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