kc3-lang/gnulib/lib/pthread_mutex_timedlock.c

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• Hash : 7b089321
  Author :
  Date : 2025-01-01T09:24:36
  

  maint: run 'make update-copyright'
  

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• lib/pthread_mutex_timedlock.c

• /* Lock a mutex, abandoning after a certain time.
     Copyright (C) 2019-2025 Free Software Foundation, Inc.
  
     This file is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as
     published by the Free Software Foundation; either version 2.1 of the
     License, or (at your option) any later version.
  
     This file is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  
  #include <config.h>
  
  /* Specification.  */
  #include <pthread.h>
  
  #include <errno.h>
  #include <limits.h>
  #include <sys/time.h>
  #include <time.h>
  
  #ifndef MIN
  # define MIN(a, b) ((a) < (b) ? (a) : (b))
  #endif
  
  int
  pthread_mutex_timedlock (pthread_mutex_t *mutex, const struct timespec *abstime)
  {
    /* Poll the mutex's state in regular intervals.  Ugh.  */
    /* POSIX says:
        "Under no circumstance shall the function fail with a timeout if
         the mutex can be locked immediately. The validity of the abstime
         parameter need not be checked if the mutex can be locked
         immediately."
       Therefore start the loop with a pthread_mutex_trylock call.  */
    for (;;)
      {
        int err;
        struct timeval currtime;
        unsigned long remaining;
  
        err = pthread_mutex_trylock (mutex);
        if (err != EBUSY)
          return err;
  
        gettimeofday (&currtime, NULL);
  
        if (currtime.tv_sec > abstime->tv_sec)
          remaining = 0;
        else
          {
            unsigned long seconds = abstime->tv_sec - currtime.tv_sec;
            remaining = seconds * 1000000000;
            if (remaining / 1000000000 != seconds) /* overflow? */
              remaining = ULONG_MAX;
            else
              {
                long nanoseconds =
                  abstime->tv_nsec - currtime.tv_usec * 1000;
                if (nanoseconds >= 0)
                  {
                    remaining += nanoseconds;
                    if (remaining < nanoseconds) /* overflow? */
                      remaining = ULONG_MAX;
                  }
                else
                  {
                    if (remaining >= - nanoseconds)
                      remaining -= (- nanoseconds);
                    else
                      remaining = 0;
                  }
              }
          }
        if (remaining == 0)
          return ETIMEDOUT;
  
        /* Sleep 1 ms.  */
        struct timespec duration =
          {
            .tv_sec = 0,
            .tv_nsec = MIN (1000000, remaining)
          };
        nanosleep (&duration, NULL);
      }
  }
  

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