-char *base_name PARAMS ((char const *path));
-char *dir_name PARAMS ((char const *path));
-size_t base_len PARAMS ((char const *path));
-size_t dir_len PARAMS ((char const *path));
+# define IS_ABSOLUTE_FILE_NAME(F) ISSLASH ((F)[FILE_SYSTEM_PREFIX_LEN (F)])
+# define IS_RELATIVE_FILE_NAME(F) (! IS_ABSOLUTE_FILE_NAME (F))
+
+char *base_name (char const *path);
+char *dir_name (char const *path);
+size_t base_len (char const *path);
+size_t dir_len (char const *path);