1//===-- Linux implementation of the pthread_rwlock_init function ----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/pthread/pthread_rwlock_init.h"
10
11#include "src/__support/CPP/new.h"
12#include "src/__support/common.h"
13#include "src/__support/libc_assert.h"
14#include "src/__support/macros/config.h"
15#include "src/__support/threads/linux/rwlock.h"
16
17#include <pthread.h>
18
19namespace LIBC_NAMESPACE_DECL {
20
21static_assert(
22 sizeof(RwLock) == sizeof(pthread_rwlock_t) &&
23 alignof(RwLock) == alignof(pthread_rwlock_t),
24 "The public pthread_rwlock_t type must be of the same size and alignment "
25 "as the internal rwlock type.");
26
27LLVM_LIBC_FUNCTION(int, pthread_rwlock_init,
28 (pthread_rwlock_t * rwlock,
29 const pthread_rwlockattr_t *__restrict attr)) {
30 pthread_rwlockattr_t rwlockattr{
31 /*pshared=*/PTHREAD_PROCESS_PRIVATE,
32 /*pref*/ PTHREAD_RWLOCK_PREFER_READER_NP,
33 };
34 // POSIX does not specify this check, so we add an assertion to catch it.
35 LIBC_ASSERT(rwlock && "rwlock is null");
36 if (attr)
37 rwlockattr = *attr;
38
39 // PTHREAD_RWLOCK_PREFER_WRITER_NP is not supported.
40 rwlock::Role preference;
41 switch (rwlockattr.pref) {
42 case PTHREAD_RWLOCK_PREFER_READER_NP:
43 preference = rwlock::Role::Reader;
44 break;
45 case PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP:
46 preference = rwlock::Role::Writer;
47 break;
48 default:
49 return EINVAL;
50 }
51 bool is_pshared;
52 switch (rwlockattr.pshared) {
53 case PTHREAD_PROCESS_PRIVATE:
54 is_pshared = false;
55 break;
56 case PTHREAD_PROCESS_SHARED:
57 is_pshared = true;
58 break;
59 default:
60 return EINVAL;
61 }
62
63 new (rwlock) RwLock(preference, is_pshared);
64 return 0;
65}
66
67} // namespace LIBC_NAMESPACE_DECL
68

source code of libc/src/pthread/pthread_rwlock_init.cpp