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 <assert.h>
  12 #include <string.h>
  13 #include <unistd.h>
  14
  15 #include <common/common.h>
  16
  17 /*
  18  * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
  19  */
  20 static inline void __lttng_poll_free(void *events)
  21 {
  22         free(events);
  23 }
  24
  25 /*
  26  * epoll(7) implementation.
  27  */
  28 #ifdef HAVE_EPOLL
  29 #include <sys/epoll.h>
  30 #include <stdio.h>
  31 #include <features.h>
  32 #include <common/compat/fcntl.h>
  33
  34 /* See man epoll(7) for this define path */
  35 #define COMPAT_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  36
  37 enum {
  38         /* Polling variables compatibility for epoll */
  39         LPOLLIN = EPOLLIN,
  40         LPOLLPRI = EPOLLPRI,
  41         LPOLLOUT = EPOLLOUT,
  42         LPOLLRDNORM = EPOLLRDNORM,
  43         LPOLLRDBAND = EPOLLRDBAND,
  44         LPOLLWRNORM = EPOLLWRNORM,
  45         LPOLLWRBAND = EPOLLWRBAND,
  46         LPOLLMSG = EPOLLMSG,
  47         LPOLLERR = EPOLLERR,
  48         LPOLLHUP = EPOLLHUP,
  49         LPOLLNVAL = EPOLLHUP,
  50         LPOLLRDHUP = EPOLLRDHUP,
  51         /* Close on exec feature of epoll */
  52 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
  53         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  54 #else
  55         /*
  56          * EPOLL_CLOEXEC was added in glibc 2.8 (usually used in conjunction with
  57          * epoll_create1(..)), but since neither EPOLL_CLOEXEC exists nor
  58          * epoll_create1(..), we set it to FD_CLOEXEC so that we can pass it
  59          * directly to fcntl(..) instead.
  60          */
  61         LTTNG_CLOEXEC = FD_CLOEXEC,
  62 #endif
  63 };
  64
  65 struct compat_epoll_event {
  66         int epfd;
  67         uint32_t nb_fd;       /* Current number of fd in events */
  68         uint32_t alloc_size; /* Size of events array */
  69         uint32_t init_size;     /* Initial size of events array */
  70         struct epoll_event *events;
  71 };
  72 #define lttng_poll_event compat_epoll_event
  73
  74 static inline int __lttng_epoll_get_prev_fd(struct lttng_poll_event *events,
  75                 int index, uint32_t nb_fd)
  76 {
  77         assert(events);
  78         assert(index != nb_fd);
  79
  80         if (index == 0 || nb_fd == 0) {
  81                 return -1;
  82         } else {
  83                 return events->events[index - 1].data.fd;
  84         }
  85 }
  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 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
  96         __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
  97
  98 /* Create the epoll set. */
  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 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 105 static inline int compat_glibc_epoll_create(int size __attribute__((unused)),
 106                 int flags)
 107 {
 108         return epoll_create1(flags);
 109 }
 110 #else
 111 static inline int compat_glibc_epoll_create(int size, int flags)
 112 {
 113         /*
 114          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 115          * epoll_create(..) also means that we lose the possibility to
 116          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 117          * fcntl(..).
 118          */
 119         int efd = epoll_create(size);
 120         assert(fcntl(efd, F_SETFD, flags) != -1);
 121         return efd;
 122 }
 123 #endif
 124
 125 /*
 126  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 127  * data structure (events).
 128  */
 129 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout,
 130                 bool interruptible);
 131 #define lttng_poll_wait(events, timeout) \
 132         compat_epoll_wait(events, timeout, false)
 133 #define lttng_poll_wait_interruptible(events, timeout) \
 134         compat_epoll_wait(events, timeout, true)
 135
 136 /*
 137  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 138  */
 139 extern int compat_epoll_add(struct lttng_poll_event *events,
 140                 int fd, uint32_t req_events);
 141 #define lttng_poll_add(events, fd, req_events) \
 142         compat_epoll_add(events, fd, req_events)
 143
 144 /*
 145  * Remove a fd from the epoll set.
 146  */
 147 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 148 #define lttng_poll_del(events, fd) \
 149         compat_epoll_del(events, fd)
 150
 151 /*
 152  * Modify an fd's events in the epoll set.
 153  */
 154 extern int compat_epoll_mod(struct lttng_poll_event *events,
 155                 int fd, uint32_t req_events);
 156 #define lttng_poll_mod(events, fd, req_events) \
 157         compat_epoll_mod(events, fd, req_events)
 158
 159 /*
 160  * Set up the poll set limits variable poll_max_size
 161  */
 162 extern int compat_epoll_set_max_size(void);
 163 #define lttng_poll_set_max_size() \
 164         compat_epoll_set_max_size()
 165
 166 /*
 167  * This function memset with zero the structure since it can be reused at each
 168  * round of a main loop. Being in a loop and using a non static number of fds,
 169  * this function must be called to insure coherent events with associted fds.
 170  */
 171 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 172 {
 173         if (events && events->events) {
 174                 memset(events->events, 0,
 175                                 events->nb_fd * sizeof(struct epoll_event));
 176         }
 177 }
 178
 179 /*
 180  * Initialize an already allocated poll event data structure. For epoll(), the
 181  * epfd is set to -1 to indicate that it's not usable.
 182  */
 183 static inline void lttng_poll_init(struct lttng_poll_event *events)
 184 {
 185         memset(events, 0, sizeof(struct lttng_poll_event));
 186         /* Set fd to -1 so if clean before created, we don't close 0. */
 187         events->epfd = -1;
 188 }
 189
 190 /*
 191  * Clean the events structure of a lttng_poll_event. It's the caller
 192  * responsability to free the lttng_poll_event memory.
 193  */
 194 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 195 {
 196         int ret;
 197
 198         if (!events) {
 199                 return;
 200         }
 201
 202         if (events->epfd >= 0) {
 203                 ret = close(events->epfd);
 204                 if (ret) {
 205                         PERROR("close");
 206                 }
 207         }
 208
 209         __lttng_poll_free((void *) events->events);
 210 }
 211
 212 #else   /* HAVE_EPOLL */
 213 /*
 214  * Fallback on poll(2) API
 215  */
 216
 217 /* Needed for some poll event values */
 218 #ifndef __USE_XOPEN
 219 #define __USE_XOPEN
 220 #endif
 221
 222 /* Needed for some poll event values */
 223 #ifndef __USE_GNU
 224 #define __USE_GNU
 225 #endif
 226
 227 #include <poll.h>
 228 #include <stdint.h>
 229
 230 enum {
 231         /* Polling variables compatibility for poll */
 232         LPOLLIN = POLLIN,
 233         LPOLLPRI = POLLPRI,
 234         LPOLLOUT = POLLOUT,
 235         LPOLLRDNORM = POLLRDNORM,
 236         LPOLLRDBAND = POLLRDBAND,
 237         LPOLLWRNORM = POLLWRNORM,
 238         LPOLLWRBAND = POLLWRBAND,
 239 #if __linux__
 240         LPOLLMSG = POLLMSG,
 241         LPOLLRDHUP = POLLRDHUP,
 242 #elif (defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__sun__) || defined(__APPLE__))
 243         LPOLLMSG = 0,
 244         LPOLLRDHUP = 0,
 245 #else
 246 #error "Please add support for your OS."
 247 #endif /* __linux__ */
 248         LPOLLERR = POLLERR,
 249         LPOLLHUP = POLLHUP | POLLNVAL,
 250         /* Close on exec feature does not exist for poll(2) */
 251         LTTNG_CLOEXEC = 0xdead,
 252 };
 253
 254 struct compat_poll_event_array {
 255         uint32_t nb_fd;       /* Current number of fd in events */
 256         uint32_t alloc_size; /* Size of events array */
 257         /* Initial size of the pollset. We never shrink below that. */
 258         uint32_t init_size;
 259         struct pollfd *events;
 260 };
 261
 262 struct compat_poll_event {
 263         /*
 264          * Modified by the wait action. Updated using current fields if the
 265          * need_update flag is set.
 266          */
 267         struct compat_poll_event_array wait;
 268         /*
 269          * This is modified by add/del actions being the _current_ flow of
 270          * execution before a poll wait is done.
 271          */
 272         struct compat_poll_event_array current;
 273
 274         /* Indicate if wait.events need to be updated from current. */
 275         int need_update:1;
 276 };
 277 #define lttng_poll_event compat_poll_event
 278
 279 static inline int __lttng_poll_get_prev_fd(struct lttng_poll_event *events,
 280                 int index, uint32_t nb_fd)
 281 {
 282         assert(events);
 283         assert(index != nb_fd);
 284
 285         if (index == 0 || nb_fd == 0) {
 286                 return -1;
 287         } else {
 288                 return events->current.events[index - 1].fd;
 289         }
 290 }
 291
 292 /*
 293  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 294  * being the index of the events array.
 295  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 296  * current list for test compatibility purposes.
 297  */
 298 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->wait.events[i].fd
 299 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->wait.events[i].revents
 300 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->current.nb_fd
 301 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->wait.events_size
 302 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd) \
 303         __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 304
 305 /*
 306  * Create a pollfd structure of size 'size'.
 307  */
 308 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 309 #define lttng_poll_create(events, size, flags) \
 310         compat_poll_create(events, size)
 311
 312 /*
 313  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 314  * structure.
 315  */
 316 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout,
 317                 bool interruptible);
 318 #define lttng_poll_wait(events, timeout) \
 319         compat_poll_wait(events, timeout, false)
 320 #define lttng_poll_wait_interruptible(events, timeout) \
 321         compat_poll_wait(events, timeout, true)
 322
 323 /*
 324  * Add the fd to the pollfd structure. Resize if needed.
 325  */
 326 extern int compat_poll_add(struct lttng_poll_event *events,
 327                 int fd, uint32_t req_events);
 328 #define lttng_poll_add(events, fd, req_events) \
 329         compat_poll_add(events, fd, req_events)
 330
 331 /*
 332  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 333  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 334  * one is freed().
 335  */
 336 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 337 #define lttng_poll_del(events, fd) \
 338         compat_poll_del(events, fd)
 339
 340 /*
 341  * Modify an fd's events in the poll set.
 342  */
 343 extern int compat_poll_mod(struct lttng_poll_event *events,
 344                 int fd, uint32_t req_events);
 345 #define lttng_poll_mod(events, fd, req_events) \
 346         compat_poll_mod(events, fd, req_events)
 347
 348 /*
 349  * Set up the poll set limits variable poll_max_size
 350  */
 351 extern int compat_poll_set_max_size(void);
 352 #define lttng_poll_set_max_size() \
 353         compat_poll_set_max_size()
 354
 355 /*
 356  * No need to reset a pollfd structure for poll(2)
 357  */
 358 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 359 {}
 360
 361 /*
 362  * Initialize an already allocated poll event data structure.
 363  */
 364 static inline void lttng_poll_init(struct lttng_poll_event *events)
 365 {
 366         memset(events, 0, sizeof(struct lttng_poll_event));
 367 }
 368
 369 /*
 370  * Clean the events structure of a lttng_poll_event. It's the caller
 371  * responsability to free the lttng_poll_event memory.
 372  */
 373 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 374 {
 375         if (events) {
 376                 __lttng_poll_free((void *) events->wait.events);
 377                 __lttng_poll_free((void *) events->current.events);
 378         }
 379 }
 380
 381 #endif /* HAVE_EPOLL */
 382
 383 #endif /* _LTT_POLL_H */