pdf.js/web/preferences.js
Jonas Jenwald 1f9d1f3696 [Firefox] Disable the ability to change preferences directly from the viewer
Please note that we've never had any functionality in the viewer itself that *set* preferences, and we've thus only ever read them.
For the GENERIC viewer it obviously makes sense for the user to be able to modify preferences, e.g. via the console, but that doesn't really apply to the *built-in* Firefox PDF Viewer since preferences are already accessible via `about:config` there. Hence it does seems somewhat strange to expose, a limited part of, the Firefox preference system in this way when we're not even using it.

Note that the unused preference setting-code also include a fair amount of *additional* validation on the platform-side, such as limiting any possible preference changes to the `pdfjs.`-branch and also an explicit white-list of preference names[1], to make sure that this is safe; please see:
 - https://searchfox.org/mozilla-central/rev/4e8f62a231e71dc53eb50b6d74afca21d6b254e9/toolkit/components/pdfjs/content/PdfStreamConverter.sys.mjs#458-495
 - https://searchfox.org/mozilla-central/rev/4e8f62a231e71dc53eb50b6d74afca21d6b254e9/toolkit/modules/AsyncPrefs.sys.mjs#21-48

Assuming that this patch lands, I'll follow-up with a mozilla-central patch to remove the code mentioned above.

---
[1] This hard-coded list contains preferences that no longer exist, and also at least one (fairly obvious) typo.
2023-06-21 20:14:16 +02:00

178 lines
5.7 KiB
JavaScript

/* Copyright 2013 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { AppOptions, OptionKind } from "./app_options.js";
/**
* BasePreferences - Abstract base class for storing persistent settings.
* Used for settings that should be applied to all opened documents,
* or every time the viewer is loaded.
*/
class BasePreferences {
#defaults = Object.freeze(
typeof PDFJSDev === "undefined"
? AppOptions.getAll(OptionKind.PREFERENCE)
: PDFJSDev.eval("DEFAULT_PREFERENCES")
);
#prefs = Object.create(null);
#initializedPromise = null;
constructor() {
if (this.constructor === BasePreferences) {
throw new Error("Cannot initialize BasePreferences.");
}
if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("CHROME")) {
Object.defineProperty(this, "defaults", {
get() {
return this.#defaults;
},
});
}
this.#initializedPromise = this._readFromStorage(this.#defaults).then(
prefs => {
for (const name in this.#defaults) {
const prefValue = prefs?.[name];
// Ignore preferences whose types don't match the default values.
if (typeof prefValue === typeof this.#defaults[name]) {
this.#prefs[name] = prefValue;
}
}
}
);
}
/**
* Stub function for writing preferences to storage.
* @param {Object} prefObj The preferences that should be written to storage.
* @returns {Promise} A promise that is resolved when the preference values
* have been written.
*/
async _writeToStorage(prefObj) {
throw new Error("Not implemented: _writeToStorage");
}
/**
* Stub function for reading preferences from storage.
* @param {Object} prefObj The preferences that should be read from storage.
* @returns {Promise} A promise that is resolved with an {Object} containing
* the preferences that have been read.
*/
async _readFromStorage(prefObj) {
throw new Error("Not implemented: _readFromStorage");
}
/**
* Reset the preferences to their default values and update storage.
* @returns {Promise} A promise that is resolved when the preference values
* have been reset.
*/
async reset() {
if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
throw new Error("Please use `about:config` to change preferences.");
}
await this.#initializedPromise;
const prefs = this.#prefs;
this.#prefs = Object.create(null);
return this._writeToStorage(this.#defaults).catch(reason => {
// Revert all preference values, since writing to storage failed.
this.#prefs = prefs;
throw reason;
});
}
/**
* Set the value of a preference.
* @param {string} name The name of the preference that should be changed.
* @param {boolean|number|string} value The new value of the preference.
* @returns {Promise} A promise that is resolved when the value has been set,
* provided that the preference exists and the types match.
*/
async set(name, value) {
if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) {
throw new Error("Please use `about:config` to change preferences.");
}
await this.#initializedPromise;
const defaultValue = this.#defaults[name],
prefs = this.#prefs;
if (defaultValue === undefined) {
throw new Error(`Set preference: "${name}" is undefined.`);
} else if (value === undefined) {
throw new Error("Set preference: no value is specified.");
}
const valueType = typeof value,
defaultType = typeof defaultValue;
if (valueType !== defaultType) {
if (valueType === "number" && defaultType === "string") {
value = value.toString();
} else {
throw new Error(
`Set preference: "${value}" is a ${valueType}, expected a ${defaultType}.`
);
}
} else {
if (valueType === "number" && !Number.isInteger(value)) {
throw new Error(`Set preference: "${value}" must be an integer.`);
}
}
this.#prefs[name] = value;
return this._writeToStorage(this.#prefs).catch(reason => {
// Revert all preference values, since writing to storage failed.
this.#prefs = prefs;
throw reason;
});
}
/**
* Get the value of a preference.
* @param {string} name The name of the preference whose value is requested.
* @returns {Promise} A promise resolved with a {boolean|number|string}
* containing the value of the preference.
*/
async get(name) {
await this.#initializedPromise;
const defaultValue = this.#defaults[name];
if (defaultValue === undefined) {
throw new Error(`Get preference: "${name}" is undefined.`);
}
return this.#prefs[name] ?? defaultValue;
}
/**
* Get the values of all preferences.
* @returns {Promise} A promise that is resolved with an {Object} containing
* the values of all preferences.
*/
async getAll() {
await this.#initializedPromise;
const obj = Object.create(null);
for (const name in this.#defaults) {
obj[name] = this.#prefs[name] ?? this.#defaults[name];
}
return obj;
}
}
export { BasePreferences };