[PATCH v4 1/7] string.h: add str_has_suffix() helper for test string ends with specify string

[Ye Bin <yebin10@huawei.com>]

str_has_suffix() is test string if ends with specify string, and also
this API may return the index of where the suffix was found.

Signed-off-by: Ye Bin <yebin10@huawei.com>
---
 include/linux/string.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index 433c207a01da..2fb0f22237fe 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -405,4 +405,32 @@ static __always_inline size_t str_has_prefix(const char *str, const char *prefix
 	return strncmp(str, prefix, len) == 0 ? len : 0;
 }
 
+/**
+ * str_has_suffix - Test if a string has a given suffix
+ * @str: The string to test
+ * @suffix: The string to see if @str ends with
+ * @index: The index into @str of where @suffix is if found (NULL to ignore)
+ *
+ * Returns:
+ * * strlen(@suffix) if @str ends with @suffix
+ * * 0 if @str does not end with @suffix
+ */
+static __always_inline size_t str_has_suffix(const char *str, const char *suffix,
+					     size_t *index)
+{
+	size_t len = strlen(suffix);
+	size_t str_len = strlen(str);
+
+	if (len > str_len)
+		return 0;
+
+	if (strncmp(str + str_len - len, suffix, len))
+		return 0;
+
+	if (index)
+		*index = str_len - len;
+
+	return len;
+}
+
 #endif /* _LINUX_STRING_H_ */
-- 
2.31.1