1 files changed, 49 insertions, 0 deletions
diff --git a/libc/src/pthread/pthread_rwlock_timedrdlock.cpp b/libc/src/pthread/pthread_rwlock_timedrdlock.cpp
new file mode 100644
index 000000000000..6ce69ea738a9
--- /dev/null
+++ b/libc/src/pthread/pthread_rwlock_timedrdlock.cpp
@@ -0,0 +1,49 @@
+//===-- Implementation of the Rwlock's timedrdlock function ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/pthread/pthread_rwlock_timedrdlock.h"
+
+#include "src/__support/common.h"
+#include "src/__support/libc_assert.h"
+#include "src/__support/macros/optimization.h"
+#include "src/__support/threads/linux/rwlock.h"
+#include "src/__support/time/linux/abs_timeout.h"
+
+#include <errno.h>
+#include <pthread.h>
+
+namespace LIBC_NAMESPACE {
+
+static_assert(
+    sizeof(RwLock) == sizeof(pthread_rwlock_t) &&
+        alignof(RwLock) == alignof(pthread_rwlock_t),
+    "The public pthread_rwlock_t type must be of the same size and alignment "
+    "as the internal rwlock type.");
+
+LLVM_LIBC_FUNCTION(int, pthread_rwlock_timedrdlock,
+                   (pthread_rwlock_t * rwlock,
+                    const struct timespec *abstime)) {
+  if (!rwlock)
+    return EINVAL;
+  RwLock *rw = reinterpret_cast<RwLock *>(rwlock);
+  LIBC_ASSERT(abstime && "timedrdlock called with a null timeout");
+  auto timeout =
+      internal::AbsTimeout::from_timespec(*abstime, /*is_realtime=*/true);
+  if (LIBC_LIKELY(timeout.has_value()))
+    return static_cast<int>(rw->read_lock(timeout.value()));
+
+  switch (timeout.error()) {
+  case internal::AbsTimeout::Error::Invalid:
+    return EINVAL;
+  case internal::AbsTimeout::Error::BeforeEpoch:
+    return ETIMEDOUT;
+  }
+  __builtin_unreachable();
+}
+
+} // namespace LIBC_NAMESPACE