[libvirt] [PATCH 3/3] Fix probing of QED file format

[Peter Krempa]

On 12/13/12 15:26, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
>
> The QED file format is non-versioned, so although the magic
> value matched, libvirt rejected it due to lack of a version
> number to compare against. We need to distinguish this case
> by allowing a value of '-2' to indicate a non-versioned file
> where only the magic is required to match
>
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>   src/util/storage_file.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/src/util/storage_file.c b/src/util/storage_file.c
> index 69a66ff..c0bb977 100644
> --- a/src/util/storage_file.c
> +++ b/src/util/storage_file.c
> @@ -174,8 +174,8 @@ static struct FileTypeInfo const fileTypeInfo[] = {
>       },
>       [VIR_STORAGE_FILE_QED] = {
>           /* http://wiki.qemu.org/Features/QED */
> -        "QED\0", NULL,
> -        LV_LITTLE_ENDIAN, -1, -1,
> +        "QED", NULL,
> +        LV_LITTLE_ENDIAN, -2, -1,
>           QED_HDR_IMAGE_SIZE, 8, 1, -1, qedGetBackingStore,
>       },
>       [VIR_STORAGE_FILE_VMDK] = {
> @@ -612,6 +612,12 @@ virStorageFileMatchesVersion(int format,
>       if (fileTypeInfo[format].versionOffset == -1)
>           return false;
>
> +    /* -2 == non-versioned file format, so trivially match */
> +    if (fileTypeInfo[format].versionOffset == -2) {
> +        VIR_WARN("Non-versioned file matches");

Are you sure you want to log this as a warning? Since we know that this 
file is unversioned do we need to spam the user's log with that?

> +        return true;
> +    }
> +
>       if ((fileTypeInfo[format].versionOffset + 4) > buflen)
>           return false;
>
>