src/common/compat/compat-poll.c

   1 /*
   2  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _LGPL_SOURCE
  19 #include <assert.h>
  20 #include <stdlib.h>
  21 #include <sys/resource.h>
  22 #include <sys/time.h>
  23
  24 #include <common/defaults.h>
  25 #include <common/error.h>
  26 #include <common/macros.h>
  27 #include <common/utils.h>
  28
  29 #include "poll.h"
  30
  31 unsigned int poll_max_size;
  32
  33 /*
  34  * Resize the epoll events structure of the new size.
  35  *
  36  * Return 0 on success or else -1 with the current events pointer untouched.
  37  */
  38 static int resize_poll_event(struct compat_poll_event_array *array,
  39                 uint32_t new_size)
  40 {
  41         struct pollfd *ptr;
  42
  43         assert(array);
  44
  45         /* Refuse to resize the array more than the max size. */
  46         if (new_size > poll_max_size) {
  47                 goto error;
  48         }
  49
  50         ptr = realloc(array->events, new_size * sizeof(*ptr));
  51         if (ptr == NULL) {
  52                 PERROR("realloc epoll add");
  53                 goto error;
  54         }
  55         if (new_size > array->alloc_size) {
  56                 /* Zero newly allocated memory */
  57                 memset(ptr + array->alloc_size, 0,
  58                         (new_size - array->alloc_size) * sizeof(*ptr));
  59         }
  60         array->events = ptr;
  61         array->alloc_size = new_size;
  62
  63         return 0;
  64
  65 error:
  66         return -1;
  67 }
  68
  69 /*
  70  * Update events with the current events object.
  71  */
  72 static int update_current_events(struct lttng_poll_event *events)
  73 {
  74         int ret;
  75         struct compat_poll_event_array *current, *wait;
  76
  77         assert(events);
  78
  79         current = &events->current;
  80         wait = &events->wait;
  81
  82         wait->nb_fd = current->nb_fd;
  83         if (current->alloc_size != wait->alloc_size) {
  84                 ret = resize_poll_event(wait, current->alloc_size);
  85                 if (ret < 0) {
  86                         goto error;
  87                 }
  88         }
  89         memcpy(wait->events, current->events,
  90                         current->nb_fd * sizeof(*current->events));
  91
  92         /* Update is done. */
  93         events->need_update = 0;
  94
  95         return 0;
  96
  97 error:
  98         return -1;
  99 }
 100
 101 /*
 102  * Create pollfd data structure.
 103  */
 104 int compat_poll_create(struct lttng_poll_event *events, int size)
 105 {
 106         struct compat_poll_event_array *current, *wait;
 107
 108         if (events == NULL || size <= 0) {
 109                 ERR("Wrong arguments for poll create");
 110                 goto error;
 111         }
 112
 113         if (!poll_max_size) {
 114                 ERR("poll_max_size not initialized yet");
 115                 goto error;
 116         }
 117
 118         /* Don't bust the limit here */
 119         if (size > poll_max_size) {
 120                 size = poll_max_size;
 121         }
 122
 123         /* Reset everything before begining the allocation. */
 124         memset(events, 0, sizeof(struct lttng_poll_event));
 125
 126         current = &events->current;
 127         wait = &events->wait;
 128
 129         /* This *must* be freed by using lttng_poll_free() */
 130         wait->events = zmalloc(size * sizeof(struct pollfd));
 131         if (wait->events == NULL) {
 132                 PERROR("zmalloc struct pollfd");
 133                 goto error;
 134         }
 135
 136         wait->alloc_size = wait->init_size = size;
 137
 138         current->events = zmalloc(size * sizeof(struct pollfd));
 139         if (current->events == NULL) {
 140                 PERROR("zmalloc struct current pollfd");
 141                 goto error;
 142         }
 143
 144         current->alloc_size = current->init_size = size;
 145
 146         return 0;
 147
 148 error:
 149         return -1;
 150 }
 151
 152 /*
 153  * Add fd to pollfd data structure with requested events.
 154  */
 155 int compat_poll_add(struct lttng_poll_event *events, int fd,
 156                 uint32_t req_events)
 157 {
 158         int new_size, ret, i;
 159         struct compat_poll_event_array *current;
 160
 161         if (events == NULL || events->current.events == NULL || fd < 0) {
 162                 ERR("Bad compat poll add arguments");
 163                 goto error;
 164         }
 165
 166         current = &events->current;
 167
 168         /* Check if fd we are trying to add is already there. */
 169         for (i = 0; i < current->nb_fd; i++) {
 170                 if (current->events[i].fd == fd) {
 171                         errno = EEXIST;
 172                         goto error;
 173                 }
 174         }
 175
 176         /* Resize array if needed. */
 177         new_size = 1U << utils_get_count_order_u32(current->nb_fd + 1);
 178         if (new_size != current->alloc_size && new_size >= current->init_size) {
 179                 ret = resize_poll_event(current, new_size);
 180                 if (ret < 0) {
 181                         goto error;
 182                 }
 183         }
 184
 185         current->events[current->nb_fd].fd = fd;
 186         current->events[current->nb_fd].events = req_events;
 187         current->nb_fd++;
 188         events->need_update = 1;
 189
 190         DBG("fd %d of %d added to pollfd", fd, current->nb_fd);
 191
 192         return 0;
 193
 194 error:
 195         return -1;
 196 }
 197
 198 /*
 199  * Remove a fd from the pollfd structure.
 200  */
 201 int compat_poll_del(struct lttng_poll_event *events, int fd)
 202 {
 203         int new_size, i, count = 0, ret;
 204         struct compat_poll_event_array *current;
 205
 206         if (events == NULL || events->current.events == NULL || fd < 0) {
 207                 ERR("Wrong arguments for poll del");
 208                 goto error;
 209         }
 210
 211         /* Ease our life a bit. */
 212         current = &events->current;
 213
 214         for (i = 0; i < current->nb_fd; i++) {
 215                 /* Don't put back the fd we want to delete */
 216                 if (current->events[i].fd != fd) {
 217                         current->events[count].fd = current->events[i].fd;
 218                         current->events[count].events = current->events[i].events;
 219                         count++;
 220                 }
 221         }
 222         /* No fd duplicate should be ever added into array. */
 223         assert(current->nb_fd - 1 == count);
 224         current->nb_fd = count;
 225
 226         /* Resize array if needed. */
 227         new_size = 1U << utils_get_count_order_u32(current->nb_fd);
 228         if (new_size != current->alloc_size && new_size >= current->init_size) {
 229                 ret = resize_poll_event(current, new_size);
 230                 if (ret < 0) {
 231                         goto error;
 232                 }
 233         }
 234
 235         events->need_update = 1;
 236
 237         return 0;
 238
 239 error:
 240         return -1;
 241 }
 242
 243 /*
 244  * Wait on poll() with timeout. Blocking call.
 245  */
 246 int compat_poll_wait(struct lttng_poll_event *events, int timeout)
 247 {
 248         int ret;
 249
 250         if (events == NULL || events->current.events == NULL) {
 251                 ERR("poll wait arguments error");
 252                 goto error;
 253         }
 254         assert(events->current.nb_fd >= 0);
 255
 256         if (events->current.nb_fd == 0) {
 257                 /* Return an invalid error to be consistent with epoll. */
 258                 errno = EINVAL;
 259                 events->wait.nb_fd = 0;
 260                 goto error;
 261         }
 262
 263         if (events->need_update) {
 264                 ret = update_current_events(events);
 265                 if (ret < 0) {
 266                         errno = ENOMEM;
 267                         goto error;
 268                 }
 269         }
 270
 271         do {
 272                 ret = poll(events->wait.events, events->wait.nb_fd, timeout);
 273         } while (ret == -1 && errno == EINTR);
 274         if (ret < 0) {
 275                 /* At this point, every error is fatal */
 276                 PERROR("poll wait");
 277                 goto error;
 278         }
 279
 280         /*
 281          * poll() should always iterate on all FDs since we handle the pollset in
 282          * user space and after poll returns, we have to try every fd for a match.
 283          */
 284         return events->wait.nb_fd;
 285
 286 error:
 287         return -1;
 288 }
 289
 290 /*
 291  * Setup poll set maximum size.
 292  */
 293 int compat_poll_set_max_size(void)
 294 {
 295         int ret, retval = 0;
 296         struct rlimit lim;
 297
 298         ret = getrlimit(RLIMIT_NOFILE, &lim);
 299         if (ret < 0) {
 300                 PERROR("getrlimit poll RLIMIT_NOFILE");
 301                 retval = -1;
 302                 goto end;
 303         }
 304
 305         poll_max_size = lim.rlim_cur;
 306 end:
 307         if (poll_max_size == 0) {
 308                 poll_max_size = DEFAULT_POLL_SIZE;
 309         }
 310         DBG("poll set max size set to %u", poll_max_size);
 311         return retval;
 312 }