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dmg: use qemu block API

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Use bdrv_pwrite to access the backing device instead of pread, and
convert the driver to implementing the bdrv_open method which gives
it an already opened BlockDriverState for the underlying device.

Dmg actually does an lseek to a negative offset in the open routine,
which we replace with offset arithmetics after doing a bdrv_getlength.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2010-05-12 16:31:49 +02:00 committed by Kevin Wolf
parent 16cdf7ce1a
commit 64a31d5c3d
1 changed files with 26 additions and 30 deletions
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56
block/dmg.c
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@ -28,8 +28,6 @@
#include <zlib.h>
typedef struct BDRVDMGState {
int fd;
/* each chunk contains a certain number of sectors,
* offsets[i] is the offset in the .dmg file,
* lengths[i] is the length of the compressed chunk,
@ -58,23 +56,23 @@ static int dmg_probe(const uint8_t *buf, int buf_size, const char *filename)
return 0;
}
static off_t read_off(int fd, int64_t offset)
static off_t read_off(BlockDriverState *bs, int64_t offset)
{
uint64_t buffer;
if (pread(fd, &buffer, 8, offset) < 8)
if (bdrv_pread(bs->file, offset, &buffer, 8) < 8)
return 0;
return be64_to_cpu(buffer);
}
static off_t read_uint32(int fd, int64_t offset)
static off_t read_uint32(BlockDriverState *bs, int64_t offset)
{
uint32_t buffer;
if (pread(fd, &buffer, 4, offset) < 4)
if (bdrv_pread(bs->file, offset, &buffer, 4) < 4)
return 0;
return be32_to_cpu(buffer);
}
static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
static int dmg_open(BlockDriverState *bs, int flags)
{
BDRVDMGState *s = bs->opaque;
off_t info_begin,info_end,last_in_offset,last_out_offset;
@ -82,29 +80,27 @@ static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
uint32_t max_compressed_size=1,max_sectors_per_chunk=1,i;
int64_t offset;
s->fd = open(filename, O_RDONLY | O_BINARY);
if (s->fd < 0)
return -errno;
bs->read_only = 1;
s->n_chunks = 0;
s->offsets = s->lengths = s->sectors = s->sectorcounts = NULL;
/* read offset of info blocks */
offset = lseek(s->fd, -0x1d8, SEEK_END);
offset = bdrv_getlength(bs->file);
if (offset < 0) {
goto fail;
}
offset -= 0x1d8;
info_begin = read_off(s->fd, offset);
info_begin = read_off(bs, offset);
if (info_begin == 0) {
goto fail;
}
if (read_uint32(s->fd, info_begin) != 0x100) {
if (read_uint32(bs, info_begin) != 0x100) {
goto fail;
}
count = read_uint32(s->fd, info_begin + 4);
count = read_uint32(bs, info_begin + 4);
if (count == 0) {
goto fail;
}
@ -117,12 +113,12 @@ static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
while (offset < info_end) {
uint32_t type;
count = read_uint32(s->fd, offset);
count = read_uint32(bs, offset);
if(count==0)
goto fail;
offset += 4;
type = read_uint32(s->fd, offset);
type = read_uint32(bs, offset);
if (type == 0x6d697368 && count >= 244) {
int new_size, chunk_count;
@ -138,7 +134,7 @@ static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
s->sectorcounts = qemu_realloc(s->sectorcounts, new_size);
for(i=s->n_chunks;i<s->n_chunks+chunk_count;i++) {
s->types[i] = read_uint32(s->fd, offset);
s->types[i] = read_uint32(bs, offset);
offset += 4;
if(s->types[i]!=0x80000005 && s->types[i]!=1 && s->types[i]!=2) {
if(s->types[i]==0xffffffff) {
@ -152,16 +148,16 @@ static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
}
offset += 4;
s->sectors[i] = last_out_offset+read_off(s->fd, offset);
s->sectors[i] = last_out_offset+read_off(bs, offset);
offset += 8;
s->sectorcounts[i] = read_off(s->fd, offset);
s->sectorcounts[i] = read_off(bs, offset);
offset += 8;
s->offsets[i] = last_in_offset+read_off(s->fd, offset);
s->offsets[i] = last_in_offset+read_off(bs, offset);
offset += 8;
s->lengths[i] = read_off(s->fd, offset);
s->lengths[i] = read_off(bs, offset);
offset += 8;
if(s->lengths[i]>max_compressed_size)
@ -183,7 +179,6 @@ static int dmg_open(BlockDriverState *bs, const char *filename, int flags)
return 0;
fail:
close(s->fd);
return -1;
}
@ -213,8 +208,10 @@ static inline uint32_t search_chunk(BDRVDMGState* s,int sector_num)
return s->n_chunks; /* error */
}
static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
{
BDRVDMGState *s = bs->opaque;
if(!is_sector_in_chunk(s,s->current_chunk,sector_num)) {
int ret;
uint32_t chunk = search_chunk(s,sector_num);
@ -231,8 +228,8 @@ static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
* inflated. */
i=0;
do {
ret = pread(s->fd, s->compressed_chunk+i, s->lengths[chunk]-i,
s->offsets[chunk] + i);
ret = bdrv_pread(bs->file, s->offsets[chunk] + i,
s->compressed_chunk+i, s->lengths[chunk]-i);
if(ret<0 && errno==EINTR)
ret=0;
i+=ret;
@ -253,8 +250,8 @@ static inline int dmg_read_chunk(BDRVDMGState *s,int sector_num)
return -1;
break; }
case 1: /* copy */
ret = pread(s->fd, s->uncompressed_chunk, s->lengths[chunk],
s->offsets[chunk]);
ret = bdrv_pread(bs->file, s->offsets[chunk],
s->uncompressed_chunk, s->lengths[chunk]);
if (ret != s->lengths[chunk])
return -1;
break;
@ -275,7 +272,7 @@ static int dmg_read(BlockDriverState *bs, int64_t sector_num,
for(i=0;i<nb_sectors;i++) {
uint32_t sector_offset_in_chunk;
if(dmg_read_chunk(s, sector_num+i) != 0)
if(dmg_read_chunk(bs, sector_num+i) != 0)
return -1;
sector_offset_in_chunk = sector_num+i-s->sectors[s->current_chunk];
memcpy(buf+i*512,s->uncompressed_chunk+sector_offset_in_chunk*512,512);
@ -286,7 +283,6 @@ static int dmg_read(BlockDriverState *bs, int64_t sector_num,
static void dmg_close(BlockDriverState *bs)
{
BDRVDMGState *s = bs->opaque;
close(s->fd);
if(s->n_chunks>0) {
free(s->types);
free(s->offsets);
@ -303,7 +299,7 @@ static BlockDriver bdrv_dmg = {
.format_name = "dmg",
.instance_size = sizeof(BDRVDMGState),
.bdrv_probe = dmg_probe,
.bdrv_file_open = dmg_open,
.bdrv_open = dmg_open,
.bdrv_read = dmg_read,
.bdrv_close = dmg_close,
};