singlefile storage resets file permissions

I'm using vdirsyncer to create a local cache of a number of remote storages. vdirsyncer creates the singlefile storage files with the permissions 0600. For my use case, the result file needs to be readable by other OS users, i.e. with permissions 0644. The problem is that after changing the permissions manually on the command line, every subsequent invocation of vdirsyncer will reset the permissions to 0600.

This appears to happen due to the way python-atomicwrites implemented the operation, see https://github.com/untitaker/python-atomicwrites/issues/42. The proposed workaround appears to be to leave resetting the permissions to the caller (and since the repository has been archived two years ago, that appears to be unlinkely to change).

• vdirsyncer version 0.19.2
• Python version 3.12.3
• operating system Gentoo Linux

Start by locating the singlefile storage write path and its use of python-atomicwrites, then reproduce the issue by changing a generated file to 0644 and invoking vdirsyncer again. Check the relevant storage tests and add coverage for the expected permissions behavior; done means a subsequent invocation no longer resets the file permissions unexpectedly.