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[Qemu-devel] [PATCH v2 09/12] block/dmg: use SectorNumber from BLKX head
From: |
Peter Wu |
Subject: |
[Qemu-devel] [PATCH v2 09/12] block/dmg: use SectorNumber from BLKX header |
Date: |
Tue, 6 Jan 2015 18:48:12 +0100 |
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: Peter Wu <address@hidden>
---
v2: initial patch after suggestions from John Snow to read and use
these fields.
---
block/dmg.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/block/dmg.c b/block/dmg.c
index 130efac..57922c5 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -189,7 +189,6 @@ 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;
@@ -205,6 +204,7 @@ 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) */
@@ -213,6 +213,9 @@ 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;
@@ -233,10 +236,6 @@ 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;
@@ -245,7 +244,7 @@ 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);
@@ -419,7 +418,6 @@ 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;
--
2.2.1
- [Qemu-devel] [PATCH v2 00/12] block/dmg: (compatibility) fixes and bzip2 support, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 05/12] block/dmg: validate chunk size to avoid overflow, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 04/12] block/dmg: process a buffer instead of reading ints, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 07/12] block/dmg: set virtual size to a non-zero value, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 08/12] block/dmg: fix sector data offset calculation, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 09/12] block/dmg: use SectorNumber from BLKX header,
Peter Wu <=
- [Qemu-devel] [PATCH v2 03/12] block/dmg: extract processing of resource forks, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 01/12] block/dmg: properly detect the UDIF trailer, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 02/12] block/dmg: extract mish block decoding functionality, Peter Wu, 2015/01/06
- [Qemu-devel] [PATCH v2 06/12] block/dmg: process XML plists, Peter Wu, 2015/01/06