From 581ef15e3e5512727242786b2ac4a6f8654ad688 Mon Sep 17 00:00:00 2001 From: Peter Wu Date: Sat, 27 Dec 2014 11:38:14 +0100 Subject: 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 a continuous input offset. Signed-off-by: Peter Wu --- block/dmg.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/block/dmg.c b/block/dmg.c index 984997f0d9..93b597f21e 100644 --- a/block/dmg.c +++ b/block/dmg.c @@ -179,6 +179,7 @@ static int64_t dmg_find_koly_offset(BlockDriverState *file_bs) 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_in_offset; uint64_t last_out_offset; /* exported for dmg_open */ @@ -194,6 +195,7 @@ static int dmg_read_mish_block(BDRVDMGState *s, DmgHeaderState *ds, size_t new_size; uint32_t chunk_count; int64_t offset = 0; + 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) */ @@ -246,7 +248,12 @@ 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; + /* If this offset is below the previous chunk end, then assume that all + * following offsets are after the previous chunks. */ + if (s->offsets[i] + in_offset < ds->last_in_offset) { + in_offset = ds->last_in_offset; + } + s->offsets[i] += in_offset; offset += 8; s->lengths[i] = buff_read_uint64(buffer, offset); @@ -400,6 +407,7 @@ static int dmg_open(BlockDriverState *bs, QDict *options, int flags, bs->read_only = 1; s->n_chunks = 0; s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL; + ds.data_fork_offset = 0; ds.last_in_offset = 0; ds.last_out_offset = 0; ds.max_compressed_size = 1; @@ -412,6 +420,12 @@ 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; + } + /* offset of resource fork (RsrcForkOffset) */ ret = read_uint64(bs, offset + 0x28, &rsrc_fork_offset); if (ret < 0) { -- cgit v1.2.1