cosmopolitan/libc/calls/nanosleep.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/struct/timespec.h"
#include "libc/errno.h"
#include "libc/sysv/consts/clock.h"

/**
 * Sleeps for relative amount of time.
 *
 * @param req is the duration of time we should sleep
 * @param rem if non-null will be updated with the remainder of unslept
 *     time when -1 w/ `EINTR` is returned otherwise `rem` is undefined
 * @return 0 on success, or -1 w/ errno
 * @raise EINVAL if `req->tv_nsec ∉ [0,1000000000)`
 * @raise ECANCELED if thread was cancelled in masked mode
 * @raise EINTR if a signal was delivered and `rem` is updated
 * @raise EFAULT if `req` is NULL or `req` / `rem` is a bad pointer
 * @raise ENOSYS on bare metal
 * @see clock_nanosleep()
 * @cancellationpoint
 * @norestart
 */
int nanosleep(const struct timespec *req, struct timespec *rem) {
  int rc;
  if (!(rc = clock_nanosleep(CLOCK_REALTIME, 0, req, rem))) {
    return 0;
  } else {
    errno = rc;
    return -1;
  }
}