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 LTTNG_HIDDEN
 126 int compat_epoll_create(struct lttng_poll_event *events,
 127                 int size, int flags);
 128 #define lttng_poll_create(events, size, flags) \
 129         compat_epoll_create(events, size, flags)
 130
 131 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 132 static inline int compat_glibc_epoll_create(int size __attribute__((unused)),
 133                 int flags)
 134 {
 135         return epoll_create1(flags);
 136 }
 137 #else
 138 static inline int compat_glibc_epoll_create(int size, int flags)
 139 {
 140         /*
 141          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 142          * epoll_create(..) also means that we lose the possibility to
 143          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 144          * fcntl(..).
 145          */
 146         int efd = epoll_create(size);
 147         assert(fcntl(efd, F_SETFD, flags) != -1);
 148         return efd;
 149 }
 150 #endif
 151
 152 /*
 153  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 154  * data structure (events).
 155  */
 156 LTTNG_HIDDEN
 157 int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 158 #define lttng_poll_wait(events, timeout) \
 159         compat_epoll_wait(events, timeout)
 160
 161 /*
 162  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 163  */
 164 LTTNG_HIDDEN
 165 int compat_epoll_add(struct lttng_poll_event *events,
 166                 int fd, uint32_t req_events);
 167 #define lttng_poll_add(events, fd, req_events) \
 168         compat_epoll_add(events, fd, req_events)
 169
 170 /*
 171  * Remove a fd from the epoll set.
 172  */
 173 LTTNG_HIDDEN
 174 int compat_epoll_del(struct lttng_poll_event *events, int fd);
 175 #define lttng_poll_del(events, fd) \
 176         compat_epoll_del(events, fd)
 177
 178 /*
 179  * Modify an fd's events in the epoll set.
 180  */
 181 LTTNG_HIDDEN
 182 int compat_epoll_mod(struct lttng_poll_event *events,
 183                 int fd, uint32_t req_events);
 184 #define lttng_poll_mod(events, fd, req_events) \
 185         compat_epoll_add(events, fd, req_events)
 186
 187 /*
 188  * Set up the poll set limits variable poll_max_size
 189  */
 190 LTTNG_HIDDEN
 191 int compat_epoll_set_max_size(void);
 192 #define lttng_poll_set_max_size() \
 193         compat_epoll_set_max_size()
 194
 195 /*
 196  * This function memset with zero the structure since it can be reused at each
 197  * round of a main loop. Being in a loop and using a non static number of fds,
 198  * this function must be called to insure coherent events with associted fds.
 199  */
 200 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 201 {
 202         if (events && events->events) {
 203                 memset(events->events, 0,
 204                                 events->nb_fd * sizeof(struct epoll_event));
 205         }
 206 }
 207
 208 /*
 209  * Initialize an already allocated poll event data structure. For epoll(), the
 210  * epfd is set to -1 to indicate that it's not usable.
 211  */
 212 static inline void lttng_poll_init(struct lttng_poll_event *events)
 213 {
 214         memset(events, 0, sizeof(struct lttng_poll_event));
 215         /* Set fd to -1 so if clean before created, we don't close 0. */
 216         events->epfd = -1;
 217 }
 218
 219 /*
 220  * Clean the events structure of a lttng_poll_event. It's the caller
 221  * responsability to free the lttng_poll_event memory.
 222  */
 223 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 224 {
 225         int ret;
 226
 227         if (!events) {
 228                 return;
 229         }
 230
 231         if (events->epfd >= 0) {
 232                 ret = close(events->epfd);
 233                 if (ret) {
 234                         PERROR("close");
 235                 }
 236         }
 237
 238         __lttng_poll_free((void *) events->events);
 239 }
 240
 241 #else   /* HAVE_EPOLL */
 242 /*
 243  * Fallback on poll(2) API
 244  */
 245
 246 /* Needed for some poll event values */
 247 #ifndef __USE_XOPEN
 248 #define __USE_XOPEN
 249 #endif
 250
 251 /* Needed for some poll event values */
 252 #ifndef __USE_GNU
 253 #define __USE_GNU
 254 #endif
 255
 256 #include <poll.h>
 257 #include <stdint.h>
 258
 259 enum {
 260         /* Polling variables compatibility for poll */
 261         LPOLLIN = POLLIN,
 262         LPOLLPRI = POLLPRI,
 263         LPOLLOUT = POLLOUT,
 264         LPOLLRDNORM = POLLRDNORM,
 265         LPOLLRDBAND = POLLRDBAND,
 266         LPOLLWRNORM = POLLWRNORM,
 267         LPOLLWRBAND = POLLWRBAND,
 268 #if __linux__
 269         LPOLLMSG = POLLMSG,
 270         LPOLLRDHUP = POLLRDHUP,
 271 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 272         LPOLLMSG = 0,
 273         LPOLLRDHUP = 0,
 274 #else
 275 #error "Please add support for your OS."
 276 #endif /* __linux__ */
 277         LPOLLERR = POLLERR,
 278         LPOLLHUP = POLLHUP | POLLNVAL,
 279         /* Close on exec feature does not exist for poll(2) */
 280         LTTNG_CLOEXEC = 0xdead,
 281 };
 282
 283 struct compat_poll_event_array {
 284         uint32_t nb_fd;       /* Current number of fd in events */
 285         uint32_t alloc_size; /* Size of events array */
 286         /* Initial size of the pollset. We never shrink below that. */
 287         uint32_t init_size;
 288         struct pollfd *events;
 289 };
 290
 291 struct compat_poll_event {
 292         /*
 293          * Modified by the wait action. Updated using current fields if the
 294          * need_update flag is set.
 295          */
 296         struct compat_poll_event_array wait;
 297         /*
 298          * This is modified by add/del actions being the _current_ flow of
 299          * execution before a poll wait is done.
 300          */
 301         struct compat_poll_event_array current;
 302
 303         /* Indicate if wait.events need to be updated from current. */
 304         int need_update:1;
 305 };
 306 #define lttng_poll_event compat_poll_event
 307
 308 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 309                 int index, uint32_t nb_fd)
 310 {
 311         assert(events);
 312         assert(index != nb_fd);
 313
 314         if (index == 0 || nb_fd == 0) {
 315                 return -1;
 316         } else {
 317                 return events->current.events[index - 1].fd;
 318         }
 319 }
 320
 321 /*
 322  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 323  * being the index of the events array.
 324  */
 325 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 326 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 327 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->wait.nb_fd
 328 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 329 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 330         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 331
 332 /*
 333  * Create a pollfd structure of size 'size'.
 334  */
 335 LTTNG_HIDDEN
 336 int compat_poll_create(struct lttng_poll_event *events, int size);
 337 #define lttng_poll_create(events, size, flags) \
 338         compat_poll_create(events, size)
 339
 340 /*
 341  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 342  * structure.
 343  */
 344 LTTNG_HIDDEN
 345 int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 346 #define lttng_poll_wait(events, timeout) \
 347         compat_poll_wait(events, timeout)
 348
 349 /*
 350  * Add the fd to the pollfd structure. Resize if needed.
 351  */
 352 LTTNG_HIDDEN
 353 int compat_poll_add(struct lttng_poll_event *events,
 354                 int fd, uint32_t req_events);
 355 #define lttng_poll_add(events, fd, req_events) \
 356         compat_poll_add(events, fd, req_events)
 357
 358 /*
 359  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 360  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 361  * one is freed().
 362  */
 363 LTTNG_HIDDEN
 364 int compat_poll_del(struct lttng_poll_event *events, int fd);
 365 #define lttng_poll_del(events, fd) \
 366         compat_poll_del(events, fd)
 367
 368 /*
 369  * Modify an fd's events in the epoll set.
 370  */
 371 LTTNG_HIDDEN
 372 int compat_poll_mod(struct lttng_poll_event *events,
 373                 int fd, uint32_t req_events);
 374 #define lttng_poll_mod(events, fd, req_events) \
 375         compat_poll_add(events, fd, req_events)
 376
 377 /*
 378  * Set up the poll set limits variable poll_max_size
 379  */
 380 LTTNG_HIDDEN
 381 int compat_poll_set_max_size(void);
 382 #define lttng_poll_set_max_size() \
 383         compat_poll_set_max_size()
 384
 385 /*
 386  * No need to reset a pollfd structure for poll(2)
 387  */
 388 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 389 {}
 390
 391 /*
 392  * Initialize an already allocated poll event data structure.
 393  */
 394 static inline void lttng_poll_init(struct lttng_poll_event *events)
 395 {
 396         memset(events, 0, sizeof(struct lttng_poll_event));
 397 }
 398
 399 /*
 400  * Clean the events structure of a lttng_poll_event. It's the caller
 401  * responsability to free the lttng_poll_event memory.
 402  */
 403 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 404 {
 405         if (events) {
 406                 __lttng_poll_free((void *) events->wait.events);
 407                 __lttng_poll_free((void *) events->current.events);
 408         }
 409 }
 410
 411 #endif /* HAVE_EPOLL */
 412
 413 #endif /* _LTT_POLL_H */