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block/bochs: Fix error handling for seek_to_sector() 

Currently, seek_to_sector() returns -1 both for errors and unallocated
sectors, resulting in silent errors. As 0 is an invalid offset of data
clusters (bitmap_offset is greater than 0 because s->data_offset is
greater than 0), just return 0 for unallocated sectors and -errno in
case of error. This should then be propagated by bochs_read(), the sole
user of seek_to_sector().

That function also has a case of "return -1 in case of error", which is
fixed by this patch as well.

bochs_read() is called by bochs_co_read() which passes the return value
through, therefore it is indeed correct for bochs_read() to return
-errno.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2014-04-29 19:03:15 +02:00 committed by Kevin Wolf
parent b93f995081
commit e1b42f456f
1 changed files with 14 additions and 9 deletions
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23
block/bochs.c
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@ -187,13 +187,14 @@ static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
uint64_t offset = sector_num * 512;
uint64_t extent_index, extent_offset, bitmap_offset;
char bitmap_entry;
int ret;
// seek to sector
extent_index = offset / s->extent_size;
extent_offset = (offset % s->extent_size) / 512;
if (s->catalog_bitmap[extent_index] == 0xffffffff) {
return -1; /* not allocated */
return 0; /* not allocated */
}
bitmap_offset = s->data_offset +
@ -201,13 +202,14 @@ static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
(s->extent_blocks + s->bitmap_blocks));
/* read in bitmap for current extent */
if (bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
&bitmap_entry, 1) != 1) {
return -1;
ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
&bitmap_entry, 1);
if (ret < 0) {
return ret;
}
if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
return -1; /* not allocated */
return 0; /* not allocated */
}
return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
@ -220,13 +222,16 @@ static int bochs_read(BlockDriverState *bs, int64_t sector_num,
while (nb_sectors > 0) {
int64_t block_offset = seek_to_sector(bs, sector_num);
if (block_offset >= 0) {
if (block_offset < 0) {
return block_offset;
} else if (block_offset > 0) {
ret = bdrv_pread(bs->file, block_offset, buf, 512);
if (ret != 512) {
return -1;
if (ret < 0) {
return ret;
}
} else
} else {
memset(buf, 0, 512);
}
nb_sectors--;
sector_num++;
buf += 512;