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