From a1f9ef061542624eb397dac481e805d678b43ea1 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Wed, 30 Sep 2020 22:18:13 +0200
Subject: [PATCH] Fix the build when _GNU_SOURCE is defined to a non-empty
 value

Fix #3432.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
---
 ChangeLog.d/_GNU_SOURCE-redefined.txt | 3 +++
 library/entropy_poll.c                | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)
 create mode 100644 ChangeLog.d/_GNU_SOURCE-redefined.txt

diff --git a/ChangeLog.d/_GNU_SOURCE-redefined.txt b/ChangeLog.d/_GNU_SOURCE-redefined.txt
new file mode 100644
index 000000000..59c8a153f
--- /dev/null
+++ b/ChangeLog.d/_GNU_SOURCE-redefined.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix the build when the macro _GNU_SOURCE is defined to a non-empty value.
+     Fix #3432.
diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index 4bf660e05..5250a7bfe 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -17,7 +17,7 @@
  *  limitations under the License.
  */
 
-#if defined(__linux__)
+#if defined(__linux__) && !defined(_GNU_SOURCE)
 /* Ensure that syscall() is available even when compiling with -std=c99 */
 #define _GNU_SOURCE
 #endif