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Add posix semaphores support

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There's still some bugs to work out on Windows and OpenBSD.
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Justine Tunney 2022-10-14 08:25:47 -07:00
parent f52f65b2e3
commit 8111462789
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36 changed files with 779 additions and 59 deletions
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libc/thread/sem_open.c Normal file
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/*-*- 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 2022 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/assert.h"
#include "libc/calls/calls.h"
#include "libc/runtime/runtime.h"
#include "libc/sysv/consts/at.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "libc/thread/semaphore.h"
#include "libc/thread/semaphore.internal.h"
/**
* Initializes and opens named semaphore.
*
* @param name can be absolute path or should be component w/o slashes
* @param oflga can have `O_CREAT` and/or `O_EXCL`
* @return semaphore object which needs sem_close(), or SEM_FAILED w/ errno
* @raise ENOTDIR if a directory component in `name` exists as non-directory
* @raise ENAMETOOLONG if symlink-resolved `name` length exceeds `PATH_MAX`
* @raise ENAMETOOLONG if component in `name` exists longer than `NAME_MAX`
* @raise ELOOP if `flags` had `O_NOFOLLOW` and `name` is a symbolic link
* @raise ENOSPC if file system is full when `name` would be `O_CREAT`ed
* @raise ELOOP if a loop was detected resolving components of `name`
* @raise EEXIST if `O_CREAT|O_EXCL` is used and semaphore exists
* @raise EACCES if we didn't have permission to create semaphore
* @raise EMFILE if process `RLIMIT_NOFILE` has been reached
* @raise ENFILE if system-wide file limit has been reached
* @raise EINTR if signal was delivered instead
*/
sem_t *sem_open(const char *name, int oflag, ...) {
int fd;
sem_t *sem;
va_list va;
unsigned mode;
char path[PATH_MAX];
va_start(va, oflag);
mode = va_arg(va, unsigned);
va_end(va);
oflag |= O_RDWR | O_CLOEXEC;
if ((fd = openat(AT_FDCWD, __sem_name(name, path), oflag, mode)) == -1) {
return SEM_FAILED;
}
if (ftruncate(fd, sizeof(sem_t)) == -1) {
_npassert(!close(fd));
return SEM_FAILED;
}
sem = mmap(0, sizeof(sem_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (sem != MAP_FAILED) sem->sem_pshared = true;
_npassert(!close(fd));
return sem;
}