mirror of
https://github.com/jart/cosmopolitan.git
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55 lines
2.8 KiB
C
55 lines
2.8 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/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/pthread.h"
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/**
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* Releases mutex.
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* @return 0 on success or error number on failure
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* @raises EPERM if in error check mode and not owned by caller
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*/
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int(pthread_mutex_unlock)(pthread_mutex_t *mutex) {
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int me, owner;
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switch (mutex->attr) {
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case PTHREAD_MUTEX_ERRORCHECK:
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me = gettid();
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owner = atomic_load_explicit(&mutex->lock, memory_order_relaxed);
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if (owner != me) {
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assert(!"perm lock");
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return EPERM;
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}
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// fallthrough
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case PTHREAD_MUTEX_RECURSIVE:
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if (--mutex->reent) return 0;
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// fallthrough
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case PTHREAD_MUTEX_NORMAL:
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atomic_store_explicit(&mutex->lock, 0, memory_order_relaxed);
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if (atomic_load_explicit(&mutex->waits, memory_order_relaxed) > 0) {
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_pthread_mutex_wake(mutex);
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}
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return 0;
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default:
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assert(!"inva lock");
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return EINVAL;
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}
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}
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