compat/clock_nanosleep.c

   1 /*****************************************************************************
   2  * clock_nanosleep.c: POSIX clock_nanosleep() replacement
   3  *****************************************************************************
   4  * Copyright © 2020 VLC authors and VideoLAN
   5  *
   6  * Author: Marvin Scholz <epirat07 at gmail dot com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #ifdef __APPLE__
  24
  25 #ifdef HAVE_CONFIG_H
  26 # include <config.h>
  27 #endif
  28
  29 #include <assert.h>
  30 #include <pthread.h>
  31 #include <sys/errno.h>
  32 #include <sys/types.h>
  33 #include <sys/time.h>
  34 #include <sys/sysctl.h>
  35 #include <mach/clock_types.h>
  36
  37 int clock_nanosleep(clockid_t clock_id, int flags,
  38         const struct timespec *rqtp, struct timespec *rmtp)
  39 {
  40     // Validate timespec
  41     if (rqtp == NULL || rqtp->tv_sec < 0 ||
  42             rqtp->tv_nsec < 0 || (unsigned long)rqtp->tv_nsec >= NSEC_PER_SEC) {
  43         errno = EINVAL;
  44         return -1;
  45     }
  46
  47     // Validate clock
  48     switch (clock_id) {
  49         case CLOCK_MONOTONIC:
  50         case CLOCK_REALTIME:
  51             break;
  52         default:
  53             errno = EINVAL;
  54             return -1;
  55     }
  56
  57     if (flags == TIMER_ABSTIME) {
  58         struct timespec ts_rel;
  59         struct timespec ts_now;
  60
  61         do {
  62             // Get current time with requested clock
  63             if (clock_gettime(clock_id, &ts_now) != 0)
  64                 return -1;
  65
  66             // Calculate relative timespec
  67             ts_rel.tv_sec  = rqtp->tv_sec  - ts_now.tv_sec;
  68             ts_rel.tv_nsec = rqtp->tv_nsec - ts_now.tv_nsec;
  69             if (ts_rel.tv_nsec < 0) {
  70                 ts_rel.tv_sec  -= 1;
  71                 ts_rel.tv_nsec += NSEC_PER_SEC;
  72             }
  73
  74             // Check if time already elapsed
  75             if (ts_rel.tv_sec < 0 || (ts_rel.tv_sec == 0 && ts_rel.tv_nsec == 0)) {
  76                 pthread_testcancel();
  77                 return 0;
  78             }
  79
  80             // "The absolute clock_nanosleep() function has no effect on the
  81             // structure referenced by rmtp", so do not pass rmtp here
  82         } while (nanosleep(&ts_rel, NULL) == 0);
  83
  84         // If nanosleep failed or was interrupted by a signal,
  85         // return so the caller can handle it appropriately
  86         return -1;
  87     } else if (flags == 0) {
  88         return nanosleep(rqtp, rmtp);
  89     } else {
  90         // Invalid flags
  91         errno = EINVAL;
  92         return -1;
  93     }
  94 }
  95
  96 #endif