block/dmg: process XML plists

block/dmg: process XML plists

The format is simple enough to avoid using a full-blown XML parser. It
assumes that all BLKX items begin with the "mish" magic word, therefore
it is not a problem if other values get matched which are not a BLKX
block.

The offsets are based on the description at
http://newosxbook.com/DMG.html

For compatibility with glib 2.12, use g_base64_decode (which
additionally requires an extra buffer allocation) instead of
g_base64_decode_inplace (which is only available since glib 2.20).

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1420566495-13284-7-git-send-email-peter@lekensteyn.nl
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>