146 lines
4.2 KiB
C
146 lines
4.2 KiB
C
/* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
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* Junior University
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*
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* We are making the OpenFlow specification and associated documentation
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* (Software) available for public use and benefit with the expectation
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* that others will use, modify and enhance the Software and contribute
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* those enhancements back to the community. However, since we would
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* like to make the Software available for broadest use, with as few
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* restrictions as possible permission is hereby granted, free of
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* charge, to any person obtaining a copy of this Software to deal in
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* the Software under the copyrights without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* The name and trademarks of copyright holder(s) may NOT be used in
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* advertising or publicity pertaining to the Software or any
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* derivatives without specific, written prior permission.
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*/
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#include <config.h>
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#include "signals.h"
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#include <assert.h>
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#include <errno.h>
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#include <limits.h>
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#include <signal.h>
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#include <unistd.h>
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#include "poll-loop.h"
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#include "socket-util.h"
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#include "util.h"
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#if defined(_NSIG)
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#define N_SIGNALS _NSIG
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#elif defined(NSIG)
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#define N_SIGNALS NSIG
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#else
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/* We could try harder to get the maximum signal number, but in practice we
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* only care about SIGHUP, which is normally signal 1 anyway. */
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#define N_SIGNALS 32
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#endif
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struct signal {
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int signr;
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};
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static volatile sig_atomic_t signaled[N_SIGNALS];
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static int fds[2];
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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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*
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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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void
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signal_init(void)
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{
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static bool inited;
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if (!inited) {
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inited = true;
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if (pipe(fds)) {
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ofp_fatal(errno, "could not create pipe");
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}
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set_nonblocking(fds[0]);
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set_nonblocking(fds[1]);
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}
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}
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/* Sets up a handler for 'signr' and returns a structure that represents it.
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*
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* Only one handler for a given signal may be registered at a time. */
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struct signal *
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signal_register(int signr)
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{
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struct sigaction sa;
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struct signal *s;
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signal_init();
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/* Set up signal handler. */
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assert(signr >= 1 && signr < N_SIGNALS);
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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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if (sigaction(signr, &sa, NULL)) {
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ofp_fatal(errno, "sigaction(%d) failed", signr);
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}
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/* Return structure. */
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s = xmalloc(sizeof *s);
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s->signr = signr;
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return s;
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}
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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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bool
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signal_poll(struct signal *s)
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{
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char buf[_POSIX_PIPE_BUF];
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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 true;
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}
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return false;
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}
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/* Causes the next call to poll_block() to wake up when signal_poll(s) would
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* return true. */
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void
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signal_wait(struct signal *s)
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{
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if (signaled[s->signr]) {
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poll_immediate_wake();
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} else {
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poll_fd_wait(fds[0], POLLIN);
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}
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}
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static void
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signal_handler(int signr)
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{
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if (signr >= 1 && signr < N_SIGNALS) {
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write(fds[1], "", 1);
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signaled[signr] = true;
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}
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}
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