Fix: lttng_poll_mod calls compat_(e)poll_add
[lttng-tools.git] / src / common / compat / poll.h
1 /*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #ifndef _LTT_POLL_H
19 #define _LTT_POLL_H
20
21 #include <assert.h>
22 #include <string.h>
23 #include <unistd.h>
24
25 #include <common/common.h>
26
27 /*
28 * Maximum number of fd we can monitor.
29 *
30 * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
31 * be used for the maximum size of the poll set. If this interface is not
32 * available, according to the manpage, the max_user_watches value is 1/25 (4%)
33 * of the available low memory divided by the registration cost in bytes which
34 * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
35 *
36 * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
37 * getrlimit(2).
38 */
39 extern unsigned int poll_max_size;
40
41 /*
42 * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
43 */
44 static inline void __lttng_poll_free(void *events)
45 {
46 free(events);
47 }
48
49 /*
50 * epoll(7) implementation.
51 */
52 #ifdef HAVE_EPOLL
53 #include <sys/epoll.h>
54 #include <stdio.h>
55 #include <features.h>
56 #include <common/compat/fcntl.h>
57
58 /* See man epoll(7) for this define path */
59 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
60
61 enum {
62 /* Polling variables compatibility for epoll */
63 LPOLLIN = EPOLLIN,
64 LPOLLPRI = EPOLLPRI,
65 LPOLLOUT = EPOLLOUT,
66 LPOLLRDNORM = EPOLLRDNORM,
67 LPOLLRDBAND = EPOLLRDBAND,
68 LPOLLWRNORM = EPOLLWRNORM,
69 LPOLLWRBAND = EPOLLWRBAND,
70 LPOLLMSG = EPOLLMSG,
71 LPOLLERR = EPOLLERR,
72 LPOLLHUP = EPOLLHUP,
73 LPOLLNVAL = EPOLLHUP,
74 LPOLLRDHUP = EPOLLRDHUP,
75 /* Close on exec feature of epoll */
76 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
77 LTTNG_CLOEXEC = EPOLL_CLOEXEC,
78 #else
79 /*
80 * EPOLL_CLOEXEC was added in glibc 2.8 (usually used in conjunction with
81 * epoll_create1(..)), but since neither EPOLL_CLOEXEC exists nor
82 * epoll_create1(..), we set it to FD_CLOEXEC so that we can pass it
83 * directly to fcntl(..) instead.
84 */
85 LTTNG_CLOEXEC = FD_CLOEXEC,
86 #endif
87 };
88
89 struct compat_epoll_event {
90 int epfd;
91 uint32_t nb_fd; /* Current number of fd in events */
92 uint32_t alloc_size; /* Size of events array */
93 uint32_t init_size; /* Initial size of events array */
94 struct epoll_event *events;
95 };
96 #define lttng_poll_event compat_epoll_event
97
98 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
99 int index, uint32_t nb_fd)
100 {
101 assert(events);
102 assert(index != nb_fd);
103
104 if (index == 0 || nb_fd == 0) {
105 return -1;
106 } else {
107 return events->events[index - 1].data.fd;
108 }
109 }
110
111 /*
112 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
113 * being the index of the events array.
114 */
115 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
116 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
117 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
118 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
119 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
120 __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
121
122 /*
123 * Create the epoll set. No memory allocation is done here.
124 */
125 extern int compat_epoll_create(struct lttng_poll_event *events,
126 int size, int flags);
127 #define lttng_poll_create(events, size, flags) \
128 compat_epoll_create(events, size, flags)
129
130 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
131 static inline int compat_glibc_epoll_create(int size __attribute__((unused)),
132 int flags)
133 {
134 return epoll_create1(flags);
135 }
136 #else
137 static inline int compat_glibc_epoll_create(int size, int flags)
138 {
139 /*
140 * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
141 * epoll_create(..) also means that we lose the possibility to
142 * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
143 * fcntl(..).
144 */
145 int efd = epoll_create(size);
146 assert(fcntl(efd, F_SETFD, flags) != -1);
147 return efd;
148 }
149 #endif
150
151 /*
152 * Wait on epoll set with the number of fd registered to the lttng_poll_event
153 * data structure (events).
154 */
155 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
156 #define lttng_poll_wait(events, timeout) \
157 compat_epoll_wait(events, timeout)
158
159 /*
160 * Add a fd to the epoll set and resize the epoll_event structure if needed.
161 */
162 extern int compat_epoll_add(struct lttng_poll_event *events,
163 int fd, uint32_t req_events);
164 #define lttng_poll_add(events, fd, req_events) \
165 compat_epoll_add(events, fd, req_events)
166
167 /*
168 * Remove a fd from the epoll set.
169 */
170 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
171 #define lttng_poll_del(events, fd) \
172 compat_epoll_del(events, fd)
173
174 /*
175 * Modify an fd's events in the epoll set.
176 */
177 extern int compat_epoll_mod(struct lttng_poll_event *events,
178 int fd, uint32_t req_events);
179 #define lttng_poll_mod(events, fd, req_events) \
180 compat_epoll_mod(events, fd, req_events)
181
182 /*
183 * Set up the poll set limits variable poll_max_size
184 */
185 extern int compat_epoll_set_max_size(void);
186 #define lttng_poll_set_max_size() \
187 compat_epoll_set_max_size()
188
189 /*
190 * This function memset with zero the structure since it can be reused at each
191 * round of a main loop. Being in a loop and using a non static number of fds,
192 * this function must be called to insure coherent events with associted fds.
193 */
194 static inline void lttng_poll_reset(struct lttng_poll_event *events)
195 {
196 if (events && events->events) {
197 memset(events->events, 0,
198 events->nb_fd * sizeof(struct epoll_event));
199 }
200 }
201
202 /*
203 * Initialize an already allocated poll event data structure. For epoll(), the
204 * epfd is set to -1 to indicate that it's not usable.
205 */
206 static inline void lttng_poll_init(struct lttng_poll_event *events)
207 {
208 memset(events, 0, sizeof(struct lttng_poll_event));
209 /* Set fd to -1 so if clean before created, we don't close 0. */
210 events->epfd = -1;
211 }
212
213 /*
214 * Clean the events structure of a lttng_poll_event. It's the caller
215 * responsability to free the lttng_poll_event memory.
216 */
217 static inline void lttng_poll_clean(struct lttng_poll_event *events)
218 {
219 int ret;
220
221 if (!events) {
222 return;
223 }
224
225 if (events->epfd >= 0) {
226 ret = close(events->epfd);
227 if (ret) {
228 PERROR("close");
229 }
230 }
231
232 __lttng_poll_free((void *) events->events);
233 }
234
235 #else /* HAVE_EPOLL */
236 /*
237 * Fallback on poll(2) API
238 */
239
240 /* Needed for some poll event values */
241 #ifndef __USE_XOPEN
242 #define __USE_XOPEN
243 #endif
244
245 /* Needed for some poll event values */
246 #ifndef __USE_GNU
247 #define __USE_GNU
248 #endif
249
250 #include <poll.h>
251 #include <stdint.h>
252
253 enum {
254 /* Polling variables compatibility for poll */
255 LPOLLIN = POLLIN,
256 LPOLLPRI = POLLPRI,
257 LPOLLOUT = POLLOUT,
258 LPOLLRDNORM = POLLRDNORM,
259 LPOLLRDBAND = POLLRDBAND,
260 LPOLLWRNORM = POLLWRNORM,
261 LPOLLWRBAND = POLLWRBAND,
262 #if __linux__
263 LPOLLMSG = POLLMSG,
264 LPOLLRDHUP = POLLRDHUP,
265 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
266 LPOLLMSG = 0,
267 LPOLLRDHUP = 0,
268 #else
269 #error "Please add support for your OS."
270 #endif /* __linux__ */
271 LPOLLERR = POLLERR,
272 LPOLLHUP = POLLHUP | POLLNVAL,
273 /* Close on exec feature does not exist for poll(2) */
274 LTTNG_CLOEXEC = 0xdead,
275 };
276
277 struct compat_poll_event_array {
278 uint32_t nb_fd; /* Current number of fd in events */
279 uint32_t alloc_size; /* Size of events array */
280 /* Initial size of the pollset. We never shrink below that. */
281 uint32_t init_size;
282 struct pollfd *events;
283 };
284
285 struct compat_poll_event {
286 /*
287 * Modified by the wait action. Updated using current fields if the
288 * need_update flag is set.
289 */
290 struct compat_poll_event_array wait;
291 /*
292 * This is modified by add/del actions being the _current_ flow of
293 * execution before a poll wait is done.
294 */
295 struct compat_poll_event_array current;
296
297 /* Indicate if wait.events need to be updated from current. */
298 int need_update:1;
299 };
300 #define lttng_poll_event compat_poll_event
301
302 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
303 int index, uint32_t nb_fd)
304 {
305 assert(events);
306 assert(index != nb_fd);
307
308 if (index == 0 || nb_fd == 0) {
309 return -1;
310 } else {
311 return events->current.events[index - 1].fd;
312 }
313 }
314
315 /*
316 * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
317 * being the index of the events array.
318 */
319 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
320 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
321 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->wait.nb_fd
322 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
323 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
324 __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
325
326 /*
327 * Create a pollfd structure of size 'size'.
328 */
329 extern int compat_poll_create(struct lttng_poll_event *events, int size);
330 #define lttng_poll_create(events, size, flags) \
331 compat_poll_create(events, size)
332
333 /*
334 * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
335 * structure.
336 */
337 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
338 #define lttng_poll_wait(events, timeout) \
339 compat_poll_wait(events, timeout)
340
341 /*
342 * Add the fd to the pollfd structure. Resize if needed.
343 */
344 extern int compat_poll_add(struct lttng_poll_event *events,
345 int fd, uint32_t req_events);
346 #define lttng_poll_add(events, fd, req_events) \
347 compat_poll_add(events, fd, req_events)
348
349 /*
350 * Remove the fd from the pollfd. Memory allocation is done to recreate a new
351 * pollfd, data is copied from the old pollfd to the new and, finally, the old
352 * one is freed().
353 */
354 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
355 #define lttng_poll_del(events, fd) \
356 compat_poll_del(events, fd)
357
358 /*
359 * Modify an fd's events in the epoll set.
360 */
361 extern int compat_poll_mod(struct lttng_poll_event *events,
362 int fd, uint32_t req_events);
363 #define lttng_poll_mod(events, fd, req_events) \
364 compat_poll_mod(events, fd, req_events)
365
366 /*
367 * Set up the poll set limits variable poll_max_size
368 */
369 extern int compat_poll_set_max_size(void);
370 #define lttng_poll_set_max_size() \
371 compat_poll_set_max_size()
372
373 /*
374 * No need to reset a pollfd structure for poll(2)
375 */
376 static inline void lttng_poll_reset(struct lttng_poll_event *events)
377 {}
378
379 /*
380 * Initialize an already allocated poll event data structure.
381 */
382 static inline void lttng_poll_init(struct lttng_poll_event *events)
383 {
384 memset(events, 0, sizeof(struct lttng_poll_event));
385 }
386
387 /*
388 * Clean the events structure of a lttng_poll_event. It's the caller
389 * responsability to free the lttng_poll_event memory.
390 */
391 static inline void lttng_poll_clean(struct lttng_poll_event *events)
392 {
393 if (events) {
394 __lttng_poll_free((void *) events->wait.events);
395 __lttng_poll_free((void *) events->current.events);
396 }
397 }
398
399 #endif /* HAVE_EPOLL */
400
401 #endif /* _LTT_POLL_H */
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