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

Signed-off-by: Feng Jiang <[email protected]>
---
 lib/tests/string_kunit.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c
index 9f4fc72f0886..1d08850e439c 100644
--- a/lib/tests/string_kunit.c
+++ b/lib/tests/string_kunit.c
@@ -126,6 +126,35 @@ static void string_test_strlen(struct kunit *test)
        }
 }
 
+static void string_test_strnlen(struct kunit *test)
+{
+       char *s;
+       size_t len, offset;
+       const size_t buf_size = 16 + 128 + 1; /* max_offset + max_len + '\0' */
+
+       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 < 16; offset++) {
+               for (len = 0; len <= 128; len++) {
+                       s[offset + len] = '\0';
+
+                       if (len > 0)
+                               KUNIT_EXPECT_EQ(test, strnlen(s + offset, len - 
1), len - 1);
+
+                       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 + 10), 
len);
+
+                       s[offset + len] = 'A';
+               }
+       }
+}
+
 static void string_test_strchr(struct kunit *test)
 {
        const char *test_string = "abcdefghijkl";
@@ -641,6 +670,7 @@ 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


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