1 files changed, 26 insertions, 0 deletions
diff --git a/tools/testing/selftests/net/tcp_ao/lib/utils.c b/tools/testing/selftests/net/tcp_ao/lib/utils.c
index 372daca525f5..bdf5522c9213 100644
--- a/tools/testing/selftests/net/tcp_ao/lib/utils.c
+++ b/tools/testing/selftests/net/tcp_ao/lib/utils.c
@@ -21,6 +21,32 @@ void randomize_buffer(void *buf, size_t buflen)
 	}
 }
 
+__printf(3, 4) int test_echo(const char *fname, bool append,
+			     const char *fmt, ...)
+{
+	size_t len, written;
+	va_list vargs;
+	char *msg;
+	FILE *f;
+
+	f = fopen(fname, append ? "a" : "w");
+	if (!f)
+		return -errno;
+
+	va_start(vargs, fmt);
+	msg = test_snprintf(fmt, vargs);
+	va_end(vargs);
+	if (!msg) {
+		fclose(f);
+		return -1;
+	}
+	len = strlen(msg);
+	written = fwrite(msg, 1, len, f);
+	fclose(f);
+	free(msg);
+	return written == len ? 0 : -1;
+}
+
 const struct sockaddr_in6 addr_any6 = {
 	.sin6_family	= AF_INET6,
 };