Update the read hook to take into account encrypted volumes on a partition.
GRUB disk read hooks supply an absolute sector number at which the read is
started from. If the encrypted volume is in a partition, the sector number
given to the read hook will be offset by the number of the sector at the
start of the partition. The read hook then needs to subtract the partition
start from the supplied sector to get the correct start sector for the read
into the detached header file.
Reported-by: brutser <brutser@perso.be>
Signed-off-by: Glenn Washburn <development@efficientek.com>
Tested-by: brutser <brutser@perso.be>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
0b44244025