Bug 1404656: Protect access to mDrawTarget and mImage after a SourceSurfaceSkia has been initialized. r=dvander

MozReview-Commit-ID: 6HGM22V8FbJ

gfx/2d/2D.h

@@ -519,6 +519,9 @@ public:
   /** @deprecated
    * Get the raw bitmap data of the surface.
    * Can return null if there was OOM allocating surface data.
+   *
+   * Deprecated means you shouldn't be using this!! Use Map instead.
+   * Please deny any reviews which add calls to this!
    */
   virtual uint8_t *GetData() = 0;
 

gfx/2d/SourceSurfaceSkia.cpp

@@ -17,6 +17,7 @@ namespace gfx {
 
 SourceSurfaceSkia::SourceSurfaceSkia()
   : mDrawTarget(nullptr)
+  , mChangeMutex("SourceSurfaceSkia::mChangeMutex")
 {
 }
 
@@ -40,6 +41,14 @@ SourceSurfaceSkia::GetFormat() const
   return mFormat;
 }
 
+sk_sp<SkImage>
+SourceSurfaceSkia::GetImage()
+{
+  MutexAutoLock lock(mChangeMutex);
+  sk_sp<SkImage> image = mImage;
+  return image;
+}
+
 static sk_sp<SkData>
 MakeSkData(void* aData, int32_t aHeight, size_t aStride)
 {
@@ -155,9 +164,28 @@ SourceSurfaceSkia::GetData()
   return reinterpret_cast<uint8_t*>(pixmap.writable_addr());
 }
 
+bool
+SourceSurfaceSkia::Map(MapType, MappedSurface *aMappedSurface)
+{
+  mChangeMutex.Lock();
+  aMappedSurface->mData = GetData();
+  aMappedSurface->mStride = Stride();
+  mIsMapped = !!aMappedSurface->mData;
+  return mIsMapped;
+}
+
+void
+SourceSurfaceSkia::Unmap()
+{
+  mChangeMutex.Unlock();
+  MOZ_ASSERT(mIsMapped);
+  mIsMapped = false;
+}
+
 void
 SourceSurfaceSkia::DrawTargetWillChange()
 {
+  MutexAutoLock lock(mChangeMutex);
   if (mDrawTarget) {
     // Raster snapshots do not use Skia's internal copy-on-write mechanism,
     // so we need to do an explicit copy here.

gfx/2d/SourceSurfaceSkia.h

@@ -8,6 +8,7 @@
 
 #include "2D.h"
 #include <vector>
+#include "mozilla/Mutex.h"
 #include "skia/include/core/SkCanvas.h"
 #include "skia/include/core/SkImage.h"
 
@@ -28,7 +29,7 @@ public:
   virtual IntSize GetSize() const;
   virtual SurfaceFormat GetFormat() const;
 
-  sk_sp<SkImage>& GetImage() { return mImage; }
+  sk_sp<SkImage> GetImage();
 
   bool InitFromData(unsigned char* aData,
                     const IntSize &aSize,
@@ -41,6 +42,13 @@ public:
 
   virtual uint8_t* GetData();
 
+  /**
+   * The caller is responsible for ensuring aMappedSurface is not null.
+   */
+  virtual bool Map(MapType, MappedSurface *aMappedSurface);
+
+  virtual void Unmap();
+
   virtual int32_t Stride() { return mStride; }
 
 private:
@@ -53,6 +61,7 @@ private:
   IntSize mSize;
   int32_t mStride;
   RefPtr<DrawTargetSkia> mDrawTarget;
+  Mutex mChangeMutex;
 };
 
 } // namespace gfx