polkit-vr-setcap-nice.rules

polkit.addRule(function (action, subject) {
    const setcapBinary = "/usr/bin/setcap";
    const allowedCapability = "CAP_SYS_NICE=eip";
    const steamVrCompositorLauncherBinary = "/home/" + subject.user + "/.local/share/Steam/steamapps/common/SteamVR/bin/linux64/vrcompositor-launcher";
    const steamVrCompositorLauncherBinaryAlt = "/home/" + subject.user + "/.steam/steam/steamapps/common/SteamVR/bin/linux64/vrcompositor-launcher";
    const monadoServiceBinary = "/usr/bin/monado-service";

    if (action.id == "org.freedesktop.policykit.exec" &&
        action.lookup("program") == setcapBinary) {
        // Check if action has "command_line" key
        if (action.lookup("command_line")) {
            const argv = action.lookup('command_line').split(' ');
        }
        if (argv && argv.length == 3 &&
            argv[1] == allowedCapability &&
            (argv[2] == steamVrCompositorLauncherBinary ||
            argv[2] == steamVrCompositorLauncherBinaryAlt)) {
            polkit.log("Allowed setcap CAP_SYS_NICE=eip for SteamVR compositor launcher as requested by user '" + subject.user + "'");
            return polkit.Result.YES;
        } else if (argv && argv.length == 3 &&
            argv[1] == allowedCapability &&
            argv[2] == monadoServiceBinary) {
            polkit.log("Allowed setcap CAP_SYS_NICE=eip for Monado Service as requested by user '" + subject.user + "'");
            return polkit.Result.YES;
        }
    }
});