[libc-commits] [libc] [libc] Add sys/eventfd.h header and eventfd function. (PR #234028)

[Pavel Labath via libc-commits]

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@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for eventfd.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_EVENTFD_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_EVENTFD_H
+
+#include "hdr/errno_macros.h"
+#include "src/__support/OSUtil/linux/syscall.h" // For syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> eventfd(unsigned int initval, int flags) {
+#ifdef SYS_eventfd2
+  return syscall_checked<int>(SYS_eventfd2, initval, flags);
+#elif defined(SYS_eventfd)
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labath wrote:

It looks like eventfd2 was introduced back in linux 2.6.27. I think we can use it unconditionally.

https://github.com/llvm/llvm-project/pull/234028