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-rw-r--r--lib/tevent/tevent_select.c302
1 files changed, 302 insertions, 0 deletions
diff --git a/lib/tevent/tevent_select.c b/lib/tevent/tevent_select.c
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+++ b/lib/tevent/tevent_select.c
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+/*
+ 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
+
+*/
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "system/select.h"
+#include "tevent.h"
+#include "tevent_util.h"
+#include "tevent_internal.h"
+
+struct select_event_context {
+ /* a pointer back to the generic event_context */
+ struct event_context *ev;
+
+ /* list of filedescriptor events */
+ struct fd_event *fd_events;
+
+ /* list of timed events */
+ struct timed_event *timed_events;
+
+ /* the maximum file descriptor number in fd_events */
+ int maxfd;
+
+ /* information for exiting from the event loop */
+ int exit_code;
+
+ /* this is incremented when the loop over events causes something which
+ could change the events yet to be processed */
+ uint32_t destruction_count;
+};
+
+/*
+ create a select_event_context structure.
+*/
+static int select_event_context_init(struct event_context *ev)
+{
+ struct select_event_context *select_ev;
+
+ select_ev = talloc_zero(ev, struct select_event_context);
+ if (!select_ev) return -1;
+ select_ev->ev = ev;
+
+ ev->additional_data = select_ev;
+ return 0;
+}
+
+/*
+ recalculate the maxfd
+*/
+static void calc_maxfd(struct select_event_context *select_ev)
+{
+ struct fd_event *fde;
+
+ select_ev->maxfd = 0;
+ for (fde = select_ev->fd_events; fde; fde = fde->next) {
+ if (fde->fd > select_ev->maxfd) {
+ select_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 select_event_fd_destructor(struct fd_event *fde)
+{
+ struct event_context *ev = fde->event_ctx;
+ struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
+ struct select_event_context);
+
+ if (select_ev->maxfd == fde->fd) {
+ select_ev->maxfd = EVENT_INVALID_MAXFD;
+ }
+
+ DLIST_REMOVE(select_ev->fd_events, fde);
+ select_ev->destruction_count++;
+
+ 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 *select_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 select_event_context *select_ev = talloc_get_type(ev->additional_data,
+ struct select_event_context);
+ struct fd_event *fde;
+
+ 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(select_ev->fd_events, fde);
+ if (fde->fd > select_ev->maxfd) {
+ select_ev->maxfd = fde->fd;
+ }
+ talloc_set_destructor(fde, select_event_fd_destructor);
+
+ return fde;
+}
+
+
+/*
+ return the fd event flags
+*/
+static uint16_t select_event_get_fd_flags(struct fd_event *fde)
+{
+ return fde->flags;
+}
+
+/*
+ set the fd event flags
+*/
+static void select_event_set_fd_flags(struct fd_event *fde, uint16_t flags)
+{
+ struct event_context *ev;
+ struct select_event_context *select_ev;
+
+ if (fde->flags == flags) return;
+
+ ev = fde->event_ctx;
+ select_ev = talloc_get_type(ev->additional_data, struct select_event_context);
+
+ fde->flags = flags;
+}
+
+/*
+ event loop handling using select()
+*/
+static int select_event_loop_select(struct select_event_context *select_ev, struct timeval *tvalp)
+{
+ fd_set r_fds, w_fds;
+ struct fd_event *fde;
+ int selrtn;
+ uint32_t destruction_count = ++select_ev->destruction_count;
+
+ /* we maybe need to recalculate the maxfd */
+ if (select_ev->maxfd == EVENT_INVALID_MAXFD) {
+ calc_maxfd(select_ev);
+ }
+
+ FD_ZERO(&r_fds);
+ FD_ZERO(&w_fds);
+
+ /* setup any fd events */
+ for (fde = select_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 (select_ev->ev->num_signal_handlers &&
+ common_event_check_signal(select_ev->ev)) {
+ return 0;
+ }
+
+ selrtn = select(select_ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp);
+
+ if (selrtn == -1 && errno == EINTR &&
+ select_ev->ev->num_signal_handlers) {
+ common_event_check_signal(select_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(select_ev->ev, EV_DEBUG_FATAL,
+ "ERROR: EBADF on select_event_loop_once\n");
+ select_ev->exit_code = EBADF;
+ return -1;
+ }
+
+ if (selrtn == 0 && tvalp) {
+ /* we don't care about a possible delay here */
+ common_event_loop_timer_delay(select_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 = select_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(select_ev->ev, fde, flags, fde->private_data);
+ if (destruction_count != select_ev->destruction_count) {
+ break;
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+/*
+ do a single event loop using the events defined in ev
+*/
+static int select_event_loop_once(struct event_context *ev)
+{
+ struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
+ struct select_event_context);
+ struct timeval tval;
+
+ tval = common_event_loop_timer_delay(ev);
+ if (ev_timeval_is_zero(&tval)) {
+ return 0;
+ }
+
+ return select_event_loop_select(select_ev, &tval);
+}
+
+/*
+ return on failure or (with 0) if all fd events are removed
+*/
+static int select_event_loop_wait(struct event_context *ev)
+{
+ struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
+ struct select_event_context);
+ select_ev->exit_code = 0;
+
+ while (select_ev->fd_events && select_ev->exit_code == 0) {
+ if (select_event_loop_once(ev) != 0) {
+ break;
+ }
+ }
+
+ return select_ev->exit_code;
+}
+
+static const struct event_ops select_event_ops = {
+ .context_init = select_event_context_init,
+ .add_fd = select_event_add_fd,
+ .get_fd_flags = select_event_get_fd_flags,
+ .set_fd_flags = select_event_set_fd_flags,
+ .add_timed = common_event_add_timed,
+ .add_signal = common_event_add_signal,
+ .loop_once = select_event_loop_once,
+ .loop_wait = select_event_loop_wait,
+};
+
+bool events_select_init(void)
+{
+ return event_register_backend("select", &select_event_ops);
+}
+