src/common/compat/poll.hpp

   1 /*
   2  * Copyright (C) 2011 EfficiOS Inc.
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-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.hpp>
  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.hpp>
  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 #include <poll.h>
 217 #include <stdint.h>
 218
 219 enum {
 220         /* Polling variables compatibility for poll */
 221         LPOLLIN = POLLIN,
 222         LPOLLPRI = POLLPRI,
 223         LPOLLOUT = POLLOUT,
 224         LPOLLRDNORM = POLLRDNORM,
 225         LPOLLRDBAND = POLLRDBAND,
 226         LPOLLWRNORM = POLLWRNORM,
 227         LPOLLWRBAND = POLLWRBAND,
 228 #ifdef __USE_GNU
 229         LPOLLMSG = POLLMSG,
 230         LPOLLRDHUP = POLLRDHUP,
 231 #else
 232         LPOLLMSG = 0,
 233         LPOLLRDHUP = 0,
 234 #endif /* __USE_GNU */
 235         LPOLLERR = POLLERR,
 236         LPOLLHUP = POLLHUP | POLLNVAL,
 237         /* Close on exec feature does not exist for poll(2) */
 238         LTTNG_CLOEXEC = 0xdead,
 239 };
 240
 241 struct compat_poll_event_array {
 242         uint32_t nb_fd;       /* Current number of fd in events */
 243         uint32_t alloc_size; /* Size of events array */
 244         /* Initial size of the pollset. We never shrink below that. */
 245         uint32_t init_size;
 246         struct pollfd *events;
 247 };
 248
 249 struct compat_poll_event {
 250         /*
 251          * Modified by the wait action. Updated using current fields if the
 252          * need_update flag is set.
 253          */
 254         struct compat_poll_event_array wait;
 255         /*
 256          * This is modified by add/del actions being the _current_ flow of
 257          * execution before a poll wait is done.
 258          */
 259         struct compat_poll_event_array current;
 260
 261         /* Indicate if wait.events need to be updated from current. */
 262         int need_update:1;
 263 };
 264 #define lttng_poll_event compat_poll_event
 265
 266 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 267                 int index, uint32_t nb_fd)
 268 {
 269         LTTNG_ASSERT(events);
 270         LTTNG_ASSERT(index != nb_fd);
 271
 272         if (index == 0 || nb_fd == 0) {
 273                 return -1;
 274         } else {
 275                 return events->current.events[index - 1].fd;
 276         }
 277 }
 278
 279 /*
 280  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 281  * being the index of the events array.
 282  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 283  * current list for test compatibility purposes.
 284  */
 285 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 286 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 287 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->current.nb_fd
 288 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 289 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 290         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 291
 292 /*
 293  * Create a pollfd structure of size 'size'.
 294  */
 295 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 296 #define lttng_poll_create(events, size, flags) \
 297         compat_poll_create(events, size)
 298
 299 /*
 300  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 301  * structure.
 302  */
 303 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout,
 304                 bool interruptible);
 305 #define lttng_poll_wait(events, timeout) \
 306         compat_poll_wait(events, timeout, false)
 307 #define lttng_poll_wait_interruptible(events, timeout) \
 308         compat_poll_wait(events, timeout, true)
 309
 310 /*
 311  * Add the fd to the pollfd structure. Resize if needed.
 312  */
 313 extern int compat_poll_add(struct lttng_poll_event *events,
 314                 int fd, uint32_t req_events);
 315 #define lttng_poll_add(events, fd, req_events) \
 316         compat_poll_add(events, fd, req_events)
 317
 318 /*
 319  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 320  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 321  * one is freed().
 322  */
 323 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 324 #define lttng_poll_del(events, fd) \
 325         compat_poll_del(events, fd)
 326
 327 /*
 328  * Modify an fd's events in the poll set.
 329  */
 330 extern int compat_poll_mod(struct lttng_poll_event *events,
 331                 int fd, uint32_t req_events);
 332 #define lttng_poll_mod(events, fd, req_events) \
 333         compat_poll_mod(events, fd, req_events)
 334
 335 /*
 336  * Set up the poll set limits variable poll_max_size
 337  */
 338 extern int compat_poll_set_max_size(void);
 339 #define lttng_poll_set_max_size() \
 340         compat_poll_set_max_size()
 341
 342 /*
 343  * No need to reset a pollfd structure for poll(2)
 344  */
 345 static inline void lttng_poll_reset(
 346                 struct lttng_poll_event *events __attribute__((unused)))
 347 {}
 348
 349 /*
 350  * Initialize an already allocated poll event data structure.
 351  */
 352 static inline void lttng_poll_init(struct lttng_poll_event *events)
 353 {
 354         memset(events, 0, sizeof(struct lttng_poll_event));
 355 }
 356
 357 /*
 358  * Clean the events structure of a lttng_poll_event. It's the caller
 359  * responsability to free the lttng_poll_event memory.
 360  */
 361 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 362 {
 363         if (events) {
 364                 __lttng_poll_free((void *) events->wait.events);
 365                 __lttng_poll_free((void *) events->current.events);
 366         }
 367 }
 368
 369 #endif /* HAVE_EPOLL */
 370
 371 #endif /* _LTT_POLL_H */