Re: [PATCH v2] iotest: Unbreak 302 with python 3.13

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Feb 28, 2025 at 09:57:08PM +0200, Nir Soffer wrote:
> This test depends on TarFile.addfile() to add tar member header without
> writing the member data, which we write ourself using qemu-nbd. Python
> 3.13 changed the function in a backward incompatible way[1] to require a
> file object for tarinfo with non-zero size, breaking the test:
> 
>      -[{"name": "vm.ovf", "offset": 512, "size": 6}, {"name": "disk", "offset": 1536, "size": 393216}]
>      +Traceback (most recent call last):
>      +  File "/home/stefanha/qemu/tests/qemu-iotests/302", line 118, in <module>
>      +    tar.addfile(disk)
>      +    ~~~~~~~~~~~^^^^^^
>      +  File "/usr/lib64/python3.13/tarfile.py", line 2262, in addfile
>      +    raise ValueError("fileobj not provided for non zero-size regular file")
>      +ValueError: fileobj not provided for non zero-size regular file
> 
> The new behavior makes sense for most users, but breaks our unusual
> usage. Fix the test to add the member header directly using public but
> undocumented attributes. This is more fragile but the test works again.
> 
> This also fixes a bug in the previous code - when calling addfile()
> without a fileobject, tar.offset points to the start of the member data
> instead of the end.
> 
> [1] https://github.com/python/cpython/pull/117988
> 
> Signed-off-by: Nir Soffer <nirsof@gmail.com>
> ---
>  tests/qemu-iotests/302 | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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