Bug 1376971 - Part 2: add GetLoadingPrincipalForXULNode. r=baku

Refactor GetContentPolicyTypeForUIImageLoading to have another function
called GetLoadingPrincipalForXULNode.

dom/base/nsContentUtils.cpp

@@ -10444,6 +10444,44 @@ nsContentUtils::AppendNativeAnonymousChildren(
   }
 }
 
+/* static */ bool
+nsContentUtils::GetLoadingPrincipalForXULNode(nsIContent* aLoadingNode,
+                                              nsIPrincipal** aLoadingPrincipal)
+{
+  MOZ_ASSERT(aLoadingNode);
+  MOZ_ASSERT(aLoadingPrincipal);
+
+  bool result = false;
+  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadingNode->NodePrincipal();
+  nsAutoString loadingStr;
+  aLoadingNode->GetAttr(kNameSpaceID_None, nsGkAtoms::loadingprincipal,
+                        loadingStr);
+  if (loadingStr.IsEmpty()) {
+    // Fall back to mContent's principal (SystemPrincipal) if 'loadingprincipal'
+    // isn't specified.
+    loadingPrincipal.forget(aLoadingPrincipal);
+    return result;
+  }
+
+  nsCOMPtr<nsISupports> serializedPrincipal;
+  NS_DeserializeObject(NS_ConvertUTF16toUTF8(loadingStr),
+                       getter_AddRefs(serializedPrincipal));
+  loadingPrincipal = do_QueryInterface(serializedPrincipal);
+  if (loadingPrincipal) {
+    // We only allow specifying loadingprincipal attribute on a node loaded by
+    // SystemPrincipal.
+    MOZ_ASSERT(nsContentUtils::IsSystemPrincipal(aLoadingNode->NodePrincipal()),
+               "aLoadingNode Should be loaded with SystemPrincipal");
+
+    result = true;
+  } else {
+    // Fallback if the deserialization is failed.
+    loadingPrincipal = aLoadingNode->NodePrincipal();
+  }
+
+  loadingPrincipal.forget(aLoadingPrincipal);
+  return result;
+}
 
 /* static */ void
 nsContentUtils::GetContentPolicyTypeForUIImageLoading(nsIContent* aLoadingNode,
@@ -10453,38 +10491,23 @@ nsContentUtils::GetContentPolicyTypeForUIImageLoading(nsIContent* aLoadingNode,
 {
   MOZ_ASSERT(aRequestContextID);
 
-  // Use the serialized loadingPrincipal from the image element. Fall back
-  // to mContent's principal (SystemPrincipal) if not available.
-  aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
-  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadingNode->NodePrincipal();
-  nsAutoString imageLoadingPrincipal;
-  aLoadingNode->GetAttr(kNameSpaceID_None, nsGkAtoms::loadingprincipal,
-                        imageLoadingPrincipal);
-  if (!imageLoadingPrincipal.IsEmpty()) {
-    nsCOMPtr<nsISupports> serializedPrincipal;
-    NS_DeserializeObject(NS_ConvertUTF16toUTF8(imageLoadingPrincipal),
-                         getter_AddRefs(serializedPrincipal));
-    loadingPrincipal = do_QueryInterface(serializedPrincipal);
+  bool result = GetLoadingPrincipalForXULNode(aLoadingNode, aLoadingPrincipal);
+  if (result) {
+    // Set the content policy type to TYPE_INTERNAL_IMAGE_FAVICON for
+    // indicating it's a favicon loading.
+    aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON;
 
-    if (loadingPrincipal) {
-      // Set the content policy type to TYPE_INTERNAL_IMAGE_FAVICON for
-      // indicating it's a favicon loading.
-      aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE_FAVICON;
-
-      nsAutoString requestContextID;
-      aLoadingNode->GetAttr(kNameSpaceID_None, nsGkAtoms::requestcontextid,
-                            requestContextID);
-      nsresult rv;
-      int64_t val  = requestContextID.ToInteger64(&rv);
-      *aRequestContextID = NS_SUCCEEDED(rv)
-        ? val
-        : 0;
-    } else {
-      // Fallback if the deserialization is failed.
-      loadingPrincipal = aLoadingNode->NodePrincipal();
-    }
+    nsAutoString requestContextID;
+    aLoadingNode->GetAttr(kNameSpaceID_None, nsGkAtoms::requestcontextid,
+                          requestContextID);
+    nsresult rv;
+    int64_t val  = requestContextID.ToInteger64(&rv);
+    *aRequestContextID = NS_SUCCEEDED(rv)
+      ? val
+      : 0;
+  } else {
+    aContentPolicyType = nsIContentPolicy::TYPE_INTERNAL_IMAGE;
   }
-  loadingPrincipal.forget(aLoadingPrincipal);
 }
 
 /* static */ nsresult

dom/base/nsContentUtils.h

@@ -3038,6 +3038,19 @@ public:
                                             nsTArray<nsIContent*>& aKids,
                                             uint32_t aFlags);
 
+  /**
+   * Query loadingPrincipal if it is specified as 'loadingprincipal' attribute on
+   * aLoadingNode, otherwise the NodePrincipal of aLoadingNode is returned
+   * (which is System Principal).
+   *
+   * Return true if aLoadingPrincipal has 'loadingprincipal' attributes, and
+   * the value 'loadingprincipal' is also successfully deserialized, otherwise
+   * return false.
+   */
+  static bool
+  GetLoadingPrincipalForXULNode(nsIContent* aLoadingNode,
+                                nsIPrincipal** aLoadingPrincipal);
+
   /**
    * Returns the content policy type that should be used for loading images
    * for displaying in the UI.  The sources of such images can be <xul:image>,