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 
nanosleep(const struct timespec * __req,struct timespec * __rem)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   useconds_t __micro_sec =
25       static_cast<useconds_t>((__req->tv_nsec + 999) / 1000);
26   time_t __sec = __req->tv_sec;
27   if (__micro_sec > 999999) {
28     ++__sec;
29     __micro_sec -= 1000000;
30   }
31   __sec = sleep(static_cast<unsigned int>(__sec));
32   if (__sec) {
33     if (__rem) {
34       // Updating the remaining time to sleep in case of unsuccessful call to sleep().
35       __rem->tv_sec = __sec;
36       __rem->tv_nsec = __micro_sec * 1000;
37     }
38     errno = EINTR;
39     return -1;
40   }
41   if (__micro_sec) {
42     int __rt = usleep(__micro_sec);
43     if (__rt != 0 && __rem) {
44       // The usleep() does not provide the amount of remaining time upon its failure,
45       // so the time slept will be ignored.
46       __rem->tv_sec = 0;
47       __rem->tv_nsec = __micro_sec * 1000;
48       // The errno is already set.
49       return -1;
50     }
51     return __rt;
52   }
53   return 0;
54 }
55 
56 #endif // _LIBCPP_SUPPORT_IBM_NANOSLEEP_H
57