On Wed, Apr 10, 2013 at 04:11:48PM +0800, Dong Xu Wang wrote: > +The Header is included in the first bytes: > +(HEADER_SIZE is defined in 40-43 bytes.) > + Byte 0 - 3: magic > + add-cow magic string ("ACOW"). > + > + 4 - 7: backing file name offset > + Offset in the add-cow file at which the backing > + file name is stored (NB: The string is not > + lNUL-terminated).
s/lNUL/NUL/ > + 24 - 31: features > + Bitmask of features. If a feature bit is set > + but not recognized, the add-cow file should be > + dropped. They are not used in now. "If a feature bit is set but not recognized, the opening the add-cow file must fail. No features bits are currently defined."