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-rw-r--r--lib/tevent/tevent_standard.c607
1 files changed, 607 insertions, 0 deletions
diff --git a/lib/tevent/tevent_standard.c b/lib/tevent/tevent_standard.c
new file mode 100644
index 0000000000..c63d092173
--- /dev/null
+++ b/lib/tevent/tevent_standard.c
@@ -0,0 +1,607 @@
+/*
+ Unix SMB/CIFS implementation.
+ main select loop and event handling
+ Copyright (C) Andrew Tridgell 2003-2005
+ Copyright (C) Stefan Metzmacher 2005
+
+ 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,
+ 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/>.
+*/
+
+/*
+ This is SAMBA's default event loop code
+
+ - we try to use epoll if configure detected support for it
+ otherwise we use select()
+ - if epoll is broken on the system or the kernel doesn't support it
+ at runtime we fallback to select()
+*/
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "system/network.h"
+#include "system/select.h" /* needed for HAVE_EVENTS_EPOLL */
+#include "tevent.h"
+#include "tevent_util.h"
+#include "tevent_internal.h"
+
+struct std_event_context {
+ /* a pointer back to the generic event_context */
+ struct event_context *ev;
+
+ /* list of filedescriptor events */
+ struct fd_event *fd_events;
+
+ /* the maximum file descriptor number in fd_events */
+ int maxfd;
+
+ /* information for exiting from the event loop */
+ int exit_code;
+
+ /* this is changed by the destructors for the fd event
+ type. It is used to detect event destruction by event
+ handlers, which means the code that is calling the event
+ handler needs to assume that the linked list is no longer
+ valid
+ */
+ uint32_t destruction_count;
+
+ /* when using epoll this is the handle from epoll_create */
+ int epoll_fd;
+
+ /* our pid at the time the epoll_fd was created */
+ pid_t pid;
+};
+
+/* use epoll if it is available */
+#if HAVE_EVENTS_EPOLL
+/*
+ called when a epoll call fails, and we should fallback
+ to using select
+*/
+static void epoll_fallback_to_select(struct std_event_context *std_ev, const char *reason)
+{
+ ev_debug(std_ev->ev, EV_DEBUG_FATAL,
+ "%s (%s) - falling back to select()\n",
+ reason, strerror(errno));
+ close(std_ev->epoll_fd);
+ std_ev->epoll_fd = -1;
+ talloc_set_destructor(std_ev, NULL);
+}
+
+/*
+ map from EVENT_FD_* to EPOLLIN/EPOLLOUT
+*/
+static uint32_t epoll_map_flags(uint16_t flags)
+{
+ uint32_t ret = 0;
+ if (flags & EVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
+ if (flags & EVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
+ return ret;
+}
+
+/*
+ free the epoll fd
+*/
+static int epoll_ctx_destructor(struct std_event_context *std_ev)
+{
+ if (std_ev->epoll_fd != -1) {
+ close(std_ev->epoll_fd);
+ }
+ std_ev->epoll_fd = -1;
+ return 0;
+}
+
+/*
+ init the epoll fd
+*/
+static void epoll_init_ctx(struct std_event_context *std_ev)
+{
+ std_ev->epoll_fd = epoll_create(64);
+ std_ev->pid = getpid();
+ talloc_set_destructor(std_ev, epoll_ctx_destructor);
+}
+
+static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *fde);
+
+/*
+ reopen the epoll handle when our pid changes
+ see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
+ demonstration of why this is needed
+ */
+static void epoll_check_reopen(struct std_event_context *std_ev)
+{
+ struct fd_event *fde;
+
+ if (std_ev->pid == getpid()) {
+ return;
+ }
+
+ close(std_ev->epoll_fd);
+ std_ev->epoll_fd = epoll_create(64);
+ if (std_ev->epoll_fd == -1) {
+ ev_debug(std_ev->ev, EV_DEBUG_FATAL,
+ "Failed to recreate epoll handle after fork\n");
+ return;
+ }
+ std_ev->pid = getpid();
+ for (fde=std_ev->fd_events;fde;fde=fde->next) {
+ epoll_add_event(std_ev, fde);
+ }
+}
+
+#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0)
+#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1)
+#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2)
+
+/*
+ add the epoll event to the given fd_event
+*/
+static void epoll_add_event(struct std_event_context *std_ev, struct fd_event *fde)
+{
+ struct epoll_event event;
+ if (std_ev->epoll_fd == -1) return;
+
+ fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+ /* if we don't want events yet, don't add an epoll_event */
+ if (fde->flags == 0) return;
+
+ ZERO_STRUCT(event);
+ event.events = epoll_map_flags(fde->flags);
+ event.data.ptr = fde;
+ if (epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
+ epoll_fallback_to_select(std_ev, "EPOLL_CTL_ADD failed");
+ }
+ fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+
+ /* only if we want to read we want to tell the event handler about errors */
+ if (fde->flags & EVENT_FD_READ) {
+ fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+ }
+}
+
+/*
+ delete the epoll event for given fd_event
+*/
+static void epoll_del_event(struct std_event_context *std_ev, struct fd_event *fde)
+{
+ struct epoll_event event;
+ if (std_ev->epoll_fd == -1) return;
+
+ fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+ /* if there's no epoll_event, we don't need to delete it */
+ if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
+
+ ZERO_STRUCT(event);
+ event.events = epoll_map_flags(fde->flags);
+ event.data.ptr = fde;
+ epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event);
+ fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
+}
+
+/*
+ change the epoll event to the given fd_event
+*/
+static void epoll_mod_event(struct std_event_context *std_ev, struct fd_event *fde)
+{
+ struct epoll_event event;
+ if (std_ev->epoll_fd == -1) return;
+
+ fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+ ZERO_STRUCT(event);
+ event.events = epoll_map_flags(fde->flags);
+ event.data.ptr = fde;
+ if (epoll_ctl(std_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
+ epoll_fallback_to_select(std_ev, "EPOLL_CTL_MOD failed");
+ }
+
+ /* only if we want to read we want to tell the event handler about errors */
+ if (fde->flags & EVENT_FD_READ) {
+ fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+ }
+}
+
+static void epoll_change_event(struct std_event_context *std_ev, struct fd_event *fde)
+{
+ bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
+ bool want_read = (fde->flags & EVENT_FD_READ);
+ bool want_write= (fde->flags & EVENT_FD_WRITE);
+
+ if (std_ev->epoll_fd == -1) return;
+
+ fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
+
+ /* there's already an event */
+ if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
+ if (want_read || (want_write && !got_error)) {
+ epoll_mod_event(std_ev, fde);
+ return;
+ }
+ /*
+ * if we want to match the select behavior, we need to remove the epoll_event
+ * when the caller isn't interested in events.
+ *
+ * this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
+ */
+ epoll_del_event(std_ev, fde);
+ return;
+ }
+
+ /* there's no epoll_event attached to the fde */
+ if (want_read || (want_write && !got_error)) {
+ epoll_add_event(std_ev, fde);
+ return;
+ }
+}
+
+/*
+ event loop handling using epoll
+*/
+static int epoll_event_loop(struct std_event_context *std_ev, struct timeval *tvalp)
+{
+ int ret, i;
+#define MAXEVENTS 8
+ struct epoll_event events[MAXEVENTS];
+ uint32_t destruction_count = ++std_ev->destruction_count;
+ int timeout = -1;
+
+ if (std_ev->epoll_fd == -1) return -1;
+
+ if (tvalp) {
+ /* it's better to trigger timed events a bit later than to early */
+ timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000);
+ }
+
+ if (std_ev->ev->num_signal_handlers &&
+ common_event_check_signal(std_ev->ev)) {
+ return 0;
+ }
+
+ ret = epoll_wait(std_ev->epoll_fd, events, MAXEVENTS, timeout);
+
+ if (ret == -1 && errno == EINTR && std_ev->ev->num_signal_handlers) {
+ if (common_event_check_signal(std_ev->ev)) {
+ return 0;
+ }
+ }
+
+ if (ret == -1 && errno != EINTR) {
+ epoll_fallback_to_select(std_ev, "epoll_wait() failed");
+ return -1;
+ }
+
+ if (ret == 0 && tvalp) {
+ /* we don't care about a possible delay here */
+ common_event_loop_timer_delay(std_ev->ev);
+ return 0;
+ }
+
+ for (i=0;i<ret;i++) {
+ struct fd_event *fde = talloc_get_type(events[i].data.ptr,
+ struct fd_event);
+ uint16_t flags = 0;
+
+ if (fde == NULL) {
+ epoll_fallback_to_select(std_ev, "epoll_wait() gave bad data");
+ return -1;
+ }
+ if (events[i].events & (EPOLLHUP|EPOLLERR)) {
+ fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
+ /*
+ * if we only wait for EVENT_FD_WRITE, we should not tell the
+ * event handler about it, and remove the epoll_event,
+ * as we only report errors when waiting for read events,
+ * to match the select() behavior
+ */
+ if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
+ epoll_del_event(std_ev, fde);
+ continue;
+ }
+ flags |= EVENT_FD_READ;
+ }
+ if (events[i].events & EPOLLIN) flags |= EVENT_FD_READ;
+ if (events[i].events & EPOLLOUT) flags |= EVENT_FD_WRITE;
+ if (flags) {
+ fde->handler(std_ev->ev, fde, flags, fde->private_data);
+ if (destruction_count != std_ev->destruction_count) {
+ break;
+ }
+ }
+ }
+
+ return 0;
+}
+#else
+#define epoll_init_ctx(std_ev)
+#define epoll_add_event(std_ev,fde)
+#define epoll_del_event(std_ev,fde)
+#define epoll_change_event(std_ev,fde)
+#define epoll_event_loop(std_ev,tvalp) (-1)
+#define epoll_check_reopen(std_ev)
+#endif
+
+/*
+ create a std_event_context structure.
+*/
+static int std_event_context_init(struct event_context *ev)
+{
+ struct std_event_context *std_ev;
+
+ std_ev = talloc_zero(ev, struct std_event_context);
+ if (!std_ev) return -1;
+ std_ev->ev = ev;
+ std_ev->epoll_fd = -1;
+
+ epoll_init_ctx(std_ev);
+
+ ev->additional_data = std_ev;
+ return 0;
+}
+
+/*
+ recalculate the maxfd
+*/
+static void calc_maxfd(struct std_event_context *std_ev)
+{
+ struct fd_event *fde;
+
+ std_ev->maxfd = 0;
+ for (fde = std_ev->fd_events; fde; fde = fde->next) {
+ if (fde->fd > std_ev->maxfd) {
+ std_ev->maxfd = fde->fd;
+ }
+ }
+}
+
+
+/* to mark the ev->maxfd invalid
+ * this means we need to recalculate it
+ */
+#define EVENT_INVALID_MAXFD (-1)
+
+/*
+ destroy an fd_event
+*/
+static int std_event_fd_destructor(struct fd_event *fde)
+{
+ struct event_context *ev = fde->event_ctx;
+ struct std_event_context *std_ev = talloc_get_type(ev->additional_data,
+ struct std_event_context);
+
+ epoll_check_reopen(std_ev);
+
+ if (std_ev->maxfd == fde->fd) {
+ std_ev->maxfd = EVENT_INVALID_MAXFD;
+ }
+
+ DLIST_REMOVE(std_ev->fd_events, fde);
+ std_ev->destruction_count++;
+
+ epoll_del_event(std_ev, fde);
+
+ if (fde->flags & EVENT_FD_AUTOCLOSE) {
+ close(fde->fd);
+ fde->fd = -1;
+ }
+
+ return 0;
+}
+
+/*
+ add a fd based event
+ return NULL on failure (memory allocation error)
+*/
+static struct fd_event *std_event_add_fd(struct event_context *ev, TALLOC_CTX *mem_ctx,
+ int fd, uint16_t flags,
+ event_fd_handler_t handler,
+ void *private_data)
+{
+ struct std_event_context *std_ev = talloc_get_type(ev->additional_data,
+ struct std_event_context);
+ struct fd_event *fde;
+
+ epoll_check_reopen(std_ev);
+
+ fde = talloc(mem_ctx?mem_ctx:ev, struct fd_event);
+ if (!fde) return NULL;
+
+ fde->event_ctx = ev;
+ fde->fd = fd;
+ fde->flags = flags;
+ fde->handler = handler;
+ fde->private_data = private_data;
+ fde->additional_flags = 0;
+ fde->additional_data = NULL;
+
+ DLIST_ADD(std_ev->fd_events, fde);
+ if ((std_ev->maxfd != EVENT_INVALID_MAXFD)
+ && (fde->fd > std_ev->maxfd)) {
+ std_ev->maxfd = fde->fd;
+ }
+ talloc_set_destructor(fde, std_event_fd_destructor);
+
+ epoll_add_event(std_ev, fde);
+
+ return fde;
+}
+
+
+/*
+ return the fd event flags
+*/
+static uint16_t std_event_get_fd_flags(struct fd_event *fde)
+{
+ return fde->flags;
+}
+
+/*
+ set the fd event flags
+*/
+static void std_event_set_fd_flags(struct fd_event *fde, uint16_t flags)
+{
+ struct event_context *ev;
+ struct std_event_context *std_ev;
+
+ if (fde->flags == flags) return;
+
+ ev = fde->event_ctx;
+ std_ev = talloc_get_type(ev->additional_data, struct std_event_context);
+
+ fde->flags = flags;
+
+ epoll_check_reopen(std_ev);
+
+ epoll_change_event(std_ev, fde);
+}
+
+/*
+ event loop handling using select()
+*/
+static int std_event_loop_select(struct std_event_context *std_ev, struct timeval *tvalp)
+{
+ fd_set r_fds, w_fds;
+ struct fd_event *fde;
+ int selrtn;
+ uint32_t destruction_count = ++std_ev->destruction_count;
+
+ /* we maybe need to recalculate the maxfd */
+ if (std_ev->maxfd == EVENT_INVALID_MAXFD) {
+ calc_maxfd(std_ev);
+ }
+
+ FD_ZERO(&r_fds);
+ FD_ZERO(&w_fds);
+
+ /* setup any fd events */
+ for (fde = std_ev->fd_events; fde; fde = fde->next) {
+ if (fde->flags & EVENT_FD_READ) {
+ FD_SET(fde->fd, &r_fds);
+ }
+ if (fde->flags & EVENT_FD_WRITE) {
+ FD_SET(fde->fd, &w_fds);
+ }
+ }
+
+ if (std_ev->ev->num_signal_handlers &&
+ common_event_check_signal(std_ev->ev)) {
+ return 0;
+ }
+
+ selrtn = select(std_ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp);
+
+ if (selrtn == -1 && errno == EINTR &&
+ std_ev->ev->num_signal_handlers) {
+ common_event_check_signal(std_ev->ev);
+ return 0;
+ }
+
+ if (selrtn == -1 && errno == EBADF) {
+ /* the socket is dead! this should never
+ happen as the socket should have first been
+ made readable and that should have removed
+ the event, so this must be a bug. This is a
+ fatal error. */
+ ev_debug(std_ev->ev, EV_DEBUG_FATAL,
+ "ERROR: EBADF on std_event_loop_once\n");
+ std_ev->exit_code = EBADF;
+ return -1;
+ }
+
+ if (selrtn == 0 && tvalp) {
+ /* we don't care about a possible delay here */
+ common_event_loop_timer_delay(std_ev->ev);
+ return 0;
+ }
+
+ if (selrtn > 0) {
+ /* at least one file descriptor is ready - check
+ which ones and call the handler, being careful to allow
+ the handler to remove itself when called */
+ for (fde = std_ev->fd_events; fde; fde = fde->next) {
+ uint16_t flags = 0;
+
+ if (FD_ISSET(fde->fd, &r_fds)) flags |= EVENT_FD_READ;
+ if (FD_ISSET(fde->fd, &w_fds)) flags |= EVENT_FD_WRITE;
+ if (flags) {
+ fde->handler(std_ev->ev, fde, flags, fde->private_data);
+ if (destruction_count != std_ev->destruction_count) {
+ break;
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+/*
+ do a single event loop using the events defined in ev
+*/
+static int std_event_loop_once(struct event_context *ev)
+{
+ struct std_event_context *std_ev = talloc_get_type(ev->additional_data,
+ struct std_event_context);
+ struct timeval tval;
+
+ tval = common_event_loop_timer_delay(ev);
+ if (ev_timeval_is_zero(&tval)) {
+ return 0;
+ }
+
+ epoll_check_reopen(std_ev);
+
+ if (epoll_event_loop(std_ev, &tval) == 0) {
+ return 0;
+ }
+
+ return std_event_loop_select(std_ev, &tval);
+}
+
+/*
+ return on failure or (with 0) if all fd events are removed
+*/
+static int std_event_loop_wait(struct event_context *ev)
+{
+ struct std_event_context *std_ev = talloc_get_type(ev->additional_data,
+ struct std_event_context);
+ std_ev->exit_code = 0;
+
+ while (std_ev->fd_events && std_ev->exit_code == 0) {
+ if (std_event_loop_once(ev) != 0) {
+ break;
+ }
+ }
+
+ return std_ev->exit_code;
+}
+
+static const struct event_ops std_event_ops = {
+ .context_init = std_event_context_init,
+ .add_fd = std_event_add_fd,
+ .get_fd_flags = std_event_get_fd_flags,
+ .set_fd_flags = std_event_set_fd_flags,
+ .add_timed = common_event_add_timed,
+ .add_signal = common_event_add_signal,
+ .loop_once = std_event_loop_once,
+ .loop_wait = std_event_loop_wait,
+};
+
+
+bool events_standard_init(void)
+{
+ return event_register_backend("standard", &std_event_ops);
+}
+