From 8caeedac3ed17491cd77240211ed13be80072a15 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Mon, 26 Jan 2026 14:18:53 +0100
Subject: [PATCH] system/linux: detect native openat2() support at configure
 time

The Linux man-pages notes about openat2(): "glibc provides no wrapper
for openat2(), necessitating the use of syscall(2)"

.. but glibc 2.43 finally added a wrapper which caused a conflict with
our existing definition.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/2417
---
 src/system/linux/meson.build |  6 +++++-
 src/system/linux/openat2.h   | 11 ++++++++++-

diff --git a/src/system/linux/meson.build b/src/system/linux/meson.build
index 36a98f2127..4a0d6267ad 100644
--- a/src/system/linux/meson.build
+++ b/src/system/linux/meson.build
@@ -1,7 +1,11 @@
 system_linux_features = configuration_data()
 
 if host_machine.system() == 'linux'
-  system_linux_features.set('HAVE_OPENAT2', compiler.has_header('linux/openat2.h'))
+  have_native_openat2 = compiler.has_header_symbol('fcntl.h', 'openat2')
+  # openat2() support was added to glibc 2.43
+  system_linux_features.set('HAVE_NATIVE_OPENAT2', have_native_openat2)
+  # if not provided by the C library, we roll our own using syscall()
+  system_linux_features.set('HAVE_OPENAT2', have_native_openat2 or compiler.has_header('linux/openat2.h'))
 endif
 
 configure_file(output: 'Features.h', configuration: system_linux_features)
diff --git a/src/system/linux/openat2.h b/src/system/linux/openat2.h
index fdf3820983..807df97cb3 100644
--- a/src/system/linux/openat2.h
+++ b/src/system/linux/openat2.h
@@ -4,7 +4,14 @@
 
 #pragma once
 
-#include <fcntl.h> // for O_*
+#include "system/linux/Features.h" // for HAVE_NATIVE_OPENAT2
+
+#include <fcntl.h>
+
+#ifndef HAVE_NATIVE_OPENAT2
+/* if the C library does not provide an openat2() wrappper, we roll
+   our own */
+
 #include <linux/openat2.h> // for RESOLVE_*
 #include <sys/syscall.h>
 #include <unistd.h>
@@ -15,3 +22,5 @@ openat2(int dirfd, const char *pathname,
 {
 	return syscall(__NR_openat2, dirfd, pathname, how, size);
 }
+
+#endif // !HAVE_NATIVE_OPENAT2