Comment 7 for bug 1745999

I installed okular on Ubuntu 17.10 via snap (“sudo snap install okular”). The okular snap seems to use “strict” confinement and is thus unable to access files outside the user’s home directory even for reading. However, for a “viewer”-type application like okular, this is very problematic:

– When downloading a file (e.g. PDF) in a browser like Firefox and choosing to open the file (instead of saving it somewhere in the home directory), the browser will typically place the file in /tmp/ and then open it using the default viewer for that file type. Since /tmp/ is outside the user’s home directory, okular is unable to open the file.

– When opening documentation which is installed to system directories (e.g. /usr/share/…) along with its corresponding application, okular is likewise unable to open the documentation files for viewing. For example, the “texdoc” program for the TeX typesetting system looks up the documentation for a specified package (typically in PDF format) and runs the default (PDF) viewer to show the documentation. This fails if the okular snap application is set as the default PDF viewer.

– Any files on mounted file systems, such as external storage (USB drives, SD cards, external hard drives…), network shares, etc., cannot be viewed with okular.

Attempting to open any such files results in a dialog with the following error message: “Could not open file:///path/to/file”. This does not provide any explanation for the reason of the failure.