*
* The string is taken from a minimal ASCII text descriptor leaf after
* the immediate entry with @key. The string is zero-terminated.
+ * An overlong string is silently truncated such that it and the
+ * zero byte fit into @size.
+ *
* Returns strlen(buf) or a negative error code.
*/
int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)