Commit 66ec3bba authored by Peter Wu's avatar Peter Wu Committed by Kevin Wolf
Browse files

block/dmg: use SectorNumber from BLKX header 

Previously the sector table parsing relied on the previous offset of
the DMG file. Now it uses the sector number from the BLKX header
(see http://newosxbook.com/DMG.html

).

The implementation of dmg2img (from vu1tur) does not base the output
sector on the location of the terminator (0xffffffff) either so it
should be safe to drop this dependency on the previous state.

(It makes somehow makes sense, a terminator should halt further
processing of a block and is perhaps used to preallocate some space.)

Signed-off-by: default avatarPeter Wu <peter@lekensteyn.nl>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
Message-id: 1420566495-13284-10-git-send-email-peter@lekensteyn.nl
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent c6d34865

block/dmg.c

+5 −7
Original line number Diff line number Diff line
@@ -187,7 +187,6 @@ typedef struct DmgHeaderState { 
    /* used internally by dmg_read_mish_block to remember offsets of blocks

     * across calls */

    uint64_t data_fork_offset;

    uint64_t last_out_offset;

    /* exported for dmg_open */

    uint32_t max_compressed_size;

    uint32_t max_sectors_per_chunk;
@@ -203,6 +202,7 @@ static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds, 
    int64_t offset = 0;

    uint64_t data_offset;

    uint64_t in_offset = ds->data_fork_offset;

    uint64_t out_offset;



    type = buff_read_uint32(buffer, offset);

    /* skip data that is not a valid MISH block (invalid magic or too small) */
@@ -211,6 +211,9 @@ static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds, 
        return 0;

    }



    /* chunk offsets are relative to this sector number */

    out_offset = buff_read_uint64(buffer, offset + 8);



    /* location in data fork for (compressed) blob (in bytes) */

    data_offset = buff_read_uint64(buffer, offset + 0x18);

    in_offset += data_offset;
@@ -231,10 +234,6 @@ static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds, 
        offset += 4;

        if (s->types[i] != 0x80000005 && s->types[i] != 1 &&

            s->types[i] != 2) {

            if (s->types[i] == 0xffffffff && i > 0) {

                ds->last_out_offset = s->sectors[i - 1] +

                                      s->sectorcounts[i - 1];

            }

            chunk_count--;

            i--;

            offset += 36;
@@ -243,7 +242,7 @@ static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds, 
        offset += 4;



        s->sectors[i] = buff_read_uint64(buffer, offset);

        s->sectors[i] += ds->last_out_offset;

        s->sectors[i] += out_offset;

        offset += 8;



        s->sectorcounts[i] = buff_read_uint64(buffer, offset);
@@ -418,7 +417,6 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, 
    s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;

    /* used by dmg_read_mish_block to keep track of the current I/O position */

    ds.data_fork_offset = 0;

    ds.last_out_offset = 0;

    ds.max_compressed_size = 1;

    ds.max_sectors_per_chunk = 1;