summaryrefslogtreecommitdiffstats
path: root/tevent_signal.c
diff options
context:
space:
mode:
Diffstat (limited to 'tevent_signal.c')
-rw-r--r--tevent_signal.c539
1 files changed, 539 insertions, 0 deletions
diff --git a/tevent_signal.c b/tevent_signal.c
new file mode 100644
index 0000000..eab3654
--- /dev/null
+++ b/tevent_signal.c
@@ -0,0 +1,539 @@
+/*
+ Unix SMB/CIFS implementation.
+
+ common events code for signal events
+
+ Copyright (C) Andrew Tridgell 2007
+
+ ** 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
+ 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"
+#include "system/filesys.h"
+#include "system/wait.h"
+#define TEVENT_DEPRECATED 1
+#include "tevent.h"
+#include "tevent_internal.h"
+#include "tevent_util.h"
+
+/* 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 TEVENT_SA_INFO_QUEUE_COUNT 256
+
+size_t tevent_num_signals(void)
+{
+ return TEVENT_NUM_SIGNALS;
+}
+
+size_t tevent_sa_info_queue_count(void)
+{
+ return TEVENT_SA_INFO_QUEUE_COUNT;
+}
+
+struct tevent_sigcounter {
+ uint32_t count;
+ uint32_t seen;
+};
+
+#if defined(HAVE___SYNC_FETCH_AND_ADD)
+#define TEVENT_SIG_INCREMENT(s) __sync_fetch_and_add(&((s).count), 1)
+#elif defined(HAVE_ATOMIC_ADD_32)
+#define TEVENT_SIG_INCREMENT(s) atomic_add_32(&((s).count), 1)
+#else
+#define TEVENT_SIG_INCREMENT(s) (s).count++
+#endif
+#define TEVENT_SIG_SEEN(s, n) (s).seen += (n)
+#define TEVENT_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 tevent_sig_state {
+ struct tevent_common_signal_list *sig_handlers[TEVENT_NUM_SIGNALS+1];
+ struct sigaction *oldact[TEVENT_NUM_SIGNALS+1];
+ struct tevent_sigcounter signal_count[TEVENT_NUM_SIGNALS+1];
+ struct tevent_sigcounter got_signal;
+#ifdef SA_SIGINFO
+ /* with SA_SIGINFO we get quite a lot of info per signal */
+ siginfo_t *sig_info[TEVENT_NUM_SIGNALS+1];
+ struct tevent_sigcounter sig_blocked[TEVENT_NUM_SIGNALS+1];
+#endif
+} *sig_state;
+
+/*
+ return number of sigcounter events not processed yet
+*/
+static uint32_t tevent_sig_count(struct tevent_sigcounter s)
+{
+ return s.count - s.seen;
+}
+
+/*
+ signal handler - redirects to registered signals
+*/
+static void tevent_common_signal_handler(int signum)
+{
+ struct tevent_common_signal_list *sl;
+ struct tevent_context *ev = NULL;
+ int saved_errno = errno;
+
+ TEVENT_SIG_INCREMENT(sig_state->signal_count[signum]);
+ TEVENT_SIG_INCREMENT(sig_state->got_signal);
+
+ /* Write to each unique event context. */
+ for (sl = sig_state->sig_handlers[signum]; sl; sl = sl->next) {
+ if (sl->se->event_ctx && sl->se->event_ctx != ev) {
+ ev = sl->se->event_ctx;
+ tevent_common_wakeup(ev);
+ }
+ }
+
+ errno = saved_errno;
+}
+
+#ifdef SA_SIGINFO
+/*
+ signal handler with SA_SIGINFO - redirects to registered signals
+*/
+static void tevent_common_signal_handler_info(int signum, siginfo_t *info,
+ void *uctx)
+{
+ uint32_t count = tevent_sig_count(sig_state->signal_count[signum]);
+ /* sig_state->signal_count[signum].seen % TEVENT_SA_INFO_QUEUE_COUNT
+ * is the base of the unprocessed signals in the ringbuffer. */
+ uint32_t ofs = (sig_state->signal_count[signum].seen + count) %
+ TEVENT_SA_INFO_QUEUE_COUNT;
+ sig_state->sig_info[signum][ofs] = *info;
+
+ tevent_common_signal_handler(signum);
+
+ /* handle SA_SIGINFO */
+ if (count+1 == TEVENT_SA_INFO_QUEUE_COUNT) {
+ /* we've filled the info array - block this signal until
+ these ones are delivered */
+#ifdef HAVE_UCONTEXT_T
+ /*
+ * This is the only way for this to work.
+ * By default signum is blocked inside this
+ * signal handler using a temporary mask,
+ * but what we really need to do now is
+ * block it in the callers mask, so it
+ * stays blocked when the temporary signal
+ * handler mask is replaced when we return
+ * from here. The callers mask can be found
+ * in the ucontext_t passed in as the
+ * void *uctx argument.
+ */
+ ucontext_t *ucp = (ucontext_t *)uctx;
+ sigaddset(&ucp->uc_sigmask, signum);
+#else
+ /*
+ * WARNING !!! WARNING !!!!
+ *
+ * This code doesn't work.
+ * By default signum is blocked inside this
+ * signal handler, but calling sigprocmask
+ * modifies the temporary signal mask being
+ * used *inside* this handler, which will be
+ * replaced by the callers signal mask once
+ * we return from here. See Samba
+ * bug #9550 for details.
+ */
+ sigset_t set;
+ sigemptyset(&set);
+ sigaddset(&set, signum);
+ sigprocmask(SIG_BLOCK, &set, NULL);
+#endif
+ TEVENT_SIG_INCREMENT(sig_state->sig_blocked[signum]);
+ }
+}
+#endif
+
+static int tevent_common_signal_list_destructor(struct tevent_common_signal_list *sl)
+{
+ if (sig_state->sig_handlers[sl->se->signum]) {
+ DLIST_REMOVE(sig_state->sig_handlers[sl->se->signum], sl);
+ }
+ return 0;
+}
+
+/*
+ destroy a signal event
+*/
+static int tevent_signal_destructor(struct tevent_signal *se)
+{
+ if (se->destroyed) {
+ tevent_common_check_double_free(se, "tevent_signal double free");
+ goto done;
+ }
+ se->destroyed = true;
+
+ TALLOC_FREE(se->additional_data);
+
+ if (se->event_ctx != NULL) {
+ tevent_trace_signal_callback(se->event_ctx, se, TEVENT_EVENT_TRACE_DETACH);
+ DLIST_REMOVE(se->event_ctx->signal_events, se);
+ }
+
+ if (sig_state->sig_handlers[se->signum] == NULL) {
+ /* restore old handler, if any */
+ if (sig_state->oldact[se->signum]) {
+ sigaction(se->signum, sig_state->oldact[se->signum], NULL);
+ TALLOC_FREE(sig_state->oldact[se->signum]);
+ }
+#ifdef SA_SIGINFO
+ if (se->sa_flags & SA_SIGINFO) {
+ if (sig_state->sig_info[se->signum]) {
+ TALLOC_FREE(sig_state->sig_info[se->signum]);
+ }
+ }
+#endif
+ }
+
+ se->event_ctx = NULL;
+done:
+ if (se->busy) {
+ return -1;
+ }
+ se->wrapper = NULL;
+
+ return 0;
+}
+
+/*
+ add a signal event
+ return NULL on failure (memory allocation error)
+*/
+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 tevent_signal *se;
+ struct tevent_common_signal_list *sl;
+ sigset_t set, oldset;
+ int ret;
+
+ ret = tevent_common_wakeup_init(ev);
+ if (ret != 0) {
+ errno = ret;
+ return NULL;
+ }
+
+ if (signum >= TEVENT_NUM_SIGNALS) {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ /* the sig_state needs to be on a global context as it can last across
+ multiple event contexts */
+ if (sig_state == NULL) {
+ sig_state = talloc_zero(NULL, struct tevent_sig_state);
+ if (sig_state == NULL) {
+ return NULL;
+ }
+ }
+
+ se = talloc_zero(mem_ctx?mem_ctx:ev, struct tevent_signal);
+ if (se == NULL) return NULL;
+
+ sl = talloc_zero(se, struct tevent_common_signal_list);
+ if (!sl) {
+ talloc_free(se);
+ return NULL;
+ }
+ sl->se = se;
+
+ *se = (struct tevent_signal) {
+ .event_ctx = ev,
+ .signum = signum,
+ .sa_flags = sa_flags,
+ .handler = handler,
+ .private_data = private_data,
+ .handler_name = handler_name,
+ .location = location,
+ .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;
+ }
+
+ /* 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 = tevent_common_signal_handler;
+ act.sa_flags = sa_flags;
+#ifdef SA_SIGINFO
+ if (sa_flags & SA_SIGINFO) {
+ 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_zero_array(sig_state, siginfo_t,
+ TEVENT_SA_INFO_QUEUE_COUNT);
+ if (sig_state->sig_info[signum] == NULL) {
+ talloc_free(se);
+ return NULL;
+ }
+ }
+ }
+#endif
+ sig_state->oldact[signum] = talloc_zero(sig_state, struct sigaction);
+ if (sig_state->oldact[signum] == NULL) {
+ talloc_free(se);
+ return NULL;
+ }
+ if (sigaction(signum, &act, sig_state->oldact[signum]) == -1) {
+ talloc_free(sig_state->oldact[signum]);
+ sig_state->oldact[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);
+ tevent_trace_signal_callback(se->event_ctx, se, TEVENT_EVENT_TRACE_ATTACH);
+ 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);
+
+ return se;
+}
+
+int tevent_common_invoke_signal_handler(struct tevent_signal *se,
+ int signum, int count, void *siginfo,
+ bool *removed)
+{
+ struct tevent_context *handler_ev = se->event_ctx;
+ bool remove = false;
+
+ if (removed != NULL) {
+ *removed = false;
+ }
+
+ if (se->event_ctx == NULL) {
+ return 0;
+ }
+
+ se->busy = true;
+ if (se->wrapper != NULL) {
+ handler_ev = se->wrapper->wrap_ev;
+
+ tevent_wrapper_push_use_internal(handler_ev, se->wrapper);
+ se->wrapper->ops->before_signal_handler(
+ se->wrapper->wrap_ev,
+ se->wrapper->private_state,
+ se->wrapper->main_ev,
+ se,
+ signum,
+ count,
+ siginfo,
+ se->handler_name,
+ se->location);
+ }
+ tevent_trace_signal_callback(se->event_ctx, se, TEVENT_EVENT_TRACE_BEFORE_HANDLER);
+ se->handler(handler_ev, se, signum, count, siginfo, se->private_data);
+ if (se->wrapper != NULL) {
+ se->wrapper->ops->after_signal_handler(
+ se->wrapper->wrap_ev,
+ se->wrapper->private_state,
+ se->wrapper->main_ev,
+ se,
+ signum,
+ count,
+ siginfo,
+ se->handler_name,
+ se->location);
+ tevent_wrapper_pop_use_internal(handler_ev, se->wrapper);
+ }
+ se->busy = false;
+
+#ifdef SA_RESETHAND
+ if (se->sa_flags & SA_RESETHAND) {
+ remove = true;
+ }
+#endif
+
+ if (se->destroyed) {
+ talloc_set_destructor(se, NULL);
+ remove = true;
+ }
+
+ if (remove) {
+ TALLOC_FREE(se);
+ if (removed != NULL) {
+ *removed = true;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ check if a signal is pending
+ return != 0 if a signal was pending
+*/
+int tevent_common_check_signal(struct tevent_context *ev)
+{
+ int i;
+
+ if (!sig_state || !TEVENT_SIG_PENDING(sig_state->got_signal)) {
+ return 0;
+ }
+
+ for (i=0;i<TEVENT_NUM_SIGNALS+1;i++) {
+ struct tevent_common_signal_list *sl, *next;
+ struct tevent_sigcounter counter = sig_state->signal_count[i];
+ uint32_t count = tevent_sig_count(counter);
+ int ret;
+#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 (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) {
+ uint32_t j;
+
+ clear_processed_siginfo = true;
+
+ for (j=0;j<count;j++) {
+ /* sig_state->signal_count[i].seen
+ * % TEVENT_SA_INFO_QUEUE_COUNT is
+ * the base position of the unprocessed
+ * signals in the ringbuffer. */
+ uint32_t ofs = (counter.seen + j)
+ % TEVENT_SA_INFO_QUEUE_COUNT;
+ bool removed = false;
+
+ ret = tevent_common_invoke_signal_handler(
+ se, i, 1,
+ (void*)&sig_state->sig_info[i][ofs],
+ &removed);
+ if (ret != 0) {
+ tevent_abort(ev, "tevent_common_invoke_signal_handler() failed");
+ }
+ if (removed) {
+ break;
+ }
+ }
+ continue;
+ }
+#endif
+
+ ret = tevent_common_invoke_signal_handler(se, i, count,
+ NULL, NULL);
+ if (ret != 0) {
+ tevent_abort(ev, "tevent_common_invoke_signal_handler() failed");
+ }
+ }
+
+#ifdef SA_SIGINFO
+ if (clear_processed_siginfo && sig_state->sig_info[i] != NULL) {
+ uint32_t j;
+ for (j=0;j<count;j++) {
+ uint32_t ofs = (counter.seen + j)
+ % TEVENT_SA_INFO_QUEUE_COUNT;
+ memset((void*)&sig_state->sig_info[i][ofs],
+ '\0',
+ sizeof(siginfo_t));
+ }
+ }
+#endif
+
+ TEVENT_SIG_SEEN(sig_state->signal_count[i], count);
+ TEVENT_SIG_SEEN(sig_state->got_signal, count);
+
+#ifdef SA_SIGINFO
+ if (TEVENT_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
+ TEVENT_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);
+ TEVENT_SIG_SEEN(sig_state->sig_blocked[i],
+ tevent_sig_count(sig_state->sig_blocked[i]));
+ sigprocmask(SIG_UNBLOCK, &set, NULL);
+ }
+#endif
+ }
+
+ return 1;
+}
+
+void tevent_cleanup_pending_signal_handlers(struct tevent_signal *se)
+{
+ tevent_signal_destructor(se);
+ talloc_set_destructor(se, NULL);
+ return;
+}
+
+void tevent_signal_set_tag(struct tevent_signal *se, uint64_t tag)
+{
+ if (se == NULL) {
+ return;
+ }
+
+ se->tag = tag;
+}
+
+uint64_t tevent_signal_get_tag(const struct tevent_signal *se)
+{
+ if (se == NULL) {
+ return 0;
+ }
+
+ return se->tag;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 08:22:43 +0000