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Tar files made in macOS generate "xattr" errors when expanded in Linux

27 points by heresie-dabord 4 days ago | 14 comments

Ex-Apple engineer here. This is, for better or worse, just the way Apple approaches this type of problem. From Apple's perspective, this is the way to preserve Finder / Gatekeeper / metadata semantics. It avoids silent data loss when round-tripping archives between Macs. This behavior also maintains consistency with copyfile(3) (as well as the Archive Utility behavior).

Apple treats tar less like “portable Unix interchange” and more like “archive this filesystem object faithfully.” That is very Apple, and very libarchive. ;-)

This is probably going to get worse (as Apple continues to add macOS-specific metadata), so your workaround is very helpful.

I haven't tested it in a while, but at one point, setting the COPYFILE_DISABLE=1 env variable would disable the inclusion of macOS-specific metadata.

Terretta 2 days ago

Arguably, principle of least surprise is very Apple.

If I point "tape archive" at a file system, I want that file system archived to tape. And so, tar does.

If I don't, well, that's a fine option, and there's a fine option for that.

So it's less of a "workaround" or something that "gets worse", than, "No, I don't really want a tape archive of this filesystem, only of some of it." And that's supported.

That said, never seeing another .DS_Store should be a system-wide option!

JoshTriplett 53 minutes ago

> Arguably, principle of least surprise is very Apple.

Principle of least surprise is good engineering practice. The question is always whose surprise. Someone who expects tar to behave like other UNIX systems is going to be surprised by this. Someone who expects tar on Apple to have perfect fidelity would be surprised by not-this.

I increasingly feel like build systems should never be relying on any "native" utilities from the host system, and should instead be bringing them in via dependencies. You can't have this problem if your packaging system pulls in a specific portable `tar` library.

taftster 2 hours ago

> That said, never seeing another .DS_Store should be a system-wide option!

Yes please.

ryandrake 16 minutes ago

.DS_Store, .fseventsd, .Spotlight-V100, .Trashes, and ._this and ._that

These can all die in a fire too, as far as I am concerned. macOS loves to treat the user's filesystem as its own personal garbage dump.

gerdesj 3 minutes ago

thumbs.db and those weird MS alternative stream files for recording origination.

filesystem attributes are for decorating files with meaning. Anything else that attempts to use filesystems in "interesting" ways is silly.

Apple and MS really ought to consider why they do this sort of fragile, idiosyncratic nonsense.

matheusmoreira 45 minutes ago

It's a good attitude to have, in my opinion. Portability is overrated. Linux developers should be doing a lot more of this. We should be making everything work better for us without caring how it's going to impact other irrelevant platforms. Let the people who actually care about those platforms worry about such things.

cozzyd 33 minutes ago

It would at least be nice if there was a way to keep apple users from shitting all over the filesystem with remote mounts and ds_store files. Perhaps by automatically unmounting if one is detected.

jmclnx 33 minutes ago

To me, the big question is why Apple needs all these file attribute ? If the files are extracted OK, just ignore the errors :)

pier25 2 hours ago

I use these settings when creating a tar file for deploy:

    tar --no-xattrs --no-mac-metadata -czf

chmaynard 23 minutes ago

Homebrew installs GNU tar as "gtar". On my M4 MacBook:

  $ which gtar
  gtar is /opt/homebrew/bin/gtar

angry_octet 35 minutes ago

We might also ask, why doesn't Linux also track such meta-data? Are Linux users not also subject to drive-by downloads impersonating valid files? Should we be one chmod a+x away from compromise?

danielheath 26 minutes ago

Yes, we should be.

My computer should run programs when I tell it to run them.

Don’t blunt _every_ tool just to make them harder to cut yourself on.

firesteelrain 59 minutes ago

You can either send stderr to /dev/null or use --warning=no-unknown-keyword to suppress them cleanly.

But still interesting nonetheless why they are added