SpecialPowersParent.jsm

/* 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/. */

"use strict";

var EXPORTED_SYMBOLS = ["SpecialPowersParent"];

const { AppConstants } = ChromeUtils.import(
  "resource://gre/modules/AppConstants.jsm"
);
var { XPCOMUtils } = ChromeUtils.import(
  "resource://gre/modules/XPCOMUtils.jsm"
);
var { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");

XPCOMUtils.defineLazyModuleGetters(this, {
  ExtensionData: "resource://gre/modules/Extension.jsm",
  ExtensionTestCommon: "resource://testing-common/ExtensionTestCommon.jsm",
  PerTestCoverageUtils: "resource://testing-common/PerTestCoverageUtils.jsm",
  ServiceWorkerCleanUp: "resource://gre/modules/ServiceWorkerCleanUp.jsm",
  SpecialPowersSandbox: "resource://specialpowers/SpecialPowersSandbox.jsm",
  HiddenFrame: "resource://gre/modules/HiddenFrame.jsm",
});

class SpecialPowersError extends Error {
  get name() {
    return "SpecialPowersError";
  }
}

function getTestPlugin(pluginName) {
  var ph = Cc["@mozilla.org/plugin/host;1"].getService(Ci.nsIPluginHost);
  var tags = ph.getPluginTags();
  var name = pluginName || "Test Plug-in";
  for (var tag of tags) {
    if (tag.name == name) {
      return tag;
    }
  }

  return null;
}

const PREF_TYPES = {
  [Ci.nsIPrefBranch.PREF_INVALID]: "INVALID",
  [Ci.nsIPrefBranch.PREF_INT]: "INT",
  [Ci.nsIPrefBranch.PREF_BOOL]: "BOOL",
  [Ci.nsIPrefBranch.PREF_STRING]: "CHAR",
  number: "INT",
  boolean: "BOOL",
  string: "CHAR",
};

// We share a single preference environment stack between all
// SpecialPowers instances, across all processes.
let prefUndoStack = [];
let inPrefEnvOp = false;

function doPrefEnvOp(fn) {
  if (inPrefEnvOp) {
    throw new Error(
      "Reentrant preference environment operations not supported"
    );
  }
  inPrefEnvOp = true;
  try {
    return fn();
  } finally {
    inPrefEnvOp = false;
  }
}

// Supplies the unique IDs for tasks created by SpecialPowers.spawn(),
// used to bounce assertion messages back down to the correct child.
let nextTaskID = 1;

// The default actor to send assertions to if a task originated in a
// window without a test harness.
let defaultAssertHandler;

class SpecialPowersParent extends JSWindowActorParent {
  constructor() {
    super();

    this._messageManager = Services.mm;
    this._serviceWorkerListener = null;

    this._observer = this.observe.bind(this);

    this.didDestroy = this.uninit.bind(this);

    this._registerObservers = {
      _self: this,
      _topics: [],
      _add(topic) {
        if (!this._topics.includes(topic)) {
          this._topics.push(topic);
          Services.obs.addObserver(this, topic);
        }
      },
      observe(aSubject, aTopic, aData) {
        var msg = { aData };
        switch (aTopic) {
          case "perm-changed":
            var permission = aSubject.QueryInterface(Ci.nsIPermission);

            // specialPowersAPI will consume this value, and it is used as a
            // fake permission, but only type will be used.
            //
            // We need to ensure that it looks the same as a real permission,
            // so we fake these properties.
            msg.permission = {
              principal: {
                originAttributes: {},
              },
              type: permission.type,
            };
            this._self.sendAsyncMessage("specialpowers-" + aTopic, msg);
            return;
          case "csp-on-violate-policy":
            // the subject is either an nsIURI or an nsISupportsCString
            let subject = null;
            if (aSubject instanceof Ci.nsIURI) {
              subject = aSubject.asciiSpec;
            } else if (aSubject instanceof Ci.nsISupportsCString) {
              subject = aSubject.data;
            } else {
              throw new Error("Subject must be nsIURI or nsISupportsCString");
            }
            msg = {
              subject,
              data: aData,
            };
            this._self.sendAsyncMessage("specialpowers-" + aTopic, msg);
            return;
          case "xfo-on-violate-policy":
            let uriSpec = null;
            if (aSubject instanceof Ci.nsIURI) {
              uriSpec = aSubject.asciiSpec;
            } else {
              throw new Error("Subject must be nsIURI");
            }
            msg = {
              subject: uriSpec,
              data: aData,
            };
            this._self.sendAsyncMessage("specialpowers-" + aTopic, msg);
            return;
          default:
            this._self.sendAsyncMessage("specialpowers-" + aTopic, msg);
        }
      },
    };

    this.init();

    this._crashDumpDir = null;
    this._processCrashObserversRegistered = false;
    this._chromeScriptListeners = [];
    this._extensions = new Map();
    this._taskActors = new Map();
  }

  init() {
    Services.obs.addObserver(this._observer, "http-on-modify-request");

    // We would like to check that tests don't leave service workers around
    // after they finish, but that information lives in the parent process.
    // Ideally, we'd be able to tell the child processes whenever service
    // workers are registered or unregistered so they would know at all times,
    // but service worker lifetimes are complicated enough to make that
    // difficult. For the time being, let the child process know when a test
    // registers a service worker so it can ask, synchronously, at the end if
    // the service worker had unregister called on it.
    let swm = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
      Ci.nsIServiceWorkerManager
    );
    let self = this;
    this._serviceWorkerListener = {
      onRegister() {
        self.onRegister();
      },

      onUnregister() {
        // no-op
      },
    };
    swm.addListener(this._serviceWorkerListener);
  }

  uninit() {
    if (defaultAssertHandler === this) {
      defaultAssertHandler = null;
    }

    var obs = Services.obs;
    obs.removeObserver(this._observer, "http-on-modify-request");
    this._registerObservers._topics.splice(0).forEach(element => {
      obs.removeObserver(this._registerObservers, element);
    });
    this._removeProcessCrashObservers();

    let swm = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
      Ci.nsIServiceWorkerManager
    );
    swm.removeListener(this._serviceWorkerListener);
  }

  observe(aSubject, aTopic, aData) {
    function addDumpIDToMessage(propertyName) {
      try {
        var id = aSubject.getPropertyAsAString(propertyName);
      } catch (ex) {
        id = null;
      }
      if (id) {
        message.dumpIDs.push({ id, extension: "dmp" });
        message.dumpIDs.push({ id, extension: "extra" });
      }
    }

    switch (aTopic) {
      case "http-on-modify-request":
        if (aSubject instanceof Ci.nsIChannel) {
          let uri = aSubject.URI.spec;
          this.sendAsyncMessage("specialpowers-http-notify-request", { uri });
        }
        break;

      case "plugin-crashed":
      case "ipc:content-shutdown":
        var message = { type: "crash-observed", dumpIDs: [] };
        aSubject = aSubject.QueryInterface(Ci.nsIPropertyBag2);
        if (aTopic == "plugin-crashed") {
          addDumpIDToMessage("pluginDumpID");

          let pluginID = aSubject.getPropertyAsAString("pluginDumpID");
          let additionalMinidumps = aSubject.getPropertyAsACString(
            "additionalMinidumps"
          );
          if (additionalMinidumps.length != 0) {
            let dumpNames = additionalMinidumps.split(",");
            for (let name of dumpNames) {
              message.dumpIDs.push({
                id: pluginID + "-" + name,
                extension: "dmp",
              });
            }
          }
        } else {
          // ipc:content-shutdown
          if (!aSubject.hasKey("abnormal")) {
            return; // This is a normal shutdown, ignore it
          }

          addDumpIDToMessage("dumpID");
        }
        this.sendAsyncMessage("SPProcessCrashService", message);
        break;
    }
  }

  _getCrashDumpDir() {
    if (!this._crashDumpDir) {
      this._crashDumpDir = Services.dirsvc.get("ProfD", Ci.nsIFile);
      this._crashDumpDir.append("minidumps");
    }
    return this._crashDumpDir;
  }

  _getPendingCrashDumpDir() {
    if (!this._pendingCrashDumpDir) {
      this._pendingCrashDumpDir = Services.dirsvc.get("UAppData", Ci.nsIFile);
      this._pendingCrashDumpDir.append("Crash Reports");
      this._pendingCrashDumpDir.append("pending");
    }
    return this._pendingCrashDumpDir;
  }

  _deleteCrashDumpFiles(aFilenames) {
    var crashDumpDir = this._getCrashDumpDir();
    if (!crashDumpDir.exists()) {
      return false;
    }

    var success = aFilenames.length != 0;
    aFilenames.forEach(function(crashFilename) {
      var file = crashDumpDir.clone();
      file.append(crashFilename);
      if (file.exists()) {
        file.remove(false);
      } else {
        success = false;
      }
    });
    return success;
  }

  _findCrashDumpFiles(aToIgnore) {
    var crashDumpDir = this._getCrashDumpDir();
    var entries = crashDumpDir.exists() && crashDumpDir.directoryEntries;
    if (!entries) {
      return [];
    }

    var crashDumpFiles = [];
    while (entries.hasMoreElements()) {
      var file = entries.nextFile;
      var path = String(file.path);
      if (path.match(/\.(dmp|extra)$/) && !aToIgnore[path]) {
        crashDumpFiles.push(path);
      }
    }
    return crashDumpFiles.concat();
  }

  _deletePendingCrashDumpFiles() {
    var crashDumpDir = this._getPendingCrashDumpDir();
    var removed = false;
    if (crashDumpDir.exists()) {
      let entries = crashDumpDir.directoryEntries;
      while (entries.hasMoreElements()) {
        let file = entries.nextFile;
        if (file.isFile()) {
          file.remove(false);
          removed = true;
        }
      }
    }
    return removed;
  }

  _addProcessCrashObservers() {
    if (this._processCrashObserversRegistered) {
      return;
    }

    Services.obs.addObserver(this._observer, "plugin-crashed");
    Services.obs.addObserver(this._observer, "ipc:content-shutdown");
    this._processCrashObserversRegistered = true;
  }

  _removeProcessCrashObservers() {
    if (!this._processCrashObserversRegistered) {
      return;
    }

    Services.obs.removeObserver(this._observer, "plugin-crashed");
    Services.obs.removeObserver(this._observer, "ipc:content-shutdown");
    this._processCrashObserversRegistered = false;
  }

  onRegister() {
    this.sendAsyncMessage("SPServiceWorkerRegistered", { registered: true });
  }

  _getURI(url) {
    return Services.io.newURI(url);
  }
  _notifyCategoryAndObservers(subject, topic, data) {
    const serviceMarker = "service,";

    // First create observers from the category manager.

    let observers = [];

    for (let { value: contractID } of Services.catMan.enumerateCategory(
      topic
    )) {
      let factoryFunction;
      if (contractID.substring(0, serviceMarker.length) == serviceMarker) {
        contractID = contractID.substring(serviceMarker.length);
        factoryFunction = "getService";
      } else {
        factoryFunction = "createInstance";
      }

      try {
        let handler = Cc[contractID][factoryFunction]();
        if (handler) {
          let observer = handler.QueryInterface(Ci.nsIObserver);
          observers.push(observer);
        }
      } catch (e) {}
    }

    // Next enumerate the registered observers.
    for (let observer of Services.obs.enumerateObservers(topic)) {
      if (observer instanceof Ci.nsIObserver && !observers.includes(observer)) {
        observers.push(observer);
      }
    }

    observers.forEach(function(observer) {
      try {
        observer.observe(subject, topic, data);
      } catch (e) {}
    });
  }

  /*
    Iterate through one atomic set of pref actions and perform sets/clears as appropriate.
    All actions performed must modify the relevant pref.
  */
  _applyPrefs(actions) {
    for (let pref of actions) {
      if (pref.action == "set") {
        this._setPref(pref.name, pref.type, pref.value, pref.iid);
      } else if (pref.action == "clear") {
        Services.prefs.clearUserPref(pref.name);
      }
    }
  }

  /**
   * Take in a list of pref changes to make, pushes their current values
   * onto the restore stack, and makes the changes.  When the test
   * finishes, these changes are reverted.
   *
   * |inPrefs| must be an object with up to two properties: "set" and "clear".
   * pushPrefEnv will set prefs as indicated in |inPrefs.set| and will unset
   * the prefs indicated in |inPrefs.clear|.
   *
   * For example, you might pass |inPrefs| as:
   *
   *  inPrefs = {'set': [['foo.bar', 2], ['magic.pref', 'baz']],
   *             'clear': [['clear.this'], ['also.this']] };
   *
   * Notice that |set| and |clear| are both an array of arrays.  In |set|, each
   * of the inner arrays must have the form [pref_name, value] or [pref_name,
   * value, iid].  (The latter form is used for prefs with "complex" values.)
   *
   * In |clear|, each inner array should have the form [pref_name].
   *
   * If you set the same pref more than once (or both set and clear a pref),
   * the behavior of this method is undefined.
   */
  pushPrefEnv(inPrefs) {
    return doPrefEnvOp(() => {
      let pendingActions = [];
      let cleanupActions = [];

      for (let [action, prefs] of Object.entries(inPrefs)) {
        for (let pref of prefs) {
          let name = pref[0];
          let value = null;
          let iid = null;
          let type = PREF_TYPES[Services.prefs.getPrefType(name)];
          let originalValue = null;

          if (pref.length == 3) {
            value = pref[1];
            iid = pref[2];
          } else if (pref.length == 2) {
            value = pref[1];
          }

          /* If pref is not found or invalid it doesn't exist. */
          if (type !== "INVALID") {
            if (
              (Services.prefs.prefHasUserValue(name) && action == "clear") ||
              action == "set"
            ) {
              originalValue = this._getPref(name, type);
            }
          } else if (action == "set") {
            /* name doesn't exist, so 'clear' is pointless */
            if (iid) {
              type = "COMPLEX";
            }
          }

          if (type === "INVALID") {
            type = PREF_TYPES[typeof value];
          }
          if (type === "INVALID") {
            throw new Error("Unexpected preference type");
          }

          pendingActions.push({ action, type, name, value, iid });

          /* Push original preference value or clear into cleanup array */
          var cleanupTodo = { type, name, value: originalValue, iid };
          if (originalValue == null) {
            cleanupTodo.action = "clear";
          } else {
            cleanupTodo.action = "set";
          }
          cleanupActions.push(cleanupTodo);
        }
      }

      prefUndoStack.push(cleanupActions);
      this._applyPrefs(pendingActions);
    });
  }

  async popPrefEnv() {
    return doPrefEnvOp(() => {
      let env = prefUndoStack.pop();
      if (env) {
        this._applyPrefs(env);
        return true;
      }
      return false;
    });
  }

  flushPrefEnv() {
    while (prefUndoStack.length) {
      this.popPrefEnv();
    }
  }

  _setPref(name, type, value, iid) {
    switch (type) {
      case "BOOL":
        return Services.prefs.setBoolPref(name, value);
      case "INT":
        return Services.prefs.setIntPref(name, value);
      case "CHAR":
        return Services.prefs.setCharPref(name, value);
      case "COMPLEX":
        return Services.prefs.setComplexValue(name, iid, value);
    }
    throw new Error(`Unexpected preference type: ${type}`);
  }

  _getPref(name, type, defaultValue, iid) {
    switch (type) {
      case "BOOL":
        if (defaultValue !== undefined) {
          return Services.prefs.getBoolPref(name, defaultValue);
        }
        return Services.prefs.getBoolPref(name);
      case "INT":
        if (defaultValue !== undefined) {
          return Services.prefs.getIntPref(name, defaultValue);
        }
        return Services.prefs.getIntPref(name);
      case "CHAR":
        if (defaultValue !== undefined) {
          return Services.prefs.getCharPref(name, defaultValue);
        }
        return Services.prefs.getCharPref(name);
      case "COMPLEX":
        return Services.prefs.getComplexValue(name, iid);
    }
    throw new Error(`Unexpected preference type: ${type}`);
  }

  _toggleMuteAudio(aMuted) {
    let browser = this.browsingContext.top.embedderElement;
    if (aMuted) {
      browser.mute();
    } else {
      browser.unmute();
    }
  }

  /**
   * messageManager callback function
   * This will get requests from our API in the window and process them in chrome for it
   **/
  // eslint-disable-next-line complexity
  receiveMessage(aMessage) {
    // We explicitly return values in the below code so that this function
    // doesn't trigger a flurry of warnings about "does not always return
    // a value".
    switch (aMessage.name) {
      case "SPToggleMuteAudio":
        return this._toggleMuteAudio(aMessage.data.mute);

      case "Ping":
        return undefined;

      case "SpecialPowers.Quit":
        Services.startup.quit(Ci.nsIAppStartup.eForceQuit);
        return undefined;

      case "SpecialPowers.Focus":
        if (this.manager.rootFrameLoader) {
          this.manager.rootFrameLoader.ownerElement.focus();
        }
        return undefined;

      case "SpecialPowers.CreateFiles":
        return (async () => {
          let filePaths = [];
          if (!this._createdFiles) {
            this._createdFiles = [];
          }
          let createdFiles = this._createdFiles;

          let promises = [];
          aMessage.data.forEach(function(request) {
            const filePerms = 0o666;
            let testFile = Services.dirsvc.get("ProfD", Ci.nsIFile);
            if (request.name) {
              testFile.appendRelativePath(request.name);
            } else {
              testFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, filePerms);
            }
            let outStream = Cc[
              "@mozilla.org/network/file-output-stream;1"
            ].createInstance(Ci.nsIFileOutputStream);
            outStream.init(
              testFile,
              0x02 | 0x08 | 0x20, // PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE
              filePerms,
              0
            );
            if (request.data) {
              outStream.write(request.data, request.data.length);
            }
            outStream.close();
            promises.push(
              File.createFromFileName(testFile.path, request.options).then(
                function(file) {
                  filePaths.push(file);
                }
              )
            );
            createdFiles.push(testFile);
          });

          await Promise.all(promises);
          return filePaths;
        })().catch(e => {
          Cu.reportError(e);
          return Promise.reject(String(e));
        });

      case "SpecialPowers.RemoveFiles":
        if (this._createdFiles) {
          this._createdFiles.forEach(function(testFile) {
            try {
              testFile.remove(false);
            } catch (e) {}
          });
          this._createdFiles = null;
        }
        return undefined;

      case "Wakeup":
        return undefined;

      case "PushPrefEnv":
        return this.pushPrefEnv(aMessage.data);

      case "PopPrefEnv":
        return this.popPrefEnv();

      case "FlushPrefEnv":
        return this.flushPrefEnv();

      case "SPPrefService": {
        let prefs = Services.prefs;
        let prefType = aMessage.json.prefType.toUpperCase();
        let { prefName, prefValue, iid, defaultValue } = aMessage.json;

        if (aMessage.json.op == "get") {
          if (!prefName || !prefType) {
            throw new SpecialPowersError(
              "Invalid parameters for get in SPPrefService"
            );
          }

          // return null if the pref doesn't exist
          if (
            defaultValue === undefined &&
            prefs.getPrefType(prefName) == prefs.PREF_INVALID
          ) {
            return null;
          }
          return this._getPref(prefName, prefType, defaultValue, iid);
        } else if (aMessage.json.op == "set") {
          if (!prefName || !prefType || prefValue === undefined) {
            throw new SpecialPowersError(
              "Invalid parameters for set in SPPrefService"
            );
          }

          return this._setPref(prefName, prefType, prefValue, iid);
        } else if (aMessage.json.op == "clear") {
          if (!prefName) {
            throw new SpecialPowersError(
              "Invalid parameters for clear in SPPrefService"
            );
          }

          prefs.clearUserPref(prefName);
        } else {
          throw new SpecialPowersError("Invalid operation for SPPrefService");
        }

        return undefined; // See comment at the beginning of this function.
      }

      case "SPProcessCrashService": {
        switch (aMessage.json.op) {
          case "register-observer":
            this._addProcessCrashObservers();
            break;
          case "unregister-observer":
            this._removeProcessCrashObservers();
            break;
          case "delete-crash-dump-files":
            return this._deleteCrashDumpFiles(aMessage.json.filenames);
          case "find-crash-dump-files":
            return this._findCrashDumpFiles(
              aMessage.json.crashDumpFilesToIgnore
            );
          case "delete-pending-crash-dump-files":
            return this._deletePendingCrashDumpFiles();
          default:
            throw new SpecialPowersError(
              "Invalid operation for SPProcessCrashService"
            );
        }
        return undefined; // See comment at the beginning of this function.
      }

      case "SPProcessCrashManagerWait": {
        let promises = aMessage.json.crashIds.map(crashId => {
          return Services.crashmanager.ensureCrashIsPresent(crashId);
        });
        return Promise.all(promises);
      }

      case "SPPermissionManager": {
        let msg = aMessage.json;
        let principal = msg.principal;

        switch (msg.op) {
          case "add":
            Services.perms.addFromPrincipal(
              principal,
              msg.type,
              msg.permission,
              msg.expireType,
              msg.expireTime
            );
            break;
          case "remove":
            Services.perms.removeFromPrincipal(principal, msg.type);
            break;
          case "has":
            let hasPerm = Services.perms.testPermissionFromPrincipal(
              principal,
              msg.type
            );
            return hasPerm == Ci.nsIPermissionManager.ALLOW_ACTION;
          case "test":
            let testPerm = Services.perms.testPermissionFromPrincipal(
              principal,
              msg.type
            );
            return testPerm == msg.value;
          default:
            throw new SpecialPowersError(
              "Invalid operation for SPPermissionManager"
            );
        }
        return undefined; // See comment at the beginning of this function.
      }

      case "SPSetTestPluginEnabledState": {
        var plugin = getTestPlugin(aMessage.data.pluginName);
        if (!plugin) {
          return undefined;
        }
        var oldEnabledState = plugin.enabledState;
        plugin.enabledState = aMessage.data.newEnabledState;
        return oldEnabledState;
      }

      case "SPObserverService": {
        let topic = aMessage.json.observerTopic;
        switch (aMessage.json.op) {
          case "notify":
            let data = aMessage.json.observerData;
            Services.obs.notifyObservers(null, topic, data);
            break;
          case "add":
            this._registerObservers._add(topic);
            break;
          default:
            throw new SpecialPowersError(
              "Invalid operation for SPObserverervice"
            );
        }
        return undefined; // See comment at the beginning of this function.
      }

      case "SPLoadChromeScript": {
        let id = aMessage.json.id;
        let scriptName;

        let jsScript = aMessage.json.function.body;
        if (aMessage.json.url) {
          scriptName = aMessage.json.url;
        } else if (aMessage.json.function) {
          scriptName =
            aMessage.json.function.name ||
            "<loadChromeScript anonymous function>";
        } else {
          throw new SpecialPowersError("SPLoadChromeScript: Invalid script");
        }

        // Setup a chrome sandbox that has access to sendAsyncMessage
        // and {add,remove}MessageListener in order to communicate with
        // the mochitest.
        let sb = new SpecialPowersSandbox(
          scriptName,
          data => {
            this.sendAsyncMessage("Assert", data);
          },
          aMessage.data
        );

        Object.assign(sb.sandbox, {
          sendAsyncMessage: (name, message) => {
            this.sendAsyncMessage("SPChromeScriptMessage", {
              id,
              name,
              message,
            });
          },
          addMessageListener: (name, listener) => {
            this._chromeScriptListeners.push({ id, name, listener });
          },
          removeMessageListener: (name, listener) => {
            let index = this._chromeScriptListeners.findIndex(function(obj) {
              return (
                obj.id == id && obj.name == name && obj.listener == listener
              );
            });
            if (index >= 0) {
              this._chromeScriptListeners.splice(index, 1);
            }
          },
          actorParent: this.manager,
        });

        // Evaluate the chrome script
        try {
          Cu.evalInSandbox(jsScript, sb.sandbox, "1.8", scriptName, 1);
        } catch (e) {
          throw new SpecialPowersError(
            "Error while executing chrome script '" +
              scriptName +
              "':\n" +
              e +
              "\n" +
              e.fileName +
              ":" +
              e.lineNumber
          );
        }
        return undefined; // See comment at the beginning of this function.
      }

      case "SPChromeScriptMessage": {
        let id = aMessage.json.id;
        let name = aMessage.json.name;
        let message = aMessage.json.message;
        let result;
        for (let listener of this._chromeScriptListeners) {
          if (listener.name == name && listener.id == id) {
            result = listener.listener(message);
          }
        }
        return result;
      }

      case "SPImportInMainProcess": {
        var message = { hadError: false, errorMessage: null };
        try {
          ChromeUtils.import(aMessage.data);
        } catch (e) {
          message.hadError = true;
          message.errorMessage = e.toString();
        }
        return message;
      }

      case "SPCleanUpSTSData": {
        let origin = aMessage.data.origin;
        let flags = aMessage.data.flags;
        let uri = Services.io.newURI(origin);
        let sss = Cc["@mozilla.org/ssservice;1"].getService(
          Ci.nsISiteSecurityService
        );
        sss.resetState(Ci.nsISiteSecurityService.HEADER_HSTS, uri, flags);
        return undefined;
      }

      case "SPRequestDumpCoverageCounters": {
        return PerTestCoverageUtils.afterTest();
      }

      case "SPRequestResetCoverageCounters": {
        return PerTestCoverageUtils.beforeTest();
      }

      case "SPCheckServiceWorkers": {
        let swm = Cc["@mozilla.org/serviceworkers/manager;1"].getService(
          Ci.nsIServiceWorkerManager
        );
        let regs = swm.getAllRegistrations();

        // XXX This code is shared with specialpowers.js.
        let workers = new Array(regs.length);
        for (let i = 0; i < regs.length; ++i) {
          let { scope, scriptSpec } = regs.queryElementAt(
            i,
            Ci.nsIServiceWorkerRegistrationInfo
          );
          workers[i] = { scope, scriptSpec };
        }
        return { workers };
      }

      case "SPLoadExtension": {
        let id = aMessage.data.id;
        let ext = aMessage.data.ext;
        let extension = ExtensionTestCommon.generate(ext);

        let resultListener = (...args) => {
          this.sendAsyncMessage("SPExtensionMessage", {
            id,
            type: "testResult",
            args,
          });
        };

        let messageListener = (...args) => {
          args.shift();
          this.sendAsyncMessage("SPExtensionMessage", {
            id,
            type: "testMessage",
            args,
          });
        };

        // Register pass/fail handlers.
        extension.on("test-result", resultListener);
        extension.on("test-eq", resultListener);
        extension.on("test-log", resultListener);
        extension.on("test-done", resultListener);

        extension.on("test-message", messageListener);

        this._extensions.set(id, extension);
        return undefined;
      }

      case "SPStartupExtension": {
        let id = aMessage.data.id;
        // This is either an Extension, or (if useAddonManager is set) a MockExtension.
        let extension = this._extensions.get(id);
        extension.on("startup", (eventName, ext) => {
          if (!ext) {
            // ext is only set by the "startup" event from Extension.jsm.
            // Unfortunately ext-backgroundPage.js emits an event with the same
            // name, but without the extension object as parameter.
            return;
          }
          if (AppConstants.platform === "android") {
            // We need a way to notify the embedding layer that a new extension
            // has been installed, so that the java layer can be updated too.
            Services.obs.notifyObservers(null, "testing-installed-addon", id);
          }
          // ext is always the "real" Extension object, even when "extension"
          // is a MockExtension.
          this.sendAsyncMessage("SPExtensionMessage", {
            id,
            type: "extensionSetId",
            args: [ext.id, ext.uuid],
          });
        });

        // Make sure the extension passes the packaging checks when
        // they're run on a bare archive rather than a running instance,
        // as the add-on manager runs them.
        let extensionData = new ExtensionData(extension.rootURI);
        return extensionData
          .loadManifest()
          .then(
            () => {
              return extensionData.initAllLocales().then(() => {
                if (extensionData.errors.length) {
                  return Promise.reject("Extension contains packaging errors");
                }
                return undefined;
              });
            },
            () => {
              // loadManifest() will throw if we're loading an embedded
              // extension, so don't worry about locale errors in that
              // case.
            }
          )
          .then(async () => {
            // browser tests do not call startup in ExtensionXPCShellUtils or MockExtension,
            // in that case we have an ID here and we need to set the override.
            if (extension.id) {
              await ExtensionTestCommon.setIncognitoOverride(extension);
            }
            return extension.startup().then(
              () => {},
              e => {
                dump(`Extension startup failed: ${e}\n${e.stack}`);
                throw e;
              }
            );
          });
      }

      case "SPExtensionMessage": {
        let id = aMessage.data.id;
        let extension = this._extensions.get(id);
        extension.testMessage(...aMessage.data.args);
        return undefined;
      }

      case "SPUnloadExtension": {
        let id = aMessage.data.id;
        let extension = this._extensions.get(id);
        this._extensions.delete(id);
        return extension.shutdown().then(() => {
          return extension._uninstallPromise;
        });
      }

      case "SetAsDefaultAssertHandler": {
        defaultAssertHandler = this;
        return undefined;
      }

      case "Spawn": {
        let {
          browsingContext,
          task,
          args,
          caller,
          hasHarness,
          imports,
        } = aMessage.data;

        let spParent = browsingContext.currentWindowGlobal.getActor(
          "SpecialPowers"
        );

        let taskId = nextTaskID++;
        if (hasHarness) {
          spParent._taskActors.set(taskId, this);
        }

        return spParent
          .sendQuery("Spawn", { task, args, caller, taskId, imports })
          .finally(() => spParent._taskActors.delete(taskId));
      }

      case "Snapshot": {
        let { browsingContext, rect, background } = aMessage.data;

        return browsingContext.currentWindowGlobal
          .drawSnapshot(rect, 1.0, background)
          .then(async image => {
            let hiddenFrame = new HiddenFrame();
            let win = await hiddenFrame.get();

            let canvas = win.document.createElement("canvas");
            canvas.width = image.width;
            canvas.height = image.height;

            const ctx = canvas.getContext("2d");
            ctx.drawImage(image, 0, 0);

            let data = ctx.getImageData(0, 0, image.width, image.height);
            hiddenFrame.destroy();
            return data;
          });
      }

      case "ProxiedAssert": {
        let { taskId, data } = aMessage.data;

        let actor = this._taskActors.get(taskId) || defaultAssertHandler;
        actor.sendAsyncMessage("Assert", data);

        return undefined;
      }

      case "SPRemoveAllServiceWorkers": {
        return ServiceWorkerCleanUp.removeAll();
      }

      case "SPRemoveServiceWorkerDataForExampleDomain": {
        return ServiceWorkerCleanUp.removeFromHost("example.com");
      }

      case "SPGenerateMediaControlKeyTestEvent": {
        ChromeUtils.generateMediaControlKeysTestEvent(aMessage.data.event);
        return undefined;
      }

      default:
        throw new SpecialPowersError(
          `Unrecognized Special Powers API: ${aMessage.name}`
        );
    }
    // This should be unreachable. If it ever becomes reachable, ESLint
    // will produce an error about inconsistent return values.
  }
}