mobile-config-firefox/src/mobile-config-autoconfig.js

// Copyright 2023 Arnaud Ferraris, Oliver Smith
// SPDX-License-Identifier: MPL-2.0
// This is a Firefox autoconfig file:
// https://support.mozilla.org/en-US/kb/customizing-firefox-using-autoconfig
// Import custom userChrome.css on startup or new profile creation
// Log file: $(find ~/.mozilla -name mobile-config-firefox.log)

const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://gre/modules/FileUtils.jsm");

var updated = false;
var fragments_cache = {}; // cache for css_file_get_fragments()

// Create <profile>/chrome/ directory if not already present
var chromeDir = Services.dirsvc.get("ProfD", Ci.nsIFile);
chromeDir.append("chrome");
if (!chromeDir.exists()) {
    chromeDir.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
}

var logFile = chromeDir.clone();
logFile.append("mobile-config-firefox.log");
var mode = FileUtils.MODE_WRONLY | FileUtils.MODE_CREATE | FileUtils.MODE_APPEND;
var logFileStream = FileUtils.openFileOutputStream(logFile, mode);

function log(line) {
    var date = new Date().toISOString().replace("T", " ").slice(0, 19);
    line = "[" + date + "] " + line + "\n";
    logFileStream.write(line, line.length);
}

// Debug function for logging object attributes
function log_obj(obj) {
    var prop;
    var value;

    for (var prop in obj) {
        try {
            value = obj[prop];
        } catch(e) {
            value = e;
        }
        log(" - " + prop + ": " + value);
    }
}

function get_firefox_version() {
    try {
        return Services.appinfo.lastAppVersion;
    } catch(e) {
        log("Failed to get FF version: " + e);
        return 0;
    }
}

function trigger_firefox_restart() {
    log("Triggering Firefox restart");
    var appStartup = Cc["@mozilla.org/toolkit/app-startup;1"].getService(Ci.nsIAppStartup);
    appStartup.quit(Ci.nsIAppStartup.eForceQuit | Ci.nsIAppStartup.eRestart);
}

function set_default_prefs() {
    log("Setting default preferences");
    // Select a mobile user agent for firefox (same as tor browser on android)
    defaultPref('general.useragent.override', 'Mozilla/5.0 (Android 10; Mobile; rv:110.0) Gecko/110.0 Firefox/110.0');

    // Do not suggest facebook, ebay, reddit etc. in the urlbar. Same as
    // Settings -> Privacy & Security -> Address Bar -> Shortcuts. As
    // side-effect, the urlbar results are not immediatelly opened once
    // clicking the urlbar.
    defaultPref('browser.urlbar.suggest.topsites', false);

    // Do not suggest search engines. Even though amazon is removed via
    // policies.json, it gets installed shortly after the browser is opened.
    // With this option, at least there is no big "Search with Amazon" message
    // in the urlbar results as soon as typing the letter "a".
    defaultPref('browser.urlbar.suggest.engines', false);

    // Show about:home in new tabs, so it's not just a weird looking completely
    // empty page.
    defaultPref('browser.newtabpage.enabled', true);
}

// Get an array of paths to the fragments for one CSS file
// name: either "userChrome" or "userContent"
function css_file_get_fragments(name) {
    if (name in fragments_cache)
        return fragments_cache[name];

    var ret = [];
    var path = "/etc/mobile-config-firefox/" + name + ".files";
    log("Reading fragments from file: " + path);
    var file = new FileUtils.File(path);

    var istream = Cc["@mozilla.org/network/file-input-stream;1"].
                  createInstance(Components.interfaces.nsIFileInputStream);
    istream.init(file, 0x01, 0444, 0);
    istream.QueryInterface(Components.interfaces.nsILineInputStream);

    var has_more;
    do {
        var line = {};
        has_more = istream.readLine(line);
        ret.push("/etc/mobile-config-firefox/" + line.value);
    } while (has_more);

    istream.close();

    fragments_cache[name] = ret;
    return ret;
}

// Create a nsIFile object with one of the CSS files in the user's profile as
// path. The file doesn't need to exist at this point.
// name: either "userChrome" or "userContent"
function css_file_get(name) {
    var ret = chromeDir.clone();
    ret.append(name + ".css");
    return ret;
}

// Delete either userChrome.css or userContent.css inside the user's profile if
// they have an older timestamp than the CSS fragments (or list of CSS
// fragments) installed system-wide.
// name: either "userChrome" or "userContent"
// file: return of css_file_get()
function css_file_delete_outdated(name, file) {
    var depends = css_file_get_fragments(name).slice(); /* copy the array */
    depends.push("/etc/mobile-config-firefox/" + name + ".files");
    for (var i in depends) {
        var depend = depends[i];
        var file_depend = new FileUtils.File(depend);

        if (file.lastModifiedTime < file_depend.lastModifiedTime) {
            log("Removing outdated file: " + file.path + " (newer: "
                + depend + ")");
            file.remove(false);
            return;
        }
    }

    log("File is up-to-date: " + file.path);
    return;
}

// Create userChrome.css / userContent.css in the user's profile, based on the
// CSS fragments stored in /etc/mobile-config-firefox.
// name: either "userChrome" or "userContent"
// file: return of css_file_get()
function css_file_merge(name, file) {
    log("Creating CSS file from fragments: " + file.path);

    var ostream = Cc["@mozilla.org/network/file-output-stream;1"].
                  createInstance(Components.interfaces.nsIFileOutputStream);
    ostream.init(file, 0x02 | 0x08 | 0x20, 0644, 0);

    var fragments = css_file_get_fragments(name);
    for (var i in fragments) {
        var line;
        var fragment = fragments[i];
        log("- " + fragment);
        line = "/* === " + fragment + " === */\n"
        ostream.write(line, line.length);

        var file_fragment = new FileUtils.File(fragment);

        var istream = Cc["@mozilla.org/network/file-input-stream;1"].
                      createInstance(Components.interfaces.nsIFileInputStream);
        istream.init(file_fragment, 0x01, 0444, 0);
        istream.QueryInterface(Components.interfaces.nsILineInputStream);

        var has_more;
        do {
            var line = {};
            has_more = istream.readLine(line);
            line = line.value + "\n";
            ostream.write(line, line.length);
        } while (has_more);

        istream.close();
    }

    ostream.close();
    updated = true;
}

function css_files_update() {
    var ff_version = get_firefox_version();
    log("Firefox version: " + ff_version);

    var names = ["userChrome", "userContent"];
    for (var i in names) {
        var name = names[i];
        var file = css_file_get(name);

        if (file.exists()) {
            css_file_delete_outdated(name, file);
        }

        if (!file.exists()) {
            css_file_merge(name, file);
        }
    }
}

log("Running mobile-config-autoconfig.js");

css_files_update();

// Restart Firefox immediately if one of the files got updated
if (updated == true)
    trigger_firefox_restart();
else
    set_default_prefs();

log("Done");
logFileStream.close();