Portable Kiwix, allow to custom all local storage/configuration locations

[kelson42]

In a case of a portable Kiwix (running on a portable USB drive for example), we want to keep everything local on USB drive. We don't want to interfere with a potential local instance. Therefore, none of the data and configuration files should be written at the usual locations.

A portable Kiwix is technically defined when there is (an empty) file .portable just beside the Kiwix binary. Detecting the presence of that file will activate the portable mode.

The portable mode will read/write the data files to another (predefined) location positioned relatively position to the Kiwix binary:

• data/kiwix-desktop.session
• data/kiwix.session
• data/*.zim
• ...

In such a mode nothing should be written outside the local Kiwix data directory.

This issue superseeds older issuer #630

[sgourdas]

@kelson42 for implementation purposes, if the .portable is present, can I assume that the packager will have also created the data directory as well?

[kelson42]

@kelson42 for implementation purposes, if the .portable is present, can I assume that the packager will have also created the data directory as well?

Yes you can

[sgourdas]

Since getDataDirectory() will need to be modified, so as to not complicate things with libkiwix, I will wait a bit on this until #1169 is merged.

[kelson42]

@sgourdas Any news here? We need to be able to mov a bit in parallel as it might take again a few additional days to update the libkiwix with your PR.

[sgourdas]

Ok, I will start parallel work on this