cosmopolitan/libc/intrin/pthread_mutex_unlock.c
Jōshin e16a7d8f3b
flip et / noet in modelines
`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/'
```
2023-12-07 22:17:11 -05:00

73 lines
3.2 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et 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/calls/calls.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/runtime/internal.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/mu.h"
/**
* Releases mutex.
*
* This function does nothing in vfork() children.
*
* @return 0 on success or error number on failure
* @raises EPERM if in error check mode and not owned by caller
* @vforksafe
*/
errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
int t;
LOCKTRACE("pthread_mutex_unlock(%t)", mutex);
if (mutex->_type == PTHREAD_MUTEX_NORMAL && //
mutex->_pshared == PTHREAD_PROCESS_PRIVATE && //
_weaken(nsync_mu_unlock)) {
_weaken(nsync_mu_unlock)((nsync_mu *)mutex);
return 0;
}
if (mutex->_type == PTHREAD_MUTEX_NORMAL) {
atomic_store_explicit(&mutex->_lock, 0, memory_order_release);
return 0;
}
t = gettid();
// we allow unlocking an initialized lock that wasn't locked, but we
// don't allow unlocking a lock held by another thread, or unlocking
// recursive locks from a forked child, since it should be re-init'd
if (mutex->_owner && (mutex->_owner != t || mutex->_pid != __pid)) {
return EPERM;
}
if (mutex->_depth) {
--mutex->_depth;
return 0;
}
mutex->_owner = 0;
atomic_store_explicit(&mutex->_lock, 0, memory_order_release);
return 0;
}