libc/src/pthread/pthread_rwlock_timedrdlock.cpp

   1 //===-- Implementation of the Rwlock's timedrdlock 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_timedrdlock.h"
  10 #include "src/__support/common.h"
  11 #include "src/__support/libc_assert.h"
  12 #include "src/__support/macros/config.h"
  13 #include "src/__support/macros/optimization.h"
  14 #include "src/__support/threads/linux/rwlock.h"
  15 #include "src/__support/time/linux/abs_timeout.h"
  16 #include "src/errno/libc_errno.h"
  17
  18 #include <pthread.h>
  19
  20 namespace LIBC_NAMESPACE_DECL {
  21
  22 static_assert(
  23     sizeof(RwLock) == sizeof(pthread_rwlock_t) &&
  24         alignof(RwLock) == alignof(pthread_rwlock_t),
  25     "The public pthread_rwlock_t type must be of the same size and alignment "
  26     "as the internal rwlock type.");
  27
  28 LLVM_LIBC_FUNCTION(int, pthread_rwlock_timedrdlock,
  29                    (pthread_rwlock_t * rwlock,
  30                     const struct timespec *abstime)) {
  31   if (!rwlock)
  32     return EINVAL;
  33   RwLock *rw = reinterpret_cast<RwLock *>(rwlock);
  34   LIBC_ASSERT(abstime && "timedrdlock called with a null timeout");
  35   auto timeout =
  36       internal::AbsTimeout::from_timespec(*abstime, /*is_realtime=*/true);
  37   if (LIBC_LIKELY(timeout.has_value()))
  38     return static_cast<int>(rw->read_lock(timeout.value()));
  39
  40   switch (timeout.error()) {
  41   case internal::AbsTimeout::Error::Invalid:
  42     return EINVAL;
  43   case internal::AbsTimeout::Error::BeforeEpoch:
  44     return ETIMEDOUT;
  45   }
  46   __builtin_unreachable();
  47 }
  48
  49 } // namespace LIBC_NAMESPACE_DECL