+/*!
+ * @brief open metadata, possibly as root
+ *
+ * Return only metadata but try very hard ie at first try as user, then try as root.
+ *
+ * @param name name of file/dir
+ * @param flags ADFLAGS_DIR: name is a directory \n
+ * ADFLAGS_CREATE: force creation of header file, but only as user, not as root\n
+ * ADFLAGS_OPENFORKS: test if name is open by another afpd process
+ *
+ * @param adp pointer to struct adouble
+ *
+ * @note caller MUST pass ADFLAGS_DIR for directories. Whether ADFLAGS_CREATE really creates
+ * a adouble file depends on various other volume options, eg. ADVOL_CACHE