Function getTypeOutputInfo

src/backend/utils/cache/lsyscache.c:3507–3533

* getTypeOutputInfo * * Get info needed for printing values of a type */

 *		Get info needed for printing values of a type
 */
void
getTypeOutputInfo(Oid type, Oid *typOutput, bool *typIsVarlena)
{
	HeapTuple	typeTuple;
	Form_pg_type pt;

	typeTuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(type));
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", type);
	pt = (Form_pg_type) GETSTRUCT(typeTuple);

	if (!pt->typisdefined)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type %s is only a shell",
						format_type_be(type))));
	if (!OidIsValid(pt->typoutput))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("no output function available for type %s",
						format_type_be(type))));

	*typOutput = pt->typoutput;
	*typIsVarlena = (!pt->typbyval) && (pt->typlen == -1);

	ReleaseSysCache(typeTuple);
}

/*
 * getTypeBinaryInputInfo