Re: [PATCH v3] block: Raise an error when backing file parameter is an empty string

[Connor Kuehl <ckuehl@redhat.com>]

On 8/13/20 8:47 AM, Connor Kuehl wrote:
> Providing an empty string for the backing file parameter like so:
> 
> 	qemu-img create -f qcow2 -b '' /tmp/foo
> 
> allows the flow of control to reach and subsequently fail an assert
> statement because passing an empty string to
> 
> 	bdrv_get_full_backing_filename_from_filename()
> 
> simply results in NULL being returned without an error being raised.
> 
> To fix this, let's check for an empty string when getting the value from
> the opts list.
> 
> Reported-by: Attila Fazekas <afazekas@redhat.com>
> Fixes: https://bugzilla.redhat.com/1809553
> Signed-off-by: Connor Kuehl <ckuehl@redhat.com>
> ---
> v3:
>    - Moved test case into 049 instead of taking up
>      298.
> 
> v2:
>    - Removed 4 spaces to resolve pylint warning
>    - Updated format to be 'iotests.imgfmt' instead
>      of hardcoding 'qcow2'
>    - Use temporary file instead of '/tmp/foo'
>    - Give a size parameter to qemu-img
>    - Run test for qcow2, qcow, qed and *not* raw

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