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b81f65bc8d
Bug 1570440 - [Web content] Firefox Crashes on CNN.COM (Windows7) This change addresses an issue where VRShMem can be in an invalid state when there is no VR process available. In this case, the VRExternalShmem struct is allocated on the heap rather than accessed via shared memory. When VRService stops, it clears this pointer, but cannot re-access it when it restarts. Thus, this results in a nullptr crash when a tab Enters, Exits, and Re-enters VR. The fix is to distinguish between in-proc heap allocation vs cross-proc shared memory so that VRService can decide to make the call to LeaveShMem in its Stop function. This will keep the heap allocation alive across service restarts and prevent the null crash. Differential Revision: https://phabricator.services.mozilla.com/D40681 --HG-- extra : moz-landing-system : lando
96 lines
3.5 KiB
C++
96 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef GFX_VR_VRSHMEM_H
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#define GFX_VR_VRSHMEM_H
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// This file declares VRShMem, which is used for cross-platform, cross-process
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// communication between VR components.
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// A shared memory handle is opened for the struct of type VRExternalShmem, and
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// different processes write or read members of it to share data. Note that no
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// process should be reading or writing to the same members, except for the
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// versioning members used for synchronization.
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#include "moz_external_vr.h"
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#include "base/process.h" // for base::ProcessHandle
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#include <functional>
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namespace mozilla {
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namespace gfx {
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class VRShMem final {
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public:
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VRShMem(volatile VRExternalShmem* aShmem, bool aRequiresMutex);
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~VRShMem() = default;
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void CreateShMem(bool aCreateOnSharedMemory);
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void CreateShMemForAndroid();
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void ClearShMem();
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void CloseShMem();
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bool JoinShMem();
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void LeaveShMem();
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void PushBrowserState(VRBrowserState& aBrowserState, bool aNotifyCond);
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void PullBrowserState(mozilla::gfx::VRBrowserState& aState);
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void PushSystemState(const mozilla::gfx::VRSystemState& aState);
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void PullSystemState(
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VRDisplayState& aDisplayState, VRHMDSensorState& aSensorState,
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VRControllerState (&aControllerState)[kVRControllerMaxCount],
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bool& aEnumerationCompleted,
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const std::function<bool()>& aWaitCondition = nullptr);
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void PushWindowState(VRWindowState& aState);
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void PullWindowState(VRWindowState& aState);
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bool HasExternalShmem() const { return mExternalShmem != nullptr; }
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bool IsSharedExternalShmem() const { return mIsSharedExternalShmem; }
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volatile VRExternalShmem* GetExternalShmem() const;
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bool IsDisplayStateShutdown() const;
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private:
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bool IsCreatedOnSharedMemory() const;
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// mExternalShmem can have one of three sources:
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// - Allocated outside of this class on the heap and passed in via
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// constructor, or acquired via GeckoVRManager (for GeckoView scenario).
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// This is usually for scenarios where there is no VR process for cross-
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// proc communication, and VRService is receiving the object.
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// --> mIsSharedExternalShmem == true, IsCreatedOnSharedMemory() == false
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// --> [Windows 7, Mac, Android, Linux]
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// - Allocated inside this class on the heap. This is usually for scenarios
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// where there is no VR process, and VRManager is creating the object.
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// --> mIsSharedExternalShmem == false, IsCreatedOnSharedMemory() == false
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// --> [Windows 7, Mac, Linux]
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// - Allocated inside this class on shared memory. This is usually for
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// scenarios where there is a VR process and cross-process communication
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// is necessary
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// --> mIsSharedExternalShmem == false, IsCreatedOnSharedMemory() == true
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// --> [Windows 10 with VR process enabled]
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volatile VRExternalShmem* mExternalShmem = nullptr;
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// This member is true when mExternalShmem was allocated externally, via
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// being passed into the constructor or accessed via GeckoVRManager
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bool mIsSharedExternalShmem;
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#if defined(XP_WIN)
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bool mRequiresMutex;
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#endif
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#if defined(XP_MACOSX)
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int mShmemFD;
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#elif defined(XP_WIN)
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base::ProcessHandle mShmemFile;
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base::ProcessHandle mMutex;
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#endif
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#if !defined(MOZ_WIDGET_ANDROID)
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int64_t mBrowserGeneration = 0;
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#endif
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};
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} // namespace gfx
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} // namespace mozilla
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#endif |