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 #include <common/compat/fcntl.hpp>
  29
  30 #include <features.h>
  31 #include <stdio.h>
  32 #include <sys/epoll.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
  75 __lttng_epoll_get_prev_fd(struct lttng_poll_event *events, int index, uint32_t nb_fd)
  76 {
  77         LTTNG_ASSERT(events);
  78         LTTNG_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) __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, int size, int flags);
  99 #define lttng_poll_create(events, size, flags) compat_epoll_create(events, size, flags)
 100
 101 #if defined(HAVE_EPOLL_CREATE1) && defined(EPOLL_CLOEXEC)
 102 static inline int compat_glibc_epoll_create(int size __attribute__((unused)), int flags)
 103 {
 104         return epoll_create1(flags);
 105 }
 106 #else
 107 static inline int compat_glibc_epoll_create(int size, int flags)
 108 {
 109         /*
 110          * epoll_create1 was added in glibc 2.9, but unfortunatly reverting to
 111          * epoll_create(..) also means that we lose the possibility to
 112          * directly set the EPOLL_CLOEXEC, so try and do it anyway but through
 113          * fcntl(..).
 114          */
 115         int efd = epoll_create(size);
 116         LTTNG_ASSERT(fcntl(efd, F_SETFD, flags) != -1);
 117         return efd;
 118 }
 119 #endif
 120
 121 /*
 122  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 123  * data structure (events).
 124  */
 125 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout, bool interruptible);
 126 #define lttng_poll_wait(events, timeout)               compat_epoll_wait(events, timeout, false)
 127 #define lttng_poll_wait_interruptible(events, timeout) compat_epoll_wait(events, timeout, true)
 128
 129 /*
 130  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 131  */
 132 extern int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events);
 133 #define lttng_poll_add(events, fd, req_events) compat_epoll_add(events, fd, req_events)
 134
 135 /*
 136  * Remove a fd from the epoll set.
 137  */
 138 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 139 #define lttng_poll_del(events, fd) compat_epoll_del(events, fd)
 140
 141 /*
 142  * Modify an fd's events in the epoll set.
 143  */
 144 extern int compat_epoll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events);
 145 #define lttng_poll_mod(events, fd, req_events) compat_epoll_mod(events, fd, req_events)
 146
 147 /*
 148  * Set up the poll set limits variable poll_max_size
 149  */
 150 extern int compat_epoll_set_max_size();
 151 #define lttng_poll_set_max_size() compat_epoll_set_max_size()
 152
 153 /*
 154  * This function memset with zero the structure since it can be reused at each
 155  * round of a main loop. Being in a loop and using a non static number of fds,
 156  * this function must be called to insure coherent events with associted fds.
 157  */
 158 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 159 {
 160         if (events && events->events) {
 161                 memset(events->events, 0, events->nb_fd * sizeof(struct epoll_event));
 162         }
 163 }
 164
 165 /*
 166  * Initialize an already allocated poll event data structure. For epoll(), the
 167  * epfd is set to -1 to indicate that it's not usable.
 168  */
 169 static inline void lttng_poll_init(struct lttng_poll_event *events)
 170 {
 171         memset(events, 0, sizeof(struct lttng_poll_event));
 172         /* Set fd to -1 so if clean before created, we don't close 0. */
 173         events->epfd = -1;
 174 }
 175
 176 /*
 177  * Clean the events structure of a lttng_poll_event. It's the caller
 178  * responsability to free the lttng_poll_event memory.
 179  */
 180 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 181 {
 182         int ret;
 183
 184         if (!events) {
 185                 return;
 186         }
 187
 188         if (events->epfd >= 0) {
 189                 ret = close(events->epfd);
 190                 if (ret) {
 191                         PERROR("close");
 192                 }
 193         }
 194
 195         __lttng_poll_free((void *) events->events);
 196 }
 197
 198 #else /* HAVE_EPOLL */
 199 /*
 200  * Fallback on poll(2) API
 201  */
 202
 203 #include <poll.h>
 204 #include <stdint.h>
 205
 206 enum {
 207         /* Polling variables compatibility for poll */
 208         LPOLLIN = POLLIN,
 209         LPOLLPRI = POLLPRI,
 210         LPOLLOUT = POLLOUT,
 211         LPOLLRDNORM = POLLRDNORM,
 212         LPOLLRDBAND = POLLRDBAND,
 213         LPOLLWRNORM = POLLWRNORM,
 214         LPOLLWRBAND = POLLWRBAND,
 215 #ifdef __USE_GNU
 216         LPOLLMSG = POLLMSG,
 217         LPOLLRDHUP = POLLRDHUP,
 218 #else
 219         LPOLLMSG = 0,
 220         LPOLLRDHUP = 0,
 221 #endif /* __USE_GNU */
 222         LPOLLERR = POLLERR,
 223         LPOLLHUP = POLLHUP | POLLNVAL,
 224         /* Close on exec feature does not exist for poll(2) */
 225         LTTNG_CLOEXEC = 0xdead,
 226 };
 227
 228 struct compat_poll_event_array {
 229         uint32_t nb_fd; /* Current number of fd in events */
 230         uint32_t alloc_size; /* Size of events array */
 231         /* Initial size of the pollset. We never shrink below that. */
 232         uint32_t init_size;
 233         struct pollfd *events;
 234 };
 235
 236 struct compat_poll_event {
 237         /*
 238          * Modified by the wait action. Updated using current fields if the
 239          * need_update flag is set.
 240          */
 241         struct compat_poll_event_array wait;
 242         /*
 243          * This is modified by add/del actions being the _current_ flow of
 244          * execution before a poll wait is done.
 245          */
 246         struct compat_poll_event_array current;
 247
 248         /* Indicate if wait.events need to be updated from current. */
 249         int need_update:1;
 250 };
 251 #define lttng_poll_event                               compat_poll_event
 252
 253 static inline int
 254 __lttng_poll_get_prev_fd(struct lttng_poll_event *events, int index, uint32_t nb_fd)
 255 {
 256         LTTNG_ASSERT(events);
 257         LTTNG_ASSERT(index != nb_fd);
 258
 259         if (index == 0 || nb_fd == 0) {
 260                 return -1;
 261         } else {
 262                 return events->current.events[index - 1].fd;
 263         }
 264 }
 265
 266 /*
 267  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 268  * being the index of the events array.
 269  * LTTNG_POLL_GETNB is always used after lttng_poll_wait, thus we can use the
 270  * current list for test compatibility purposes.
 271  */
 272 #define LTTNG_POLL_GETFD(e, i)                         LTTNG_REF(e)->wait.events[i].fd
 273 #define LTTNG_POLL_GETEV(e, i)                         LTTNG_REF(e)->wait.events[i].revents
 274 #define LTTNG_POLL_GETNB(e)                            LTTNG_REF(e)->current.nb_fd
 275 #define LTTNG_POLL_GETSZ(e)                            LTTNG_REF(e)->wait.events_size
 276 #define LTTNG_POLL_GET_PREV_FD(e, i, nb_fd)            __lttng_poll_get_prev_fd(LTTNG_REF(e), i, nb_fd)
 277
 278 /*
 279  * Create a pollfd structure of size 'size'.
 280  */
 281 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 282 #define lttng_poll_create(events, size, flags)         compat_poll_create(events, size)
 283
 284 /*
 285  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 286  * structure.
 287  */
 288 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout, bool interruptible);
 289 #define lttng_poll_wait(events, timeout)               compat_poll_wait(events, timeout, false)
 290 #define lttng_poll_wait_interruptible(events, timeout) compat_poll_wait(events, timeout, true)
 291
 292 /*
 293  * Add the fd to the pollfd structure. Resize if needed.
 294  */
 295 extern int compat_poll_add(struct lttng_poll_event *events, int fd, uint32_t req_events);
 296 #define lttng_poll_add(events, fd, req_events)         compat_poll_add(events, fd, req_events)
 297
 298 /*
 299  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 300  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 301  * one is freed().
 302  */
 303 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 304 #define lttng_poll_del(events, fd)                     compat_poll_del(events, fd)
 305
 306 /*
 307  * Modify an fd's events in the poll set.
 308  */
 309 extern int compat_poll_mod(struct lttng_poll_event *events, int fd, uint32_t req_events);
 310 #define lttng_poll_mod(events, fd, req_events)         compat_poll_mod(events, fd, req_events)
 311
 312 /*
 313  * Set up the poll set limits variable poll_max_size
 314  */
 315 extern int compat_poll_set_max_size(void);
 316 #define lttng_poll_set_max_size()                      compat_poll_set_max_size()
 317
 318 /*
 319  * No need to reset a pollfd structure for poll(2)
 320  */
 321 static inline void lttng_poll_reset(struct lttng_poll_event *events __attribute__((unused)))
 322 {
 323 }
 324
 325 /*
 326  * Initialize an already allocated poll event data structure.
 327  */
 328 static inline void lttng_poll_init(struct lttng_poll_event *events)
 329 {
 330         memset(events, 0, sizeof(struct lttng_poll_event));
 331 }
 332
 333 /*
 334  * Clean the events structure of a lttng_poll_event. It's the caller
 335  * responsability to free the lttng_poll_event memory.
 336  */
 337 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 338 {
 339         if (events) {
 340                 __lttng_poll_free((void *) events->wait.events);
 341                 __lttng_poll_free((void *) events->current.events);
 342         }
 343 }
 344
 345 #endif /* HAVE_EPOLL */
 346
 347 #endif /* _LTT_POLL_H */