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 LTTNG_HIDDEN
 106 int compat_poll_create(struct lttng_poll_event *events, int size)
 107 {
 108         struct compat_poll_event_array *current, *wait;
 109
 110         if (events == NULL || size <= 0) {
 111                 ERR("Wrong arguments for poll create");
 112                 goto error;
 113         }
 114
 115         if (!poll_max_size) {
 116                 if (lttng_poll_set_max_size()) {
 117                         goto error;
 118                 }
 119         }
 120
 121         /* Don't bust the limit here */
 122         if (size > poll_max_size) {
 123                 size = poll_max_size;
 124         }
 125
 126         /* Reset everything before begining the allocation. */
 127         memset(events, 0, sizeof(struct lttng_poll_event));
 128
 129         current = &events->current;
 130         wait = &events->wait;
 131
 132         /* This *must* be freed by using lttng_poll_free() */
 133         wait->events = zmalloc(size * sizeof(struct pollfd));
 134         if (wait->events == NULL) {
 135                 PERROR("zmalloc struct pollfd");
 136                 goto error;
 137         }
 138
 139         wait->alloc_size = wait->init_size = size;
 140
 141         current->events = zmalloc(size * sizeof(struct pollfd));
 142         if (current->events == NULL) {
 143                 PERROR("zmalloc struct current pollfd");
 144                 goto error;
 145         }
 146
 147         current->alloc_size = current->init_size = size;
 148
 149         return 0;
 150
 151 error:
 152         return -1;
 153 }
 154
 155 /*
 156  * Add fd to pollfd data structure with requested events.
 157  */
 158 int compat_poll_add(struct lttng_poll_event *events, int fd,
 159                 uint32_t req_events)
 160 {
 161         int new_size, ret, i;
 162         struct compat_poll_event_array *current;
 163
 164         if (events == NULL || events->current.events == NULL || fd < 0) {
 165                 ERR("Bad compat poll add arguments");
 166                 goto error;
 167         }
 168
 169         current = &events->current;
 170
 171         /* Check if fd we are trying to add is already there. */
 172         for (i = 0; i < current->nb_fd; i++) {
 173                 if (current->events[i].fd == fd) {
 174                         errno = EEXIST;
 175                         goto error;
 176                 }
 177         }
 178
 179         /* Resize array if needed. */
 180         new_size = 1U << utils_get_count_order_u32(current->nb_fd + 1);
 181         if (new_size != current->alloc_size && new_size >= current->init_size) {
 182                 ret = resize_poll_event(current, new_size);
 183                 if (ret < 0) {
 184                         goto error;
 185                 }
 186         }
 187
 188         current->events[current->nb_fd].fd = fd;
 189         current->events[current->nb_fd].events = req_events;
 190         current->nb_fd++;
 191         events->need_update = 1;
 192
 193         DBG("fd %d of %d added to pollfd", fd, current->nb_fd);
 194
 195         return 0;
 196
 197 error:
 198         return -1;
 199 }
 200
 201 /*
 202  * Modify an fd's events..
 203  */
 204 LTTNG_HIDDEN
 205 int compat_poll_mod(struct lttng_poll_event *events, int fd,
 206                 uint32_t req_events)
 207 {
 208         int i;
 209         bool fd_found = false;
 210         struct compat_poll_event_array *current;
 211
 212         if (events == NULL || events->current.events == NULL || fd < 0) {
 213                 ERR("Bad compat poll mod arguments");
 214                 goto error;
 215         }
 216
 217         current = &events->current;
 218
 219         for (i = 0; i < current->nb_fd; i++) {
 220                 if (current->events[i].fd == fd) {
 221                         fd_found = true;
 222                         current->events[i].events = req_events;
 223                         events->need_update = 1;
 224                         break;
 225                 }
 226         }
 227
 228         if (!fd_found) {
 229                 goto error;
 230         }
 231
 232         return 0;
 233
 234 error:
 235         return -1;
 236 }
 237
 238 /*
 239  * Remove a fd from the pollfd structure.
 240  */
 241 LTTNG_HIDDEN
 242 int compat_poll_del(struct lttng_poll_event *events, int fd)
 243 {
 244         int new_size, i, count = 0, ret;
 245         struct compat_poll_event_array *current;
 246
 247         if (events == NULL || events->current.events == NULL || fd < 0) {
 248                 ERR("Wrong arguments for poll del");
 249                 goto error;
 250         }
 251
 252         /* Ease our life a bit. */
 253         current = &events->current;
 254
 255         for (i = 0; i < current->nb_fd; i++) {
 256                 /* Don't put back the fd we want to delete */
 257                 if (current->events[i].fd != fd) {
 258                         current->events[count].fd = current->events[i].fd;
 259                         current->events[count].events = current->events[i].events;
 260                         count++;
 261                 }
 262         }
 263         /* No fd duplicate should be ever added into array. */
 264         assert(current->nb_fd - 1 == count);
 265         current->nb_fd = count;
 266
 267         /* Resize array if needed. */
 268         new_size = 1U << utils_get_count_order_u32(current->nb_fd);
 269         if (new_size != current->alloc_size && new_size >= current->init_size) {
 270                 ret = resize_poll_event(current, new_size);
 271                 if (ret < 0) {
 272                         goto error;
 273                 }
 274         }
 275
 276         events->need_update = 1;
 277
 278         return 0;
 279
 280 error:
 281         return -1;
 282 }
 283
 284 /*
 285  * Wait on poll() with timeout. Blocking call.
 286  */
 287 LTTNG_HIDDEN
 288 int compat_poll_wait(struct lttng_poll_event *events, int timeout)
 289 {
 290         int ret;
 291
 292         if (events == NULL || events->current.events == NULL) {
 293                 ERR("poll wait arguments error");
 294                 goto error;
 295         }
 296         assert(events->current.nb_fd >= 0);
 297
 298         if (events->current.nb_fd == 0) {
 299                 /* Return an invalid error to be consistent with epoll. */
 300                 errno = EINVAL;
 301                 events->wait.nb_fd = 0;
 302                 goto error;
 303         }
 304
 305         if (events->need_update) {
 306                 ret = update_current_events(events);
 307                 if (ret < 0) {
 308                         errno = ENOMEM;
 309                         goto error;
 310                 }
 311         }
 312
 313         do {
 314                 ret = poll(events->wait.events, events->wait.nb_fd, timeout);
 315         } while (ret == -1 && errno == EINTR);
 316         if (ret < 0) {
 317                 /* At this point, every error is fatal */
 318                 PERROR("poll wait");
 319                 goto error;
 320         }
 321
 322         /*
 323          * poll() should always iterate on all FDs since we handle the pollset in
 324          * user space and after poll returns, we have to try every fd for a match.
 325          */
 326         return events->wait.nb_fd;
 327
 328 error:
 329         return -1;
 330 }
 331
 332 /*
 333  * Setup poll set maximum size.
 334  */
 335 LTTNG_HIDDEN
 336 int compat_poll_set_max_size(void)
 337 {
 338         int ret, retval = 0;
 339         struct rlimit lim;
 340
 341         ret = getrlimit(RLIMIT_NOFILE, &lim);
 342         if (ret < 0) {
 343                 PERROR("getrlimit poll RLIMIT_NOFILE");
 344                 retval = -1;
 345                 goto end;
 346         }
 347
 348         poll_max_size = lim.rlim_cur;
 349 end:
 350         if (poll_max_size == 0) {
 351                 poll_max_size = DEFAULT_POLL_SIZE;
 352         }
 353         DBG("poll set max size set to %u", poll_max_size);
 354         return retval;
 355 }