Copy plugin should follow symlinks that point outside of the snap

[Renat]

We need the option to copy symlinks as symlinks with their metadata in the copy plugin.

Here is the possible solution.

https://github.com/ubuntu-core/snapcraft/pull/209

[Kyle Fazzari (kyrofa)]

Thanks for the bug, Renat. However, would you mind fleshing it out a little? Give a scenario, expected results, and actual results if possible.

[Renat (renat2017)]

We build our QT application inside a buildroot with all necessary libraries into squashfs, where it should run in chrooted mode.

To port it into snappy I decided just to copy some folders with copy plugin. That's why I need to copy symlinks as symlinks and not as regular files.

[Kyle Fazzari (kyrofa)]

Understood Renat, thanks for the information. Yeah, the PR looks good other than the static checks.

[Kyle Fazzari (kyrofa)]

Note that I've targeted trunk for this, which means it'll be in Snapcraft 2.x. If you need it in Snapcraft 1.x please let me know.

[Kyle Fazzari (kyrofa)]

The copy plugin copies symlinks as of 2.7 as a side effect of another fix, but it needs to make sure it follows symlinks that will be invalid when snapped, so I'll repurpose this bug.

[Kyle Fazzari (kyrofa)]

Fix here: https://github.com/ubuntu-core/snapcraft/pull/426