Bug 1238042 - Extract a helper function to check if a JSObject is a global with a particular about: URI. r=ehsan

--HG--
extra : commitid : 9MHQnTiMoX9

dom/base/FeedWriterEnabled.h

@@ -5,43 +5,14 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "js/TypeDecls.h"
-#include "nsGlobalWindow.h"
-#include "nsIPrincipal.h"
-#include "nsIURI.h"
-#include "nsString.h"
-#include "xpcpublic.h"
+#include "nsContentUtils.h"
 
 namespace mozilla {
 
 struct FeedWriterEnabled {
   static bool IsEnabled(JSContext* cx, JSObject* aGlobal)
   {
-    // Make sure the global is a window
-    nsGlobalWindow* win = xpc::WindowGlobalOrNull(aGlobal);
-    if (!win) {
-      return false;
-    }
-
-    // Make sure that the principal is about:feeds.
-    nsCOMPtr<nsIPrincipal> principal = win->GetPrincipal();
-    NS_ENSURE_TRUE(principal, false);
-    nsCOMPtr<nsIURI> uri;
-    principal->GetURI(getter_AddRefs(uri));
-    if (!uri) {
-      return false;
-    }
-
-    // First check the scheme to avoid getting long specs in the common case.
-    bool isAbout = false;
-    uri->SchemeIs("about", &isAbout);
-    if (!isAbout) {
-      return false;
-    }
-
-    // Now check the spec itself
-    nsAutoCString spec;
-    uri->GetSpec(spec);
-    return spec.EqualsLiteral("about:feeds");
+    return nsContentUtils::IsSpecificAboutPage(aGlobal, "about:feeds");
   }
 };
 

dom/base/nsContentUtils.cpp

@@ -8894,3 +8894,37 @@ nsContentUtils::SerializeNodeToMarkup(nsINode* aRoot,
     }
   }
 }
+
+bool
+nsContentUtils::IsSpecificAboutPage(JSObject* aGlobal, const char* aUri)
+{
+  // aUri must start with about: or this isn't the right function to be using.
+  MOZ_ASSERT(strncmp(aUri, "about:", 6) == 0);
+
+  // Make sure the global is a window
+  nsGlobalWindow* win = xpc::WindowGlobalOrNull(aGlobal);
+  if (!win) {
+    return false;
+  }
+
+  // Make sure that the principal is about:feeds.
+  nsCOMPtr<nsIPrincipal> principal = win->GetPrincipal();
+  NS_ENSURE_TRUE(principal, false);
+  nsCOMPtr<nsIURI> uri;
+  principal->GetURI(getter_AddRefs(uri));
+  if (!uri) {
+    return false;
+  }
+
+  // First check the scheme to avoid getting long specs in the common case.
+  bool isAbout = false;
+  uri->SchemeIs("about", &isAbout);
+  if (!isAbout) {
+    return false;
+  }
+
+  // Now check the spec itself
+  nsAutoCString spec;
+  uri->GetSpec(spec);
+  return spec.EqualsASCII(aUri);
+}

dom/base/nsContentUtils.h

@@ -2565,6 +2565,14 @@ public:
                                     bool aDescendentsOnly,
                                     nsAString& aOut);
 
+  /*
+   * Returns true iff the provided JSObject is a global, and its URI matches
+   * the provided about: URI.
+   * @param aGlobal the JSObject whose URI to check, if it is a global.
+   * @param aUri the URI to match, e.g. "about:feeds"
+   */
+  static bool IsSpecificAboutPage(JSObject* aGlobal, const char* aUri);
+
 private:
   static bool InitializeEventTable();