Bug 1209739 - Make nsImageRenderer::PrepareImage() fail unless an image has STATUS_LOAD_COMPLETE. r=tn

layout/base/nsCSSRendering.cpp

@@ -4619,6 +4619,40 @@ nsImageRenderer::~nsImageRenderer()
 {
 }
 
+static bool
+ShouldTreatAsCompleteDueToSyncDecode(const nsStyleImage* aImage,
+                                     uint32_t aFlags)
+{
+  if (!(aFlags & nsImageRenderer::FLAG_SYNC_DECODE_IMAGES)) {
+    return false;
+  }
+
+  if (aImage->GetType() != eStyleImageType_Image) {
+    return false;
+  }
+
+  uint32_t status = 0;
+  if (NS_FAILED(aImage->GetImageData()->GetImageStatus(&status))) {
+    return false;
+  }
+
+  if (status & imgIRequest::STATUS_ERROR) {
+    // The image is "complete" since it's a corrupt image. If we created an
+    // imgIContainer at all, return true.
+    nsCOMPtr<imgIContainer> image;
+    aImage->GetImageData()->GetImage(getter_AddRefs(image));
+    return bool(image);
+  }
+
+  if (!(status & imgIRequest::STATUS_LOAD_COMPLETE)) {
+    // We must have loaded all of the image's data and the size must be
+    // available, or else sync decoding won't be able to decode the image.
+    return false;
+  }
+
+  return true;
+}
+
 bool
 nsImageRenderer::PrepareImage()
 {
@@ -4628,22 +4662,17 @@ nsImageRenderer::PrepareImage()
   }
 
   if (!mImage->IsComplete()) {
-    // Make sure the image is actually decoding
+    // Make sure the image is actually decoding.
     mImage->StartDecoding();
 
-    // check again to see if we finished
+    // Check again to see if we finished.
-    if (!mImage->IsComplete()) {
+    // We cannot prepare the image for rendering if it is not fully loaded.
-      // We can not prepare the image for rendering if it is not fully loaded.
+    // Special case: If we requested a sync decode and the image has loaded, push
-      //
+    // on through because the Draw() will do a sync decode then.
-      // Special case: If we requested a sync decode and we have an image, push
+    if (!mImage->IsComplete() &&
-      // on through because the Draw() will do a sync decode then
+        !ShouldTreatAsCompleteDueToSyncDecode(mImage, mFlags)) {
-      nsCOMPtr<imgIContainer> img;
+      mPrepareResult = DrawResult::NOT_READY;
-      if (!((mFlags & FLAG_SYNC_DECODE_IMAGES) &&
+      return false;
-            (mType == eStyleImageType_Image) &&
-            (NS_SUCCEEDED(mImage->GetImageData()->GetImage(getter_AddRefs(img)))))) {
-        mPrepareResult = DrawResult::NOT_READY;
-        return false;
-      }
     }
   }