import-tar: create archive from tarball

[enkore]

Split from #176

[ThomasWaldmann]

Note: should be done after 1.2, borg is expected to be more modular / untangled by then.

[enkore]

This is pretty simple actually, since the model used by the various tar's is fairly close to what Borg does. (Also, the stdlib tarfile module handles all the dirty work for us). See PR, not much code.

[enkore]

#2234 is the implementation PoC for this that can be recycled later for a real implementation.

[guillaume-uH57J9]

I am looking for a way to transfer an archive between borg repositories. My use case is syncing a local and remote repository.

By gluing together tar import + tar export I could transfer archives between repositories, and move toward my goal.

[enkore]

Oof, I actually thought this was merged back then and I was so confused why import-tar seemingly vanished from the CLI and the docs.

[ceriath]

@enkore so what is happening with this, will it be merged/reimplemented? Is there any way to restore a backup from an exported tar with borg?

[ThomasWaldmann]

#2233 (comment) about being "untangled":

• there was some recent work in master branch that split file discovery and file processing.
• also there is code now getting a list of files from stdin and feeding that into file processing.

So there has been a bit work in this direction, but not yet at the right place needed for import-tar (like having some in-memory object having all the metadata and data and giving that to "put that into this archive code").

[ThomasWaldmann]

The implementation is now merged to master branch and everybody interested is invited to help with some practical testing.
I personally did not do much practical testing, but I implemented a little test coverage by automated tests, but not very much.

See borg help import-tar and borg help export-tar. Also see there about current limitations (== what is expected to not work).

Stuff to test:

• 0 bytes, mid-sized, huge files
• char/block device files, fifos
• hardlinks and symlinks
• uncompressed, misc. compressions
• inputs created by borg export-tar, inputs create by other tar software
• misc. error conditions, interruptions

Please open new issues if you find bugs or ask here if you have questions.