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authorChristoph Hellwig <hch@lst.de>2010-05-04 12:44:08 +0200
committerKevin Wolf <kwolf@redhat.com>2010-05-17 10:20:04 +0200
commitefbca10f10af2c0d7282e5dc49713479be98880b (patch)
tree61aab2b2b30a026a84f084994d5bc8d72cfbbc82 /block
parent38d8dfa193e9a45f0f08b06aab2ba2a94f40a041 (diff)
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bochs: use pread
Use pread instead of lseek + read in preparation of using the qemu block API. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/bochs.c63
1 files changed, 20 insertions, 43 deletions
diff --git a/block/bochs.c b/block/bochs.c
index e952670..b54f54d 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -125,7 +125,7 @@ static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
s->fd = fd;
- if (read(fd, &bochs, sizeof(bochs)) != sizeof(bochs)) {
+ if (pread(fd, &bochs, sizeof(bochs), 0) != sizeof(bochs)) {
goto fail;
}
@@ -144,14 +144,10 @@ static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
}
- if (lseek(s->fd, le32_to_cpu(bochs.header), SEEK_SET) == (off_t)-1) {
- goto fail;
- }
-
s->catalog_size = le32_to_cpu(bochs.extra.redolog.catalog);
s->catalog_bitmap = qemu_malloc(s->catalog_size * 4);
- if (read(s->fd, s->catalog_bitmap, s->catalog_size * 4) !=
- s->catalog_size * 4)
+ if (pread(s->fd, s->catalog_bitmap, s->catalog_size * 4,
+ le32_to_cpu(bochs.header)) != s->catalog_size * 4)
goto fail;
for (i = 0; i < s->catalog_size; i++)
le32_to_cpus(&s->catalog_bitmap[i]);
@@ -169,54 +165,35 @@ static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
return -1;
}
-static inline int seek_to_sector(BlockDriverState *bs, int64_t sector_num)
+static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
{
BDRVBochsState *s = bs->opaque;
int64_t offset = sector_num * 512;
- int64_t extent_index, extent_offset, bitmap_offset, block_offset;
+ int64_t extent_index, extent_offset, bitmap_offset;
char bitmap_entry;
// seek to sector
extent_index = offset / s->extent_size;
extent_offset = (offset % s->extent_size) / 512;
- if (s->catalog_bitmap[extent_index] == 0xffffffff)
- {
-// fprintf(stderr, "page not allocated [%x - %x:%x]\n",
-// sector_num, extent_index, extent_offset);
- return -1; // not allocated
+ if (s->catalog_bitmap[extent_index] == 0xffffffff) {
+ return -1; /* not allocated */
}
bitmap_offset = s->data_offset + (512 * s->catalog_bitmap[extent_index] *
(s->extent_blocks + s->bitmap_blocks));
- block_offset = bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
-
-// fprintf(stderr, "sect: %x [ext i: %x o: %x] -> %x bitmap: %x block: %x\n",
-// sector_num, extent_index, extent_offset,
-// le32_to_cpu(s->catalog_bitmap[extent_index]),
-// bitmap_offset, block_offset);
-
- // read in bitmap for current extent
- if (lseek(s->fd, bitmap_offset + (extent_offset / 8), SEEK_SET) ==
- (off_t)-1) {
- return -1;
- }
- if (read(s->fd, &bitmap_entry, 1) != 1)
+ /* read in bitmap for current extent */
+ if (pread(s->fd, &bitmap_entry, 1, bitmap_offset + (extent_offset / 8))
+ != 1) {
return -1;
-
- if (!((bitmap_entry >> (extent_offset % 8)) & 1))
- {
-// fprintf(stderr, "sector (%x) in bitmap not allocated\n",
-// sector_num);
- return -1; // not allocated
}
- if (lseek(s->fd, block_offset, SEEK_SET) == (off_t)-1) {
- return -1;
+ if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
+ return -1; /* not allocated */
}
- return 0;
+ return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
}
static int bochs_read(BlockDriverState *bs, int64_t sector_num,
@@ -226,13 +203,13 @@ static int bochs_read(BlockDriverState *bs, int64_t sector_num,
int ret;
while (nb_sectors > 0) {
- if (!seek_to_sector(bs, sector_num))
- {
- ret = read(s->fd, buf, 512);
- if (ret != 512)
- return -1;
- }
- else
+ int64_t block_offset = seek_to_sector(bs, sector_num);
+ if (block_offset >= 0) {
+ ret = pread(s->fd, buf, 512, block_offset);
+ if (ret != 512) {
+ return -1;
+ }
+ } else
memset(buf, 0, 512);
nb_sectors--;
sector_num++;