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