1538954 - Make GetSystemParentDirectory configurable

Status: NEW

(Firefox :: General, enhancement, P5)

Description

[Ethan Glasser-Camp (:glasserc)]

This is inspired by https://github.com/NixOS/nixpkgs/issues/47340.

Firefox defines a function called GetSysteMParentDirectory which (among other things) is the location used to find native host messaging manifests. On Linux this is currently hardcoded to either /usr/lib/mozilla or /usr/lib64/mozilla. This causes various problems:

• No matter which location is chosen, it's going to be wrong on some systems (bug 1428821).

• On Linuxes with more exotic filesystems, in particular NixOS, there may not be a /usr/lib or a /usr/lib64. Indeed, when NixOS builds Firefox from source they patch it to add a MOZ_SYSTEM_DIR environment variable: https://github.com/NixOS/nixpkgs/blob/master/pkgs/applications/networking/browsers/firefox/env_var_for_system_dir.patch .

I think we should consider shipping such a patch ourselves. In the short term, this would mitigate issues like bug 1318461 because distributors could write wrappers that set this environment variable. Additionally, this gives NixOS the tools they need to support native messaging hosts without us having to do anything Nix-specific.