2 Unix SMB/CIFS implementation.
3 main select loop and event handling
4 Copyright (C) Andrew Tridgell 2003-2005
5 Copyright (C) Stefan Metzmacher 2005-2009
7 ** NOTE! The following LGPL license applies to the tevent
8 ** library. This does NOT imply that all of Samba is released
11 This library is free software; you can redistribute it and/or
12 modify it under the terms of the GNU Lesser General Public
13 License as published by the Free Software Foundation; either
14 version 3 of the License, or (at your option) any later version.
16 This library is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 Lesser General Public License for more details.
21 You should have received a copy of the GNU Lesser General Public
22 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 #include "system/filesys.h"
27 #include "system/select.h"
29 #include "tevent_util.h"
30 #include "tevent_internal.h"
32 struct select_event_context {
33 /* a pointer back to the generic event_context */
34 struct tevent_context *ev;
36 /* the maximum file descriptor number in fd_events */
39 /* information for exiting from the event loop */
42 /* this is incremented when the loop over events causes something which
43 could change the events yet to be processed */
44 uint32_t destruction_count;
48 create a select_event_context structure.
50 static int select_event_context_init(struct tevent_context *ev)
52 struct select_event_context *select_ev;
54 select_ev = talloc_zero(ev, struct select_event_context);
55 if (!select_ev) return -1;
58 ev->additional_data = select_ev;
65 static void calc_maxfd(struct select_event_context *select_ev)
67 struct tevent_fd *fde;
70 for (fde = select_ev->ev->fd_events; fde; fde = fde->next) {
71 if (fde->fd > select_ev->maxfd) {
72 select_ev->maxfd = fde->fd;
78 /* to mark the ev->maxfd invalid
79 * this means we need to recalculate it
81 #define EVENT_INVALID_MAXFD (-1)
86 static int select_event_fd_destructor(struct tevent_fd *fde)
88 struct tevent_context *ev = fde->event_ctx;
89 struct select_event_context *select_ev = NULL;
92 select_ev = talloc_get_type(ev->additional_data,
93 struct select_event_context);
95 if (select_ev->maxfd == fde->fd) {
96 select_ev->maxfd = EVENT_INVALID_MAXFD;
99 select_ev->destruction_count++;
102 return tevent_common_fd_destructor(fde);
107 return NULL on failure (memory allocation error)
109 static struct tevent_fd *select_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
110 int fd, uint16_t flags,
111 tevent_fd_handler_t handler,
113 const char *handler_name,
114 const char *location)
116 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
117 struct select_event_context);
118 struct tevent_fd *fde;
120 fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
121 handler, private_data,
122 handler_name, location);
123 if (!fde) return NULL;
125 if (fde->fd > select_ev->maxfd) {
126 select_ev->maxfd = fde->fd;
128 talloc_set_destructor(fde, select_event_fd_destructor);
134 event loop handling using select()
136 static int select_event_loop_select(struct select_event_context *select_ev, struct timeval *tvalp)
139 struct tevent_fd *fde;
141 uint32_t destruction_count = ++select_ev->destruction_count;
143 /* we maybe need to recalculate the maxfd */
144 if (select_ev->maxfd == EVENT_INVALID_MAXFD) {
145 calc_maxfd(select_ev);
151 /* setup any fd events */
152 for (fde = select_ev->ev->fd_events; fde; fde = fde->next) {
153 if (fde->flags & TEVENT_FD_READ) {
154 FD_SET(fde->fd, &r_fds);
156 if (fde->flags & TEVENT_FD_WRITE) {
157 FD_SET(fde->fd, &w_fds);
161 if (select_ev->ev->signal_events &&
162 tevent_common_check_signal(select_ev->ev)) {
166 selrtn = select(select_ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp);
168 if (selrtn == -1 && errno == EINTR &&
169 select_ev->ev->signal_events) {
170 tevent_common_check_signal(select_ev->ev);
174 if (selrtn == -1 && errno == EBADF) {
175 /* the socket is dead! this should never
176 happen as the socket should have first been
177 made readable and that should have removed
178 the event, so this must be a bug. This is a
180 tevent_debug(select_ev->ev, TEVENT_DEBUG_FATAL,
181 "ERROR: EBADF on select_event_loop_once\n");
182 select_ev->exit_code = EBADF;
186 if (selrtn == 0 && tvalp) {
187 /* we don't care about a possible delay here */
188 tevent_common_loop_timer_delay(select_ev->ev);
193 /* at least one file descriptor is ready - check
194 which ones and call the handler, being careful to allow
195 the handler to remove itself when called */
196 for (fde = select_ev->ev->fd_events; fde; fde = fde->next) {
199 if (FD_ISSET(fde->fd, &r_fds)) flags |= TEVENT_FD_READ;
200 if (FD_ISSET(fde->fd, &w_fds)) flags |= TEVENT_FD_WRITE;
202 fde->handler(select_ev->ev, fde, flags, fde->private_data);
203 if (destruction_count != select_ev->destruction_count) {
214 do a single event loop using the events defined in ev
216 static int select_event_loop_once(struct tevent_context *ev)
218 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
219 struct select_event_context);
222 tval = tevent_common_loop_timer_delay(ev);
223 if (ev_timeval_is_zero(&tval)) {
227 return select_event_loop_select(select_ev, &tval);
231 return on failure or (with 0) if all fd events are removed
233 static int select_event_loop_wait(struct tevent_context *ev)
235 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
236 struct select_event_context);
237 select_ev->exit_code = 0;
239 while (ev->fd_events && select_ev->exit_code == 0) {
240 if (select_event_loop_once(ev) != 0) {
245 return select_ev->exit_code;
248 static const struct tevent_ops select_event_ops = {
249 .context_init = select_event_context_init,
250 .add_fd = select_event_add_fd,
251 .set_fd_close_fn= tevent_common_fd_set_close_fn,
252 .get_fd_flags = tevent_common_fd_get_flags,
253 .set_fd_flags = tevent_common_fd_set_flags,
254 .add_timer = tevent_common_add_timer,
255 .add_signal = tevent_common_add_signal,
256 .loop_once = select_event_loop_once,
257 .loop_wait = select_event_loop_wait,
260 bool tevent_select_init(void)
262 return tevent_register_backend("select", &select_event_ops);