import/export-tar: support xattrs, ACLs and such via PAX format

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import/export-tar: support xattrs, ACLs and such via PAX format #2521

Open enkore opened 7 years ago

enkore commented 7 years ago

PAX/POSIX format basically means one gets to put arbitrary key/value parts into file metadata in a backwards-compatible fashion.

GNU tar supports a proprietary extension for xattrs, apparently invented by Jörg Schilling: Just put them into the SCHILY.xattr.<xattr>key. (Source: GNU tar 1.29 source, file src/xheader.c, xhdr_tab)

https://www.gnu.org/software/tar/manual/html_node/Extended-File-Attributes.html

ThomasWaldmann commented 3 years ago

ThomasWaldmann commented 2 years ago

update from #5830: PAX format support is now basically present, SCHILY-style xattrs/ACLs support still todo.

ThomasWaldmann commented 1 week ago

Borg contributors could help with this, implementing this does not need too much knowledge of borg internals.

How this could be improved:

implement SCHILY-style xattrs in import-tar (search for "PAX" in the borg source)
do roundtrip testing, e.g. GNU tar c -> borg import-tar -> borg extract
implement SCHILY-style xattrs in export-tar
do roundtrip testing, e.g. GNU tar c -> borg import-tar -> borg export-tar -> GNU tar x
automate the roundtrip testing in our testsuite (we already use tar elsewhere in the tests)
after xattrs are done and merged into master, work on ACLs.