Commit e78f6b30 authored by Jonathan Kew's avatar Jonathan Kew
Browse files

Bug 1848890 - Guard access to FontList::mBlocks with the font-list lock. r=jnicol a=RyanVM 

Differential Revision: https://phabricator.services.mozilla.com/D187690
parent 7106ae10

gfx/thebes/SharedFontList-impl.h

+1 −5
Original line number Diff line number Diff line
@@ -334,11 +334,7 @@ class FontList { 
    mozilla::UniquePtr<base::SharedMemory> mShmem;

  };



  Header& GetHeader() {

    // It's invalid to try and access this before the first block exists.

    MOZ_ASSERT(mBlocks.Length() > 0);

    return *static_cast<Header*>(mBlocks[0]->Memory());

  }

  Header& GetHeader() const;



  /**

   * Create a new shared memory block and append to the FontList's list

gfx/thebes/SharedFontList.cpp

+18 −0
Original line number Diff line number Diff line
@@ -725,6 +725,24 @@ FontList::FontList(uint32_t aGeneration) { 


FontList::~FontList() { DetachShmBlocks(); }



FontList::Header& FontList::GetHeader() const MOZ_NO_THREAD_SAFETY_ANALYSIS {

  // We only need to lock if we're not on the main thread.

  bool isMainThread = NS_IsMainThread();

  if (!isMainThread) {

    gfxPlatformFontList::PlatformFontList()->Lock();

  }



  // It's invalid to try and access this before the first block exists.

  MOZ_ASSERT(mBlocks.Length() > 0);

  auto& result = *static_cast<Header*>(mBlocks[0]->Memory());



  if (!isMainThread) {

    gfxPlatformFontList::PlatformFontList()->Unlock();

  }



  return result;

}



bool FontList::AppendShmBlock(uint32_t aSizeNeeded) {

  MOZ_ASSERT(XRE_IsParentProcess());

  uint32_t size = std::max(aSizeNeeded, SHM_BLOCK_SIZE);

gfx/thebes/gfxPlatformFontList.cpp

+1 −0
Original line number Diff line number Diff line
@@ -2984,6 +2984,7 @@ base::SharedMemoryHandle gfxPlatformFontList::ShareShmBlockToProcess( 
void gfxPlatformFontList::ShmBlockAdded(uint32_t aGeneration, uint32_t aIndex,

                                        base::SharedMemoryHandle aHandle) {

  if (SharedFontList()) {

    AutoLock lock(mLock);

    SharedFontList()->ShmBlockAdded(aGeneration, aIndex, std::move(aHandle));

  }

}