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 #include <stdbool.h>
  24
  25 #include <common/defaults.h>
  26 #include <common/error.h>
  27 #include <common/macros.h>
  28 #include <common/utils.h>
  29
  30 #include "poll.h"
  31
  32 unsigned int poll_max_size;
  33
  34 /*
  35  * Resize the epoll events structure of the new size.
  36  *
  37  * Return 0 on success or else -1 with the current events pointer untouched.
  38  */
  39 static int resize_poll_event(struct compat_poll_event_array *array,
  40                 uint32_t new_size)
  41 {
  42         struct pollfd *ptr;
  43
  44         assert(array);
  45
  46         /* Refuse to resize the array more than the max size. */
  47         if (new_size > poll_max_size) {
  48                 goto error;
  49         }
  50
  51         ptr = realloc(array->events, new_size * sizeof(*ptr));
  52         if (ptr == NULL) {
  53                 PERROR("realloc epoll add");
  54                 goto error;
  55         }
  56         if (new_size > array->alloc_size) {
  57                 /* Zero newly allocated memory */
  58                 memset(ptr + array->alloc_size, 0,
  59                         (new_size - array->alloc_size) * sizeof(*ptr));
  60         }
  61         array->events = ptr;
  62         array->alloc_size = new_size;
  63
  64         return 0;
  65
  66 error:
  67         return -1;
  68 }
  69
  70 /*
  71  * Update events with the current events object.
  72  */
  73 static int update_current_events(struct lttng_poll_event *events)
  74 {
  75         int ret;
  76         struct compat_poll_event_array *current, *wait;
  77
  78         assert(events);
  79
  80         current = &events->current;
  81         wait = &events->wait;
  82
  83         wait->nb_fd = current->nb_fd;
  84         if (current->alloc_size != wait->alloc_size) {
  85                 ret = resize_poll_event(wait, current->alloc_size);
  86                 if (ret < 0) {
  87                         goto error;
  88                 }
  89         }
  90         memcpy(wait->events, current->events,
  91                         current->nb_fd * sizeof(*current->events));
  92
  93         /* Update is done. */
  94         events->need_update = 0;
  95
  96         return 0;
  97
  98 error:
  99         return -1;
 100 }
 101
 102 /*
 103  * Create pollfd data structure.
 104  */
 105 int compat_poll_create(struct lttng_poll_event *events, int size)
 106 {
 107         struct compat_poll_event_array *current, *wait;
 108
 109         if (events == NULL || size <= 0) {
 110                 ERR("Wrong arguments for poll create");
 111                 goto error;
 112         }
 113
 114         if (!poll_max_size) {
 115                 if (lttng_poll_set_max_size()) {
 116                         goto error;
 117                 }
 118         }
 119
 120         /* Don't bust the limit here */
 121         if (size > poll_max_size) {
 122                 size = poll_max_size;
 123         }
 124
 125         /* Reset everything before begining the allocation. */
 126         memset(events, 0, sizeof(struct lttng_poll_event));
 127
 128         current = &events->current;
 129         wait = &events->wait;
 130
 131         /* This *must* be freed by using lttng_poll_free() */
 132         wait->events = zmalloc(size * sizeof(struct pollfd));
 133         if (wait->events == NULL) {
 134                 PERROR("zmalloc struct pollfd");
 135                 goto error;
 136         }
 137
 138         wait->alloc_size = wait->init_size = size;
 139
 140         current->events = zmalloc(size * sizeof(struct pollfd));
 141         if (current->events == NULL) {
 142                 PERROR("zmalloc struct current pollfd");
 143                 goto error;
 144         }
 145
 146         current->alloc_size = current->init_size = size;
 147
 148         return 0;
 149
 150 error:
 151         return -1;
 152 }
 153
 154 /*
 155  * Add fd to pollfd data structure with requested events.
 156  */
 157 int compat_poll_add(struct lttng_poll_event *events, int fd,
 158                 uint32_t req_events)
 159 {
 160         int new_size, ret, i;
 161         struct compat_poll_event_array *current;
 162
 163         if (events == NULL || events->current.events == NULL || fd < 0) {
 164                 ERR("Bad compat poll add arguments");
 165                 goto error;
 166         }
 167
 168         current = &events->current;
 169
 170         /* Check if fd we are trying to add is already there. */
 171         for (i = 0; i < current->nb_fd; i++) {
 172                 if (current->events[i].fd == fd) {
 173                         errno = EEXIST;
 174                         goto error;
 175                 }
 176         }
 177
 178         /* Resize array if needed. */
 179         new_size = 1U << utils_get_count_order_u32(current->nb_fd + 1);
 180         if (new_size != current->alloc_size && new_size >= current->init_size) {
 181                 ret = resize_poll_event(current, new_size);
 182                 if (ret < 0) {
 183                         goto error;
 184                 }
 185         }
 186
 187         current->events[current->nb_fd].fd = fd;
 188         current->events[current->nb_fd].events = req_events;
 189         current->nb_fd++;
 190         events->need_update = 1;
 191
 192         DBG("fd %d of %d added to pollfd", fd, current->nb_fd);
 193
 194         return 0;
 195
 196 error:
 197         return -1;
 198 }
 199
 200 /*
 201  * Modify an fd's events..
 202  */
 203 int compat_poll_mod(struct lttng_poll_event *events, int fd,
 204                 uint32_t req_events)
 205 {
 206         int ret, i;
 207         bool fd_found = false;
 208         struct compat_poll_event_array *current;
 209
 210         if (events == NULL || events->current.events == NULL || fd < 0) {
 211                 ERR("Bad compat poll mod arguments");
 212                 goto error;
 213         }
 214
 215         current = &events->current;
 216
 217         for (i = 0; i < current->nb_fd; i++) {
 218                 if (current->events[i].fd == fd) {
 219                         fd_found = true;
 220                         current->events[i].events = req_events;
 221                         events->need_update = 1;
 222                         break;
 223                 }
 224         }
 225
 226         if (!fd_found) {
 227                 goto error;
 228         }
 229
 230         return 0;
 231
 232 error:
 233         return -1;
 234 }
 235
 236 /*
 237  * Remove a fd from the pollfd structure.
 238  */
 239 int compat_poll_del(struct lttng_poll_event *events, int fd)
 240 {
 241         int new_size, i, count = 0, ret;
 242         struct compat_poll_event_array *current;
 243
 244         if (events == NULL || events->current.events == NULL || fd < 0) {
 245                 ERR("Wrong arguments for poll del");
 246                 goto error;
 247         }
 248
 249         /* Ease our life a bit. */
 250         current = &events->current;
 251
 252         for (i = 0; i < current->nb_fd; i++) {
 253                 /* Don't put back the fd we want to delete */
 254                 if (current->events[i].fd != fd) {
 255                         current->events[count].fd = current->events[i].fd;
 256                         current->events[count].events = current->events[i].events;
 257                         count++;
 258                 }
 259         }
 260         /* No fd duplicate should be ever added into array. */
 261         assert(current->nb_fd - 1 == count);
 262         current->nb_fd = count;
 263
 264         /* Resize array if needed. */
 265         new_size = 1U << utils_get_count_order_u32(current->nb_fd);
 266         if (new_size != current->alloc_size && new_size >= current->init_size) {
 267                 ret = resize_poll_event(current, new_size);
 268                 if (ret < 0) {
 269                         goto error;
 270                 }
 271         }
 272
 273         events->need_update = 1;
 274
 275         return 0;
 276
 277 error:
 278         return -1;
 279 }
 280
 281 /*
 282  * Wait on poll() with timeout. Blocking call.
 283  */
 284 int compat_poll_wait(struct lttng_poll_event *events, int timeout)
 285 {
 286         int ret;
 287
 288         if (events == NULL || events->current.events == NULL) {
 289                 ERR("poll wait arguments error");
 290                 goto error;
 291         }
 292         assert(events->current.nb_fd >= 0);
 293
 294         if (events->current.nb_fd == 0) {
 295                 /* Return an invalid error to be consistent with epoll. */
 296                 errno = EINVAL;
 297                 events->wait.nb_fd = 0;
 298                 goto error;
 299         }
 300
 301         if (events->need_update) {
 302                 ret = update_current_events(events);
 303                 if (ret < 0) {
 304                         errno = ENOMEM;
 305                         goto error;
 306                 }
 307         }
 308
 309         do {
 310                 ret = poll(events->wait.events, events->wait.nb_fd, timeout);
 311         } while (ret == -1 && errno == EINTR);
 312         if (ret < 0) {
 313                 /* At this point, every error is fatal */
 314                 PERROR("poll wait");
 315                 goto error;
 316         }
 317
 318         /*
 319          * poll() should always iterate on all FDs since we handle the pollset in
 320          * user space and after poll returns, we have to try every fd for a match.
 321          */
 322         return events->wait.nb_fd;
 323
 324 error:
 325         return -1;
 326 }
 327
 328 /*
 329  * Setup poll set maximum size.
 330  */
 331 int compat_poll_set_max_size(void)
 332 {
 333         int ret, retval = 0;
 334         struct rlimit lim;
 335
 336         ret = getrlimit(RLIMIT_NOFILE, &lim);
 337         if (ret < 0) {
 338                 PERROR("getrlimit poll RLIMIT_NOFILE");
 339                 retval = -1;
 340                 goto end;
 341         }
 342
 343         poll_max_size = lim.rlim_cur;
 344 end:
 345         if (poll_max_size == 0) {
 346                 poll_max_size = DEFAULT_POLL_SIZE;
 347         }
 348         DBG("poll set max size set to %u", poll_max_size);
 349         return retval;
 350 }