[LTP] [PATCH v2] gethostname: Add negative test for gethostname

[Yang Xu]

Add negative cases for gethostname(), when errno is ENAMETOOLONG

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 runtest/syscalls                              |  1 +
 .../kernel/syscalls/gethostname/.gitignore    |  1 +
 .../syscalls/gethostname/gethostname02.c      | 31 +++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100644 testcases/kernel/syscalls/gethostname/gethostname02.c

diff --git a/runtest/syscalls b/runtest/syscalls
index de4f5a633..cc1e39c05 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -477,6 +477,7 @@ gethostbyname_r01 gethostbyname_r01
 gethostid01 gethostid01
 
 gethostname01 gethostname01
+gethostname02 gethostname02
 
 getitimer01 getitimer01
 getitimer02 getitimer02
diff --git a/testcases/kernel/syscalls/gethostname/.gitignore b/testcases/kernel/syscalls/gethostname/.gitignore
index d09d5d288..d6e4cffcb 100644
--- a/testcases/kernel/syscalls/gethostname/.gitignore
+++ b/testcases/kernel/syscalls/gethostname/.gitignore
@@ -1 +1,2 @@
 /gethostname01
+/gethostname02
diff --git a/testcases/kernel/syscalls/gethostname/gethostname02.c b/testcases/kernel/syscalls/gethostname/gethostname02.c
new file mode 100644
index 000000000..250e5f2fd
--- /dev/null
+++ b/testcases/kernel/syscalls/gethostname/gethostname02.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2024 FUJITSU LIMITED. All Rights Reserved.
+ * Author: Yang Xu <xuyang2018.jy@fujitsu.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * Verify that gethostname(2) fails with
+ *
+ * - ENAMETOOLONG when len is smaller than the actual size
+ */
+
+#include "tst_test.h"
+
+static void verify_gethostname(void)
+{
+	char hostname[HOST_NAME_MAX];
+	int real_length;
+
+	SAFE_GETHOSTNAME(hostname, sizeof(hostname));
+	real_length = strlen(hostname);
+
+	TST_EXP_FAIL(gethostname(hostname, real_length - 1), ENAMETOOLONG,
+		"len is smaller than the actual size");
+}
+
+static struct tst_test test = {
+	.test_all = verify_gethostname,
+};
-- 
2.39.3