cosmopolitan/libc/calls/sleep.c
Justine Tunney 2278327eba
Implement support for POSIX thread cancellations
This change makes some miracle modifications to the System Five system
call support, which lets us have safe, correct, and atomic handling of
thread cancellations. It all turned out to be cheaper than anticipated
because it wasn't necessary to modify the system call veneers. We were
able to encode the cancellability of each system call into the magnums
found in libc/sysv/syscalls.sh. Since cancellations are so waq, we are
also supporting a lovely Musl Libc mask feature for raising ECANCELED.
2022-11-04 01:04:43 -07:00

45 lines
2.5 KiB
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. │
│ │
│ 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/limits.h"
#include "libc/sysv/consts/clock.h"
#include "libc/time/time.h"
/**
* Sleeps for particular number of seconds.
*
* @return 0 if the full time elapsed, otherwise we assume an interrupt
* was delivered, in which case the errno condition is ignored, and
* this function shall return the number of unslept seconds rounded
* using the ceiling function
* @see clock_nanosleep()
* @cancellationpoint
* @asyncsignalsafe
* @norestart
*/
unsigned sleep(unsigned seconds) {
unsigned unslept;
struct timespec tv = {seconds};
if (!clock_nanosleep(CLOCK_REALTIME, 0, &tv, &tv)) return 0;
unslept = tv.tv_sec;
if (tv.tv_nsec && unslept < UINT_MAX) {
++unslept;
}
return unslept;
}