return 0;
}
-/* Helper: set the signal handler for evsignal to handler in base, so that
- * we can restore the original handler when we clear the current one. */
+/* Helper: resize saved signal handler array up to the highest signal
+ number. A dynamic array is used to keep footprint on the low side. */
int
-evsig_set_handler_(struct event_base *base,
- int evsignal, void (__cdecl *handler)(int))
+evsig_ensure_saved_(struct evsig_info *sig, int evsignal)
{
-#ifdef EVENT__HAVE_SIGACTION
- struct sigaction sa;
-#else
- ev_sighandler_t sh;
-#endif
- struct evsig_info *sig = &base->sig;
- void *p;
-
- /*
- * resize saved signal handler array up to the highest signal number.
- * a dynamic array is used to keep footprint on the low side.
- */
if (evsignal >= sig->sh_old_max) {
+ void *p;
int new_max = evsignal + 1;
event_debug(("%s: evsignal (%d) >= sh_old_max (%d), resizing",
__func__, evsignal, sig->sh_old_max));
sig->sh_old_max = new_max;
sig->sh_old = p;
}
+ return 0;
+}
+
+/* Helper: set the signal handler for evsignal to handler in base, so that
+ * we can restore the original handler when we clear the current one. */
+int
+evsig_set_handler_(struct event_base *base,
+ int evsignal, void (__cdecl *handler)(int))
+{
+#ifdef EVENT__HAVE_SIGACTION
+ struct sigaction sa;
+#else
+ ev_sighandler_t sh;
+#endif
+ struct evsig_info *sig = &base->sig;
+
+ /* ensure saved array is large enough */
+ if (evsig_ensure_saved_(sig, evsignal) < 0)
+ return (-1);
/* allocate space for previous handler out of dynamic array */
sig->sh_old[evsignal] = mm_malloc(sizeof *sig->sh_old[evsignal]);
--- /dev/null
+/*
+ * Signal handling backend based on signalfd(2) system call
+ * Written by Dmitry Antipov <dantipov@cloudlinux.com> 2022
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "event2/event-config.h"
+
+#include <unistd.h>
+#include <sys/signalfd.h>
+
+#include "event2/event.h"
+#include "event-internal.h"
+#include "evmap-internal.h"
+#include "evsignal-internal.h"
+#include "evthread-internal.h"
+
+static int sigfd_add(struct event_base *, evutil_socket_t, short, short, void *);
+static int sigfd_del(struct event_base *, evutil_socket_t, short, short, void *);
+
+static const struct eventop sigfdops = {
+ "signalfd_signal",
+ NULL,
+ sigfd_add,
+ sigfd_del,
+ NULL,
+ NULL,
+ 0, 0, 0
+};
+
+static void
+sigfd_cb(evutil_socket_t fd, short what, void *arg)
+{
+ struct signalfd_siginfo fdsi;
+ struct event_base *base = arg;
+ ssize_t ret = read(fd, &fdsi, sizeof(fdsi));
+
+ EVUTIL_ASSERT(ret == sizeof(fdsi));
+ EVUTIL_ASSERT(fdsi.ssi_signo > 0 && fdsi.ssi_signo < NSIG);
+ EVUTIL_ASSERT(base->sig.ev_sigevent[fdsi.ssi_signo] != NULL);
+
+ EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+ evmap_signal_active_(base, fdsi.ssi_signo, 1);
+ EVBASE_RELEASE_LOCK(base, th_base_lock);
+}
+
+static void
+sigfd_free_sigevent(struct event_base *base, int signo)
+{
+ int ret;
+ struct event* sigev = base->sig.ev_sigevent[signo];
+
+ EVUTIL_ASSERT(sigev != NULL);
+ event_del_nolock_(sigev, EVENT_DEL_AUTOBLOCK);
+ ret = close(sigev->ev_fd);
+ EVUTIL_ASSERT(ret == 0);
+ mm_free(sigev);
+ base->sig.ev_sigevent[signo] = NULL;
+}
+
+static int
+sigfd_add(struct event_base *base, int signo, short old, short events, void *p)
+{
+ int sigfd;
+ sigset_t mask;
+ struct event* sigev;
+ struct evsig_info *sig = &base->sig;
+
+ /* EV_SIGNAL event passed from evmap_signal_add_() when setting
+ up and from evmap_signal_reinit_iter_fn() during reinit. */
+ EVUTIL_ASSERT(p != NULL);
+
+ EVUTIL_ASSERT(signo > 0 && signo < NSIG);
+ sigev = base->sig.ev_sigevent[signo];
+
+ if (sigev != NULL) {
+ if (old) {
+ /* We're performing reinit after fork(). This is
+ required at least for epoll(2)-based backend
+ because if the process uses fork(2) to create
+ a child process, then the child will be able
+ to read(2) signals that are sent to it using the
+ signalfd(2) file descriptor, but epoll_wait(2)
+ will not indicate that the signalfd file
+ descriptor is ready. */
+ sigfd_free_sigevent(base, signo);
+ } else {
+ /* We have an active signal fd
+ for this signal already. */
+ return 0;
+ }
+ }
+
+ /* Save previous handler just like evsig_set_handler_() does. */
+ if (evsig_ensure_saved_(sig, signo) < 0)
+ return -1;
+
+ sig->sh_old[signo] = mm_malloc(sizeof *sig->sh_old[signo]);
+ if (sig->sh_old[signo] == NULL) {
+ event_warn("malloc() failed");
+ return -1;
+ }
+
+ if (sigaction(signo, NULL, sig->sh_old[signo]) == -1) {
+ event_warn("sigaction() failed");
+ mm_free(sig->sh_old[signo]);
+ sig->sh_old[signo] = NULL;
+ return -1;
+ }
+
+ /* Block the signal from being handled according to its default
+ disposition so it may be received via the descriptor. */
+ sigemptyset(&mask);
+ sigaddset(&mask, signo);
+ if (sigprocmask(SIG_BLOCK, &mask, NULL)) {
+ event_warn("sigprocmask() failed");
+ return -1;
+ }
+
+ sigfd = signalfd(-1, &mask, SFD_NONBLOCK | SFD_CLOEXEC);
+ if (sigfd < 0) {
+ event_warn("signalfd() failed");
+ goto unblock;
+ }
+
+ /* EV_READ event used to wakeup corresponding EV_SIGNAL ones. */
+ sigev = event_new(base, sigfd, EV_READ | EV_PERSIST, sigfd_cb, base);
+ if (!sigev)
+ goto close_fd;
+
+ /* This was blindly copied from evsig_init_(). */
+ sigev->ev_flags |= EVLIST_INTERNAL;
+ event_priority_set(sigev, 0);
+
+ if (event_add_nolock_(sigev, NULL, 0) < 0)
+ goto free_ev;
+
+ base->sig.ev_sigevent[signo] = sigev;
+ return 0;
+free_ev:
+ mm_free(sigev);
+close_fd:
+ close(sigfd);
+unblock:
+ sigprocmask(SIG_UNBLOCK, &mask, NULL);
+ return -1;
+}
+
+static int
+sigfd_del(struct event_base *base, int signo, short old, short events, void *p)
+{
+ sigset_t mask;
+ struct event *sigev;
+ struct evsig_info *sig = &base->sig;
+
+ EVUTIL_ASSERT(signo > 0 && signo < NSIG);
+ sigev = base->sig.ev_sigevent[signo];
+ EVUTIL_ASSERT(sigev != NULL);
+
+ sigemptyset(&mask);
+ sigaddset(&mask, signo);
+ if (sigprocmask(SIG_UNBLOCK, &mask, NULL)) {
+ event_warn("sigprocmask() failed");
+ return -1;
+ }
+
+ /* Restore previous handler, if any. */
+ if (signo < sig->sh_old_max) {
+ struct sigaction *sa = sig->sh_old[signo];
+ if (sa) {
+ if (sigaction(signo, sa, NULL) == -1) {
+ event_warn("sigaction() failed");
+ return -1;
+ }
+ mm_free(sa);
+ sig->sh_old[signo] = NULL;
+ }
+ }
+
+ sigfd_free_sigevent(base, signo);
+ return 0;
+}
+
+int sigfd_init_(struct event_base *base)
+{
+ EVUTIL_ASSERT(base != NULL);
+ if ((base->flags & EVENT_BASE_FLAG_DISALLOW_SIGNALFD) ||
+ getenv("EVENT_DISALLOW_SIGNALFD"))
+ return -1;
+ base->evsigsel = &sigfdops;
+ return 0;
+}
projects / libevent / commitdiff