Zip packages are not extracted properly with snapcraft 2.35

[Soren Friis]

We have a snapcraft build that downloads various zip packages and does something with the content. The issue can also be reproduced with a snapcraft.yaml file with the following content:

*******************************************************************************

name: test
version: '123'
grade: stable
confinement: devmode
summary: fdsfsdfsfd
description: fdsfdsfsdfd

parts:
  fonts:
    plugin: dump
    source: https://01.org/sites/default/files/downloads/clear-sans/clearsans-1.00.zip
    source-type: zip
    organize:
      'TTF': usr/share/fonts/truetype/clear-sans
    stage:
      - usr/share/fonts/truetype/clear-sans

*******************************************************************************

After upgrading from snapcraft 2.34 to 2.35 on Ubuntu 16.04 LTS, the unzipping fails:

Pulling fonts
Downloading 'clearsans-1.00.zip'[====================================================================================================================================================] 100%
Traceback (most recent call last):
  File "/usr/bin/snapcraft", line 9, in <module>
    load_entry_point('snapcraft==2.35', 'console_scripts', 'snapcraft')()
...
  File "/usr/lib/python3/dist-packages/snapcraft/internal/sources/_zip.py", line 58, in provision
    extracted_file = f.extract(info.filename, path=dst)
  File "/usr/lib/python3.5/zipfile.py", line 1335, in extract
    return self._extract_member(member, path, pwd)
  File "/usr/lib/python3.5/zipfile.py", line 1398, in _extract_member
    open(targetpath, "wb") as target:
PermissionError: [Errno 13] Permission denied: '/home/sfriis/SW/moosepoint/moosepoint_snap/parts/fonts/src/EOT/ClearSans-Bold.eot'

It somehow manages to create a completely empty directory (named EOT in this case) which you cannot even run ls on.

By commenting out line 59 in /usr/lib/python3/dist-packages/snapcraft/internal/sources/_zip.py, this problem is going away.

[Kyle Fazzari (kyrofa)]

This was indeed a feature added in v2.35 trying to work around a zip bug in Python. However, the fix did not take into account the possibility of zip files being created on non-unix systems, as the bug actually mentions.

[Kyle Fazzari (kyrofa)]

Proposed fix is here: https://github.com/snapcore/snapcraft/pull/1862