+int sd_is_fifo(int fd, const char *path);
+
+/*
+ Helper call for identifying a passed file descriptor. Returns 1 if
+ the file descriptor is a special character device on the file
+ system stored under the specified path, 0 otherwise.
+ If path is NULL a path name check will not be done and the call
+ only verifies if the file descriptor refers to a special character.
+ Returns a negative errno style error code on failure.
+
+ See sd_is_special(3) for more information.
+*/
+int sd_is_special(int fd, const char *path);