Bug 1819287 - Make nsContentUtils::StringifyJSON more flexible; r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D171215

dom/base/SerializedStackHolder.cpp

@@ -133,7 +133,8 @@ void ConvertSerializedStackToJSON(UniquePtr<SerializedStackHolder> aStackHolder,
   }
 
   JS::Rooted<JS::Value> convertedValue(cx, JS::ObjectValue(*converted));
-  if (!nsContentUtils::StringifyJSON(cx, convertedValue, aStackString)) {
+  if (!nsContentUtils::StringifyJSON(cx, convertedValue, aStackString,
+                                     UndefinedIsNullStringLiteral)) {
     JS_ClearPendingException(cx);
     return;
   }

dom/base/nsContentUtils.cpp

@@ -10628,16 +10628,28 @@ static bool JSONCreator(const char16_t* aBuf, uint32_t aLen, void* aData) {
 
 /* static */
 bool nsContentUtils::StringifyJSON(JSContext* aCx, JS::Handle<JS::Value> aValue,
-                                   nsAString& aOutStr) {
+                                   nsAString& aOutStr, JSONBehavior aBehavior) {
   MOZ_ASSERT(aCx);
-  aOutStr.Truncate();
+  switch (aBehavior) {
-  JS::Rooted<JS::Value> value(aCx, aValue);
+    case UndefinedIsNullStringLiteral: {
-  nsAutoString serializedValue;
+      aOutStr.Truncate();
-  NS_ENSURE_TRUE(JS_Stringify(aCx, &value, nullptr, JS::NullHandleValue,
+      JS::Rooted<JS::Value> value(aCx, aValue);
-                              JSONCreator, &serializedValue),
+      nsAutoString serializedValue;
-                 false);
+      NS_ENSURE_TRUE(JS_Stringify(aCx, &value, nullptr, JS::NullHandleValue,
-  aOutStr = serializedValue;
+                                  JSONCreator, &serializedValue),
-  return true;
+                     false);
+      aOutStr = serializedValue;
+      return true;
+    }
+    case UndefinedIsVoidString: {
+      aOutStr.SetIsVoid(true);
+      return JS::ToJSON(aCx, aValue, nullptr, JS::NullHandleValue, JSONCreator,
+                        &aOutStr);
+    }
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid value for aBehavior");
+      return false;
+  }
 }
 
 /* static */

dom/base/nsContentUtils.h

@@ -243,7 +243,11 @@ struct EventNameMapping {
 
 namespace mozilla {
 enum class PreventDefaultResult : uint8_t { No, ByContent, ByChrome };
+
+namespace dom {
+enum JSONBehavior { UndefinedIsNullStringLiteral, UndefinedIsVoidString };
 }
+}  // namespace mozilla
 
 class nsContentUtils {
   friend class nsAutoScriptBlockerSuppressNodeRemoved;
@@ -256,6 +260,7 @@ class nsContentUtils {
   using EventMessage = mozilla::EventMessage;
   using TimeDuration = mozilla::TimeDuration;
   using Trusted = mozilla::Trusted;
+  using JSONBehavior = mozilla::dom::JSONBehavior;
 
  public:
   static nsresult Init();
@@ -3256,15 +3261,21 @@ class nsContentUtils {
   static nsresult AnonymizeURI(nsIURI* aURI, nsCString& aAnonymizedURI);
 
   /**
-   * Serializes a JSON-like JS::Value into a string, returning the string "null"
+   * Serializes a JSON-like JS::Value into a string.
-   * where JSON.stringify would return undefined.
+   * Cases where JSON.stringify would return undefined are handled according to
+   * the |aBehavior| argument:
    *
+   * - If it is |UndefinedIsNullStringLiteral|, the string "null" is returned.
+   * - If it is |UndefinedIsVoidString|, the void string is returned.
+   *
+   * The |UndefinedIsNullStringLiteral| case is likely not desirable, but is
+   * retained for now for historical reasons.
    * Usage:
    *   nsAutoString serializedValue;
-   *   nsContentUtils::StringifyJSON(cx, value, serializedValue);
+   *   nsContentUtils::StringifyJSON(cx, value, serializedValue, behavior);
    */
   static bool StringifyJSON(JSContext* aCx, JS::Handle<JS::Value> aValue,
-                            nsAString& aOutStr);
+                            nsAString& aOutStr, JSONBehavior aBehavior);
 
   /**
    * Returns true if the top level ancestor content document of aDocument hasn't

dom/base/nsFrameMessageManager.cpp

@@ -472,7 +472,9 @@ bool nsFrameMessageManager::GetParamsForMessage(JSContext* aCx,
   //    properly cases when interface is implemented in JS and used
   //    as a dictionary.
   nsAutoString json;
-  NS_ENSURE_TRUE(nsContentUtils::StringifyJSON(aCx, v, json), false);
+  NS_ENSURE_TRUE(
+      nsContentUtils::StringifyJSON(aCx, v, json, UndefinedIsNullStringLiteral),
+      false);
   NS_ENSURE_TRUE(!json.IsEmpty(), false);
 
   JS::Rooted<JS::Value> val(aCx, JS::NullValue());

dom/base/test/gtest/TestContentUtils.cpp

@@ -14,6 +14,8 @@
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/SimpleGlobalObject.h"
 
+using namespace mozilla::dom;
+
 struct IsURIInListMatch {
   nsLiteralCString pattern;
   bool firstMatch, secondMatch;
@@ -64,7 +66,8 @@ TEST(DOM_Base_ContentUtils, IsURIInList)
   }
 }
 
-TEST(DOM_Base_ContentUtils, StringifyJSON_EmptyValue)
+TEST(DOM_Base_ContentUtils,
+     StringifyJSON_EmptyValue_UndefinedIsNullStringLiteral)
 {
   JS::Rooted<JSObject*> globalObject(
       mozilla::dom::RootingCx(),
@@ -76,11 +79,12 @@ TEST(DOM_Base_ContentUtils, StringifyJSON_EmptyValue)
   nsAutoString serializedValue;
 
   ASSERT_TRUE(nsContentUtils::StringifyJSON(cx, JS::UndefinedHandleValue,
-                                            serializedValue));
+                                            serializedValue,
+                                            UndefinedIsNullStringLiteral));
   ASSERT_TRUE(serializedValue.EqualsLiteral("null"));
 }
 
-TEST(DOM_Base_ContentUtils, StringifyJSON_Object)
+TEST(DOM_Base_ContentUtils, StringifyJSON_Object_UndefinedIsNullStringLiteral)
 {
   JS::Rooted<JSObject*> globalObject(
       mozilla::dom::RootingCx(),
@@ -96,7 +100,47 @@ TEST(DOM_Base_ContentUtils, StringifyJSON_Object)
   ASSERT_TRUE(JS_DefineProperty(cx, jsObj, "key1", valueStr, JSPROP_ENUMERATE));
   JS::Rooted<JS::Value> jsValue(cx, JS::ObjectValue(*jsObj));
 
-  ASSERT_TRUE(nsContentUtils::StringifyJSON(cx, jsValue, serializedValue));
+  ASSERT_TRUE(nsContentUtils::StringifyJSON(cx, jsValue, serializedValue,
+                                            UndefinedIsNullStringLiteral));
+
+  ASSERT_TRUE(serializedValue.EqualsLiteral("{\"key1\":\"Hello World!\"}"));
+}
+
+TEST(DOM_Base_ContentUtils, StringifyJSON_EmptyValue_UndefinedIsVoidString)
+{
+  JS::Rooted<JSObject*> globalObject(
+      mozilla::dom::RootingCx(),
+      mozilla::dom::SimpleGlobalObject::Create(
+          mozilla::dom::SimpleGlobalObject::GlobalType::BindingDetail));
+  mozilla::dom::AutoJSAPI jsAPI;
+  ASSERT_TRUE(jsAPI.Init(globalObject));
+  JSContext* cx = jsAPI.cx();
+  nsAutoString serializedValue;
+
+  ASSERT_TRUE(nsContentUtils::StringifyJSON(
+      cx, JS::UndefinedHandleValue, serializedValue, UndefinedIsVoidString));
+
+  ASSERT_TRUE(serializedValue.IsVoid());
+}
+
+TEST(DOM_Base_ContentUtils, StringifyJSON_Object_UndefinedIsVoidString)
+{
+  JS::Rooted<JSObject*> globalObject(
+      mozilla::dom::RootingCx(),
+      mozilla::dom::SimpleGlobalObject::Create(
+          mozilla::dom::SimpleGlobalObject::GlobalType::BindingDetail));
+  mozilla::dom::AutoJSAPI jsAPI;
+  ASSERT_TRUE(jsAPI.Init(globalObject));
+  JSContext* cx = jsAPI.cx();
+  nsAutoString serializedValue;
+
+  JS::Rooted<JSObject*> jsObj(cx, JS_NewPlainObject(cx));
+  JS::Rooted<JSString*> valueStr(cx, JS_NewStringCopyZ(cx, "Hello World!"));
+  ASSERT_TRUE(JS_DefineProperty(cx, jsObj, "key1", valueStr, JSPROP_ENUMERATE));
+  JS::Rooted<JS::Value> jsValue(cx, JS::ObjectValue(*jsObj));
+
+  ASSERT_TRUE(nsContentUtils::StringifyJSON(cx, jsValue, serializedValue,
+                                            UndefinedIsVoidString));
 
   ASSERT_TRUE(serializedValue.EqualsLiteral("{\"key1\":\"Hello World!\"}"));
 }

dom/fs/test/gtest/FileSystemMocks.cpp

@@ -48,7 +48,8 @@ nsresult GetAsString(const RefPtr<Promise>& aPromise, nsAString& aString) {
     }
 
     case Promise::PromiseState::Resolved: {
-      if (nsContentUtils::StringifyJSON(cx, vp, aString)) {
+      if (nsContentUtils::StringifyJSON(cx, vp, aString,
+                                        UndefinedIsNullStringLiteral)) {
         return NS_OK;
       }
 

dom/l10n/DOMLocalization.cpp

@@ -142,7 +142,8 @@ void DOMLocalization::SetAttributes(
   if (aArgs.WasPassed() && aArgs.Value()) {
     nsAutoString data;
     JS::Rooted<JS::Value> val(aCx, JS::ObjectValue(*aArgs.Value()));
-    if (!nsContentUtils::StringifyJSON(aCx, val, data)) {
+    if (!nsContentUtils::StringifyJSON(aCx, val, data,
+                                       UndefinedIsNullStringLiteral)) {
       aRv.NoteJSContextException(aCx);
       return;
     }

dom/payments/PaymentRequestUtils.cpp

@@ -22,7 +22,8 @@ nsresult SerializeFromJSObject(JSContext* aCx, JS::Handle<JSObject*> aObject,
 nsresult SerializeFromJSVal(JSContext* aCx, JS::Handle<JS::Value> aValue,
                             nsAString& aSerializedValue) {
   aSerializedValue.Truncate();
-  NS_ENSURE_TRUE(nsContentUtils::StringifyJSON(aCx, aValue, aSerializedValue),
+  NS_ENSURE_TRUE(nsContentUtils::StringifyJSON(aCx, aValue, aSerializedValue,
+                                               UndefinedIsNullStringLiteral),
                  NS_ERROR_XPC_BAD_CONVERT_JS);
   NS_ENSURE_TRUE(!aSerializedValue.IsEmpty(), NS_ERROR_FAILURE);
   return NS_OK;

toolkit/components/sessionstore/SessionStoreUtils.cpp

@@ -1128,7 +1128,8 @@ MOZ_CAN_RUN_SCRIPT
 static void SetSessionData(JSContext* aCx, Element* aElement,
                            JS::MutableHandle<JS::Value> aObject) {
   nsAutoString data;
-  if (nsContentUtils::StringifyJSON(aCx, aObject, data)) {
+  if (nsContentUtils::StringifyJSON(aCx, aObject, data,
+                                    UndefinedIsNullStringLiteral)) {
     SetElementAsString(aElement, data);
   } else {
     JS_ClearPendingException(aCx);

toolkit/xre/dllservices/tests/gtest/TestUntrustedModules.cpp

@@ -230,7 +230,8 @@ class UntrustedModulesFixture : public TelemetryTestFixture {
     serializer.GetObject(&jsval);
 
     nsAutoString json;
-    EXPECT_TRUE(nsContentUtils::StringifyJSON(cx.GetJSContext(), jsval, json));
+    EXPECT_TRUE(nsContentUtils::StringifyJSON(
+        cx.GetJSContext(), jsval, json, dom::UndefinedIsNullStringLiteral));
 
     JS::Rooted<JSObject*> re(
         cx.GetJSContext(),