Commit efbca10f authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Kevin Wolf
Browse files

bochs: use pread 



Use pread instead of lseek + read in preparation of using the qemu
block API.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 38d8dfa1

block/bochs.c

+20 −43
Original line number Diff line number Diff line
@@ -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) {

    /* read in bitmap for current extent */

    if (pread(s->fd, &bitmap_entry, 1, bitmap_offset + (extent_offset / 8))

            != 1) {

        return -1;

    }



    if (read(s->fd, &bitmap_entry, 1) != 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)

        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

        } else

            memset(buf, 0, 512);

        nb_sectors--;

        sector_num++;