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block/vpc.c: Detect too-large vpc file 

VHD files technically can be up to 2Tb, but virtual pc is limited
to 127G.  Currently qemu-img refused to create vpc files > 127G,
but it is failing to return error when converting from a non-vpc
VHD file which is >127G.  It returns success, but creates a truncated
converted image.  Also, qemu-img info claims the vpc file is 127G
(and clean).

This patch detects a too-large vpc file and returns -EFBIG.  Without
this patch,

=============================================================
root@ip-10-38-123-242:~/qemu-fixed# qemu-img info /mnt/140g-dynamic.vhd
image: /mnt/140g-dynamic.vhd
file format: vpc
virtual size: 127G (136899993600 bytes)
disk size: 284K
root@ip-10-38-123-242:~/qemu-fixed# qemu-img convert -f vpc -O raw /mnt/140g-dynamic.vhd /mnt/y
root@ip-10-38-123-242:~/qemu-fixed# echo $?
0
root@ip-10-38-123-242:~/qemu-fixed# qemu-img info /mnt/y
image: /mnt/y
file format: raw
virtual size: 127G (136899993600 bytes)
disk size: 0
=============================================================

(The 140G image was truncated with no warning or error.)

With the patch, I get:

=============================================================
root@ip-10-38-123-242:~/qemu-fixed# ./qemu-img info /mnt/140g-dynamic.vhd
qemu-img: Could not open '/mnt/140g-dynamic.vhd': File too large
root@ip-10-38-123-242:~/qemu-fixed# ./qemu-img convert -f vpc -O raw /mnt/140g-dynamic.vhd /mnt/y
qemu-img: Could not open '/mnt/140g-dynamic.vhd': File too large
qemu-img: Could not open '/mnt/140g-dynamic.vhd'
=============================================================

See https://bugs.launchpad.net/qemu/+bug/814222 for details.

Signed-off-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Serge E. Hallyn 2011-07-25 18:34:35 +00:00 committed by Kevin Wolf
parent 49aa46bb4b
commit efc8243d00
1 changed files with 7 additions and 1 deletions
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8
block/vpc.c
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@ -156,6 +156,7 @@ static int vpc_open(BlockDriverState *bs, int flags)
struct vhd_dyndisk_header* dyndisk_header;
uint8_t buf[HEADER_SIZE];
uint32_t checksum;
int err = -1;
if (bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE) != HEADER_SIZE)
goto fail;
@ -176,6 +177,11 @@ static int vpc_open(BlockDriverState *bs, int flags)
bs->total_sectors = (int64_t)
be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
if (bs->total_sectors >= 65535 * 16 * 255) {
err = -EFBIG;
goto fail;
}
if (bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf, HEADER_SIZE)
!= HEADER_SIZE)
goto fail;
@ -222,7 +228,7 @@ static int vpc_open(BlockDriverState *bs, int flags)
return 0;
fail:
return -1;
return err;
}
/*