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 <signal.h>
#include "replace.h"
#include "system/filesys.h"
-#include "system/select.h"
+#include "system/wait.h"
#include "tevent.h"
#include "tevent_internal.h"
#include "tevent_util.h"
#define NUM_SIGNALS 64
-/* maximum number of SA_SIGINFO signals to hold in the queue */
-#define SA_INFO_QUEUE_COUNT 10
+/* 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;
#define SIG_SEEN(s, n) (s).seen += (n)
#define SIG_PENDING(s) ((s).seen != (s).count)
+struct tevent_common_signal_list {
+ struct tevent_common_signal_list *prev, *next;
+ struct tevent_signal *se;
+};
/*
the poor design of signals means that this table must be static global
*/
static struct sig_state {
- struct signal_event *sig_handlers[NUM_SIGNALS+1];
+ struct tevent_common_signal_list *sig_handlers[NUM_SIGNALS+1];
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;
}
/*
signal handler - redirects to registered signals
*/
-static void signal_handler(int signum)
+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;
+ /* doesn't matter if this pipe overflows */
+ res = write(ev->pipe_fds[1], &c, 1);
+ }
+ }
+
+ errno = saved_errno;
}
#ifdef SA_SIGINFO
/*
signal handler with SA_SIGINFO - redirects to registered signals
*/
-static void signal_handler_info(int signum, siginfo_t *info, void *uctx)
+static void tevent_common_signal_handler_info(int signum, siginfo_t *info,
+ 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;
- signal_handler(signum);
+ tevent_common_signal_handler(signum);
/* handle SA_SIGINFO */
if (count+1 == SA_INFO_QUEUE_COUNT) {
}
#endif
+static int tevent_common_signal_list_destructor(struct tevent_common_signal_list *sl)
+{
+ DLIST_REMOVE(sig_state->sig_handlers[sl->se->signum], sl);
+ return 0;
+}
+
/*
destroy a signal event
*/
-static int signal_event_destructor(struct signal_event *se)
+static int tevent_signal_destructor(struct tevent_signal *se)
{
- se->event_ctx->num_signal_handlers--;
- DLIST_REMOVE(sig_state->sig_handlers[se->signum], se);
+ struct tevent_common_signal_list *sl;
+ sl = talloc_get_type(se->additional_data,
+ struct tevent_common_signal_list);
+
+ if (se->event_ctx) {
+ DLIST_REMOVE(se->event_ctx->signal_events, se);
+ }
+
+ talloc_free(sl);
+
if (sig_state->sig_handlers[se->signum] == NULL) {
/* restore old handler, if any */
sigaction(se->signum, sig_state->oldact[se->signum], NULL);
}
#endif
}
+
return 0;
}
/*
this is part of the pipe hack needed to avoid the signal race condition
*/
-static void signal_pipe_handler(struct event_context *ev, struct fd_event *fde,
- uint16_t flags, void *private)
+static void signal_pipe_handler(struct tevent_context *ev, struct tevent_fd *fde,
+ 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));
}
/*
add a signal event
return NULL on failure (memory allocation error)
*/
-struct signal_event *common_event_add_signal(struct event_context *ev,
- TALLOC_CTX *mem_ctx,
- int signum,
- int sa_flags,
- event_signal_handler_t handler,
- void *private_data)
+struct tevent_signal *tevent_common_add_signal(struct tevent_context *ev,
+ TALLOC_CTX *mem_ctx,
+ int signum,
+ int sa_flags,
+ tevent_signal_handler_t handler,
+ void *private_data,
+ const char *handler_name,
+ const char *location)
{
- struct signal_event *se;
+ struct tevent_signal *se;
+ struct tevent_common_signal_list *sl;
+ sigset_t set, oldset;
if (signum >= NUM_SIGNALS) {
+ errno = EINVAL;
return NULL;
}
}
}
- se = talloc(mem_ctx?mem_ctx:ev, struct signal_event);
+ se = talloc(mem_ctx?mem_ctx:ev, struct tevent_signal);
if (se == NULL) return NULL;
se->event_ctx = ev;
- se->handler = handler;
- se->private_data = private_data;
se->signum = signum;
se->sa_flags = sa_flags;
-
+ se->handler = handler;
+ se->private_data = private_data;
+ se->handler_name = handler_name;
+ se->location = location;
+ se->additional_data = NULL;
+
+ sl = talloc(se, struct tevent_common_signal_list);
+ if (!sl) {
+ talloc_free(se);
+ return NULL;
+ }
+ sl->se = se;
+ se->additional_data = sl;
+
/* Ensure, no matter the destruction order, that we always have a handle on the global sig_state */
if (!talloc_reference(se, sig_state)) {
+ talloc_free(se);
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;
ZERO_STRUCT(act);
- act.sa_handler = signal_handler;
+ act.sa_handler = tevent_common_signal_handler;
act.sa_flags = sa_flags;
#ifdef SA_SIGINFO
if (sa_flags & SA_SIGINFO) {
act.sa_handler = NULL;
- act.sa_sigaction = signal_handler_info;
+ 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(sig_state->sig_handlers[signum], se);
+ DLIST_ADD(se->event_ctx->signal_events, se);
- talloc_set_destructor(se, signal_event_destructor);
+ /* 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);
- /* 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 = event_add_fd(ev, ev, sig_state->pipe_hack[0],
- EVENT_FD_READ, signal_pipe_handler, NULL);
- }
- ev->num_signal_handlers++;
+ talloc_set_destructor(se, tevent_signal_destructor);
+ talloc_set_destructor(sl, tevent_common_signal_list_destructor);
return se;
}
check if a signal is pending
return != 0 if a signal was pending
*/
-int common_event_check_signal(struct event_context *ev)
+int tevent_common_check_signal(struct tevent_context *ev)
{
int i;
}
for (i=0;i<NUM_SIGNALS+1;i++) {
- struct signal_event *se, *next;
+ 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;
}
- for (se=sig_state->sig_handlers[i];se;se=next) {
- next = se->next;
+ for (sl=sig_state->sig_handlers[i];sl;sl=next) {
+ struct tevent_signal *se = sl->se;
+ 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 / ira / wip.git / blobdiff