2 Unix SMB/CIFS implementation.
4 common events code for signal events
6 Copyright (C) Andrew Tridgell 2007
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include "system/filesys.h"
25 #include "system/select.h"
26 #include "lib/util/dlinklist.h"
27 #include "lib/events/events.h"
28 #include "lib/events/events_internal.h"
30 #define NUM_SIGNALS 64
32 /* maximum number of SA_SIGINFO signals to hold in the queue */
33 #define SA_INFO_QUEUE_COUNT 10
40 #define SIG_INCREMENT(s) (s).count++
41 #define SIG_SEEN(s, n) (s).seen += (n)
42 #define SIG_PENDING(s) ((s).seen != (s).count)
46 the poor design of signals means that this table must be static global
48 static struct sig_state {
49 struct signal_event *sig_handlers[NUM_SIGNALS];
50 struct sigaction *oldact[NUM_SIGNALS];
51 struct sigcounter signal_count[NUM_SIGNALS];
52 struct sigcounter got_signal;
55 /* with SA_SIGINFO we get quite a lot of info per signal */
56 siginfo_t *sig_info[NUM_SIGNALS];
57 struct sigcounter sig_blocked[NUM_SIGNALS];
62 return number of sigcounter events not processed yet
64 static uint32_t sig_count(struct sigcounter s)
66 if (s.count >= s.seen) {
67 return s.count - s.seen;
69 return 1 + (0xFFFFFFFF & ~(s.seen - s.count));
73 signal handler - redirects to registered signals
75 static void signal_handler(int signum)
78 SIG_INCREMENT(sig_state->signal_count[signum]);
79 SIG_INCREMENT(sig_state->got_signal);
80 /* doesn't matter if this pipe overflows */
81 write(sig_state->pipe_hack[1], &c, 1);
86 signal handler with SA_SIGINFO - redirects to registered signals
88 static void signal_handler_info(int signum, siginfo_t *info, void *uctx)
90 uint32_t count = sig_count(sig_state->signal_count[signum]);
91 sig_state->sig_info[signum][count] = *info;
93 signal_handler(signum);
95 /* handle SA_SIGINFO */
96 if (count+1 == SA_INFO_QUEUE_COUNT) {
97 /* we've filled the info array - block this signal until
98 these ones are delivered */
101 sigaddset(&set, signum);
102 sigprocmask(SIG_BLOCK, &set, NULL);
103 SIG_INCREMENT(sig_state->sig_blocked[signum]);
109 destroy a signal event
111 static int signal_event_destructor(struct signal_event *se)
113 se->event_ctx->num_signal_handlers--;
114 DLIST_REMOVE(sig_state->sig_handlers[se->signum], se);
115 if (sig_state->sig_handlers[se->signum] == NULL) {
116 /* restore old handler, if any */
117 sigaction(se->signum, sig_state->oldact[se->signum], NULL);
118 sig_state->oldact[se->signum] = NULL;
120 if (se->sa_flags & SA_SIGINFO) {
121 talloc_free(sig_state->sig_info[se->signum]);
122 sig_state->sig_info[se->signum] = NULL;
130 this is part of the pipe hack needed to avoid the signal race condition
132 static void signal_pipe_handler(struct event_context *ev, struct fd_event *fde,
133 uint16_t flags, void *private)
136 /* its non-blocking, doesn't matter if we read too much */
137 read(sig_state->pipe_hack[0], c, sizeof(c));
142 return NULL on failure (memory allocation error)
144 struct signal_event *common_event_add_signal(struct event_context *ev,
148 event_signal_handler_t handler,
151 struct signal_event *se;
153 if (signum >= NUM_SIGNALS) {
157 /* the sig_state needs to be on a global context as it can last across
158 multiple event contexts */
159 if (sig_state == NULL) {
160 sig_state = talloc_zero(talloc_autofree_context(), struct sig_state);
161 if (sig_state == NULL) {
166 se = talloc(mem_ctx?mem_ctx:ev, struct signal_event);
167 if (se == NULL) return NULL;
170 se->handler = handler;
171 se->private_data = private_data;
173 se->sa_flags = sa_flags;
175 /* only install a signal handler if not already installed */
176 if (sig_state->sig_handlers[signum] == NULL) {
177 struct sigaction act;
179 act.sa_handler = signal_handler;
180 act.sa_flags = sa_flags;
182 if (sa_flags & SA_SIGINFO) {
183 act.sa_handler = NULL;
184 act.sa_sigaction = signal_handler_info;
185 if (sig_state->sig_info[signum] == NULL) {
186 sig_state->sig_info[signum] = talloc_array(sig_state, siginfo_t, SA_INFO_QUEUE_COUNT);
187 if (sig_state->sig_info[signum] == NULL) {
194 sig_state->oldact[signum] = talloc(sig_state, struct sigaction);
195 if (sig_state->oldact[signum] == NULL) {
199 if (sigaction(signum, &act, sig_state->oldact[signum]) == -1) {
205 DLIST_ADD(sig_state->sig_handlers[signum], se);
207 talloc_set_destructor(se, signal_event_destructor);
209 /* we need to setup the pipe hack handler if not already
211 if (ev->pipe_fde == NULL) {
212 if (sig_state->pipe_hack[0] == 0 &&
213 sig_state->pipe_hack[1] == 0) {
214 pipe(sig_state->pipe_hack);
215 set_blocking(sig_state->pipe_hack[0], False);
216 set_blocking(sig_state->pipe_hack[1], False);
218 ev->pipe_fde = event_add_fd(ev, ev, sig_state->pipe_hack[0],
219 EVENT_FD_READ, signal_pipe_handler, NULL);
221 ev->num_signal_handlers++;
228 check if a signal is pending
229 return != 0 if a signal was pending
231 int common_event_check_signal(struct event_context *ev)
235 if (!sig_state || !SIG_PENDING(sig_state->got_signal)) {
239 for (i=0;i<NUM_SIGNALS+1;i++) {
240 struct signal_event *se, *next;
241 struct sigcounter counter = sig_state->signal_count[i];
242 uint32_t count = sig_count(counter);
247 for (se=sig_state->sig_handlers[i];se;se=next) {
250 if (se->sa_flags & SA_SIGINFO) {
252 for (j=0;j<count;j++) {
253 /* note the use of the sig_info array as a
255 int ofs = (counter.count + j) % SA_INFO_QUEUE_COUNT;
256 se->handler(ev, se, i, 1,
257 (void*)&sig_state->sig_info[i][ofs],
260 if (SIG_PENDING(sig_state->sig_blocked[i])) {
261 /* we'd filled the queue, unblock the
266 SIG_SEEN(sig_state->sig_blocked[i],
267 sig_count(sig_state->sig_blocked[i]));
268 sigprocmask(SIG_UNBLOCK, &set, NULL);
270 if (se->sa_flags & SA_RESETHAND) {
276 se->handler(ev, se, i, count, NULL, se->private_data);
277 if (se->sa_flags & SA_RESETHAND) {
281 SIG_SEEN(sig_state->signal_count[i], count);
282 SIG_SEEN(sig_state->got_signal, count);