2 * Copyright (c) 2008, 2009, 2011 Nicira Networks.
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.
24 #include "poll-loop.h"
25 #include "socket-util.h"
26 #include "type-props.h"
30 #define N_SIGNALS _NSIG
32 #define N_SIGNALS NSIG
34 /* We could try harder to get the maximum signal number, but in practice we
35 * only care about SIGHUP, which is normally signal 1 anyway. */
43 static volatile sig_atomic_t signaled[N_SIGNALS];
47 static void signal_handler(int signr);
49 /* Initializes the signals subsystem (if it is not already initialized). Calls
50 * exit() if initialization fails.
52 * Calling this function is optional; it will be called automatically by
53 * signal_start() if necessary. Calling it explicitly allows the client to
54 * prevent the process from exiting at an unexpected time. */
62 ovs_fatal(errno, "could not create pipe");
64 set_nonblocking(fds[0]);
65 set_nonblocking(fds[1]);
69 /* Sets up a handler for 'signr' and returns a structure that represents it.
71 * Only one handler for a given signal may be registered at a time. */
73 signal_register(int signr)
80 /* Set up signal handler. */
81 assert(signr >= 1 && signr < N_SIGNALS);
82 memset(&sa, 0, sizeof sa);
83 sa.sa_handler = signal_handler;
84 sigemptyset(&sa.sa_mask);
85 sa.sa_flags = SA_RESTART;
86 if (sigaction(signr, &sa, NULL)) {
87 ovs_fatal(errno, "sigaction(%d) failed", signr);
90 /* Return structure. */
91 s = xmalloc(sizeof *s);
96 /* Returns true if signal 's' has been received since the last call to this
97 * function with argument 's'. */
99 signal_poll(struct signal *s)
101 char buf[_POSIX_PIPE_BUF];
102 ignore(read(fds[0], buf, sizeof buf));
103 if (signaled[s->signr]) {
104 signaled[s->signr] = 0;
110 /* Causes the next call to poll_block() to wake up when signal_poll(s) would
113 signal_wait(struct signal *s)
115 if (signaled[s->signr]) {
116 poll_immediate_wake();
118 poll_fd_wait(fds[0], POLLIN);
123 signal_handler(int signr)
125 if (signr >= 1 && signr < N_SIGNALS) {
126 ignore(write(fds[1], "", 1));
127 signaled[signr] = true;
131 /* Returns the name of signal 'signum' as a string. The string may be in a
132 * static buffer that is reused from one call to the next.
134 * The string is probably a (possibly multi-word) description of the signal
135 * (e.g. "Hangup") instead of just the stringified version of the macro
136 * (e.g. "SIGHUP"). */
138 signal_name(int signum)
140 const char *name = NULL;
141 #ifdef HAVE_STRSIGNAL
142 name = strsignal(signum);
145 static char buffer[7 + INT_STRLEN(int) + 1];
146 sprintf(buffer, "signal %d", signum);