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
  56 /* See man epoll(7) for this define path */
  57 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  58
  59 enum {
  60         /* Polling variables compatibility for epoll */
  61         LPOLLIN = EPOLLIN,
  62         LPOLLPRI = EPOLLPRI,
  63         LPOLLOUT = EPOLLOUT,
  64         LPOLLRDNORM = EPOLLRDNORM,
  65         LPOLLRDBAND = EPOLLRDBAND,
  66         LPOLLWRNORM = EPOLLWRNORM,
  67         LPOLLWRBAND = EPOLLWRBAND,
  68         LPOLLMSG = EPOLLMSG,
  69         LPOLLERR = EPOLLERR,
  70         LPOLLHUP = EPOLLHUP,
  71         LPOLLNVAL = EPOLLHUP,
  72         LPOLLRDHUP = EPOLLRDHUP,
  73         /* Close on exec feature of epoll */
  74         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  75 };
  76
  77 struct compat_epoll_event {
  78         int epfd;
  79         uint32_t nb_fd;       /* Current number of fd in events */
  80         uint32_t alloc_size; /* Size of events array */
  81         uint32_t init_size;     /* Initial size of events array */
  82         struct epoll_event *events;
  83 };
  84 #define lttng_poll_event compat_epoll_event
  85
  86 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
  87                 int index, uint32_t nb_fd)
  88 {
  89         assert(events);
  90         assert(index != nb_fd);
  91
  92         if (index == 0 || nb_fd == 0) {
  93                 return -1;
  94         } else {
  95                 return events->events[index - 1].data.fd;
  96         }
  97 }
  98
  99 /*
 100  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 101  * being the index of the events array.
 102  */
 103 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
 104 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
 105 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 106 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 107 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 108         __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 109
 110 /*
 111  * Create the epoll set. No memory allocation is done here.
 112  */
 113 extern int compat_epoll_create(struct lttng_poll_event *events,
 114                 int size, int flags);
 115 #define lttng_poll_create(events, size, flags) \
 116         compat_epoll_create(events, size, flags)
 117
 118 /*
 119  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 120  * data structure (events).
 121  */
 122 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 123 #define lttng_poll_wait(events, timeout) \
 124         compat_epoll_wait(events, timeout)
 125
 126 /*
 127  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 128  */
 129 extern int compat_epoll_add(struct lttng_poll_event *events,
 130                 int fd, uint32_t req_events);
 131 #define lttng_poll_add(events, fd, req_events) \
 132         compat_epoll_add(events, fd, req_events)
 133
 134 /*
 135  * Remove a fd from the epoll set.
 136  */
 137 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 138 #define lttng_poll_del(events, fd) \
 139         compat_epoll_del(events, fd)
 140
 141 /*
 142  * Set up the poll set limits variable poll_max_size
 143  */
 144 extern void compat_epoll_set_max_size(void);
 145 #define lttng_poll_set_max_size() \
 146         compat_epoll_set_max_size()
 147
 148 /*
 149  * This function memset with zero the structure since it can be reused at each
 150  * round of a main loop. Being in a loop and using a non static number of fds,
 151  * this function must be called to insure coherent events with associted fds.
 152  */
 153 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 154 {
 155         if (events && events->events) {
 156                 memset(events->events, 0,
 157                                 events->nb_fd * sizeof(struct epoll_event));
 158         }
 159 }
 160
 161 /*
 162  * Clean the events structure of a lttng_poll_event. It's the caller
 163  * responsability to free the lttng_poll_event memory.
 164  */
 165 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 166 {
 167         int ret;
 168
 169         if (events) {
 170                 ret = close(events->epfd);
 171                 if (ret) {
 172                         perror("close");
 173                 }
 174                 __lttng_poll_free((void *) events->events);
 175         }
 176 }
 177
 178 #else   /* HAVE_EPOLL */
 179 /*
 180  * Fallback on poll(2) API
 181  */
 182
 183 /* Needed for some poll event values */
 184 #ifndef __USE_XOPEN
 185 #define __USE_XOPEN
 186 #endif
 187
 188 /* Needed for some poll event values */
 189 #ifndef __USE_GNU
 190 #define __USE_GNU
 191 #endif
 192
 193 #include <poll.h>
 194 #include <stdint.h>
 195
 196 enum {
 197         /* Polling variables compatibility for poll */
 198         LPOLLIN = POLLIN,
 199         LPOLLPRI = POLLPRI,
 200         LPOLLOUT = POLLOUT,
 201         LPOLLRDNORM = POLLRDNORM,
 202         LPOLLRDBAND = POLLRDBAND,
 203         LPOLLWRNORM = POLLWRNORM,
 204         LPOLLWRBAND = POLLWRBAND,
 205 #if __linux__
 206         LPOLLMSG = POLLMSG,
 207         LPOLLRDHUP = POLLRDHUP,
 208 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 209         LPOLLMSG = 0,
 210         LPOLLRDHUP = 0,
 211 #else
 212 #error "Please add support for your OS."
 213 #endif /* __linux__ */
 214         LPOLLERR = POLLERR,
 215         LPOLLHUP = POLLHUP | POLLNVAL,
 216         /* Close on exec feature does not exist for poll(2) */
 217         LTTNG_CLOEXEC = 0xdead,
 218 };
 219
 220 struct compat_poll_event_array {
 221         uint32_t nb_fd;       /* Current number of fd in events */
 222         uint32_t alloc_size; /* Size of events array */
 223         /* Initial size of the pollset. We never shrink below that. */
 224         uint32_t init_size;
 225         struct pollfd *events;
 226 };
 227
 228 struct compat_poll_event {
 229         /*
 230          * Modified by the wait action. Updated using current fields if the
 231          * need_update flag is set.
 232          */
 233         struct compat_poll_event_array wait;
 234         /*
 235          * This is modified by add/del actions being the _current_ flow of
 236          * execution before a poll wait is done.
 237          */
 238         struct compat_poll_event_array current;
 239         /* Indicate if wait.events needs to be realloc. */
 240         int need_realloc:1;
 241         /* Indicate if wait.events need to be updated from current. */
 242         int need_update:1;
 243 };
 244 #define lttng_poll_event compat_poll_event
 245
 246 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 247                 int index, uint32_t nb_fd)
 248 {
 249         assert(events);
 250         assert(index != nb_fd);
 251
 252         if (index == 0 || nb_fd == 0) {
 253                 return -1;
 254         } else {
 255                 return events->current.events[index - 1].fd;
 256         }
 257 }
 258
 259 /*
 260  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 261  * being the index of the events array.
 262  */
 263 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 264 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 265 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->wait.nb_fd
 266 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 267 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 268         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 269
 270 /*
 271  * Create a pollfd structure of size 'size'.
 272  */
 273 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 274 #define lttng_poll_create(events, size, flags) \
 275         compat_poll_create(events, size)
 276
 277 /*
 278  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 279  * structure.
 280  */
 281 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 282 #define lttng_poll_wait(events, timeout) \
 283         compat_poll_wait(events, timeout)
 284
 285 /*
 286  * Add the fd to the pollfd structure. Resize if needed.
 287  */
 288 extern int compat_poll_add(struct lttng_poll_event *events,
 289                 int fd, uint32_t req_events);
 290 #define lttng_poll_add(events, fd, req_events) \
 291         compat_poll_add(events, fd, req_events)
 292
 293 /*
 294  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 295  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 296  * one is freed().
 297  */
 298 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 299 #define lttng_poll_del(events, fd) \
 300         compat_poll_del(events, fd)
 301
 302 /*
 303  * Set up the poll set limits variable poll_max_size
 304  */
 305 extern void compat_poll_set_max_size(void);
 306 #define lttng_poll_set_max_size() \
 307         compat_poll_set_max_size()
 308
 309 /*
 310  * No need to reset a pollfd structure for poll(2)
 311  */
 312 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 313 {}
 314
 315 /*
 316  * Clean the events structure of a lttng_poll_event. It's the caller
 317  * responsability to free the lttng_poll_event memory.
 318  */
 319 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 320 {
 321         if (events) {
 322                 __lttng_poll_free((void *) events->wait.events);
 323                 __lttng_poll_free((void *) events->current.events);
 324         }
 325 }
 326
 327 #endif /* HAVE_EPOLL */
 328
 329 #endif /* _LTT_POLL_H */