1 files changed, 349 insertions, 0 deletions
diff --git a/toolkit/components/extensions/ExtensionUtils.sys.mjs b/toolkit/components/extensions/ExtensionUtils.sys.mjs
new file mode 100644
index 0000000000..cbdf900d14
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+++ b/toolkit/components/extensions/ExtensionUtils.sys.mjs
@@ -0,0 +1,349 @@
+/* -*- 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, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  setTimeout: "resource://gre/modules/Timer.sys.mjs",
+});
+
+// xpcshell doesn't handle idle callbacks well.
+ChromeUtils.defineLazyGetter(lazy, "idleTimeout", () =>
+  Services.appinfo.name === "XPCShell" ? 500 : undefined
+);
+
+// It would be nicer to go through `Services.appinfo`, but some tests need to be
+// able to replace that field with a custom implementation before it is first
+// called.
+// eslint-disable-next-line mozilla/use-services
+const appinfo = Cc["@mozilla.org/xre/app-info;1"].getService(Ci.nsIXULRuntime);
+
+let nextId = 0;
+const uniqueProcessID = appinfo.uniqueProcessID;
+// Store the process ID in a 16 bit field left shifted to end of a
+// double's mantissa.
+// Note: We can't use bitwise ops here, since they truncate to a 32 bit
+// integer and we need all 53 mantissa bits.
+const processIDMask = (uniqueProcessID & 0xffff) * 2 ** 37;
+
+function getUniqueId() {
+  // Note: We can't use bitwise ops here, since they truncate to a 32 bit
+  // integer and we need all 53 mantissa bits.
+  return processIDMask + nextId++;
+}
+
+function promiseTimeout(delay) {
+  return new Promise(resolve => lazy.setTimeout(resolve, delay));
+}
+
+/**
+ * An Error subclass for which complete error messages are always passed
+ * to extensions, rather than being interpreted as an unknown error.
+ */
+class ExtensionError extends DOMException {
+  constructor(message) {
+    super(message, "ExtensionError");
+  }
+  // Custom JS classes can't survive IPC, so need to check error name.
+  static [Symbol.hasInstance](e) {
+    return DOMException.isInstance(e) && e.name === "ExtensionError";
+  }
+}
+
+function filterStack(error) {
+  return String(error.stack).replace(
+    /(^.*(Task\.jsm|Promise-backend\.js).*\n)+/gm,
+    "<Promise Chain>\n"
+  );
+}
+
+/**
+ * An Error subclass used to recognize the errors that should
+ * to be forwarded to the worker thread and being accessible
+ * to the extension worker script (vs. the errors that should be
+ * only logged internally and raised to the worker script as
+ * the generic unexpected error).
+ */
+class WorkerExtensionError extends DOMException {
+  constructor(message) {
+    super(message, "Error");
+  }
+}
+
+/**
+ * Similar to a WeakMap, but creates a new key with the given
+ * constructor if one is not present.
+ */
+// @ts-ignore (https://github.com/microsoft/TypeScript/issues/56664)
+class DefaultWeakMap extends WeakMap {
+  constructor(defaultConstructor = undefined, init = undefined) {
+    super(init);
+    if (defaultConstructor) {
+      this.defaultConstructor = defaultConstructor;
+    }
+  }
+
+  get(key) {
+    let value = super.get(key);
+    if (value === undefined && !this.has(key)) {
+      value = this.defaultConstructor(key);
+      this.set(key, value);
+    }
+    return value;
+  }
+}
+
+class DefaultMap extends Map {
+  constructor(defaultConstructor = undefined, init = undefined) {
+    super(init);
+    if (defaultConstructor) {
+      this.defaultConstructor = defaultConstructor;
+    }
+  }
+
+  get(key) {
+    let value = super.get(key);
+    if (value === undefined && !this.has(key)) {
+      value = this.defaultConstructor(key);
+      this.set(key, value);
+    }
+    return value;
+  }
+}
+
+function getInnerWindowID(window) {
+  return window.windowGlobalChild?.innerWindowId;
+}
+
+/**
+ * A set with a limited number of slots, which flushes older entries as
+ * newer ones are added.
+ *
+ * @param {integer} limit
+ *        The maximum size to trim the set to after it grows too large.
+ * @param {integer} [slop = limit * .25]
+ *        The number of extra entries to allow in the set after it
+ *        reaches the size limit, before it is truncated to the limit.
+ * @param {Iterable} [iterable]
+ *        An iterable of initial entries to add to the set.
+ */
+class LimitedSet extends Set {
+  constructor(limit, slop = Math.round(limit * 0.25), iterable = undefined) {
+    super(iterable);
+    this.limit = limit;
+    this.slop = slop;
+  }
+
+  truncate(limit) {
+    for (let item of this) {
+      // Live set iterators can ge relatively expensive, since they need
+      // to be updated after every modification to the set. Since
+      // breaking out of the loop early will keep the iterator alive
+      // until the next full GC, we're currently better off finishing
+      // the entire loop even after we're done truncating.
+      if (this.size > limit) {
+        this.delete(item);
+      }
+    }
+  }
+
+  add(item) {
+    if (this.size >= this.limit + this.slop && !this.has(item)) {
+      this.truncate(this.limit - 1);
+    }
+    return super.add(item);
+  }
+}
+
+/**
+ * Returns a Promise which resolves when the given document's DOM has
+ * fully loaded.
+ *
+ * @param {Document} doc The document to await the load of.
+ * @returns {Promise<Document>}
+ */
+function promiseDocumentReady(doc) {
+  if (doc.readyState == "interactive" || doc.readyState == "complete") {
+    return Promise.resolve(doc);
+  }
+
+  return new Promise(resolve => {
+    doc.addEventListener(
+      "DOMContentLoaded",
+      function onReady(event) {
+        if (event.target === event.currentTarget) {
+          doc.removeEventListener("DOMContentLoaded", onReady, true);
+          resolve(doc);
+        }
+      },
+      true
+    );
+  });
+}
+
+/**
+  * Returns a Promise which resolves when the given window's document's DOM has
+  * fully loaded, the <head> stylesheets have fully loaded, and we have hit an
+  * idle time.
+  *
+  * @param {Window} window The window whose document we will await
+                           the readiness of.
+  * @returns {Promise<IdleDeadline>}
+  */
+function promiseDocumentIdle(window) {
+  return window.document.documentReadyForIdle.then(() => {
+    return new Promise(resolve =>
+      window.requestIdleCallback(resolve, { timeout: lazy.idleTimeout })
+    );
+  });
+}
+
+/**
+ * Returns a Promise which resolves when the given document is fully
+ * loaded.
+ *
+ * @param {Document} doc The document to await the load of.
+ * @returns {Promise<Document>}
+ */
+function promiseDocumentLoaded(doc) {
+  if (doc.readyState == "complete") {
+    return Promise.resolve(doc);
+  }
+
+  return new Promise(resolve => {
+    doc.defaultView.addEventListener("load", () => resolve(doc), {
+      once: true,
+    });
+  });
+}
+
+/**
+ * Returns a Promise which resolves when the given event is dispatched to the
+ * given element.
+ *
+ * @param {Element} element
+ *        The element on which to listen.
+ * @param {string} eventName
+ *        The event to listen for.
+ * @param {boolean} [useCapture = true]
+ *        If true, listen for the even in the capturing rather than
+ *        bubbling phase.
+ * @param {function(Event): boolean} [test]
+ *        An optional test function which, when called with the
+ *        observer's subject and data, should return true if this is the
+ *        expected event, false otherwise.
+ * @returns {Promise<Event>}
+ */
+function promiseEvent(
+  element,
+  eventName,
+  useCapture = true,
+  test = event => true
+) {
+  return new Promise(resolve => {
+    function listener(event) {
+      if (test(event)) {
+        element.removeEventListener(eventName, listener, useCapture);
+        resolve(event);
+      }
+    }
+    element.addEventListener(eventName, listener, useCapture);
+  });
+}
+
+/**
+ * Returns a Promise which resolves the given observer topic has been
+ * observed.
+ *
+ * @param {string} topic
+ *        The topic to observe.
+ * @param {function(any, string): boolean} [test]
+ *        An optional test function which, when called with the
+ *        observer's subject and data, should return true if this is the
+ *        expected notification, false otherwise.
+ * @returns {Promise<object>}
+ */
+function promiseObserved(topic, test = () => true) {
+  return new Promise(resolve => {
+    let observer = (subject, topic, data) => {
+      if (test(subject, data)) {
+        Services.obs.removeObserver(observer, topic);
+        resolve({ subject, data });
+      }
+    };
+    Services.obs.addObserver(observer, topic);
+  });
+}
+
+function getMessageManager(target) {
+  if (target.frameLoader) {
+    return target.frameLoader.messageManager;
+  }
+  return target;
+}
+
+function flushJarCache(jarPath) {
+  Services.obs.notifyObservers(null, "flush-cache-entry", jarPath);
+}
+function parseMatchPatterns(patterns, options) {
+  try {
+    return new MatchPatternSet(patterns, options);
+  } catch (e) {
+    let pattern;
+    for (pattern of patterns) {
+      try {
+        new MatchPattern(pattern, options);
+      } catch (e) {
+        throw new ExtensionError(`Invalid url pattern: ${pattern}`);
+      }
+    }
+    // Unexpectedly MatchPatternSet threw, but MatchPattern did not.
+    throw e;
+  }
+}
+
+/**
+ * Fetch icon content and convert it to a data: URI.
+ *
+ * @param {string} iconUrl Icon url to fetch.
+ * @returns {Promise<string>}
+ */
+async function makeDataURI(iconUrl) {
+  let response;
+  try {
+    response = await fetch(iconUrl);
+  } catch (e) {
+    // Failed to fetch, ignore engine's favicon.
+    Cu.reportError(e);
+    return;
+  }
+  let buffer = await response.arrayBuffer();
+  let contentType = response.headers.get("content-type");
+  let bytes = new Uint8Array(buffer);
+  let str = String.fromCharCode.apply(null, bytes);
+  return `data:${contentType};base64,${btoa(str)}`;
+}
+
+export var ExtensionUtils = {
+  flushJarCache,
+  getInnerWindowID,
+  getMessageManager,
+  getUniqueId,
+  filterStack,
+  makeDataURI,
+  parseMatchPatterns,
+  promiseDocumentIdle,
+  promiseDocumentLoaded,
+  promiseDocumentReady,
+  promiseEvent,
+  promiseObserved,
+  promiseTimeout,
+  DefaultMap,
+  DefaultWeakMap,
+  ExtensionError,
+  LimitedSet,
+  WorkerExtensionError,
+};