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 it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; only version 2 of the License.
   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 with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA  02111-1307, 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         free(events);
  46 }
  47
  48 /*
  49  * epoll(7) implementation.
  50  */
  51 #ifdef HAVE_EPOLL
  52 #include <sys/epoll.h>
  53
  54 /* See man epoll(7) for this define path */
  55 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  56
  57 enum {
  58         /* Polling variables compatibility for epoll */
  59         LPOLLIN = EPOLLIN,
  60         LPOLLPRI = EPOLLPRI,
  61         LPOLLOUT = EPOLLOUT,
  62         LPOLLRDNORM = EPOLLRDNORM,
  63         LPOLLRDBAND = EPOLLRDBAND,
  64         LPOLLWRNORM = EPOLLWRNORM,
  65         LPOLLWRBAND = EPOLLWRBAND,
  66         LPOLLMSG = EPOLLMSG,
  67         LPOLLERR = EPOLLERR,
  68         LPOLLHUP = EPOLLHUP,
  69         LPOLLNVAL = EPOLLHUP,
  70         LPOLLRDHUP = EPOLLRDHUP,
  71         /* Close on exec feature of epoll */
  72         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  73 };
  74
  75 struct compat_epoll_event {
  76         int epfd;
  77         uint32_t nb_fd;       /* Current number of fd in events */
  78         uint32_t events_size; /* Size of events array */
  79         struct epoll_event *events;
  80 };
  81 #define lttng_poll_event compat_epoll_event
  82
  83 /*
  84  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
  85  * being the index of the events array.
  86  */
  87 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
  88 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
  89 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
  90 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
  91
  92 /*
  93  * Create the epoll set. No memory allocation is done here.
  94  */
  95 extern int compat_epoll_create(struct lttng_poll_event *events,
  96                 int size, int flags);
  97 #define lttng_poll_create(events, size, flags) \
  98         compat_epoll_create(events, size, flags)
  99
 100 /*
 101  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 102  * data structure (events).
 103  */
 104 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 105 #define lttng_poll_wait(events, timeout) \
 106         compat_epoll_wait(events, timeout)
 107
 108 /*
 109  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 110  */
 111 extern int compat_epoll_add(struct lttng_poll_event *events,
 112                 int fd, uint32_t req_events);
 113 #define lttng_poll_add(events, fd, req_events) \
 114         compat_epoll_add(events, fd, req_events)
 115
 116 /*
 117  * Remove a fd from the epoll set.
 118  */
 119 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 120 #define lttng_poll_del(events, fd) \
 121         compat_epoll_del(events, fd)
 122
 123 /*
 124  * Set up the poll set limits variable poll_max_size
 125  */
 126 extern void compat_epoll_set_max_size(void);
 127 #define lttng_poll_set_max_size() \
 128         compat_epoll_set_max_size()
 129
 130 /*
 131  * This function memset with zero the structure since it can be reused at each
 132  * round of a main loop. Being in a loop and using a non static number of fds,
 133  * this function must be called to insure coherent events with associted fds.
 134  */
 135 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 136 {
 137         if (events && events->events) {
 138                 memset(events->events, 0,
 139                                 events->nb_fd * sizeof(struct epoll_event));
 140         }
 141 }
 142
 143 /*
 144  * Clean the events structure of a lttng_poll_event. It's the caller
 145  * responsability to free the lttng_poll_event memory.
 146  */
 147 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 148 {
 149         if (events) {
 150                 close(events->epfd);
 151                 __lttng_poll_free((void *) events->events);
 152         }
 153 }
 154
 155 #else   /* HAVE_EPOLL */
 156 /*
 157  * Fallback on poll(2) API
 158  */
 159
 160 /* Needed for some poll event values */
 161 #ifndef __USE_XOPEN
 162 #define __USE_XOPEN
 163 #endif
 164
 165 /* Needed for some poll event values */
 166 #ifndef __USE_GNU
 167 #define __USE_GNU
 168 #endif
 169
 170 #include <poll.h>
 171 #include <stdint.h>
 172
 173 enum {
 174         /* Polling variables compatibility for poll */
 175         LPOLLIN = POLLIN,
 176         LPOLLPRI = POLLPRI,
 177         LPOLLOUT = POLLOUT,
 178         LPOLLRDNORM = POLLRDNORM,
 179         LPOLLRDBAND = POLLRDBAND,
 180         LPOLLWRNORM = POLLWRNORM,
 181         LPOLLWRBAND = POLLWRBAND,
 182         LPOLLMSG = POLLMSG,
 183         LPOLLERR = POLLERR,
 184         LPOLLHUP = POLLHUP | POLLNVAL,
 185         LPOLLRDHUP = POLLRDHUP,
 186         /* Close on exec feature does not exist for poll(2) */
 187         LTTNG_CLOEXEC = 0xdead,
 188 };
 189
 190 struct compat_poll_event {
 191         uint32_t nb_fd;       /* Current number of fd in events */
 192         uint32_t events_size; /* Size of events array */
 193         struct pollfd *events;
 194 };
 195 #define lttng_poll_event compat_poll_event
 196
 197 /*
 198  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 199  * being the index of the events array.
 200  */
 201 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].fd
 202 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].revents
 203 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 204 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 205
 206 /*
 207  * Create a pollfd structure of size 'size'.
 208  */
 209 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 210 #define lttng_poll_create(events, size, flags) \
 211         compat_poll_create(events, size)
 212
 213 /*
 214  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 215  * structure.
 216  */
 217 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 218 #define lttng_poll_wait(events, timeout) \
 219         compat_poll_wait(events, timeout)
 220
 221 /*
 222  * Add the fd to the pollfd structure. Resize if needed.
 223  */
 224 extern int compat_poll_add(struct lttng_poll_event *events,
 225                 int fd, uint32_t req_events);
 226 #define lttng_poll_add(events, fd, req_events) \
 227         compat_poll_add(events, fd, req_events)
 228
 229 /*
 230  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 231  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 232  * one is freed().
 233  */
 234 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 235 #define lttng_poll_del(events, fd) \
 236         compat_poll_del(events, fd)
 237
 238 /*
 239  * Set up the poll set limits variable poll_max_size
 240  */
 241 extern void compat_poll_set_max_size(void);
 242 #define lttng_poll_set_max_size() \
 243         compat_poll_set_max_size()
 244
 245 /*
 246  * No need to reset a pollfd structure for poll(2)
 247  */
 248 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 249 {}
 250
 251 /*
 252  * Clean the events structure of a lttng_poll_event. It's the caller
 253  * responsability to free the lttng_poll_event memory.
 254  */
 255 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 256 {
 257         if (events) {
 258                 __lttng_poll_free((void *) events->events);
 259         }
 260 }
 261
 262 #endif /* HAVE_EPOLL */
 263
 264 #endif /* _LTT_POLL_H */