mirror of
https://github.com/jart/cosmopolitan.git
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77 lines
3.7 KiB
C
77 lines
3.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/at.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/thread/semaphore.h"
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#include "libc/thread/semaphore.internal.h"
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/**
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* Initializes and opens named semaphore.
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*
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* @param name can be absolute path or should be component w/o slashes
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* @param oflga can have `O_CREAT` and/or `O_EXCL`
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* @return semaphore object which needs sem_close(), or SEM_FAILED w/ errno
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* @raise ENOTDIR if a directory component in `name` exists as non-directory
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* @raise ENAMETOOLONG if symlink-resolved `name` length exceeds `PATH_MAX`
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* @raise ENAMETOOLONG if component in `name` exists longer than `NAME_MAX`
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* @raise ELOOP if `flags` had `O_NOFOLLOW` and `name` is a symbolic link
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* @raise ENOSPC if file system is full when `name` would be `O_CREAT`ed
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* @raise ELOOP if a loop was detected resolving components of `name`
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* @raise EEXIST if `O_CREAT|O_EXCL` is used and semaphore exists
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* @raise EACCES if we didn't have permission to create semaphore
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* @raise EMFILE if process `RLIMIT_NOFILE` has been reached
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* @raise ENFILE if system-wide file limit has been reached
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* @raise EINTR if signal was delivered instead
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*/
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sem_t *sem_open(const char *name, int oflag, ...) {
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int fd;
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sem_t *sem;
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va_list va;
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unsigned mode;
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char path[PATH_MAX];
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va_start(va, oflag);
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mode = va_arg(va, unsigned);
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va_end(va);
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oflag |= O_RDWR | O_CLOEXEC;
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if ((fd = openat(AT_FDCWD, __sem_name(name, path), oflag, mode)) == -1) {
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return SEM_FAILED;
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}
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if (ftruncate(fd, sizeof(sem_t)) == -1) {
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_npassert(!close(fd));
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return SEM_FAILED;
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}
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sem = mmap(0, sizeof(sem_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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if (sem != MAP_FAILED) {
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sem->sem_pshared = true;
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} else {
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sem = SEM_FAILED;
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}
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_npassert(!close(fd));
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return sem;
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}
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