Commit 44319a88 authored by Botond Ballo's avatar Botond Ballo
Browse files

Bug 1777416 - Avoid GetStateForRoot() incorrectly returning a non-root LayerTreeState. a=diannaS 

In the case where the LayerTreeState for the input content LayersID
was found, but its mParent was null for some reason, the function
was incorrectly returning the content LayerTreeState.

Instead, in such a case, where the root LayerTreeState cannot be
looked up, the function should return null.

Original Revision: https://phabricator.services.mozilla.com/D190143

Differential Revision: https://phabricator.services.mozilla.com/D192278
parent a2dd0fbc

gfx/layers/ipc/CompositorBridgeParent.cpp

+15 −12
Original line number Diff line number Diff line
@@ -1674,25 +1674,28 @@ bool CompositorBridgeParent::CallWithIndirectShadowTree( 


static CompositorBridgeParent::LayerTreeState* GetStateForRoot(

    LayersId aContentLayersId, const MonitorAutoLock& aProofOfLock) {

  CompositorBridgeParent::LayerTreeState* state = nullptr;

  CompositorBridgeParent::LayerTreeState* contentState = nullptr;

  LayerTreeMap::iterator itr = sIndirectLayerTrees.find(aContentLayersId);

  if (sIndirectLayerTrees.end() != itr) {

    state = &itr->second;

    contentState = &itr->second;

  }



  // |state| is the state for the content process, but we want the APZCTMParent

  // for the parent process owning that content process. So we have to jump to

  // the LayerTreeState for the root layer tree id for that layer tree, and use

  // the mApzcTreeManagerParent from that. This should also work with nested

  // content processes, because RootLayerTreeId() will bypass any intermediate

  // processes' ids and go straight to the root.

  if (state && state->mParent) {

    LayersId rootLayersId = state->mParent->RootLayerTreeId();

  // |contentState| is the state for the content process, but we want the

  // APZCTMParent for the parent process owning that content process. So we have

  // to jump to the LayerTreeState for the root layer tree id for that layer

  // tree, and use the mApzcTreeManagerParent from that. This should also work

  // with nested content processes, because RootLayerTreeId() will bypass any

  // intermediate processes' ids and go straight to the root.

  if (contentState && contentState->mParent) {

    LayersId rootLayersId = contentState->mParent->RootLayerTreeId();

    itr = sIndirectLayerTrees.find(rootLayersId);

    state = (sIndirectLayerTrees.end() != itr) ? &itr->second : nullptr;

    CompositorBridgeParent::LayerTreeState* rootState =

        (sIndirectLayerTrees.end() != itr) ? &itr->second : nullptr;

    return rootState;

  }



  return state;

  // Don't return contentState, that would be a lie!

  return nullptr;

}



/* static */