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
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 This is SAMBA's default event loop code
27 #include "system/filesys.h"
28 #include "system/select.h"
30 #include "tevent_util.h"
31 #include "tevent_internal.h"
33 struct select_event_context {
34 /* a pointer back to the generic event_context */
35 struct tevent_context *ev;
37 /* list of filedescriptor events */
38 struct tevent_fd *fd_events;
40 /* list of timed events */
41 struct tevent_timer *timed_events;
43 /* the maximum file descriptor number in fd_events */
46 /* information for exiting from the event loop */
49 /* this is incremented when the loop over events causes something which
50 could change the events yet to be processed */
51 uint32_t destruction_count;
55 create a select_event_context structure.
57 static int select_event_context_init(struct tevent_context *ev)
59 struct select_event_context *select_ev;
61 select_ev = talloc_zero(ev, struct select_event_context);
62 if (!select_ev) return -1;
65 ev->additional_data = select_ev;
72 static void calc_maxfd(struct select_event_context *select_ev)
74 struct tevent_fd *fde;
77 for (fde = select_ev->fd_events; fde; fde = fde->next) {
78 if (fde->fd > select_ev->maxfd) {
79 select_ev->maxfd = fde->fd;
85 /* to mark the ev->maxfd invalid
86 * this means we need to recalculate it
88 #define EVENT_INVALID_MAXFD (-1)
93 static int select_event_fd_destructor(struct tevent_fd *fde)
95 struct tevent_context *ev = fde->event_ctx;
96 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
97 struct select_event_context);
99 if (select_ev->maxfd == fde->fd) {
100 select_ev->maxfd = EVENT_INVALID_MAXFD;
103 DLIST_REMOVE(select_ev->fd_events, fde);
104 select_ev->destruction_count++;
107 fde->close_fn(ev, fde, fde->fd, fde->private_data);
116 return NULL on failure (memory allocation error)
118 static struct tevent_fd *select_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
119 int fd, uint16_t flags,
120 tevent_fd_handler_t handler,
122 const char *handler_name,
123 const char *location)
125 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
126 struct select_event_context);
127 struct tevent_fd *fde;
129 fde = talloc(mem_ctx?mem_ctx:ev, struct tevent_fd);
130 if (!fde) return NULL;
135 fde->handler = handler;
136 fde->close_fn = NULL;
137 fde->private_data = private_data;
138 fde->handler_name = handler_name;
139 fde->location = location;
140 fde->additional_flags = 0;
141 fde->additional_data = NULL;
143 DLIST_ADD(select_ev->fd_events, fde);
144 if (fde->fd > select_ev->maxfd) {
145 select_ev->maxfd = fde->fd;
147 talloc_set_destructor(fde, select_event_fd_destructor);
153 event loop handling using select()
155 static int select_event_loop_select(struct select_event_context *select_ev, struct timeval *tvalp)
158 struct tevent_fd *fde;
160 uint32_t destruction_count = ++select_ev->destruction_count;
162 /* we maybe need to recalculate the maxfd */
163 if (select_ev->maxfd == EVENT_INVALID_MAXFD) {
164 calc_maxfd(select_ev);
170 /* setup any fd events */
171 for (fde = select_ev->fd_events; fde; fde = fde->next) {
172 if (fde->flags & TEVENT_FD_READ) {
173 FD_SET(fde->fd, &r_fds);
175 if (fde->flags & TEVENT_FD_WRITE) {
176 FD_SET(fde->fd, &w_fds);
180 if (select_ev->ev->signal_events &&
181 tevent_common_check_signal(select_ev->ev)) {
185 selrtn = select(select_ev->maxfd+1, &r_fds, &w_fds, NULL, tvalp);
187 if (selrtn == -1 && errno == EINTR &&
188 select_ev->ev->signal_events) {
189 tevent_common_check_signal(select_ev->ev);
193 if (selrtn == -1 && errno == EBADF) {
194 /* the socket is dead! this should never
195 happen as the socket should have first been
196 made readable and that should have removed
197 the event, so this must be a bug. This is a
199 tevent_debug(select_ev->ev, TEVENT_DEBUG_FATAL,
200 "ERROR: EBADF on select_event_loop_once\n");
201 select_ev->exit_code = EBADF;
205 if (selrtn == 0 && tvalp) {
206 /* we don't care about a possible delay here */
207 tevent_common_loop_timer_delay(select_ev->ev);
212 /* at least one file descriptor is ready - check
213 which ones and call the handler, being careful to allow
214 the handler to remove itself when called */
215 for (fde = select_ev->fd_events; fde; fde = fde->next) {
218 if (FD_ISSET(fde->fd, &r_fds)) flags |= TEVENT_FD_READ;
219 if (FD_ISSET(fde->fd, &w_fds)) flags |= TEVENT_FD_WRITE;
221 fde->handler(select_ev->ev, fde, flags, fde->private_data);
222 if (destruction_count != select_ev->destruction_count) {
233 do a single event loop using the events defined in ev
235 static int select_event_loop_once(struct tevent_context *ev)
237 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
238 struct select_event_context);
241 tval = tevent_common_loop_timer_delay(ev);
242 if (ev_timeval_is_zero(&tval)) {
246 return select_event_loop_select(select_ev, &tval);
250 return on failure or (with 0) if all fd events are removed
252 static int select_event_loop_wait(struct tevent_context *ev)
254 struct select_event_context *select_ev = talloc_get_type(ev->additional_data,
255 struct select_event_context);
256 select_ev->exit_code = 0;
258 while (select_ev->fd_events && select_ev->exit_code == 0) {
259 if (select_event_loop_once(ev) != 0) {
264 return select_ev->exit_code;
267 static const struct tevent_ops select_event_ops = {
268 .context_init = select_event_context_init,
269 .add_fd = select_event_add_fd,
270 .set_fd_close_fn= tevent_common_fd_set_close_fn,
271 .get_fd_flags = tevent_common_fd_get_flags,
272 .set_fd_flags = tevent_common_fd_set_flags,
273 .add_timer = tevent_common_add_timer,
274 .add_signal = tevent_common_add_signal,
275 .loop_once = select_event_loop_once,
276 .loop_wait = select_event_loop_wait,
279 bool tevent_select_init(void)
281 return tevent_register_backend("select", &select_event_ops);