1 files changed, 461 insertions, 0 deletions
diff --git a/devtools/client/fronts/walker.js b/devtools/client/fronts/walker.js
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+++ b/devtools/client/fronts/walker.js
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+/* 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";
+
+const {
+  FrontClassWithSpec,
+  types,
+  registerFront,
+} = require("resource://devtools/shared/protocol.js");
+const { walkerSpec } = require("resource://devtools/shared/specs/walker.js");
+const {
+  safeAsyncMethod,
+} = require("resource://devtools/shared/async-utils.js");
+
+/**
+ * Client side of the DOM walker.
+ */
+class WalkerFront extends FrontClassWithSpec(walkerSpec) {
+  constructor(client, targetFront, parentFront) {
+    super(client, targetFront, parentFront);
+    this._isPicking = false;
+    this._orphaned = new Set();
+    this._retainedOrphans = new Set();
+
+    // Set to true if cleanup should be requested after every mutation list.
+    this.autoCleanup = true;
+
+    this._rootNodePromise = new Promise(
+      r => (this._rootNodePromiseResolve = r)
+    );
+
+    this._onRootNodeAvailable = this._onRootNodeAvailable.bind(this);
+    this._onRootNodeDestroyed = this._onRootNodeDestroyed.bind(this);
+
+    // pick/cancelPick requests can be triggered while the Walker is being destroyed.
+    this.pick = safeAsyncMethod(this.pick.bind(this), () => this.isDestroyed());
+    this.cancelPick = safeAsyncMethod(this.cancelPick.bind(this), () =>
+      this.isDestroyed()
+    );
+
+    this.before("new-mutations", this.onMutations.bind(this));
+
+    // Those events will be emitted if watchRootNode was called on the
+    // corresponding WalkerActor, which should be handled by the ResourceCommand
+    // as long as a consumer is watching for root-node resources.
+    // This should be fixed by using watchResources directly from the walker
+    // front, either with the ROOT_NODE resource, or with the DOCUMENT_EVENT
+    // resource. See Bug 1663973.
+    this.on("root-available", this._onRootNodeAvailable);
+    this.on("root-destroyed", this._onRootNodeDestroyed);
+  }
+
+  // Update the object given a form representation off the wire.
+  form(json) {
+    this.actorID = json.actor;
+
+    // The rootNode property should usually be provided via watchRootNode.
+    // However tests are currently using the walker front without explicitly
+    // calling watchRootNode, so we keep this assignment as a fallback.
+    this.rootNode = types.getType("domnode").read(json.root, this);
+
+    this.traits = json.traits;
+  }
+
+  /**
+   * Clients can use walker.rootNode to get the current root node of the
+   * walker, but during a reload the root node might be null.  This
+   * method returns a promise that will resolve to the root node when it is
+   * set.
+   */
+  async getRootNode() {
+    let rootNode = this.rootNode;
+    if (!rootNode) {
+      rootNode = await this._rootNodePromise;
+    }
+
+    return rootNode;
+  }
+
+  /**
+   * When reading an actor form off the wire, we want to hook it up to its
+   * parent or host front.  The protocol guarantees that the parent will
+   * be seen by the client in either a previous or the current request.
+   * So if we've already seen this parent return it, otherwise create
+   * a bare-bones stand-in node.  The stand-in node will be updated
+   * with a real form by the end of the deserialization.
+   */
+  ensureDOMNodeFront(id) {
+    const front = this.getActorByID(id);
+    if (front) {
+      return front;
+    }
+
+    return types.getType("domnode").read({ actor: id }, this, "standin");
+  }
+
+  /**
+   * See the documentation for WalkerActor.prototype.retainNode for
+   * information on retained nodes.
+   *
+   * From the client's perspective, `retainNode` can fail if the node in
+   * question is removed from the ownership tree before the `retainNode`
+   * request reaches the server.  This can only happen if the client has
+   * asked the server to release nodes but hasn't gotten a response
+   * yet: Either a `releaseNode` request or a `getMutations` with `cleanup`
+   * set is outstanding.
+   *
+   * If either of those requests is outstanding AND releases the retained
+   * node, this request will fail with noSuchActor, but the ownership tree
+   * will stay in a consistent state.
+   *
+   * Because the protocol guarantees that requests will be processed and
+   * responses received in the order they were sent, we get the right
+   * semantics by setting our local retained flag on the node only AFTER
+   * a SUCCESSFUL retainNode call.
+   */
+  async retainNode(node) {
+    await super.retainNode(node);
+    node.retained = true;
+  }
+
+  async unretainNode(node) {
+    await super.unretainNode(node);
+    node.retained = false;
+    if (this._retainedOrphans.has(node)) {
+      this._retainedOrphans.delete(node);
+      this._releaseFront(node);
+    }
+  }
+
+  releaseNode(node, options = {}) {
+    // NodeFront.destroy will destroy children in the ownership tree too,
+    // mimicking what the server will do here.
+    const actorID = node.actorID;
+    this._releaseFront(node, !!options.force);
+    return super.releaseNode({ actorID });
+  }
+
+  async findInspectingNode() {
+    const response = await super.findInspectingNode();
+    return response.node;
+  }
+
+  async querySelector(queryNode, selector) {
+    const response = await super.querySelector(queryNode, selector);
+    return response.node;
+  }
+
+  async getNodeActorFromWindowID(windowID) {
+    const response = await super.getNodeActorFromWindowID(windowID);
+    return response ? response.node : null;
+  }
+
+  async getNodeActorFromContentDomReference(contentDomReference) {
+    const response = await super.getNodeActorFromContentDomReference(
+      contentDomReference
+    );
+    return response ? response.node : null;
+  }
+
+  async getStyleSheetOwnerNode(styleSheetActorID) {
+    const response = await super.getStyleSheetOwnerNode(styleSheetActorID);
+    return response ? response.node : null;
+  }
+
+  async getNodeFromActor(actorID, path) {
+    const response = await super.getNodeFromActor(actorID, path);
+    return response ? response.node : null;
+  }
+
+  _releaseFront(node, force) {
+    if (node.retained && !force) {
+      node.reparent(null);
+      this._retainedOrphans.add(node);
+      return;
+    }
+
+    if (node.retained) {
+      // Forcing a removal.
+      this._retainedOrphans.delete(node);
+    }
+
+    // Release any children
+    for (const child of node.treeChildren()) {
+      this._releaseFront(child, force);
+    }
+
+    // All children will have been removed from the node by this point.
+    node.reparent(null);
+    node.destroy();
+  }
+
+  /**
+   * Get any unprocessed mutation records and process them.
+   */
+  // eslint-disable-next-line complexity
+  async getMutations(options = {}) {
+    const mutations = await super.getMutations(options);
+    const emitMutations = [];
+    for (const change of mutations) {
+      // The target is only an actorID, get the associated front.
+      const targetID = change.target;
+      const targetFront = this.getActorByID(targetID);
+
+      if (!targetFront) {
+        console.warn(
+          "Got a mutation for an unexpected actor: " +
+            targetID +
+            ", please file a bug on bugzilla.mozilla.org!"
+        );
+        console.trace();
+        continue;
+      }
+
+      const emittedMutation = Object.assign(change, { target: targetFront });
+
+      if (change.type === "childList") {
+        // Update the ownership tree according to the mutation record.
+        const addedFronts = [];
+        const removedFronts = [];
+        for (const removed of change.removed) {
+          const removedFront = this.getActorByID(removed);
+          if (!removedFront) {
+            console.error(
+              "Got a removal of an actor we didn't know about: " + removed
+            );
+            continue;
+          }
+          // Remove from the ownership tree
+          removedFront.reparent(null);
+
+          // This node is orphaned unless we get it in the 'added' list
+          // eventually.
+          this._orphaned.add(removedFront);
+          removedFronts.push(removedFront);
+        }
+        for (const added of change.added) {
+          const addedFront = this.getActorByID(added);
+          if (!addedFront) {
+            console.error(
+              "Got an addition of an actor we didn't know " + "about: " + added
+            );
+            continue;
+          }
+          addedFront.reparent(targetFront);
+
+          // The actor is reconnected to the ownership tree, unorphan
+          // it.
+          this._orphaned.delete(addedFront);
+          addedFronts.push(addedFront);
+        }
+
+        // Before passing to users, replace the added and removed actor
+        // ids with front in the mutation record.
+        emittedMutation.added = addedFronts;
+        emittedMutation.removed = removedFronts;
+
+        // If this is coming from a DOM mutation, the actor's numChildren
+        // was passed in. Otherwise, it is simulated from a frame load or
+        // unload, so don't change the front's form.
+        if ("numChildren" in change) {
+          targetFront._form.numChildren = change.numChildren;
+        }
+      } else if (change.type === "shadowRootAttached") {
+        targetFront._form.isShadowHost = true;
+      } else if (change.type === "customElementDefined") {
+        targetFront._form.customElementLocation = change.customElementLocation;
+      } else if (change.type === "unretained") {
+        // Retained orphans were force-released without the intervention of
+        // client (probably a navigated frame).
+        for (const released of change.nodes) {
+          const releasedFront = this.getActorByID(released);
+          this._retainedOrphans.delete(released);
+          this._releaseFront(releasedFront, true);
+        }
+      } else {
+        targetFront.updateMutation(change);
+      }
+
+      // Update the inlineTextChild property of the target for a selected list of
+      // mutation types.
+      if (
+        change.type === "inlineTextChild" ||
+        change.type === "childList" ||
+        change.type === "shadowRootAttached"
+      ) {
+        if (change.inlineTextChild) {
+          targetFront.inlineTextChild = types
+            .getType("domnode")
+            .read(change.inlineTextChild, this);
+        } else {
+          targetFront.inlineTextChild = undefined;
+        }
+      }
+
+      emitMutations.push(emittedMutation);
+    }
+
+    if (options.cleanup) {
+      for (const node of this._orphaned) {
+        // This will move retained nodes to this._retainedOrphans.
+        this._releaseFront(node);
+      }
+      this._orphaned = new Set();
+    }
+
+    this.emit("mutations", emitMutations);
+  }
+
+  /**
+   * Handle the `new-mutations` notification by fetching the
+   * available mutation records.
+   */
+  onMutations() {
+    // Fetch and process the mutations.
+    this.getMutations({ cleanup: this.autoCleanup }).catch(() => {});
+  }
+
+  isLocal() {
+    return !!this.conn._transport._serverConnection;
+  }
+
+  async removeNode(node) {
+    const previousSibling = await this.previousSibling(node);
+    const nextSibling = await super.removeNode(node);
+    return {
+      previousSibling,
+      nextSibling,
+    };
+  }
+
+  async children(node, options) {
+    if (!node.useChildTargetToFetchChildren) {
+      return super.children(node, options);
+    }
+    const target = await node.connectToFrame();
+
+    // We had several issues in the past where `connectToFrame` was returning the same
+    // target as the owner document one, which led to the inspector being broken.
+    // Ultimately, we shouldn't get to this point (fix should happen in connectToFrame or
+    // on the server, e.g. for Bug 1752342), but at least this will serve as a safe guard
+    // so we don't freeze/crash the inspector.
+    if (
+      target == this.targetFront &&
+      Services.prefs.getBoolPref(
+        "devtools.testing.bypass-walker-children-iframe-guard",
+        false
+      ) !== true
+    ) {
+      console.warn("connectToFrame returned an unexpected target");
+      return {
+        nodes: [],
+        hasFirst: true,
+        hasLast: true,
+      };
+    }
+
+    const walker = (await target.getFront("inspector")).walker;
+
+    // Finally retrieve the NodeFront of the remote frame's document
+    const documentNode = await walker.getRootNode();
+
+    // Force reparenting through the remote frame boundary.
+    documentNode.reparent(node);
+
+    // And return the same kind of response `walker.children` returns
+    return {
+      nodes: [documentNode],
+      hasFirst: true,
+      hasLast: true,
+    };
+  }
+
+  /**
+   * Ensure that the RootNode of this Walker has the right parent NodeFront.
+   *
+   * This method does nothing if we are on the top level target's WalkerFront,
+   * as the RootNode won't have any parent.
+   *
+   * Otherwise, if we are in an iframe's WalkerFront, we would expect the parent
+   * of the RootNode (i.e. the NodeFront for the document loaded within the iframe)
+   * to be the <iframe>'s NodeFront. Because of fission, the two NodeFront may refer
+   * to DOM Element running in distinct processes and so the NodeFront comes from
+   * two distinct Targets and two distinct WalkerFront.
+   * This is why we need this manual "reparent" code to do the glue between the
+   * two documents.
+   */
+  async reparentRemoteFrame() {
+    const parentTarget = await this.targetFront.getParentTarget();
+    if (!parentTarget) {
+      return;
+    }
+    // Don't reparent if we are on the top target
+    if (parentTarget == this.targetFront) {
+      return;
+    }
+    // Get the NodeFront for the embedder element
+    // i.e. the <iframe> element which is hosting the document that
+    const parentWalker = (await parentTarget.getFront("inspector")).walker;
+    // As this <iframe> most likely runs in another process, we have to get it through the parent
+    // target's WalkerFront.
+    const parentNode = (
+      await parentWalker.getEmbedderElement(this.targetFront.browsingContextID)
+    ).node;
+
+    // Finally, set this embedder element's node front as the
+    const documentNode = await this.getRootNode();
+    documentNode.reparent(parentNode);
+  }
+
+  _onRootNodeAvailable(rootNode) {
+    if (rootNode.isTopLevelDocument) {
+      this.rootNode = rootNode;
+      this._rootNodePromiseResolve(this.rootNode);
+    }
+  }
+
+  _onRootNodeDestroyed(rootNode) {
+    if (rootNode.isTopLevelDocument) {
+      this._rootNodePromise = new Promise(
+        r => (this._rootNodePromiseResolve = r)
+      );
+      this.rootNode = null;
+    }
+  }
+
+  /**
+   * Start the element picker on the debuggee target.
+   * @param {Boolean} doFocus - Optionally focus the content area once the picker is
+   *                            activated.
+   */
+  pick(doFocus) {
+    if (this._isPicking) {
+      return Promise.resolve();
+    }
+
+    this._isPicking = true;
+
+    return super.pick(
+      doFocus,
+      this.targetFront.commands.descriptorFront.isLocalTab
+    );
+  }
+
+  /**
+   * Stop the element picker.
+   */
+  cancelPick() {
+    if (!this._isPicking) {
+      return Promise.resolve();
+    }
+
+    this._isPicking = false;
+    return super.cancelPick();
+  }
+}
+
+exports.WalkerFront = WalkerFront;
+registerFront(WalkerFront);