[PATCH v5 2/8] lib/string_kunit: add correctness test for strnlen()

[Feng Jiang]

Add a KUnit test for strnlen() to verify correctness across
different string lengths and memory alignments.

Suggested-by: Andy Shevchenko <andy at kernel.org>
Signed-off-by: Feng Jiang <jiangfeng at kylinos.cn>
Acked-by: Andy Shevchenko <andy at kernel.org>
Tested-by: Joel Stanley <joel at jms.id.au>
---
 lib/tests/string_kunit.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c
index bc5130c6e5e9..991f01d52eb2 100644
--- a/lib/tests/string_kunit.c
+++ b/lib/tests/string_kunit.c
@@ -129,6 +129,38 @@ static void string_test_strlen(struct kunit *test)
 	}
 }
 
+static void string_test_strnlen(struct kunit *test)
+{
+	const size_t buf_size = STRING_TEST_MAX_LEN + STRING_TEST_MAX_OFFSET + 1;
+	size_t len, offset;
+	char *s;
+
+	s = kunit_kzalloc(test, buf_size, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, s);
+
+	memset(s, 'A', buf_size);
+	s[buf_size - 1] = '\0';
+
+	for (offset = 0; offset < STRING_TEST_MAX_OFFSET; offset++) {
+		for (len = 0; len <= STRING_TEST_MAX_LEN; len++) {
+			s[offset + len] = '\0';
+
+			if (len > 0)
+				KUNIT_EXPECT_EQ(test, strnlen(s + offset, len - 1), len - 1);
+			if (len > 1)
+				KUNIT_EXPECT_EQ(test, strnlen(s + offset, len - 2), len - 2);
+
+			KUNIT_EXPECT_EQ(test, strnlen(s + offset, len), len);
+
+			KUNIT_EXPECT_EQ(test, strnlen(s + offset, len + 1), len);
+			KUNIT_EXPECT_EQ(test, strnlen(s + offset, len + 2), len);
+			KUNIT_EXPECT_EQ(test, strnlen(s + offset, len + 10), len);
+
+			s[offset + len] = 'A';
+		}
+	}
+}
+
 static void string_test_strchr(struct kunit *test)
 {
 	const char *test_string = "abcdefghijkl";
@@ -644,6 +676,7 @@ static struct kunit_case string_test_cases[] = {
 	KUNIT_CASE(string_test_memset32),
 	KUNIT_CASE(string_test_memset64),
 	KUNIT_CASE(string_test_strlen),
+	KUNIT_CASE(string_test_strnlen),
 	KUNIT_CASE(string_test_strchr),
 	KUNIT_CASE(string_test_strnchr),
 	KUNIT_CASE(string_test_strspn),
-- 
2.25.1