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 <common/common.hpp>
  12
  13 #include <string.h>
  14 #include <unistd.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
  29 #include <features.h>
  30 #include <stdio.h>
  31 #include <sys/epoll.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
  74 __lttng_epoll_get_prev_fd(struct lttng_poll_event *events, 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) __lttng_epoll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
  95
  96 /* Create the epoll set. */
  97 extern int compat_epoll_create(struct lttng_poll_event *events, int size, int flags);
  98 #define lttng_poll_create(events, size, flags) compat_epoll_create(events, size, flags)
  99
 100 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 101 static inline int compat_glibc_epoll_create(int size __attribute__((unused)), int flags)
 102 {
 103         return epoll_create1(flags);
 104 }
 105 #else
 106 static inline int compat_glibc_epoll_create(int size, int flags)
 107 {
 108         /*
 109          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 110          * epoll_create(..) also means that we lose the possibility to
 111          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 112          * fcntl(..).
 113          */
 114         int efd = epoll_create(size);
 115         LTTNG_ASSERT(fcntl(efd, F_SETFD, flags) != -1);
 116         return efd;
 117 }
 118 #endif
 119
 120 /*
 121  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 122  * data structure (events).
 123  */
 124 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout, bool interruptible);
 125 #define lttng_poll_wait(events, timeout)               compat_epoll_wait(events, timeout, false)
 126 #define lttng_poll_wait_interruptible(events, timeout) compat_epoll_wait(events, timeout, true)
 127
 128 /*
 129  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 130  */
 131 extern int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events);
 132 #define lttng_poll_add(events, fd, req_events) compat_epoll_add(events, fd, req_events)
 133
 134 /*
 135  * Remove a fd from the epoll set.
 136  */
 137 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 138 #define lttng_poll_del(events, fd) compat_epoll_del(events, fd)
 139
 140 /*
 141  * Modify an fd's events in the epoll set.
 142  */
 143 extern int compat_epoll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events);
 144 #define lttng_poll_mod(events, fd, req_events) compat_epoll_mod(events, fd, req_events)
 145
 146 /*
 147  * Set up the poll set limits variable poll_max_size
 148  */
 149 extern int compat_epoll_set_max_size();
 150 #define lttng_poll_set_max_size() compat_epoll_set_max_size()
 151
 152 /*
 153  * This function memset with zero the structure since it can be reused at each
 154  * round of a main loop. Being in a loop and using a non static number of fds,
 155  * this function must be called to insure coherent events with associted fds.
 156  */
 157 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 158 {
 159         if (events && events->events) {
 160                 memset(events->events, 0, events->nb_fd * sizeof(struct epoll_event));
 161         }
 162 }
 163
 164 /*
 165  * Initialize an already allocated poll event data structure. For epoll(), the
 166  * epfd is set to -1 to indicate that it's not usable.
 167  */
 168 static inline void lttng_poll_init(struct lttng_poll_event *events)
 169 {
 170         memset(events, 0, sizeof(struct lttng_poll_event));
 171         /* Set fd to -1 so if clean before created, we don't close 0. */
 172         events->epfd = -1;
 173 }
 174
 175 /*
 176  * Clean the events structure of a lttng_poll_event. It's the caller
 177  * responsability to free the lttng_poll_event memory.
 178  */
 179 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 180 {
 181         int ret;
 182
 183         if (!events) {
 184                 return;
 185         }
 186
 187         if (events->epfd >= 0) {
 188                 ret = close(events->epfd);
 189                 if (ret) {
 190                         PERROR("close");
 191                 }
 192         }
 193
 194         __lttng_poll_free((void *) events->events);
 195 }
 196
 197 #else /* HAVE_EPOLL */
 198 /*
 199  * Fallback on poll(2) API
 200  */
 201
 202 #include <poll.h>
 203 #include <stdint.h>
 204
 205 enum {
 206         /* Polling variables compatibility for poll */
 207         LPOLLIN = POLLIN,
 208         LPOLLPRI = POLLPRI,
 209         LPOLLOUT = POLLOUT,
 210         LPOLLRDNORM = POLLRDNORM,
 211         LPOLLRDBAND = POLLRDBAND,
 212         LPOLLWRNORM = POLLWRNORM,
 213         LPOLLWRBAND = POLLWRBAND,
 214 #ifdef __USE_GNU
 215         LPOLLMSG = POLLMSG,
 216         LPOLLRDHUP = POLLRDHUP,
 217 #else
 218         LPOLLMSG = 0,
 219         LPOLLRDHUP = 0,
 220 #endif /* __USE_GNU */
 221         LPOLLERR = POLLERR,
 222         LPOLLHUP = POLLHUP | POLLNVAL,
 223         /* Close on exec feature does not exist for poll(2) */
 224         LTTNG_CLOEXEC = 0xdead,
 225 };
 226
 227 struct compat_poll_event_array {
 228         uint32_t nb_fd; /* Current number of fd in events */
 229         uint32_t alloc_size; /* Size of events array */
 230         /* Initial size of the pollset. We never shrink below that. */
 231         uint32_t init_size;
 232         struct pollfd *events;
 233 };
 234
 235 struct compat_poll_event {
 236         /*
 237          * Modified by the wait action. Updated using current fields if the
 238          * need_update flag is set.
 239          */
 240         struct compat_poll_event_array wait;
 241         /*
 242          * This is modified by add/del actions being the _current_ flow of
 243          * execution before a poll wait is done.
 244          */
 245         struct compat_poll_event_array current;
 246
 247         /* Indicate if wait.events need to be updated from current. */
 248         int need_update:1;
 249 };
 250 #define lttng_poll_event                               compat_poll_event
 251
 252 static inline int
 253 __lttng_poll_get_prev_fd(struct lttng_poll_event *events, int index, uint32_t nb_fd)
 254 {
 255         LTTNG_ASSERT(events);
 256         LTTNG_ASSERT(index != nb_fd);
 257
 258         if (index == 0 || nb_fd == 0) {
 259                 return -1;
 260         } else {
 261                 return events->current.events[index - 1].fd;
 262         }
 263 }
 264
 265 /*
 266  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 267  * being the index of the events array.
 268  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 269  * current list for test compatibility purposes.
 270  */
 271 #define LTTNG_POLL_GETFD(e, i)                         LTTNG_REF(e)->wait.events[i].fd
 272 #define LTTNG_POLL_GETEV(e, i)                         LTTNG_REF(e)->wait.events[i].revents
 273 #define LTTNG_POLL_GETNB(e)                            LTTNG_REF(e)->current.nb_fd
 274 #define LTTNG_POLL_GETSZ(e)                            LTTNG_REF(e)->wait.events_size
 275 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd)            __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 276
 277 /*
 278  * Create a pollfd structure of size 'size'.
 279  */
 280 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 281 #define lttng_poll_create(events, size, flags)         compat_poll_create(events, size)
 282
 283 /*
 284  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 285  * structure.
 286  */
 287 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout, bool interruptible);
 288 #define lttng_poll_wait(events, timeout)               compat_poll_wait(events, timeout, false)
 289 #define lttng_poll_wait_interruptible(events, timeout) compat_poll_wait(events, timeout, true)
 290
 291 /*
 292  * Add the fd to the pollfd structure. Resize if needed.
 293  */
 294 extern int compat_poll_add(struct lttng_poll_event *events, int fd, uint32_t req_events);
 295 #define lttng_poll_add(events, fd, req_events)         compat_poll_add(events, fd, req_events)
 296
 297 /*
 298  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 299  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 300  * one is freed().
 301  */
 302 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 303 #define lttng_poll_del(events, fd)                     compat_poll_del(events, fd)
 304
 305 /*
 306  * Modify an fd's events in the poll set.
 307  */
 308 extern int compat_poll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events);
 309 #define lttng_poll_mod(events, fd, req_events)         compat_poll_mod(events, fd, req_events)
 310
 311 /*
 312  * Set up the poll set limits variable poll_max_size
 313  */
 314 extern int compat_poll_set_max_size(void);
 315 #define lttng_poll_set_max_size()                      compat_poll_set_max_size()
 316
 317 /*
 318  * No need to reset a pollfd structure for poll(2)
 319  */
 320 static inline void lttng_poll_reset(struct lttng_poll_event *events __attribute__((unused)))
 321 {
 322 }
 323
 324 /*
 325  * Initialize an already allocated poll event data structure.
 326  */
 327 static inline void lttng_poll_init(struct lttng_poll_event *events)
 328 {
 329         memset(events, 0, sizeof(struct lttng_poll_event));
 330 }
 331
 332 /*
 333  * Clean the events structure of a lttng_poll_event. It's the caller
 334  * responsability to free the lttng_poll_event memory.
 335  */
 336 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 337 {
 338         if (events) {
 339                 __lttng_poll_free((void *) events->wait.events);
 340                 __lttng_poll_free((void *) events->current.events);
 341         }
 342 }
 343
 344 #endif /* HAVE_EPOLL */
 345
 346 #endif /* _LTT_POLL_H */