1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
10 * charge, to any person obtaining a copy of this Software to deal in
11 * the Software under the copyrights without restriction, including
12 * without limitation the rights to use, copy, modify, merge, publish,
13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * The name and trademarks of copyright holder(s) may NOT be used in
30 * advertising or publicity pertaining to the Software or any
31 * derivatives without specific, written prior permission.
33 #include "fatal-signal.h"
44 /* Signals to catch. */
45 static const int fatal_signals[] = { SIGTERM, SIGINT, SIGHUP };
47 /* Signals to catch as a sigset_t. */
48 static sigset_t fatal_signal_set;
50 /* Hooks to call upon catching a signal */
52 void (*func)(void *aux);
56 static struct hook hooks[MAX_HOOKS];
57 static size_t n_hooks;
59 /* Number of nesting signal blockers. */
60 static int block_level = 0;
62 /* Signal mask saved by outermost signal blocker. */
63 static sigset_t saved_signal_mask;
65 static void call_sigprocmask(int how, sigset_t* new_set, sigset_t* old_set);
66 static void signal_handler(int sig_nr);
68 /* Registers 'hook' to be called when a process termination signal is
71 fatal_signal_add_hook(void (*func)(void *aux), void *aux)
74 assert(n_hooks < MAX_HOOKS);
75 hooks[n_hooks].func = func;
76 hooks[n_hooks].aux = aux;
78 fatal_signal_unblock();
81 /* Blocks program termination signals until fatal_signal_unblock() is called.
82 * May be called multiple times with nesting; if so, fatal_signal_unblock()
83 * must be called the same number of times to unblock signals.
85 * This is needed while adjusting a data structure that will be accessed by a
86 * fatal signal hook, so that the hook is not invoked while the data structure
87 * is in an inconsistent state. */
91 static bool inited = false;
96 sigemptyset(&fatal_signal_set);
97 for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
98 int sig_nr = fatal_signals[i];
99 sigaddset(&fatal_signal_set, sig_nr);
100 if (signal(sig_nr, signal_handler) == SIG_IGN) {
101 signal(sig_nr, SIG_IGN);
106 if (++block_level == 1) {
107 call_sigprocmask(SIG_BLOCK, &fatal_signal_set, &saved_signal_mask);
111 /* Unblocks program termination signals blocked by fatal_signal_block() is
112 * called. If multiple calls to fatal_signal_block() are nested,
113 * fatal_signal_unblock() must be called the same number of times to unblock
116 fatal_signal_unblock()
118 assert(block_level > 0);
119 if (--block_level == 0) {
120 call_sigprocmask(SIG_SETMASK, &saved_signal_mask, NULL);
125 static size_t n_files, max_files;
126 static bool disabled;
128 static void unlink_files(void *aux);
129 static void do_unlink_files(void);
131 /* Registers 'file' to be unlinked when the program terminates via exit() or a
134 fatal_signal_add_file_to_unlink(const char *file)
136 static bool added_hook = false;
139 fatal_signal_add_hook(unlink_files, NULL);
140 atexit(do_unlink_files);
143 fatal_signal_block();
144 if (n_files >= max_files) {
145 max_files = max_files * 2 + 1;
146 files = xrealloc(files, sizeof *files * max_files);
148 files[n_files++] = xstrdup(file);
149 fatal_signal_unblock();
152 /* Unregisters 'file' from being unlinked when the program terminates via
153 * exit() or a fatal signal. */
155 fatal_signal_remove_file_to_unlink(const char *file)
159 fatal_signal_block();
160 for (i = 0; i < n_files; i++) {
161 if (!strcmp(files[i], file)) {
163 files[i] = files[--n_files];
167 fatal_signal_unblock();
171 unlink_files(void *aux UNUSED)
177 do_unlink_files(void)
182 for (i = 0; i < n_files; i++) {
188 /* Disables the fatal signal hook mechanism. Following a fork, one of the
189 * resulting processes can call this function to allow it to terminate without
190 * triggering fatal signal processing or removing files. Fatal signal
191 * processing is still enabled in the other process. */
193 fatal_signal_fork(void)
199 for (i = 0; i < ARRAY_SIZE(fatal_signals); i++) {
200 int sig_nr = fatal_signals[i];
201 if (signal(sig_nr, SIG_DFL) == SIG_IGN) {
202 signal(sig_nr, SIG_IGN);
208 call_sigprocmask(int how, sigset_t* new_set, sigset_t* old_set)
210 int error = sigprocmask(how, new_set, old_set);
212 fprintf(stderr, "sigprocmask: %s\n", strerror(errno));
217 signal_handler(int sig_nr)
219 volatile sig_atomic_t recurse = 0;
225 /* Call all the hooks. */
226 for (i = 0; i < n_hooks; i++) {
227 hooks[i].func(hooks[i].aux);
231 /* Re-raise the signal with the default handling so that the program
232 * termination status reflects that we were killed by this signal */
233 signal(sig_nr, SIG_DFL);