Can't install snaps that have .. *anywhere* in filename

[Michael Terry]

When playing with deb2snap and creating a snap that included ca-certificates, I ran into the problem that snappy would refuse to install the snap with the following error:

 snap contains invalid content

It turns out that deb.go has the following verify check:

 path = filepath.Clean(path)
 if strings.Contains(path, "..") {
  return "", ErrSnapInvalidContent
 }

But that's too simplistic. Consider the file that is choking:

/usr/share/ca-certificates/mozilla/AC_Raíz_Certicámara_S.A..crt

That should probably be allowed.

(Also it would help if that error message printed the bad path.)

[Michael Vogt (mvo)]

Good point, thanks!