block/dmg: fix sector data offset calculation
This patch addresses two issues: - The data fork offset was not taken into account, resulting in failure to read an InstallESD.dmg file (5164763151 bytes) which had a non-zero DataForkOffset field. - The offset of the previous block ("partition") was unconditionally added to the current block because older files would start the input offset of a new block at zero. Newer files (including vlc-2.1.5.dmg, tuxpaint-0.9.15-macosx.dmg and OS X Yosemite [MAS].dmg) failed in reads because these files have chunk offsets, relative to the begin of a data fork. Now the data offset of the mish is taken into account. While we could check that the data_offset is within the data fork, let's not do that here as it would only result in parse failures on invalid files (rather than gracefully handling such bad files). dmg_read will error out if the offset is incorrect. Signed-off-by: NPeter Wu <peter@lekensteyn.nl> Reviewed-by: NJohn Snow <jsnow@redhat.com> Message-id: 1420566495-13284-9-git-send-email-peter@lekensteyn.nl Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com> Signed-off-by: NKevin Wolf <kwolf@redhat.com>
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