[v2,2/2] vmdk: Read footer for streamOptimized images

The footer takes precedence over the header when it exists. It contains
the real grain directory offset that is missing in the header. Without
this patch, streamOptimized images with a footer cannot be read.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
v2:
- Enough footer sanity checks, I hope? :-)

 block/vmdk.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 56 insertions(+), 0 deletions(-)

On Thu, Aug 16, 2012 at 10:50 AM, Kevin Wolf <kwolf@redhat.com> wrote:
> The footer takes precedence over the header when it exists. It contains
> the real grain directory offset that is missing in the header. Without
> this patch, streamOptimized images with a footer cannot be read.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> v2:
> - Enough footer sanity checks, I hope? :-)
>
>  block/vmdk.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 56 insertions(+), 0 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

On 08/16/2012 05:50 AM, Kevin Wolf wrote:
> The footer takes precedence over the header when it exists. It contains
> the real grain directory offset that is missing in the header. Without
> this patch, streamOptimized images with a footer cannot be read.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
> v2:
> - Enough footer sanity checks, I hope? :-)
> 
>  block/vmdk.c |   56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 56 insertions(+), 0 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 9648398..bba4c61 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -35,6 +35,7 @@
>  #define VMDK4_FLAG_RGD (1 << 1)
>  #define VMDK4_FLAG_COMPRESS (1 << 16)
>  #define VMDK4_FLAG_MARKER (1 << 17)
> +#define VMDK4_GD_AT_END 0xffffffffffffffffULL
>  
>  typedef struct {
>      uint32_t version;
> @@ -115,6 +116,13 @@ typedef struct VmdkGrainMarker {
>      uint8_t  data[0];
>  } VmdkGrainMarker;
>  
> +enum {
> +    MARKER_END_OF_STREAM    = 0,
> +    MARKER_GRAIN_TABLE      = 1,
> +    MARKER_GRAIN_DIRECTORY  = 2,
> +    MARKER_FOOTER           = 3,
> +};
> +
>  static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
>  {
>      uint32_t magic;
> @@ -451,6 +459,54 @@ static int vmdk_open_vmdk4(BlockDriverState *bs,
>      if (header.capacity == 0 && header.desc_offset) {
>          return vmdk_open_desc_file(bs, flags, header.desc_offset << 9);
>      }
> +
> +    if (le64_to_cpu(header.gd_offset) == VMDK4_GD_AT_END) {
> +        /*
> +         * The footer takes precedence over the header, so read it in. The
> +         * footer starts at offset -1024 from the end: One sector for the
> +         * footer, and another one for the end-of-stream marker.
> +         */
> +        struct {
> +            struct {
> +                uint64_t val;
> +                uint32_t size;
> +                uint32_t type;
> +                uint8_t pad[512 - 16];
> +            } QEMU_PACKED footer_marker;
> +
> +            uint32_t magic;
> +            VMDK4Header header;
> +            uint8_t pad[512 - 4 - sizeof(VMDK4Header)];
> +
> +            struct {
> +                uint64_t val;
> +                uint32_t size;
> +                uint32_t type;
> +                uint8_t pad[512 - 16];
> +            } QEMU_PACKED eos_marker;
> +        } QEMU_PACKED footer;
> +
> +        ret = bdrv_pread(file,
> +            bs->file->total_sectors * 512 - 1536,
> +            &footer, sizeof(footer));
> +        if (ret < 0) {
> +            return ret;
> +        }
> +
> +        /* Some sanity checks for the footer */
> +        if (be32_to_cpu(footer.magic) != VMDK4_MAGIC ||
> +            le32_to_cpu(footer.footer_marker.size) != 0  ||
> +            le32_to_cpu(footer.footer_marker.type) != MARKER_FOOTER ||
> +            le64_to_cpu(footer.eos_marker.val) != 0  ||
> +            le32_to_cpu(footer.eos_marker.size) != 0  ||
> +            le32_to_cpu(footer.eos_marker.type) != MARKER_END_OF_STREAM)
> +        {
> +            return -EINVAL;
> +        }
> +
> +        header = footer.header;
> +    }
> +
>      l1_entry_sectors = le32_to_cpu(header.num_gtes_per_gte)
>                          * le64_to_cpu(header.granularity);
>      if (l1_entry_sectors == 0) {
> 

Reviewed-by: Jeff Cody <jcody@redhat.com>