/* * Attempt to read a disk label from a device * using the indicated strategy routine. * The label must be partly set up before this: * secpercyl, secsize and anything required for a block i/o read * operation in the driver's strategy/start routines * must be filled in before calling us. * * If dos partition table requested, attempt to load it and * find disklabel inside a DOS partition. Also, if bad block * table needed, attempt to extract it as well. Return buffer * for use in signalling errors if requested. * * Returns null on success and an error string on failure. */