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/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set sts=2 sw=2 et tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
"use strict";
var USERSCRIPT_PREFNAME = "extensions.webextensions.userScripts.enabled";
var USERSCRIPT_DISABLED_ERRORMSG = `userScripts APIs are currently experimental and must be enabled with the ${USERSCRIPT_PREFNAME} preference.`;
XPCOMUtils.defineLazyPreferenceGetter(
this,
"userScriptsEnabled",
USERSCRIPT_PREFNAME,
false
);
// eslint-disable-next-line mozilla/reject-importGlobalProperties
Cu.importGlobalProperties(["crypto", "TextEncoder"]);
var { DefaultMap, ExtensionError, getUniqueId } = ExtensionUtils;
/**
* Represents a registered userScript in the child extension process.
*
* @param {ExtensionPageContextChild} context
* The extension context which has registered the user script.
* @param {string} scriptId
* An unique id that represents the registered user script
* (generated and used internally to identify it across the different processes).
*/
class UserScriptChild {
constructor({ context, scriptId, onScriptUnregister }) {
this.context = context;
this.scriptId = scriptId;
this.onScriptUnregister = onScriptUnregister;
this.unregistered = false;
}
async unregister() {
if (this.unregistered) {
throw new ExtensionError("User script already unregistered");
}
this.unregistered = true;
await this.context.childManager.callParentAsyncFunction(
"userScripts.unregister",
[this.scriptId]
);
this.context = null;
this.onScriptUnregister();
}
api() {
const { context } = this;
// Returns the RegisteredUserScript API object.
return {
unregister: () => {
return context.wrapPromise(this.unregister());
},
};
}
}
this.userScripts = class extends ExtensionAPI {
getAPI(context) {
// Cache of the script code already converted into blob urls:
// Map<textHash, blobURLs>
const blobURLsByHash = new Map();
// Keep track of the userScript that are sharing the same blob urls,
// so that we can revoke any blob url that is not used by a registered
// userScripts:
// Map<blobURL, Set<scriptId>>
const userScriptsByBlobURL = new DefaultMap(() => new Set());
function revokeBlobURLs(scriptId, options) {
let revokedUrls = new Set();
for (let url of options.js) {
if (userScriptsByBlobURL.has(url)) {
let scriptIds = userScriptsByBlobURL.get(url);
scriptIds.delete(scriptId);
if (scriptIds.size === 0) {
revokedUrls.add(url);
userScriptsByBlobURL.delete(url);
context.cloneScope.URL.revokeObjectURL(url);
}
}
}
// Remove all the removed urls from the map of known computed hashes.
for (let [hash, url] of blobURLsByHash) {
if (revokedUrls.has(url)) {
blobURLsByHash.delete(hash);
}
}
}
// Convert a script code string into a blob URL (and use a cached one
// if the script hash is already associated to a blob URL).
const getBlobURL = async (text, scriptId) => {
// Compute the hash of the js code string and reuse the blob url if we already have
// for the same hash.
const buffer = await crypto.subtle.digest(
"SHA-1",
new TextEncoder().encode(text)
);
const hash = String.fromCharCode(...new Uint16Array(buffer));
let blobURL = blobURLsByHash.get(hash);
if (blobURL) {
userScriptsByBlobURL.get(blobURL).add(scriptId);
return blobURL;
}
const blob = new context.cloneScope.Blob([text], {
type: "text/javascript",
});
blobURL = context.cloneScope.URL.createObjectURL(blob);
// Start to track this blob URL.
userScriptsByBlobURL.get(blobURL).add(scriptId);
blobURLsByHash.set(hash, blobURL);
return blobURL;
};
function convertToAPIObject(scriptId, options) {
const registeredScript = new UserScriptChild({
context,
scriptId,
onScriptUnregister: () => revokeBlobURLs(scriptId, options),
});
const scriptAPI = Cu.cloneInto(
registeredScript.api(),
context.cloneScope,
{ cloneFunctions: true }
);
return scriptAPI;
}
// Revoke all the created blob urls once the context is destroyed.
context.callOnClose({
close() {
if (!context.cloneScope) {
return;
}
for (let blobURL of blobURLsByHash.values()) {
context.cloneScope.URL.revokeObjectURL(blobURL);
}
},
});
return {
userScripts: {
register(options) {
if (!userScriptsEnabled) {
throw new ExtensionError(USERSCRIPT_DISABLED_ERRORMSG);
}
let scriptId = getUniqueId();
return context.cloneScope.Promise.resolve().then(async () => {
options.scriptId = scriptId;
options.js = await Promise.all(
options.js.map(js => {
return js.file || getBlobURL(js.code, scriptId);
})
);
await context.childManager.callParentAsyncFunction(
"userScripts.register",
[options]
);
return convertToAPIObject(scriptId, options);
});
},
},
};
}
};