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e16a7d8f3b
`et` means `expandtab`. ```sh rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\) :vi/vi: \1 xoet\2:vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2 :vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/' ```
114 lines
4.1 KiB
C
114 lines
4.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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/calls/calls.h"
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#include "libc/calls/state.internal.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/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/runtime/internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#include "third_party/nsync/mu.h"
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/**
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* Locks mutex.
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*
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* Here's an example of using a normal mutex:
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*
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* pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
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* pthread_mutex_lock(&lock);
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* // do work...
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* pthread_mutex_unlock(&lock);
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* pthread_mutex_destroy(&lock);
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*
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* Cosmopolitan permits succinct notation for normal mutexes:
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*
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* pthread_mutex_t lock = {0};
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* pthread_mutex_lock(&lock);
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* // do work...
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* pthread_mutex_unlock(&lock);
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*
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* Here's an example of the proper way to do recursive mutexes:
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*
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* pthread_mutex_t lock;
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* pthread_mutexattr_t attr;
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* pthread_mutexattr_init(&attr);
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* pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
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* pthread_mutex_init(&lock, &attr);
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* pthread_mutexattr_destroy(&attr);
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* pthread_mutex_lock(&lock);
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* // do work...
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* pthread_mutex_unlock(&lock);
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* pthread_mutex_destroy(&lock);
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*
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* This function does nothing in vfork() children.
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*
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* @return 0 on success, or error number on failure
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* @see pthread_spin_lock()
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* @vforksafe
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*/
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errno_t pthread_mutex_lock(pthread_mutex_t *mutex) {
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int t;
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LOCKTRACE("pthread_mutex_lock(%t)", mutex);
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if (__vforked) {
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return 0;
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}
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if (mutex->_type == PTHREAD_MUTEX_NORMAL && //
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mutex->_pshared == PTHREAD_PROCESS_PRIVATE && //
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_weaken(nsync_mu_lock)) {
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_weaken(nsync_mu_lock)((nsync_mu *)mutex);
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return 0;
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}
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if (mutex->_type == PTHREAD_MUTEX_NORMAL) {
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while (atomic_exchange_explicit(&mutex->_lock, 1, memory_order_acquire)) {
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pthread_pause_np();
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}
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return 0;
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}
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t = gettid();
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if (mutex->_owner == t) {
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if (mutex->_type != PTHREAD_MUTEX_ERRORCHECK) {
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if (mutex->_depth < 63) {
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++mutex->_depth;
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return 0;
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} else {
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return EAGAIN;
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}
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} else {
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return EDEADLK;
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}
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}
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while (atomic_exchange_explicit(&mutex->_lock, 1, memory_order_acquire)) {
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pthread_pause_np();
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}
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mutex->_depth = 0;
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mutex->_owner = t;
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mutex->_pid = __pid;
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return 0;
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}
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