Commit e1b42f45 authored by Max Reitz's avatar Max Reitz Committed by Kevin Wolf
Browse files

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: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent b93f9950

block/bochs.c

+14 −9
Original line number Diff line number Diff line
@@ -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;