From 2bc1e914d078eddd3c246fb1cf982e7c35182f5e Mon Sep 17 00:00:00 2001
From: Marcel Holtmann <marcel@holtmann.org>
Date: Tue, 10 Feb 2026 17:11:08 +0100
Subject: [PATCH] udev: Fix build issue with missing _GNU_SOURCE
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  CC       src/udev.o
src/udev.c: In function ‘attach_filter’:
src/udev.c:129:40: error: ‘SO_ATTACH_FILTER’ undeclared (first use in this function)
  129 |         if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER,
      |                                        ^~~~~~~~~~~~~~~~
src/udev.c:129:40: note: each undeclared identifier is reported only once for each function it appears in
---
 src/udev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/udev.c b/src/udev.c
index 859f00bd..d8adbf0f 100644
--- a/src/udev.c
+++ b/src/udev.c
@@ -24,6 +24,7 @@
 #include <config.h>
 #endif
 
+#define _GNU_SOURCE
 #include <errno.h>
 #include <unistd.h>
 #include <sys/socket.h>