[PATCH v1 1/3] lib/string: introduce match_string() helper

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

>From time to time we have to match a string in an array. Make a simple helper
for that purpose.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/string.h |  7 +++++++
 lib/string.c           | 26 ++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index a8d90db..15e6116 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -126,6 +126,13 @@ extern void argv_free(char **argv);
 extern bool sysfs_streq(const char *s1, const char *s2);
 extern int strtobool(const char *s, bool *res);
 
+int match_string(const char * const *array, size_t len, const char *string);
+
+static inline int match_stringnul(const char * const *array, const char *string)
+{
+	return match_string(array, 0, string);
+}
+
 #ifdef CONFIG_BINARY_PRINTF
 int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
 int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
diff --git a/lib/string.c b/lib/string.c
index 13d1e84..0771359 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -542,6 +542,32 @@ bool sysfs_streq(const char *s1, const char *s2)
 EXPORT_SYMBOL(sysfs_streq);
 
 /**
+ * match_string - matches given string in an array
+ * @array:	array of strings
+ * @len:	number of strings in the array or 0 for NULL terminated arrays
+ * @string:	string to match with
+ *
+ * Return:
+ * index of a @string in the array if matches, or -1 otherwise.
+ */
+int match_string(const char * const *array, size_t len, const char *string)
+{
+	int index = 0;
+	const char *item;
+
+	do {
+		item = array[index];
+		if (!item)
+			break;
+		if (!strcmp(item, string))
+			return index;
+	} while (++index < len || !len);
+
+	return -1;
+}
+EXPORT_SYMBOL(match_string);
+
+/**
  * strtobool - convert common user inputs into boolean values
  * @s: input string
  * @res: result
-- 
2.5.1