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* Copyright (c) 2008, 2009, 2011, 2012 Nicira, Inc.
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* Copyright (c) 2008, 2009, 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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struct sigaction saved_sa;
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static volatile sig_atomic_t signaled[N_SIGNALS];
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static struct signal signals[N_SIGNALS];
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static void signal_handler(int signr);
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/* Initializes the signals subsystem (if it is not already initialized). Calls
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* exit() if initialization fails.
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* Calling this function is optional; it will be called automatically by
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* signal_start() if necessary. Calling it explicitly allows the client to
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* prevent the process from exiting at an unexpected time. */
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xpipe_nonblocking(fds);
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/* Sets up a handler for 'signr' and returns a structure that represents it.
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* Only one handler for a given signal may be registered at a time. */
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* Only one handler for a given signal may be registered. */
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signal_register(int signr)
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struct sigaction sa;
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s = xmalloc(sizeof *s);
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/* Set up signal handler. */
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ovs_assert(signr >= 1 && signr < N_SIGNALS);
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ovs_assert(!s->fds[0] && !s->fds[1]);
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xpipe_nonblocking(s->fds);
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/* Install signal handler. */
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memset(&sa, 0, sizeof sa);
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sa.sa_handler = signal_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = SA_RESTART;
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xsigaction(signr, &sa, &s->saved_sa);
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xsigaction(signr, &sa, NULL);
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/* Unregisters the handler for 's', restores the signal handler that was in
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* effect before signal_register() was called, and frees 's'. */
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signal_unregister(struct signal *s)
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xsigaction(s->signr, &s->saved_sa, NULL);
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/* Returns true if signal 's' has been received since the last call to this
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* function with argument 's'. */
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signal_poll(struct signal *s)
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char buf[_POSIX_PIPE_BUF];
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ignore(read(fds[0], buf, sizeof buf));
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if (signaled[s->signr]) {
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signaled[s->signr] = 0;
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return read(s->fds[0], buf, sizeof buf) > 0;
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/* Causes the next call to poll_block() to wake up when signal_poll(s) would
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signal_wait(struct signal *s)
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if (signaled[s->signr]) {
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poll_immediate_wake();
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poll_fd_wait(fds[0], POLLIN);
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poll_fd_wait(s->fds[0], POLLIN);
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signal_handler(int signr)
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if (signr >= 1 && signr < N_SIGNALS) {
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ignore(write(fds[1], "", 1));
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signaled[signr] = true;
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ignore(write(signals[signr].fds[1], "", 1));
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/* Returns the name of signal 'signum' as a string. The string may be in a
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* static buffer that is reused from one call to the next.
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/* Returns the name of signal 'signum' as a string. The return value is either
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* a statically allocated constant string or the 'bufsize'-byte buffer
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* 'namebuf'. 'bufsize' should be at least SIGNAL_NAME_BUFSIZE.
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* The string is probably a (possibly multi-word) description of the signal
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* (e.g. "Hangup") instead of just the stringified version of the macro
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* (e.g. "SIGHUP"). */
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signal_name(int signum)
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signal_name(int signum, char *namebuf, size_t bufsize)
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const char *name = NULL;
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#ifdef HAVE_STRSIGNAL
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name = strsignal(signum);
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#if HAVE_DECL_SYS_SIGLIST
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if (signum >= 0 && signum < ARRAY_SIZE(sys_siglist)) {
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const char *name = sys_siglist[signum];
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static char buffer[7 + INT_STRLEN(int) + 1];
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sprintf(buffer, "signal %d", signum);
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snprintf(namebuf, bufsize, "signal %d", signum);
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xsigaction(int signum, const struct sigaction *new, struct sigaction *old)
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if (sigaction(signum, new, old)) {
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char namebuf[SIGNAL_NAME_BUFSIZE];
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VLOG_FATAL("sigaction(%s) failed (%s)",
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signal_name(signum), strerror(errno));
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signal_name(signum, namebuf, sizeof namebuf),
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ovs_strerror(errno));
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xsigprocmask(int how, const sigset_t *new, sigset_t *old)
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xpthread_sigmask(int how, const sigset_t *new, sigset_t *old)
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if (sigprocmask(how, new, old)) {
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VLOG_FATAL("sigprocmask failed (%s)", strerror(errno));
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int error = pthread_sigmask(how, new, old);
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VLOG_FATAL("pthread_sigmask failed (%s)", ovs_strerror(error));