common events code for signal events
Copyright (C) Andrew Tridgell 2007
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
+
+ ** NOTE! The following LGPL license applies to the tevent
+ ** library. This does NOT imply that all of Samba is released
+ ** under the LGPL
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 3 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#define NUM_SIGNALS 64
-/* maximum number of SA_SIGINFO signals to hold in the queue */
-#define SA_INFO_QUEUE_COUNT 100
+/* maximum number of SA_SIGINFO signals to hold in the queue.
+ NB. This *MUST* be a power of 2, in order for the ring buffer
+ wrap to work correctly. Thanks to Petr Vandrovec <petr@vandrovec.name>
+ for this. */
+
+#define SA_INFO_QUEUE_COUNT 64
struct sigcounter {
uint32_t count;
struct sigaction *oldact[NUM_SIGNALS+1];
struct sigcounter signal_count[NUM_SIGNALS+1];
struct sigcounter got_signal;
- int pipe_hack[2];
#ifdef SA_SIGINFO
/* with SA_SIGINFO we get quite a lot of info per signal */
siginfo_t *sig_info[NUM_SIGNALS+1];
*/
static uint32_t sig_count(struct sigcounter s)
{
- if (s.count >= s.seen) {
- return s.count - s.seen;
- }
- return 1 + (0xFFFFFFFF & ~(s.seen - s.count));
+ return s.count - s.seen;
}
/*
static void tevent_common_signal_handler(int signum)
{
char c = 0;
+ ssize_t res;
+ struct tevent_common_signal_list *sl;
+ struct tevent_context *ev = NULL;
+ int saved_errno = errno;
+
SIG_INCREMENT(sig_state->signal_count[signum]);
SIG_INCREMENT(sig_state->got_signal);
- /* doesn't matter if this pipe overflows */
- write(sig_state->pipe_hack[1], &c, 1);
+
+ /* Write to each unique event context. */
+ for (sl = sig_state->sig_handlers[signum]; sl; sl = sl->next) {
+ if (sl->se->event_ctx != ev) {
+ ev = sl->se->event_ctx;
+ if (!ev) continue;
+ if (!ev->pipe_fds) continue;
+ /* doesn't matter if this pipe overflows */
+ res = write(ev->pipe_fds[1], &c, 1);
+ }
+ }
+
+ errno = saved_errno;
}
#ifdef SA_SIGINFO
void *uctx)
{
uint32_t count = sig_count(sig_state->signal_count[signum]);
- sig_state->sig_info[signum][count] = *info;
+ /* sig_state->signal_count[signum].seen % SA_INFO_QUEUE_COUNT
+ * is the base of the unprocessed signals in the ringbuffer. */
+ uint32_t ofs = (sig_state->signal_count[signum].seen + count) %
+ SA_INFO_QUEUE_COUNT;
+ sig_state->sig_info[signum][ofs] = *info;
tevent_common_signal_handler(signum);
this is part of the pipe hack needed to avoid the signal race condition
*/
static void signal_pipe_handler(struct tevent_context *ev, struct tevent_fd *fde,
- uint16_t flags, void *private)
+ uint16_t flags, void *_private)
{
char c[16];
+ ssize_t res;
/* its non-blocking, doesn't matter if we read too much */
- read(sig_state->pipe_hack[0], c, sizeof(c));
+ res = read(fde->fd, c, sizeof(c));
}
/*
{
struct tevent_signal *se;
struct tevent_common_signal_list *sl;
+ sigset_t set, oldset;
if (signum >= NUM_SIGNALS) {
errno = EINVAL;
return NULL;
}
+ /* we need to setup the pipe hack handler if not already
+ setup */
+ if (ev->pipe_fde == NULL) {
+ if (pipe(ev->pipe_fds) == -1) {
+ talloc_free(se);
+ return NULL;
+ }
+ ev_set_blocking(ev->pipe_fds[0], false);
+ ev_set_blocking(ev->pipe_fds[1], false);
+ ev->pipe_fde = tevent_add_fd(ev, ev, ev->pipe_fds[0],
+ TEVENT_FD_READ,
+ signal_pipe_handler, NULL);
+ if (!ev->pipe_fde) {
+ close(ev->pipe_fds[0]);
+ close(ev->pipe_fds[1]);
+ talloc_free(se);
+ return NULL;
+ }
+ }
+
/* only install a signal handler if not already installed */
if (sig_state->sig_handlers[signum] == NULL) {
struct sigaction act;
act.sa_handler = NULL;
act.sa_sigaction = tevent_common_signal_handler_info;
if (sig_state->sig_info[signum] == NULL) {
- sig_state->sig_info[signum] = talloc_array(sig_state, siginfo_t, SA_INFO_QUEUE_COUNT);
+ sig_state->sig_info[signum] = talloc_zero_array(sig_state, siginfo_t, SA_INFO_QUEUE_COUNT);
if (sig_state->sig_info[signum] == NULL) {
talloc_free(se);
return NULL;
}
DLIST_ADD(se->event_ctx->signal_events, se);
+
+ /* Make sure the signal doesn't come in while we're mangling list. */
+ sigemptyset(&set);
+ sigaddset(&set, signum);
+ sigprocmask(SIG_BLOCK, &set, &oldset);
DLIST_ADD(sig_state->sig_handlers[signum], sl);
+ sigprocmask(SIG_SETMASK, &oldset, NULL);
talloc_set_destructor(se, tevent_signal_destructor);
talloc_set_destructor(sl, tevent_common_signal_list_destructor);
- /* we need to setup the pipe hack handler if not already
- setup */
- if (ev->pipe_fde == NULL) {
- if (sig_state->pipe_hack[0] == 0 &&
- sig_state->pipe_hack[1] == 0) {
- pipe(sig_state->pipe_hack);
- ev_set_blocking(sig_state->pipe_hack[0], false);
- ev_set_blocking(sig_state->pipe_hack[1], false);
- }
- ev->pipe_fde = tevent_add_fd(ev, ev, sig_state->pipe_hack[0],
- TEVENT_FD_READ, signal_pipe_handler, NULL);
- if (!ev->pipe_fde) {
- talloc_free(se);
- return NULL;
- }
- }
-
return se;
}
struct tevent_common_signal_list *sl, *next;
struct sigcounter counter = sig_state->signal_count[i];
uint32_t count = sig_count(counter);
+#ifdef SA_SIGINFO
+ /* Ensure we null out any stored siginfo_t entries
+ * after processing for debugging purposes. */
+ bool clear_processed_siginfo = false;
+#endif
if (count == 0) {
continue;
next = sl->next;
#ifdef SA_SIGINFO
if (se->sa_flags & SA_SIGINFO) {
- int j;
+ uint32_t j;
+
+ clear_processed_siginfo = true;
+
for (j=0;j<count;j++) {
- /* note the use of the sig_info array as a
- ring buffer */
- int ofs = ((count-1) + j) % SA_INFO_QUEUE_COUNT;
- se->handler(ev, se, i, 1,
+ /* sig_state->signal_count[i].seen
+ * % SA_INFO_QUEUE_COUNT is
+ * the base position of the unprocessed
+ * signals in the ringbuffer. */
+ uint32_t ofs = (counter.seen + j)
+ % SA_INFO_QUEUE_COUNT;
+ se->handler(ev, se, i, 1,
(void*)&sig_state->sig_info[i][ofs],
se->private_data);
}
- if (SIG_PENDING(sig_state->sig_blocked[i])) {
- /* we'd filled the queue, unblock the
- signal now */
- sigset_t set;
- sigemptyset(&set);
- sigaddset(&set, i);
- SIG_SEEN(sig_state->sig_blocked[i],
- sig_count(sig_state->sig_blocked[i]));
- sigprocmask(SIG_UNBLOCK, &set, NULL);
- }
if (se->sa_flags & SA_RESETHAND) {
talloc_free(se);
}
talloc_free(se);
}
}
+
+#ifdef SA_SIGINFO
+ if (clear_processed_siginfo) {
+ uint32_t j;
+ for (j=0;j<count;j++) {
+ uint32_t ofs = (counter.seen + j)
+ % SA_INFO_QUEUE_COUNT;
+ memset((void*)&sig_state->sig_info[i][ofs],
+ '\0',
+ sizeof(siginfo_t));
+ }
+ }
+#endif
+
SIG_SEEN(sig_state->signal_count[i], count);
SIG_SEEN(sig_state->got_signal, count);
+
+#ifdef SA_SIGINFO
+ if (SIG_PENDING(sig_state->sig_blocked[i])) {
+ /* We'd filled the queue, unblock the
+ signal now the queue is empty again.
+ Note we MUST do this after the
+ SIG_SEEN(sig_state->signal_count[i], count)
+ call to prevent a new signal running
+ out of room in the sig_state->sig_info[i][]
+ ring buffer. */
+ sigset_t set;
+ sigemptyset(&set);
+ sigaddset(&set, i);
+ SIG_SEEN(sig_state->sig_blocked[i],
+ sig_count(sig_state->sig_blocked[i]));
+ sigprocmask(SIG_UNBLOCK, &set, NULL);
+ }
+#endif
}
return 1;
git.samba.org / metze / samba / wip.git / blobdiff