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 #ifdef __cplusplus
  17 extern "C" {
  18 #endif
  19
  20 /*
  21  * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
  22  */
  23 static inline void __lttng_poll_free(void *events)
  24 {
  25         free(events);
  26 }
  27
  28 #ifdef __cplusplus
  29 }
  30 #endif
  31
  32 /*
  33  * epoll(7) implementation.
  34  */
  35 #ifdef HAVE_EPOLL
  36 #include <sys/epoll.h>
  37 #include <stdio.h>
  38 #include <features.h>
  39 #include <common/compat/fcntl.h>
  40
  41 #ifdef __cplusplus
  42 extern "C" {
  43 #endif
  44
  45 /* See man epoll(7) for this define path */
  46 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  47
  48 enum {
  49         /* Polling variables compatibility for epoll */
  50         LPOLLIN = EPOLLIN,
  51         LPOLLPRI = EPOLLPRI,
  52         LPOLLOUT = EPOLLOUT,
  53         LPOLLRDNORM = EPOLLRDNORM,
  54         LPOLLRDBAND = EPOLLRDBAND,
  55         LPOLLWRNORM = EPOLLWRNORM,
  56         LPOLLWRBAND = EPOLLWRBAND,
  57         LPOLLMSG = EPOLLMSG,
  58         LPOLLERR = EPOLLERR,
  59         LPOLLHUP = EPOLLHUP,
  60         LPOLLNVAL = EPOLLHUP,
  61         LPOLLRDHUP = EPOLLRDHUP,
  62         /* Close on exec feature of epoll */
  63 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
  64         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  65 #else
  66         /*
  67          * EPOLL_CLOEXEC was added in glibc 2.8 (usually used in conjunction with
  68          * epoll_create1(..)), but since neither EPOLL_CLOEXEC exists nor
  69          * epoll_create1(..), we set it to FD_CLOEXEC so that we can pass it
  70          * directly to fcntl(..) instead.
  71          */
  72         LTTNG_CLOEXEC = FD_CLOEXEC,
  73 #endif
  74 };
  75
  76 struct compat_epoll_event {
  77         int epfd;
  78         uint32_t nb_fd;       /* Current number of fd in events */
  79         uint32_t alloc_size; /* Size of events array */
  80         uint32_t init_size;     /* Initial size of events array */
  81         struct epoll_event *events;
  82 };
  83 #define lttng_poll_event compat_epoll_event
  84
  85 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
  86                 int index, uint32_t nb_fd)
  87 {
  88         LTTNG_ASSERT(events);
  89         LTTNG_ASSERT(index != nb_fd);
  90
  91         if (index == 0 || nb_fd == 0) {
  92                 return -1;
  93         } else {
  94                 return events->events[index - 1].data.fd;
  95         }
  96 }
  97
  98 /*
  99  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 100  * being the index of the events array.
 101  */
 102 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
 103 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
 104 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 105 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 106 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 107         __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 108
 109 /* Create the epoll set. */
 110 extern int compat_epoll_create(struct lttng_poll_event *events,
 111                 int size, int flags);
 112 #define lttng_poll_create(events, size, flags) \
 113         compat_epoll_create(events, size, flags)
 114
 115 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 116 static inline int compat_glibc_epoll_create(int size __attribute__((unused)),
 117                 int flags)
 118 {
 119         return epoll_create1(flags);
 120 }
 121 #else
 122 static inline int compat_glibc_epoll_create(int size, int flags)
 123 {
 124         /*
 125          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 126          * epoll_create(..) also means that we lose the possibility to
 127          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 128          * fcntl(..).
 129          */
 130         int efd = epoll_create(size);
 131         LTTNG_ASSERT(fcntl(efd, F_SETFD, flags) != -1);
 132         return efd;
 133 }
 134 #endif
 135
 136 /*
 137  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 138  * data structure (events).
 139  */
 140 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
 141                 bool interruptible);
 142 #define lttng_poll_wait(events, timeout) \
 143         compat_epoll_wait(events, timeout, false)
 144 #define lttng_poll_wait_interruptible(events, timeout) \
 145         compat_epoll_wait(events, timeout, true)
 146
 147 /*
 148  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 149  */
 150 extern int compat_epoll_add(struct lttng_poll_event *events,
 151                 int fd, uint32_t req_events);
 152 #define lttng_poll_add(events, fd, req_events) \
 153         compat_epoll_add(events, fd, req_events)
 154
 155 /*
 156  * Remove a fd from the epoll set.
 157  */
 158 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 159 #define lttng_poll_del(events, fd) \
 160         compat_epoll_del(events, fd)
 161
 162 /*
 163  * Modify an fd's events in the epoll set.
 164  */
 165 extern int compat_epoll_mod(struct lttng_poll_event *events,
 166                 int fd, uint32_t req_events);
 167 #define lttng_poll_mod(events, fd, req_events) \
 168         compat_epoll_mod(events, fd, req_events)
 169
 170 /*
 171  * Set up the poll set limits variable poll_max_size
 172  */
 173 extern int compat_epoll_set_max_size(void);
 174 #define lttng_poll_set_max_size() \
 175         compat_epoll_set_max_size()
 176
 177 /*
 178  * This function memset with zero the structure since it can be reused at each
 179  * round of a main loop. Being in a loop and using a non static number of fds,
 180  * this function must be called to insure coherent events with associted fds.
 181  */
 182 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 183 {
 184         if (events && events->events) {
 185                 memset(events->events, 0,
 186                                 events->nb_fd * sizeof(struct epoll_event));
 187         }
 188 }
 189
 190 /*
 191  * Initialize an already allocated poll event data structure. For epoll(), the
 192  * epfd is set to -1 to indicate that it's not usable.
 193  */
 194 static inline void lttng_poll_init(struct lttng_poll_event *events)
 195 {
 196         memset(events, 0, sizeof(struct lttng_poll_event));
 197         /* Set fd to -1 so if clean before created, we don't close 0. */
 198         events->epfd = -1;
 199 }
 200
 201 /*
 202  * Clean the events structure of a lttng_poll_event. It's the caller
 203  * responsability to free the lttng_poll_event memory.
 204  */
 205 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 206 {
 207         int ret;
 208
 209         if (!events) {
 210                 return;
 211         }
 212
 213         if (events->epfd >= 0) {
 214                 ret = close(events->epfd);
 215                 if (ret) {
 216                         PERROR("close");
 217                 }
 218         }
 219
 220         __lttng_poll_free((void *) events->events);
 221 }
 222
 223 #ifdef __cplusplus
 224 }
 225 #endif
 226
 227 #else   /* HAVE_EPOLL */
 228 /*
 229  * Fallback on poll(2) API
 230  */
 231
 232 /* Needed for some poll event values */
 233 #ifndef __USE_XOPEN
 234 #define __USE_XOPEN
 235 #endif
 236
 237 /* Needed for some poll event values */
 238 #ifndef __USE_GNU
 239 #define __USE_GNU
 240 #endif
 241
 242 #include <poll.h>
 243 #include <stdint.h>
 244
 245 #ifdef __cplusplus
 246 extern "C" {
 247 #endif
 248
 249 enum {
 250         /* Polling variables compatibility for poll */
 251         LPOLLIN = POLLIN,
 252         LPOLLPRI = POLLPRI,
 253         LPOLLOUT = POLLOUT,
 254         LPOLLRDNORM = POLLRDNORM,
 255         LPOLLRDBAND = POLLRDBAND,
 256         LPOLLWRNORM = POLLWRNORM,
 257         LPOLLWRBAND = POLLWRBAND,
 258 #if __linux__
 259         LPOLLMSG = POLLMSG,
 260         LPOLLRDHUP = POLLRDHUP,
 261 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 262         LPOLLMSG = 0,
 263         LPOLLRDHUP = 0,
 264 #else
 265 #error "Please add support for your OS."
 266 #endif /* __linux__ */
 267         LPOLLERR = POLLERR,
 268         LPOLLHUP = POLLHUP | POLLNVAL,
 269         /* Close on exec feature does not exist for poll(2) */
 270         LTTNG_CLOEXEC = 0xdead,
 271 };
 272
 273 struct compat_poll_event_array {
 274         uint32_t nb_fd;       /* Current number of fd in events */
 275         uint32_t alloc_size; /* Size of events array */
 276         /* Initial size of the pollset. We never shrink below that. */
 277         uint32_t init_size;
 278         struct pollfd *events;
 279 };
 280
 281 struct compat_poll_event {
 282         /*
 283          * Modified by the wait action. Updated using current fields if the
 284          * need_update flag is set.
 285          */
 286         struct compat_poll_event_array wait;
 287         /*
 288          * This is modified by add/del actions being the _current_ flow of
 289          * execution before a poll wait is done.
 290          */
 291         struct compat_poll_event_array current;
 292
 293         /* Indicate if wait.events need to be updated from current. */
 294         int need_update:1;
 295 };
 296 #define lttng_poll_event compat_poll_event
 297
 298 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 299                 int index, uint32_t nb_fd)
 300 {
 301         LTTNG_ASSERT(events);
 302         LTTNG_ASSERT(index != nb_fd);
 303
 304         if (index == 0 || nb_fd == 0) {
 305                 return -1;
 306         } else {
 307                 return events->current.events[index - 1].fd;
 308         }
 309 }
 310
 311 /*
 312  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 313  * being the index of the events array.
 314  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 315  * current list for test compatibility purposes.
 316  */
 317 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 318 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 319 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->current.nb_fd
 320 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 321 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 322         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 323
 324 /*
 325  * Create a pollfd structure of size 'size'.
 326  */
 327 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 328 #define lttng_poll_create(events, size, flags) \
 329         compat_poll_create(events, size)
 330
 331 /*
 332  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 333  * structure.
 334  */
 335 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout,
 336                 bool interruptible);
 337 #define lttng_poll_wait(events, timeout) \
 338         compat_poll_wait(events, timeout, false)
 339 #define lttng_poll_wait_interruptible(events, timeout) \
 340         compat_poll_wait(events, timeout, true)
 341
 342 /*
 343  * Add the fd to the pollfd structure. Resize if needed.
 344  */
 345 extern int compat_poll_add(struct lttng_poll_event *events,
 346                 int fd, uint32_t req_events);
 347 #define lttng_poll_add(events, fd, req_events) \
 348         compat_poll_add(events, fd, req_events)
 349
 350 /*
 351  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 352  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 353  * one is freed().
 354  */
 355 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 356 #define lttng_poll_del(events, fd) \
 357         compat_poll_del(events, fd)
 358
 359 /*
 360  * Modify an fd's events in the poll set.
 361  */
 362 extern int compat_poll_mod(struct lttng_poll_event *events,
 363                 int fd, uint32_t req_events);
 364 #define lttng_poll_mod(events, fd, req_events) \
 365         compat_poll_mod(events, fd, req_events)
 366
 367 /*
 368  * Set up the poll set limits variable poll_max_size
 369  */
 370 extern int compat_poll_set_max_size(void);
 371 #define lttng_poll_set_max_size() \
 372         compat_poll_set_max_size()
 373
 374 /*
 375  * No need to reset a pollfd structure for poll(2)
 376  */
 377 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 378 {}
 379
 380 /*
 381  * Initialize an already allocated poll event data structure.
 382  */
 383 static inline void lttng_poll_init(struct lttng_poll_event *events)
 384 {
 385         memset(events, 0, sizeof(struct lttng_poll_event));
 386 }
 387
 388 /*
 389  * Clean the events structure of a lttng_poll_event. It's the caller
 390  * responsability to free the lttng_poll_event memory.
 391  */
 392 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 393 {
 394         if (events) {
 395                 __lttng_poll_free((void *) events->wait.events);
 396                 __lttng_poll_free((void *) events->current.events);
 397         }
 398 }
 399
 400 #ifdef __cplusplus
 401 }
 402 #endif
 403
 404 #endif /* HAVE_EPOLL */
 405
 406 #endif /* _LTT_POLL_H */