is true, 'hook_cb' is also called during normal
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* process termination, e.g. when exit() is called or when main() returns.
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/* Registers 'hook_cb' to be called from inside poll_block() following a fatal
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* signal. 'hook_cb' does not need to be async-signal-safe. In a
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* multithreaded program 'hook_cb' might be called from any thread, with
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* threads other than the one running 'hook_cb' in unknown states.
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* 'hook_cb' is not called immediately from the signal handler but rather the
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* next time the poll loop iterates, so it is freed from the usual restrictions
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* on signal handler functions.
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* If 'run_at_exit' is true, 'hook_cb' is also called during normal process
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* termination, e.g. when exit() is called or when main() returns.
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* If the current process forks, fatal_signal_fork() may be called to clear the
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* parent process's fatal signal hooks, so that 'hook_cb' is only called when
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fatal_signal_init();
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ovs_mutex_lock(&mutex);
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ovs_assert(n_hooks < MAX_HOOKS);
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hooks[n_hooks].hook_cb = hook_cb;
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hooks[n_hooks].cancel_cb = cancel_cb;
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hooks[n_hooks].aux = aux;
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hooks[n_hooks].run_at_exit = run_at_exit;
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ovs_mutex_unlock(&mutex);
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/* Handles fatal signal number 'sig_nr'.
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sig_nr = stored_sig_nr;
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if (sig_nr != SIG_ATOMIC_MAX) {
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char namebuf[SIGNAL_NAME_BUFSIZE];
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ovs_mutex_lock(&mutex);
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VLOG_WARN("terminating with signal %d (%s)",
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(int)sig_nr, signal_name(sig_nr));
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(int)sig_nr, signal_name(sig_nr, namebuf, sizeof namebuf));
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call_hooks(sig_nr);
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/* Re-raise the signal with the default handling so that the program
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* termination status reflects that we were killed by this signal */
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signal(sig_nr, SIG_DFL);
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ovs_mutex_unlock(&mutex);
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fatal_signal_add_file_to_unlink(const char *file)
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ovs_mutex_lock(&mutex);
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if (!added_hook) {
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added_hook = true;
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fatal_signal_add_hook(unlink_files, cancel_files, NULL, true);
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sset_add(&files, file);
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ovs_mutex_unlock(&mutex);
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/* Unregisters 'file' from being unlinked when the program terminates via
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fatal_signal_remove_file_to_unlink(const char *file)
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ovs_mutex_lock(&mutex);
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sset_find_and_delete(&files, file);
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ovs_mutex_unlock(&mutex);
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/* Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
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fatal_signal_unlink_file_now(const char *file)
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int error = unlink(file) ? errno : 0;
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ovs_mutex_lock(&mutex);
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error = unlink(file) ? errno : 0;
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VLOG_WARN("could not unlink \"%s\" (%s)", file, strerror(error));
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VLOG_WARN("could not unlink \"%s\" (%s)", file, ovs_strerror(error));
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fatal_signal_remove_file_to_unlink(file);
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ovs_mutex_unlock(&mutex);
added
removed
lib/fatal-signal.c
