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: Peter Wu <address@hidden>
---
v2: use sector and data offset as provided by the BLKX header. This
allows us to drop last_in_offset. The previous heuristics to detect
relative offsets is not needed anymore. Squashed the data fork
offset length check into this patch.
---
block/dmg.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/block/dmg.c b/block/dmg.c
index 57feb1b..130efac 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -188,7 +188,7 @@ static int64_t dmg_find_koly_offset(BlockDriverState
*file_bs, Error **errp)
typedef struct DmgHeaderState {
/* used internally by dmg_read_mish_block to remember offsets of blocks
* across calls */
- uint64_t last_in_offset;
+ uint64_t data_fork_offset;
uint64_t last_out_offset;
/* exported for dmg_open */
uint32_t max_compressed_size;
@@ -203,6 +203,8 @@ static int dmg_read_mish_block(BDRVDMGState *s,
DmgHeaderState *ds,
size_t new_size;
uint32_t chunk_count;
int64_t offset = 0;
+ uint64_t data_offset;
+ uint64_t in_offset = ds->data_fork_offset;
type = buff_read_uint32(buffer, offset);
/* skip data that is not a valid MISH block (invalid magic or too small)
*/
@@ -211,8 +213,12 @@ static int dmg_read_mish_block(BDRVDMGState *s,
DmgHeaderState *ds,
return 0;
}
- offset += 4;
- offset += 200;
+ /* location in data fork for (compressed) blob (in bytes) */
+ data_offset = buff_read_uint64(buffer, offset + 0x18);
+ in_offset += data_offset;
+
+ /* move to begin of chunk entries */
+ offset += 204;
chunk_count = (count - 204) / 40;
new_size = sizeof(uint64_t) * (s->n_chunks + chunk_count);
@@ -228,7 +234,6 @@ static int dmg_read_mish_block(BDRVDMGState *s,
DmgHeaderState *ds,
if (s->types[i] != 0x80000005 && s->types[i] != 1 &&
s->types[i] != 2) {
if (s->types[i] == 0xffffffff && i > 0) {
- ds->last_in_offset = s->offsets[i - 1] + s->lengths[i - 1];
ds->last_out_offset = s->sectors[i - 1] +
s->sectorcounts[i - 1];
}
@@ -255,7 +260,7 @@ static int dmg_read_mish_block(BDRVDMGState *s,
DmgHeaderState *ds,
}
s->offsets[i] = buff_read_uint64(buffer, offset);
- s->offsets[i] += ds->last_in_offset;
+ s->offsets[i] += in_offset;
offset += 8;
s->lengths[i] = buff_read_uint64(buffer, offset);
@@ -413,7 +418,7 @@ static int dmg_open(BlockDriverState *bs, QDict *options,
int flags,
s->n_chunks = 0;
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.last_in_offset = 0;
+ ds.data_fork_offset = 0;
ds.last_out_offset = 0;
ds.max_compressed_size = 1;
ds.max_sectors_per_chunk = 1;
@@ -425,6 +430,15 @@ static int dmg_open(BlockDriverState *bs, QDict *options,
int flags,
goto fail;
}
+ /* offset of data fork (DataForkOffset) */
+ ret = read_uint64(bs, offset + 0x18, &ds.data_fork_offset);
+ if (ret < 0) {
+ goto fail;
+ } else if (ds.data_fork_offset > offset) {
+ ret = -EINVAL;
+ goto fail;
+ }
+
/* offset of resource fork (RsrcForkOffset) */
ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset);
if (ret < 0) {