Fix qcow2 support for absolute backing_file paths#65
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Schamper merged 4 commits intofox-it:mainfrom Feb 24, 2026
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_open_backing_file assumed that the backing_file path
was always a filename relative to the snapshot path.
Using .with_name() to concat the whole path broke the use
case for absolute path for the backing_file causing
ValueError("Invalid name ...").
This change updates the logic to detect whether auto_backing_file is an
absolute path. If so, it is used directly; otherwise we fall back to
constructing the path relative to the snapshot location.
This will support the following use-cases:
backing file: /home/user/workdir/ubuntu-22.04.qcow2
backing file: ubuntu-22.04.qcow2
backing file: ./ubuntu-22.04-packer.qcow2
backing file: ../../ubuntu-22.04-packer.qcow2
Fixes: fox-it#64
Signed-off-by: Andreia Ocanoaia <andreia.ocanoaia@gmail.com>
Schamper
previously approved these changes
Oct 1, 2025
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Thanks @andreia-oca, I made a small change that should achieve the same. I also added some unit tests.
The reason I didn't use Path is because in dissect.target we use a custom subclass of it. Using joinpath ensures we stay within that subclass.
Could you maybe verify that it still works as expected on your end?
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #65 +/- ##
==========================================
+ Coverage 80.65% 80.81% +0.16%
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Files 26 26
Lines 2367 2367
==========================================
+ Hits 1909 1913 +4
+ Misses 458 454 -4
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Schamper
approved these changes
Feb 24, 2026
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_open_backing_file assumed that the backing_file path was always a filename relative to the snapshot path. Using .with_name() to concat the whole path broke the use case for absolute path for the backing_file causing ValueError("Invalid name ...").
This change updates the logic to detect whether auto_backing_file is an absolute path. If so, it is used directly; otherwise we fall back to constructing the path relative to the snapshot location.
This will support the following use-cases:
backing file: /home/user/workdir/ubuntu-22.04.qcow2 backing file: ubuntu-22.04.qcow2
backing file: ./ubuntu-22.04-packer.qcow2
backing file: ../../ubuntu-22.04-packer.qcow2
Fixes: #64