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 <string.h>
  22 #include <unistd.h>
  23
  24 #include <common/common.h>
  25
  26 /*
  27  * Maximum number of fd we can monitor.
  28  *
  29  * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
  30  * be used for the maximum size of the poll set. If this interface is not
  31  * available, according to the manpage, the max_user_watches value is 1/25 (4%)
  32  * of the available low memory divided by the registration cost in bytes which
  33  * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
  34  *
  35  * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
  36  * getrlimit(2).
  37  */
  38 extern unsigned int poll_max_size;
  39
  40 /*
  41  * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
  42  */
  43 static inline void __lttng_poll_free(void *events)
  44 {
  45         if (events) {
  46                 free(events);
  47         }
  48 }
  49
  50 /*
  51  * epoll(7) implementation.
  52  */
  53 #ifdef HAVE_EPOLL
  54 #include <sys/epoll.h>
  55 #include <stdio.h>
  56
  57 /* See man epoll(7) for this define path */
  58 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  59
  60 enum {
  61         /* Polling variables compatibility for epoll */
  62         LPOLLIN = EPOLLIN,
  63         LPOLLPRI = EPOLLPRI,
  64         LPOLLOUT = EPOLLOUT,
  65         LPOLLRDNORM = EPOLLRDNORM,
  66         LPOLLRDBAND = EPOLLRDBAND,
  67         LPOLLWRNORM = EPOLLWRNORM,
  68         LPOLLWRBAND = EPOLLWRBAND,
  69         LPOLLMSG = EPOLLMSG,
  70         LPOLLERR = EPOLLERR,
  71         LPOLLHUP = EPOLLHUP,
  72         LPOLLNVAL = EPOLLHUP,
  73         LPOLLRDHUP = EPOLLRDHUP,
  74         /* Close on exec feature of epoll */
  75         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  76 };
  77
  78 struct compat_epoll_event {
  79         int epfd;
  80         uint32_t nb_fd;       /* Current number of fd in events */
  81         uint32_t events_size; /* Size of events array */
  82         struct epoll_event *events;
  83 };
  84 #define lttng_poll_event compat_epoll_event
  85
  86 /*
  87  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
  88  * being the index of the events array.
  89  */
  90 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
  91 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
  92 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
  93 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
  94
  95 /*
  96  * Create the epoll set. No memory allocation is done here.
  97  */
  98 extern int compat_epoll_create(struct lttng_poll_event *events,
  99                 int size, int flags);
 100 #define lttng_poll_create(events, size, flags) \
 101         compat_epoll_create(events, size, flags)
 102
 103 /*
 104  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 105  * data structure (events).
 106  */
 107 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 108 #define lttng_poll_wait(events, timeout) \
 109         compat_epoll_wait(events, timeout)
 110
 111 /*
 112  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 113  */
 114 extern int compat_epoll_add(struct lttng_poll_event *events,
 115                 int fd, uint32_t req_events);
 116 #define lttng_poll_add(events, fd, req_events) \
 117         compat_epoll_add(events, fd, req_events)
 118
 119 /*
 120  * Remove a fd from the epoll set.
 121  */
 122 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 123 #define lttng_poll_del(events, fd) \
 124         compat_epoll_del(events, fd)
 125
 126 /*
 127  * Set up the poll set limits variable poll_max_size
 128  */
 129 extern void compat_epoll_set_max_size(void);
 130 #define lttng_poll_set_max_size() \
 131         compat_epoll_set_max_size()
 132
 133 /*
 134  * This function memset with zero the structure since it can be reused at each
 135  * round of a main loop. Being in a loop and using a non static number of fds,
 136  * this function must be called to insure coherent events with associted fds.
 137  */
 138 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 139 {
 140         if (events && events->events) {
 141                 memset(events->events, 0,
 142                                 events->nb_fd * sizeof(struct epoll_event));
 143         }
 144 }
 145
 146 /*
 147  * Clean the events structure of a lttng_poll_event. It's the caller
 148  * responsability to free the lttng_poll_event memory.
 149  */
 150 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 151 {
 152         int ret;
 153
 154         if (events) {
 155                 ret = close(events->epfd);
 156                 if (ret) {
 157                         perror("close");
 158                 }
 159                 __lttng_poll_free((void *) events->events);
 160         }
 161 }
 162
 163 #else   /* HAVE_EPOLL */
 164 /*
 165  * Fallback on poll(2) API
 166  */
 167
 168 /* Needed for some poll event values */
 169 #ifndef __USE_XOPEN
 170 #define __USE_XOPEN
 171 #endif
 172
 173 /* Needed for some poll event values */
 174 #ifndef __USE_GNU
 175 #define __USE_GNU
 176 #endif
 177
 178 #include <poll.h>
 179 #include <stdint.h>
 180
 181 enum {
 182         /* Polling variables compatibility for poll */
 183         LPOLLIN = POLLIN,
 184         LPOLLPRI = POLLPRI,
 185         LPOLLOUT = POLLOUT,
 186         LPOLLRDNORM = POLLRDNORM,
 187         LPOLLRDBAND = POLLRDBAND,
 188         LPOLLWRNORM = POLLWRNORM,
 189         LPOLLWRBAND = POLLWRBAND,
 190 #if __linux__
 191         LPOLLMSG = POLLMSG,
 192         LPOLLRDHUP = POLLRDHUP,
 193 #elif (defined(__FreeBSD__) || defined(__CYGWIN__))
 194         LPOLLMSG = 0,
 195         LPOLLRDHUP = 0,
 196 #else
 197 #error "Please add support for your OS."
 198 #endif /* __linux__ */
 199         LPOLLERR = POLLERR,
 200         LPOLLHUP = POLLHUP | POLLNVAL,
 201         /* Close on exec feature does not exist for poll(2) */
 202         LTTNG_CLOEXEC = 0xdead,
 203 };
 204
 205 struct compat_poll_event {
 206         uint32_t nb_fd;       /* Current number of fd in events */
 207         uint32_t events_size; /* Size of events array */
 208         struct pollfd *events;
 209 };
 210 #define lttng_poll_event compat_poll_event
 211
 212 /*
 213  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 214  * being the index of the events array.
 215  */
 216 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].fd
 217 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].revents
 218 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 219 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 220
 221 /*
 222  * Create a pollfd structure of size 'size'.
 223  */
 224 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 225 #define lttng_poll_create(events, size, flags) \
 226         compat_poll_create(events, size)
 227
 228 /*
 229  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 230  * structure.
 231  */
 232 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 233 #define lttng_poll_wait(events, timeout) \
 234         compat_poll_wait(events, timeout)
 235
 236 /*
 237  * Add the fd to the pollfd structure. Resize if needed.
 238  */
 239 extern int compat_poll_add(struct lttng_poll_event *events,
 240                 int fd, uint32_t req_events);
 241 #define lttng_poll_add(events, fd, req_events) \
 242         compat_poll_add(events, fd, req_events)
 243
 244 /*
 245  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 246  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 247  * one is freed().
 248  */
 249 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 250 #define lttng_poll_del(events, fd) \
 251         compat_poll_del(events, fd)
 252
 253 /*
 254  * Set up the poll set limits variable poll_max_size
 255  */
 256 extern void compat_poll_set_max_size(void);
 257 #define lttng_poll_set_max_size() \
 258         compat_poll_set_max_size()
 259
 260 /*
 261  * No need to reset a pollfd structure for poll(2)
 262  */
 263 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 264 {}
 265
 266 /*
 267  * Clean the events structure of a lttng_poll_event. It's the caller
 268  * responsability to free the lttng_poll_event memory.
 269  */
 270 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 271 {
 272         if (events) {
 273                 __lttng_poll_free((void *) events->events);
 274         }
 275 }
 276
 277 #endif /* HAVE_EPOLL */
 278
 279 #endif /* _LTT_POLL_H */