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