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
56