libcxx/include/__support/ibm/nanosleep.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___SUPPORT_IBM_NANOSLEEP_H
  11 #define _LIBCPP___SUPPORT_IBM_NANOSLEEP_H
  12
  13 #include <unistd.h>
  14
  15 inline int nanosleep(const struct timespec* __req, struct timespec* __rem) {
  16   // The nanosleep() function is not available on z/OS. Therefore, we will call
  17   // sleep() to sleep for whole seconds and usleep() to sleep for any remaining
  18   // fraction of a second. Any remaining nanoseconds will round up to the next
  19   // microsecond.
  20   if (__req->tv_sec < 0 || __req->tv_nsec < 0 || __req->tv_nsec > 999999999) {
  21     errno = EINVAL;
  22     return -1;
  23   }
  24   long __micro_sec = (__req->tv_nsec + 999) / 1000;
  25   time_t __sec     = __req->tv_sec;
  26   if (__micro_sec > 999999) {
  27     ++__sec;
  28     __micro_sec -= 1000000;
  29   }
  30   __sec = static_cast<time_t>(sleep(static_cast<unsigned int>(__sec)));
  31   if (__sec) {
  32     if (__rem) {
  33       // Updating the remaining time to sleep in case of unsuccessful call to sleep().
  34       __rem->tv_sec  = __sec;
  35       __rem->tv_nsec = __micro_sec * 1000;
  36     }
  37     errno = EINTR;
  38     return -1;
  39   }
  40   if (__micro_sec) {
  41     int __rt = usleep(static_cast<unsigned int>(__micro_sec));
  42     if (__rt != 0 && __rem) {
  43       // The usleep() does not provide the amount of remaining time upon its failure,
  44       // so the time slept will be ignored.
  45       __rem->tv_sec  = 0;
  46       __rem->tv_nsec = __micro_sec * 1000;
  47       // The errno is already set.
  48       return -1;
  49     }
  50     return __rt;
  51   }
  52   return 0;
  53 }
  54
  55 #endif // _LIBCPP___SUPPORT_IBM_NANOSLEEP_H