Install does not preserve symlink

[LecrisUT]

Just quickly writing the issue before looking more carefully. Basically I've noticed that at least on muslinux, the symlinks are not maintained and instead the linked files are copied

FROM python:alpine

RUN apk update
RUN apk add musl-dev gcc linux-headers cmake neovim bash
RUN pip install spglib

[henryiii]

Symlinks are not supported by CPython’s standard library in zipfile. Wheels are just zip files.

[LecrisUT]

Hmm, bummer. Zip files themselves support symlinks though right? Is python/cpython#107845 supposed to fix that, or that is just for the build and not for the archiving?

[henryiii]

That’s tarfile (and security related). The issue is with zipfile, tarfile does support them. There’s a 10+ year old bug report about it somewhere. Now that windows simlink support is a lot better, I think it should be revisited. But it hasn’t afaik.

I’ve also seen a third-party library that support symlinks in zipfiles. But pip doesn’t use it.

pep 660 mentions this bug.

(and yes, zip itself supports symlinks)

[henryiii]

There are older issues, but this seems to be the tracking issue: python/cpython#82102

Looks like it was on hold until security issues could be worked out with tar file. But I think those were worked out.

[LecrisUT]

Should be supported automatically when that issue is resolved right?