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         if (events) {
  47                 free(events);
  48         }
  49 }
  50
  51 /*
  52  * epoll(7) implementation.
  53  */
  54 #ifdef HAVE_EPOLL
  55 #include <sys/epoll.h>
  56 #include <stdio.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         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  77 };
  78
  79 struct compat_epoll_event {
  80         int epfd;
  81         uint32_t nb_fd;       /* Current number of fd in events */
  82         uint32_t alloc_size; /* Size of events array */
  83         uint32_t init_size;     /* Initial size of events array */
  84         struct epoll_event *events;
  85 };
  86 #define lttng_poll_event compat_epoll_event
  87
  88 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
  89                 int index, uint32_t nb_fd)
  90 {
  91         assert(events);
  92         assert(index != nb_fd);
  93
  94         if (index == 0 || nb_fd == 0) {
  95                 return -1;
  96         } else {
  97                 return events->events[index - 1].data.fd;
  98         }
  99 }
 100
 101 /*
 102  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 103  * being the index of the events array.
 104  */
 105 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
 106 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
 107 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 108 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 109 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 110         __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 111
 112 /*
 113  * Create the epoll set. No memory allocation is done here.
 114  */
 115 extern int compat_epoll_create(struct lttng_poll_event *events,
 116                 int size, int flags);
 117 #define lttng_poll_create(events, size, flags) \
 118         compat_epoll_create(events, size, flags)
 119
 120 /*
 121  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 122  * data structure (events).
 123  */
 124 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 125 #define lttng_poll_wait(events, timeout) \
 126         compat_epoll_wait(events, timeout)
 127
 128 /*
 129  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 130  */
 131 extern int compat_epoll_add(struct lttng_poll_event *events,
 132                 int fd, uint32_t req_events);
 133 #define lttng_poll_add(events, fd, req_events) \
 134         compat_epoll_add(events, fd, req_events)
 135
 136 /*
 137  * Remove a fd from the epoll set.
 138  */
 139 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 140 #define lttng_poll_del(events, fd) \
 141         compat_epoll_del(events, fd)
 142
 143 /*
 144  * Set up the poll set limits variable poll_max_size
 145  */
 146 extern void compat_epoll_set_max_size(void);
 147 #define lttng_poll_set_max_size() \
 148         compat_epoll_set_max_size()
 149
 150 /*
 151  * This function memset with zero the structure since it can be reused at each
 152  * round of a main loop. Being in a loop and using a non static number of fds,
 153  * this function must be called to insure coherent events with associted fds.
 154  */
 155 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 156 {
 157         if (events && events->events) {
 158                 memset(events->events, 0,
 159                                 events->nb_fd * sizeof(struct epoll_event));
 160         }
 161 }
 162
 163 /*
 164  * Clean the events structure of a lttng_poll_event. It's the caller
 165  * responsability to free the lttng_poll_event memory.
 166  */
 167 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 168 {
 169         int ret;
 170
 171         if (events) {
 172                 ret = close(events->epfd);
 173                 if (ret) {
 174                         perror("close");
 175                 }
 176                 __lttng_poll_free((void *) events->events);
 177         }
 178 }
 179
 180 #else   /* HAVE_EPOLL */
 181 /*
 182  * Fallback on poll(2) API
 183  */
 184
 185 /* Needed for some poll event values */
 186 #ifndef __USE_XOPEN
 187 #define __USE_XOPEN
 188 #endif
 189
 190 /* Needed for some poll event values */
 191 #ifndef __USE_GNU
 192 #define __USE_GNU
 193 #endif
 194
 195 #include <poll.h>
 196 #include <stdint.h>
 197
 198 enum {
 199         /* Polling variables compatibility for poll */
 200         LPOLLIN = POLLIN,
 201         LPOLLPRI = POLLPRI,
 202         LPOLLOUT = POLLOUT,
 203         LPOLLRDNORM = POLLRDNORM,
 204         LPOLLRDBAND = POLLRDBAND,
 205         LPOLLWRNORM = POLLWRNORM,
 206         LPOLLWRBAND = POLLWRBAND,
 207 #if __linux__
 208         LPOLLMSG = POLLMSG,
 209         LPOLLRDHUP = POLLRDHUP,
 210 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 211         LPOLLMSG = 0,
 212         LPOLLRDHUP = 0,
 213 #else
 214 #error "Please add support for your OS."
 215 #endif /* __linux__ */
 216         LPOLLERR = POLLERR,
 217         LPOLLHUP = POLLHUP | POLLNVAL,
 218         /* Close on exec feature does not exist for poll(2) */
 219         LTTNG_CLOEXEC = 0xdead,
 220 };
 221
 222 struct compat_poll_event_array {
 223         uint32_t nb_fd;       /* Current number of fd in events */
 224         uint32_t alloc_size; /* Size of events array */
 225         /* Initial size of the pollset. We never shrink below that. */
 226         uint32_t init_size;
 227         struct pollfd *events;
 228 };
 229
 230 struct compat_poll_event {
 231         /*
 232          * Modified by the wait action. Updated using current fields if the
 233          * need_update flag is set.
 234          */
 235         struct compat_poll_event_array wait;
 236         /*
 237          * This is modified by add/del actions being the _current_ flow of
 238          * execution before a poll wait is done.
 239          */
 240         struct compat_poll_event_array current;
 241         /* Indicate if wait.events needs to be realloc. */
 242         int need_realloc:1;
 243         /* Indicate if wait.events need to be updated from current. */
 244         int need_update:1;
 245 };
 246 #define lttng_poll_event compat_poll_event
 247
 248 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 249                 int index, uint32_t nb_fd)
 250 {
 251         assert(events);
 252         assert(index != nb_fd);
 253
 254         if (index == 0 || nb_fd == 0) {
 255                 return -1;
 256         } else {
 257                 return events->current.events[index - 1].fd;
 258         }
 259 }
 260
 261 /*
 262  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 263  * being the index of the events array.
 264  */
 265 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 266 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 267 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->wait.nb_fd
 268 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 269 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 270         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 271
 272 /*
 273  * Create a pollfd structure of size 'size'.
 274  */
 275 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 276 #define lttng_poll_create(events, size, flags) \
 277         compat_poll_create(events, size)
 278
 279 /*
 280  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 281  * structure.
 282  */
 283 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 284 #define lttng_poll_wait(events, timeout) \
 285         compat_poll_wait(events, timeout)
 286
 287 /*
 288  * Add the fd to the pollfd structure. Resize if needed.
 289  */
 290 extern int compat_poll_add(struct lttng_poll_event *events,
 291                 int fd, uint32_t req_events);
 292 #define lttng_poll_add(events, fd, req_events) \
 293         compat_poll_add(events, fd, req_events)
 294
 295 /*
 296  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 297  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 298  * one is freed().
 299  */
 300 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 301 #define lttng_poll_del(events, fd) \
 302         compat_poll_del(events, fd)
 303
 304 /*
 305  * Set up the poll set limits variable poll_max_size
 306  */
 307 extern void compat_poll_set_max_size(void);
 308 #define lttng_poll_set_max_size() \
 309         compat_poll_set_max_size()
 310
 311 /*
 312  * No need to reset a pollfd structure for poll(2)
 313  */
 314 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 315 {}
 316
 317 /*
 318  * Clean the events structure of a lttng_poll_event. It's the caller
 319  * responsability to free the lttng_poll_event memory.
 320  */
 321 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 322 {
 323         if (events) {
 324                 __lttng_poll_free((void *) events->wait.events);
 325                 __lttng_poll_free((void *) events->current.events);
 326         }
 327 }
 328
 329 #endif /* HAVE_EPOLL */
 330
 331 #endif /* _LTT_POLL_H */