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+/*
+ * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright 2007-2012 Niels Provos, Nick Mathewson
+ *
+ * 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 "evconfig-private.h"
+
+#ifdef EVENT__HAVE_EPOLL
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/resource.h>
+#ifdef EVENT__HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+#include <sys/queue.h>
+#include <sys/epoll.h>
+#include <signal.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#ifdef EVENT__HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+#ifdef EVENT__HAVE_SYS_TIMERFD_H
+#include <sys/timerfd.h>
+#endif
+
+#include "event-internal.h"
+#include "evsignal-internal.h"
+#include "event2/thread.h"
+#include "evthread-internal.h"
+#include "log-internal.h"
+#include "evmap-internal.h"
+#include "changelist-internal.h"
+#include "time-internal.h"
+
+/* Since Linux 2.6.17, epoll is able to report about peer half-closed connection
+ using special EPOLLRDHUP flag on a read event.
+*/
+#if !defined(EPOLLRDHUP)
+#define EPOLLRDHUP 0
+#define EARLY_CLOSE_IF_HAVE_RDHUP 0
+#else
+#define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE
+#endif
+
+#include "epolltable-internal.h"
+
+#if defined(EVENT__HAVE_SYS_TIMERFD_H) && \
+ defined(EVENT__HAVE_TIMERFD_CREATE) && \
+ defined(HAVE_POSIX_MONOTONIC) && defined(TFD_NONBLOCK) && \
+ defined(TFD_CLOEXEC)
+/* Note that we only use timerfd if TFD_NONBLOCK and TFD_CLOEXEC are available
+ and working. This means that we can't support it on 2.6.25 (where timerfd
+ was introduced) or 2.6.26, since 2.6.27 introduced those flags.
+ */
+#define USING_TIMERFD
+#endif
+
+struct epollop {
+ struct epoll_event *events;
+ int nevents;
+ int epfd;
+#ifdef USING_TIMERFD
+ int timerfd;
+#endif
+};
+
+static void *epoll_init(struct event_base *);
+static int epoll_dispatch(struct event_base *, struct timeval *);
+static void epoll_dealloc(struct event_base *);
+
+static const struct eventop epollops_changelist = {
+ "epoll (with changelist)",
+ epoll_init,
+ event_changelist_add_,
+ event_changelist_del_,
+ epoll_dispatch,
+ epoll_dealloc,
+ 1, /* need reinit */
+ EV_FEATURE_ET|EV_FEATURE_O1| EARLY_CLOSE_IF_HAVE_RDHUP,
+ EVENT_CHANGELIST_FDINFO_SIZE
+};
+
+
+static int epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
+ short old, short events, void *p);
+static int epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
+ short old, short events, void *p);
+
+const struct eventop epollops = {
+ "epoll",
+ epoll_init,
+ epoll_nochangelist_add,
+ epoll_nochangelist_del,
+ epoll_dispatch,
+ epoll_dealloc,
+ 1, /* need reinit */
+ EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_EARLY_CLOSE,
+ 0
+};
+
+#define INITIAL_NEVENT 32
+#define MAX_NEVENT 4096
+
+/* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout
+ * values bigger than (LONG_MAX - 999ULL)/HZ. HZ in the wild can be
+ * as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the
+ * largest number of msec we can support here is 2147482. Let's
+ * round that down by 47 seconds.
+ */
+#define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
+
+static void *
+epoll_init(struct event_base *base)
+{
+ int epfd = -1;
+ struct epollop *epollop;
+
+#ifdef EVENT__HAVE_EPOLL_CREATE1
+ /* First, try the shiny new epoll_create1 interface, if we have it. */
+ epfd = epoll_create1(EPOLL_CLOEXEC);
+#endif
+ if (epfd == -1) {
+ /* Initialize the kernel queue using the old interface. (The
+ size field is ignored since 2.6.8.) */
+ if ((epfd = epoll_create(32000)) == -1) {
+ if (errno != ENOSYS)
+ event_warn("epoll_create");
+ return (NULL);
+ }
+ evutil_make_socket_closeonexec(epfd);
+ }
+
+ if (!(epollop = mm_calloc(1, sizeof(struct epollop)))) {
+ close(epfd);
+ return (NULL);
+ }
+
+ epollop->epfd = epfd;
+
+ /* Initialize fields */
+ epollop->events = mm_calloc(INITIAL_NEVENT, sizeof(struct epoll_event));
+ if (epollop->events == NULL) {
+ mm_free(epollop);
+ close(epfd);
+ return (NULL);
+ }
+ epollop->nevents = INITIAL_NEVENT;
+
+ if ((base->flags & EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST) != 0 ||
+ ((base->flags & EVENT_BASE_FLAG_IGNORE_ENV) == 0 &&
+ evutil_getenv_("EVENT_EPOLL_USE_CHANGELIST") != NULL)) {
+
+ base->evsel = &epollops_changelist;
+ }
+
+#ifdef USING_TIMERFD
+ /*
+ The epoll interface ordinarily gives us one-millisecond precision,
+ so on Linux it makes perfect sense to use the CLOCK_MONOTONIC_COARSE
+ timer. But when the user has set the new PRECISE_TIMER flag for an
+ event_base, we can try to use timerfd to give them finer granularity.
+ */
+ if ((base->flags & EVENT_BASE_FLAG_PRECISE_TIMER) &&
+ base->monotonic_timer.monotonic_clock == CLOCK_MONOTONIC) {
+ int fd;
+ fd = epollop->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
+ if (epollop->timerfd >= 0) {
+ struct epoll_event epev;
+ memset(&epev, 0, sizeof(epev));
+ epev.data.fd = epollop->timerfd;
+ epev.events = EPOLLIN;
+ if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, fd, &epev) < 0) {
+ event_warn("epoll_ctl(timerfd)");
+ close(fd);
+ epollop->timerfd = -1;
+ }
+ } else {
+ if (errno != EINVAL && errno != ENOSYS) {
+ /* These errors probably mean that we were
+ * compiled with timerfd/TFD_* support, but
+ * we're running on a kernel that lacks those.
+ */
+ event_warn("timerfd_create");
+ }
+ epollop->timerfd = -1;
+ }
+ } else {
+ epollop->timerfd = -1;
+ }
+#endif
+
+ evsig_init_(base);
+
+ return (epollop);
+}
+
+static const char *
+change_to_string(int change)
+{
+ change &= (EV_CHANGE_ADD|EV_CHANGE_DEL);
+ if (change == EV_CHANGE_ADD) {
+ return "add";
+ } else if (change == EV_CHANGE_DEL) {
+ return "del";
+ } else if (change == 0) {
+ return "none";
+ } else {
+ return "???";
+ }
+}
+
+static const char *
+epoll_op_to_string(int op)
+{
+ return op == EPOLL_CTL_ADD?"ADD":
+ op == EPOLL_CTL_DEL?"DEL":
+ op == EPOLL_CTL_MOD?"MOD":
+ "???";
+}
+
+#define PRINT_CHANGES(op, events, ch, status) \
+ "Epoll %s(%d) on fd %d " status ". " \
+ "Old events were %d; " \
+ "read change was %d (%s); " \
+ "write change was %d (%s); " \
+ "close change was %d (%s)", \
+ epoll_op_to_string(op), \
+ events, \
+ ch->fd, \
+ ch->old_events, \
+ ch->read_change, \
+ change_to_string(ch->read_change), \
+ ch->write_change, \
+ change_to_string(ch->write_change), \
+ ch->close_change, \
+ change_to_string(ch->close_change)
+
+static int
+epoll_apply_one_change(struct event_base *base,
+ struct epollop *epollop,
+ const struct event_change *ch)
+{
+ struct epoll_event epev;
+ int op, events = 0;
+ int idx;
+
+ idx = EPOLL_OP_TABLE_INDEX(ch);
+ op = epoll_op_table[idx].op;
+ events = epoll_op_table[idx].events;
+
+ if (!events) {
+ EVUTIL_ASSERT(op == 0);
+ return 0;
+ }
+
+ if ((ch->read_change|ch->write_change) & EV_CHANGE_ET)
+ events |= EPOLLET;
+
+ memset(&epev, 0, sizeof(epev));
+ epev.data.fd = ch->fd;
+ epev.events = events;
+ if (epoll_ctl(epollop->epfd, op, ch->fd, &epev) == 0) {
+ event_debug((PRINT_CHANGES(op, epev.events, ch, "okay")));
+ return 0;
+ }
+
+ switch (op) {
+ case EPOLL_CTL_MOD:
+ if (errno == ENOENT) {
+ /* If a MOD operation fails with ENOENT, the
+ * fd was probably closed and re-opened. We
+ * should retry the operation as an ADD.
+ */
+ if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, ch->fd, &epev) == -1) {
+ event_warn("Epoll MOD(%d) on %d retried as ADD; that failed too",
+ (int)epev.events, ch->fd);
+ return -1;
+ } else {
+ event_debug(("Epoll MOD(%d) on %d retried as ADD; succeeded.",
+ (int)epev.events,
+ ch->fd));
+ return 0;
+ }
+ }
+ break;
+ case EPOLL_CTL_ADD:
+ if (errno == EEXIST) {
+ /* If an ADD operation fails with EEXIST,
+ * either the operation was redundant (as with a
+ * precautionary add), or we ran into a fun
+ * kernel bug where using dup*() to duplicate the
+ * same file into the same fd gives you the same epitem
+ * rather than a fresh one. For the second case,
+ * we must retry with MOD. */
+ if (epoll_ctl(epollop->epfd, EPOLL_CTL_MOD, ch->fd, &epev) == -1) {
+ event_warn("Epoll ADD(%d) on %d retried as MOD; that failed too",
+ (int)epev.events, ch->fd);
+ return -1;
+ } else {
+ event_debug(("Epoll ADD(%d) on %d retried as MOD; succeeded.",
+ (int)epev.events,
+ ch->fd));
+ return 0;
+ }
+ }
+ break;
+ case EPOLL_CTL_DEL:
+ if (errno == ENOENT || errno == EBADF || errno == EPERM) {
+ /* If a delete fails with one of these errors,
+ * that's fine too: we closed the fd before we
+ * got around to calling epoll_dispatch. */
+ event_debug(("Epoll DEL(%d) on fd %d gave %s: DEL was unnecessary.",
+ (int)epev.events,
+ ch->fd,
+ strerror(errno)));
+ return 0;
+ }
+ break;
+ default:
+ break;
+ }
+
+ event_warn(PRINT_CHANGES(op, epev.events, ch, "failed"));
+ return -1;
+}
+
+static int
+epoll_apply_changes(struct event_base *base)
+{
+ struct event_changelist *changelist = &base->changelist;
+ struct epollop *epollop = base->evbase;
+ struct event_change *ch;
+
+ int r = 0;
+ int i;
+
+ for (i = 0; i < changelist->n_changes; ++i) {
+ ch = &changelist->changes[i];
+ if (epoll_apply_one_change(base, epollop, ch) < 0)
+ r = -1;
+ }
+
+ return (r);
+}
+
+static int
+epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
+ short old, short events, void *p)
+{
+ struct event_change ch;
+ ch.fd = fd;
+ ch.old_events = old;
+ ch.read_change = ch.write_change = ch.close_change = 0;
+ if (events & EV_WRITE)
+ ch.write_change = EV_CHANGE_ADD |
+ (events & EV_ET);
+ if (events & EV_READ)
+ ch.read_change = EV_CHANGE_ADD |
+ (events & EV_ET);
+ if (events & EV_CLOSED)
+ ch.close_change = EV_CHANGE_ADD |
+ (events & EV_ET);
+
+ return epoll_apply_one_change(base, base->evbase, &ch);
+}
+
+static int
+epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
+ short old, short events, void *p)
+{
+ struct event_change ch;
+ ch.fd = fd;
+ ch.old_events = old;
+ ch.read_change = ch.write_change = ch.close_change = 0;
+ if (events & EV_WRITE)
+ ch.write_change = EV_CHANGE_DEL;
+ if (events & EV_READ)
+ ch.read_change = EV_CHANGE_DEL;
+ if (events & EV_CLOSED)
+ ch.close_change = EV_CHANGE_DEL;
+
+ return epoll_apply_one_change(base, base->evbase, &ch);
+}
+
+static int
+epoll_dispatch(struct event_base *base, struct timeval *tv)
+{
+ struct epollop *epollop = base->evbase;
+ struct epoll_event *events = epollop->events;
+ int i, res;
+ long timeout = -1;
+
+#ifdef USING_TIMERFD
+ if (epollop->timerfd >= 0) {
+ struct itimerspec is;
+ is.it_interval.tv_sec = 0;
+ is.it_interval.tv_nsec = 0;
+ if (tv == NULL) {
+ /* No timeout; disarm the timer. */
+ is.it_value.tv_sec = 0;
+ is.it_value.tv_nsec = 0;
+ } else {
+ if (tv->tv_sec == 0 && tv->tv_usec == 0) {
+ /* we need to exit immediately; timerfd can't
+ * do that. */
+ timeout = 0;
+ }
+ is.it_value.tv_sec = tv->tv_sec;
+ is.it_value.tv_nsec = tv->tv_usec * 1000;
+ }
+ /* TODO: we could avoid unnecessary syscalls here by only
+ calling timerfd_settime when the top timeout changes, or
+ when we're called with a different timeval.
+ */
+ if (timerfd_settime(epollop->timerfd, 0, &is, NULL) < 0) {
+ event_warn("timerfd_settime");
+ }
+ } else
+#endif
+ if (tv != NULL) {
+ timeout = evutil_tv_to_msec_(tv);
+ if (timeout < 0 || timeout > MAX_EPOLL_TIMEOUT_MSEC) {
+ /* Linux kernels can wait forever if the timeout is
+ * too big; see comment on MAX_EPOLL_TIMEOUT_MSEC. */
+ timeout = MAX_EPOLL_TIMEOUT_MSEC;
+ }
+ }
+
+ epoll_apply_changes(base);
+ event_changelist_remove_all_(&base->changelist, base);
+
+ EVBASE_RELEASE_LOCK(base, th_base_lock);
+
+ res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout);
+
+ EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+
+ if (res == -1) {
+ if (errno != EINTR) {
+ event_warn("epoll_wait");
+ return (-1);
+ }
+
+ return (0);
+ }
+
+ event_debug(("%s: epoll_wait reports %d", __func__, res));
+ EVUTIL_ASSERT(res <= epollop->nevents);
+
+ for (i = 0; i < res; i++) {
+ int what = events[i].events;
+ short ev = 0;
+#ifdef USING_TIMERFD
+ if (events[i].data.fd == epollop->timerfd)
+ continue;
+#endif
+
+ if (what & (EPOLLHUP|EPOLLERR)) {
+ ev = EV_READ | EV_WRITE;
+ } else {
+ if (what & EPOLLIN)
+ ev |= EV_READ;
+ if (what & EPOLLOUT)
+ ev |= EV_WRITE;
+ if (what & EPOLLRDHUP)
+ ev |= EV_CLOSED;
+ }
+
+ if (!ev)
+ continue;
+
+ evmap_io_active_(base, events[i].data.fd, ev | EV_ET);
+ }
+
+ if (res == epollop->nevents && epollop->nevents < MAX_NEVENT) {
+ /* We used all of the event space this time. We should
+ be ready for more events next time. */
+ int new_nevents = epollop->nevents * 2;
+ struct epoll_event *new_events;
+
+ new_events = mm_realloc(epollop->events,
+ new_nevents * sizeof(struct epoll_event));
+ if (new_events) {
+ epollop->events = new_events;
+ epollop->nevents = new_nevents;
+ }
+ }
+
+ return (0);
+}
+
+
+static void
+epoll_dealloc(struct event_base *base)
+{
+ struct epollop *epollop = base->evbase;
+
+ evsig_dealloc_(base);
+ if (epollop->events)
+ mm_free(epollop->events);
+ if (epollop->epfd >= 0)
+ close(epollop->epfd);
+#ifdef USING_TIMERFD
+ if (epollop->timerfd >= 0)
+ close(epollop->timerfd);
+#endif
+
+ memset(epollop, 0, sizeof(struct epollop));
+ mm_free(epollop);
+}
+
+#endif /* EVENT__HAVE_EPOLL */
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