src/common/compat/poll.h

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifndef _LTT_POLL_H
   9 #define _LTT_POLL_H
  10
  11 #include <string.h>
  12 #include <unistd.h>
  13
  14 #include <common/common.h>
  15
  16 /*
  17  * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
  18  */
  19 static inline void __lttng_poll_free(void *events)
  20 {
  21         free(events);
  22 }
  23
  24 /*
  25  * epoll(7) implementation.
  26  */
  27 #ifdef HAVE_EPOLL
  28 #include <sys/epoll.h>
  29 #include <stdio.h>
  30 #include <features.h>
  31 #include <common/compat/fcntl.h>
  32
  33 /* See man epoll(7) for this define path */
  34 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  35
  36 enum {
  37         /* Polling variables compatibility for epoll */
  38         LPOLLIN = EPOLLIN,
  39         LPOLLPRI = EPOLLPRI,
  40         LPOLLOUT = EPOLLOUT,
  41         LPOLLRDNORM = EPOLLRDNORM,
  42         LPOLLRDBAND = EPOLLRDBAND,
  43         LPOLLWRNORM = EPOLLWRNORM,
  44         LPOLLWRBAND = EPOLLWRBAND,
  45         LPOLLMSG = EPOLLMSG,
  46         LPOLLERR = EPOLLERR,
  47         LPOLLHUP = EPOLLHUP,
  48         LPOLLNVAL = EPOLLHUP,
  49         LPOLLRDHUP = EPOLLRDHUP,
  50         /* Close on exec feature of epoll */
  51 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
  52         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  53 #else
  54         /*
  55          * EPOLL_CLOEXEC was added in glibc 2.8 (usually used in conjunction with
  56          * epoll_create1(..)), but since neither EPOLL_CLOEXEC exists nor
  57          * epoll_create1(..), we set it to FD_CLOEXEC so that we can pass it
  58          * directly to fcntl(..) instead.
  59          */
  60         LTTNG_CLOEXEC = FD_CLOEXEC,
  61 #endif
  62 };
  63
  64 struct compat_epoll_event {
  65         int epfd;
  66         uint32_t nb_fd;       /* Current number of fd in events */
  67         uint32_t alloc_size; /* Size of events array */
  68         uint32_t init_size;     /* Initial size of events array */
  69         struct epoll_event *events;
  70 };
  71 #define lttng_poll_event compat_epoll_event
  72
  73 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
  74                 int index, uint32_t nb_fd)
  75 {
  76         LTTNG_ASSERT(events);
  77         LTTNG_ASSERT(index != nb_fd);
  78
  79         if (index == 0 || nb_fd == 0) {
  80                 return -1;
  81         } else {
  82                 return events->events[index - 1].data.fd;
  83         }
  84 }
  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 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
  95         __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
  96
  97 /* Create the epoll set. */
  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 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 104 static inline int compat_glibc_epoll_create(int size __attribute__((unused)),
 105                 int flags)
 106 {
 107         return epoll_create1(flags);
 108 }
 109 #else
 110 static inline int compat_glibc_epoll_create(int size, int flags)
 111 {
 112         /*
 113          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 114          * epoll_create(..) also means that we lose the possibility to
 115          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 116          * fcntl(..).
 117          */
 118         int efd = epoll_create(size);
 119         LTTNG_ASSERT(fcntl(efd, F_SETFD, flags) != -1);
 120         return efd;
 121 }
 122 #endif
 123
 124 /*
 125  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 126  * data structure (events).
 127  */
 128 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
 129                 bool interruptible);
 130 #define lttng_poll_wait(events, timeout) \
 131         compat_epoll_wait(events, timeout, false)
 132 #define lttng_poll_wait_interruptible(events, timeout) \
 133         compat_epoll_wait(events, timeout, true)
 134
 135 /*
 136  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 137  */
 138 extern int compat_epoll_add(struct lttng_poll_event *events,
 139                 int fd, uint32_t req_events);
 140 #define lttng_poll_add(events, fd, req_events) \
 141         compat_epoll_add(events, fd, req_events)
 142
 143 /*
 144  * Remove a fd from the epoll set.
 145  */
 146 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 147 #define lttng_poll_del(events, fd) \
 148         compat_epoll_del(events, fd)
 149
 150 /*
 151  * Modify an fd's events in the epoll set.
 152  */
 153 extern int compat_epoll_mod(struct lttng_poll_event *events,
 154                 int fd, uint32_t req_events);
 155 #define lttng_poll_mod(events, fd, req_events) \
 156         compat_epoll_mod(events, fd, req_events)
 157
 158 /*
 159  * Set up the poll set limits variable poll_max_size
 160  */
 161 extern int compat_epoll_set_max_size(void);
 162 #define lttng_poll_set_max_size() \
 163         compat_epoll_set_max_size()
 164
 165 /*
 166  * This function memset with zero the structure since it can be reused at each
 167  * round of a main loop. Being in a loop and using a non static number of fds,
 168  * this function must be called to insure coherent events with associted fds.
 169  */
 170 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 171 {
 172         if (events && events->events) {
 173                 memset(events->events, 0,
 174                                 events->nb_fd * sizeof(struct epoll_event));
 175         }
 176 }
 177
 178 /*
 179  * Initialize an already allocated poll event data structure. For epoll(), the
 180  * epfd is set to -1 to indicate that it's not usable.
 181  */
 182 static inline void lttng_poll_init(struct lttng_poll_event *events)
 183 {
 184         memset(events, 0, sizeof(struct lttng_poll_event));
 185         /* Set fd to -1 so if clean before created, we don't close 0. */
 186         events->epfd = -1;
 187 }
 188
 189 /*
 190  * Clean the events structure of a lttng_poll_event. It's the caller
 191  * responsability to free the lttng_poll_event memory.
 192  */
 193 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 194 {
 195         int ret;
 196
 197         if (!events) {
 198                 return;
 199         }
 200
 201         if (events->epfd >= 0) {
 202                 ret = close(events->epfd);
 203                 if (ret) {
 204                         PERROR("close");
 205                 }
 206         }
 207
 208         __lttng_poll_free((void *) events->events);
 209 }
 210
 211 #else   /* HAVE_EPOLL */
 212 /*
 213  * Fallback on poll(2) API
 214  */
 215
 216 /* Needed for some poll event values */
 217 #ifndef __USE_XOPEN
 218 #define __USE_XOPEN
 219 #endif
 220
 221 /* Needed for some poll event values */
 222 #ifndef __USE_GNU
 223 #define __USE_GNU
 224 #endif
 225
 226 #include <poll.h>
 227 #include <stdint.h>
 228
 229 enum {
 230         /* Polling variables compatibility for poll */
 231         LPOLLIN = POLLIN,
 232         LPOLLPRI = POLLPRI,
 233         LPOLLOUT = POLLOUT,
 234         LPOLLRDNORM = POLLRDNORM,
 235         LPOLLRDBAND = POLLRDBAND,
 236         LPOLLWRNORM = POLLWRNORM,
 237         LPOLLWRBAND = POLLWRBAND,
 238 #if __linux__
 239         LPOLLMSG = POLLMSG,
 240         LPOLLRDHUP = POLLRDHUP,
 241 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 242         LPOLLMSG = 0,
 243         LPOLLRDHUP = 0,
 244 #else
 245 #error "Please add support for your OS."
 246 #endif /* __linux__ */
 247         LPOLLERR = POLLERR,
 248         LPOLLHUP = POLLHUP | POLLNVAL,
 249         /* Close on exec feature does not exist for poll(2) */
 250         LTTNG_CLOEXEC = 0xdead,
 251 };
 252
 253 struct compat_poll_event_array {
 254         uint32_t nb_fd;       /* Current number of fd in events */
 255         uint32_t alloc_size; /* Size of events array */
 256         /* Initial size of the pollset. We never shrink below that. */
 257         uint32_t init_size;
 258         struct pollfd *events;
 259 };
 260
 261 struct compat_poll_event {
 262         /*
 263          * Modified by the wait action. Updated using current fields if the
 264          * need_update flag is set.
 265          */
 266         struct compat_poll_event_array wait;
 267         /*
 268          * This is modified by add/del actions being the _current_ flow of
 269          * execution before a poll wait is done.
 270          */
 271         struct compat_poll_event_array current;
 272
 273         /* Indicate if wait.events need to be updated from current. */
 274         int need_update:1;
 275 };
 276 #define lttng_poll_event compat_poll_event
 277
 278 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 279                 int index, uint32_t nb_fd)
 280 {
 281         LTTNG_ASSERT(events);
 282         LTTNG_ASSERT(index != nb_fd);
 283
 284         if (index == 0 || nb_fd == 0) {
 285                 return -1;
 286         } else {
 287                 return events->current.events[index - 1].fd;
 288         }
 289 }
 290
 291 /*
 292  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 293  * being the index of the events array.
 294  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 295  * current list for test compatibility purposes.
 296  */
 297 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 298 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 299 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->current.nb_fd
 300 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 301 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 302         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 303
 304 /*
 305  * Create a pollfd structure of size 'size'.
 306  */
 307 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 308 #define lttng_poll_create(events, size, flags) \
 309         compat_poll_create(events, size)
 310
 311 /*
 312  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 313  * structure.
 314  */
 315 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout,
 316                 bool interruptible);
 317 #define lttng_poll_wait(events, timeout) \
 318         compat_poll_wait(events, timeout, false)
 319 #define lttng_poll_wait_interruptible(events, timeout) \
 320         compat_poll_wait(events, timeout, true)
 321
 322 /*
 323  * Add the fd to the pollfd structure. Resize if needed.
 324  */
 325 extern int compat_poll_add(struct lttng_poll_event *events,
 326                 int fd, uint32_t req_events);
 327 #define lttng_poll_add(events, fd, req_events) \
 328         compat_poll_add(events, fd, req_events)
 329
 330 /*
 331  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 332  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 333  * one is freed().
 334  */
 335 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 336 #define lttng_poll_del(events, fd) \
 337         compat_poll_del(events, fd)
 338
 339 /*
 340  * Modify an fd's events in the poll set.
 341  */
 342 extern int compat_poll_mod(struct lttng_poll_event *events,
 343                 int fd, uint32_t req_events);
 344 #define lttng_poll_mod(events, fd, req_events) \
 345         compat_poll_mod(events, fd, req_events)
 346
 347 /*
 348  * Set up the poll set limits variable poll_max_size
 349  */
 350 extern int compat_poll_set_max_size(void);
 351 #define lttng_poll_set_max_size() \
 352         compat_poll_set_max_size()
 353
 354 /*
 355  * No need to reset a pollfd structure for poll(2)
 356  */
 357 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 358 {}
 359
 360 /*
 361  * Initialize an already allocated poll event data structure.
 362  */
 363 static inline void lttng_poll_init(struct lttng_poll_event *events)
 364 {
 365         memset(events, 0, sizeof(struct lttng_poll_event));
 366 }
 367
 368 /*
 369  * Clean the events structure of a lttng_poll_event. It's the caller
 370  * responsability to free the lttng_poll_event memory.
 371  */
 372 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 373 {
 374         if (events) {
 375                 __lttng_poll_free((void *) events->wait.events);
 376                 __lttng_poll_free((void *) events->current.events);
 377         }
 378 }
 379
 380 #endif /* HAVE_EPOLL */
 381
 382 #endif /* _LTT_POLL_H */