1 files changed, 42 insertions, 0 deletions
diff --git a/tools/testing/selftests/landlock/wait-pipe.c b/tools/testing/selftests/landlock/wait-pipe.c
new file mode 100644
index 000000000000..0dbcd260a0fa
--- /dev/null
+++ b/tools/testing/selftests/landlock/wait-pipe.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Write in a pipe and wait.
+ *
+ * Used by layout1.umount_sandboxer from fs_test.c
+ *
+ * Copyright © 2024-2025 Microsoft Corporation
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[])
+{
+	int pipe_child, pipe_parent;
+	char buf;
+
+	/* The first argument must be the file descriptor number of a pipe. */
+	if (argc != 3) {
+		fprintf(stderr, "Wrong number of arguments (not two)\n");
+		return 1;
+	}
+
+	pipe_child = atoi(argv[1]);
+	pipe_parent = atoi(argv[2]);
+
+	/* Signals that we are waiting. */
+	if (write(pipe_child, ".", 1) != 1) {
+		perror("Failed to write to first argument");
+		return 1;
+	}
+
+	/* Waits for the parent do its test. */
+	if (read(pipe_parent, &buf, 1) != 1) {
+		perror("Failed to write to the second argument");
+		return 1;
+	}
+
+	return 0;
+}