-struct signal {
- struct sigaction saved_sa;
- int signr;
-};
-
-static volatile sig_atomic_t signaled[N_SIGNALS];
-
-static int fds[2];
-
-static void signal_handler(int signr);
-
-/* Initializes the signals subsystem (if it is not already initialized). Calls
- * exit() if initialization fails.
- *
- * Calling this function is optional; it will be called automatically by
- * signal_start() if necessary. Calling it explicitly allows the client to
- * prevent the process from exiting at an unexpected time. */
-void
-signal_init(void)
-{
- static bool inited;
- if (!inited) {
- inited = true;
- xpipe_nonblocking(fds);
- }
-}
-
-/* Sets up a handler for 'signr' and returns a structure that represents it.
- *
- * Only one handler for a given signal may be registered at a time. */
-struct signal *
-signal_register(int signr)
-{
- struct sigaction sa;
- struct signal *s;
-
- signal_init();
-
- s = xmalloc(sizeof *s);
- s->signr = signr;
-
- /* Set up signal handler. */
- ovs_assert(signr >= 1 && signr < N_SIGNALS);
- memset(&sa, 0, sizeof sa);
- sa.sa_handler = signal_handler;
- sigemptyset(&sa.sa_mask);
- sa.sa_flags = SA_RESTART;
- xsigaction(signr, &sa, &s->saved_sa);
-
- return s;
-}
-
-/* Unregisters the handler for 's', restores the signal handler that was in
- * effect before signal_register() was called, and frees 's'. */
-void
-signal_unregister(struct signal *s)
-{
- if (s) {
- xsigaction(s->signr, &s->saved_sa, NULL);
- free(s);
- }
-}
-
-/* Returns true if signal 's' has been received since the last call to this
- * function with argument 's'. */
-bool
-signal_poll(struct signal *s)
-{
- char buf[_POSIX_PIPE_BUF];
- ignore(read(fds[0], buf, sizeof buf));
- if (signaled[s->signr]) {
- signaled[s->signr] = 0;
- return true;
- }
- return false;
-}
-
-/* Causes the next call to poll_block() to wake up when signal_poll(s) would
- * return true. */
-void
-signal_wait(struct signal *s)
-{
- if (signaled[s->signr]) {
- poll_immediate_wake();
- } else {
- poll_fd_wait(fds[0], POLLIN);
- }
-}
-\f
-static void
-signal_handler(int signr)
-{
- if (signr >= 1 && signr < N_SIGNALS) {
- ignore(write(fds[1], "", 1));
- signaled[signr] = true;
- }
-}
-