Bug 1038993 - Add UnsafeInPrerendering extended attribute to WebIDL. r=peterv

dom/bindings/BindingUtils.cpp

@@ -2356,6 +2356,14 @@ CheckPermissions(JSContext* aCx, JSObject* aObj, const char* const aPermissions[
   return false;
 }
 
+bool
+CheckSafetyInPrerendering(JSContext* aCx, JSObject* aObj)
+{
+  //TODO: Check if page is being prerendered.
+  //Returning false for now.
+  return false;
+}
+
 bool
 GenericBindingGetter(JSContext* cx, unsigned argc, JS::Value* vp)
 {

dom/bindings/BindingUtils.h

@@ -2937,6 +2937,10 @@ AssertReturnTypeMatchesJitinfo(const JSJitInfo* aJitinfo,
 bool
 CheckPermissions(JSContext* aCx, JSObject* aObj, const char* const aPermissions[]);
 
+//Returns true if page is being prerendered.
+bool
+CheckSafetyInPrerendering(JSContext* aCx, JSObject* aObj);
+
 bool
 CallerSubsumes(JSObject* aObject);
 

dom/bindings/Codegen.py

@@ -6320,6 +6320,21 @@ class CGPerSignatureCall(CGThing):
         self.arguments = arguments
         self.argCount = len(arguments)
         cgThings = []
+
+        # Here, we check if the current getter, setter, method, interface or
+        # inherited interfaces have the UnsafeInPrerendering extended attribute
+        # and if so, we add a check to make sure it is safe.
+        if (idlNode.getExtendedAttribute("UnsafeInPrerendering") or
+            descriptor.interface.getExtendedAttribute("UnsafeInPrerendering") or
+            any(i.getExtendedAttribute("UnsafeInPrerendering")
+                for i in descriptor.interface.getInheritedInterfaces())):
+                cgThings.append(CGGeneric(dedent(
+                    """
+                    if (mozilla::dom::CheckSafetyInPrerendering(cx, obj)) {
+                        //TODO: Handle call into unsafe API during Prerendering (Bug 730101)
+                        return false;
+                    }
+                    """)))
         lenientFloatCode = None
         if idlNode.getExtendedAttribute('LenientFloat') is not None:
             if setter:

dom/bindings/parser/WebIDL.py

@@ -1196,6 +1196,7 @@ class IDLInterface(IDLObjectWithScope):
                   identifier == "OverrideBuiltins" or
                   identifier == "ChromeOnly" or
                   identifier == "Unforgeable" or
+                  identifier == "UnsafeInPrerendering" or
                   identifier == "LegacyEventInit"):
                 # Known extended attributes that do not take values
                 if not attr.noArguments():
@@ -3309,6 +3310,7 @@ class IDLAttribute(IDLInterfaceMember):
               identifier == "Frozen" or
               identifier == "AvailableIn" or
               identifier == "NewObject" or
+              identifier == "UnsafeInPrerendering" or
               identifier == "CheckPermissions"):
             # Known attributes that we don't need to do anything with here
             pass
@@ -3902,6 +3904,7 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
         elif (identifier == "Throws" or
               identifier == "NewObject" or
               identifier == "ChromeOnly" or
+              identifier == "UnsafeInPrerendering" or
               identifier == "Pref" or
               identifier == "Func" or
               identifier == "AvailableIn" or

dom/bindings/test/TestBindingHeader.h

@@ -184,6 +184,10 @@ public:
   int8_t CachedWritableByte();
   void SetCachedWritableByte(int8_t);
 
+  void UnsafePrerenderMethod();
+  int32_t UnsafePrerenderWritable();
+  void SetUnsafePrerenderWritable(int32_t);
+  int32_t UnsafePrerenderReadonly();
   int16_t ReadonlyShort();
   int16_t WritableShort();
   void SetWritableShort(int16_t);

dom/bindings/test/TestCodeGen.webidl

@@ -137,6 +137,12 @@ interface TestInterface {
   [StoreInSlot, Pure]
   attribute byte cachedWritableByte;
 
+  [UnsafeInPrerendering]
+  void unsafePrerenderMethod();
+  [UnsafeInPrerendering]
+  attribute long unsafePrerenderWritable;
+  [UnsafeInPrerendering]
+  readonly attribute long unsafePrerenderReadonly;
   readonly attribute short readonlyShort;
   attribute short writableShort;
   void passShort(short arg);