--- /dev/null
+/*
+ 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 <ccan/tevent/tevent.h>
+#include <ccan/tevent/tevent_internal.h>
+#include <ccan/tevent/tevent_util.h>
+#include <signal.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#define TEVENT_NUM_SIGNALS 64
+
+/* 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 64
+
+struct tevent_sigcounter {
+ uint32_t count;
+ uint32_t seen;
+};
+
+#define TEVENT_SIG_INCREMENT(s) (s).count++
+#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)
+{
+ char c = 0;
+ ssize_t res;
+ 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;
+ /* 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 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 */
+ sigset_t set;
+ sigemptyset(&set);
+ sigaddset(&set, signum);
+ sigprocmask(SIG_BLOCK, &set, NULL);
+ 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)
+{
+ 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 */
+ if (sig_state->oldact[se->signum]) {
+ sigaction(se->signum, sig_state->oldact[se->signum], NULL);
+ sig_state->oldact[se->signum] = NULL;
+ }
+#ifdef SA_SIGINFO
+ if (se->sa_flags & SA_SIGINFO) {
+ if (sig_state->sig_info[se->signum]) {
+ talloc_free(sig_state->sig_info[se->signum]);
+ sig_state->sig_info[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 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 */
+ res = read(fde->fd, c, sizeof(c));
+}
+
+/*
+ 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;
+
+ 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(mem_ctx?mem_ctx:ev, struct tevent_signal);
+ if (se == NULL) return NULL;
+
+ se->event_ctx = ev;
+ 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 = 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(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(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);
+
+ return se;
+}
+
+
+/*
+ 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);
+#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;
+ se->handler(ev, se, i, 1,
+ (void*)&sig_state->sig_info[i][ofs],
+ se->private_data);
+ }
+ if (se->sa_flags & SA_RESETHAND) {
+ talloc_free(se);
+ }
+ continue;
+ }
+#endif
+ se->handler(ev, se, i, count, NULL, se->private_data);
+ if (se->sa_flags & SA_RESETHAND) {
+ 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)
+ % 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)
+{
+ struct tevent_common_signal_list *sl;
+ sl = talloc_get_type(se->additional_data,
+ struct tevent_common_signal_list);
+
+ tevent_common_signal_list_destructor(sl);
+
+ if (sig_state->sig_handlers[se->signum] == NULL) {
+ if (sig_state->oldact[se->signum]) {
+ sigaction(se->signum, sig_state->oldact[se->signum], NULL);
+ sig_state->oldact[se->signum] = NULL;
+ }
+ }
+ return;
+}
projects / ccan-lca-2011.git / blobdiff