fix: improve _z_string_compare

Co-authored-by: Alexander Bushnev <[email protected]>

src/collections/string.c

@@ -102,10 +102,20 @@ void _z_string_free(_z_string_t **str) {
 }
 
 int _z_string_compare(const _z_string_t *left, const _z_string_t *right) {
-    if (_z_string_len(left) <= _z_string_len(right)) {
-        return strncmp(_z_string_data(left), _z_string_data(right), _z_string_len(left));
+    size_t len_left = _z_string_len(left);
+    size_t len_right = _z_string_len(right);
+
+    int result = strncmp(_z_string_data(left), _z_string_data(right), len_left < len_right ? len_left : len_right);
+
+    if (result == 0) {
+        if (len_left < len_right) {
+            return -1;
+        } else if (len_left > len_right) {
+            return 1;
+        }
     }
-    return strncmp(_z_string_data(left), _z_string_data(right), _z_string_len(right));
+
+    return result;
 }
 
 bool _z_string_equals(const _z_string_t *left, const _z_string_t *right) {