Introduce safer CJS_Return::Success() and Failure().

Avoid the possibility of ever re-introducing the issue noticed
last week.

Remove some redundant JSGetStringFromID() calls.

Change-Id: I56687c2191bd72e378f747083f34080e50cbe490
Reviewed-on: https://pdfium-review.googlesource.com/40490
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 13 insertions, 10 deletions

diff --git a/fxjs/xfa/cjx_tree.cpp b/fxjs/xfa/cjx_tree.cpp
index 3a266eb450..be74b44a93 100644
--- a/fxjs/xfa/cjx_tree.cpp
+++ b/fxjs/xfa/cjx_tree.cpp
@@ -33,12 +33,12 @@ CJS_Return CJX_Tree::resolveNode(
     CFX_V8* runtime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
+    return CJS_Return::Failure(JSMessage::kParamError);
 
   WideString expression = runtime->ToWideString(params[0]);
   CFXJSE_Engine* pScriptContext = GetDocument()->GetScriptContext();
   if (!pScriptContext)
-    return CJS_Return();
+    return CJS_Return::Success();
 
   CXFA_Object* refNode = GetXFAObject();
   if (refNode->GetElementType() == XFA_Element::Xfa)
@@ -51,7 +51,7 @@ CJS_Return CJX_Tree::resolveNode(
   if (!pScriptContext->ResolveObjects(ToNode(refNode),
                                       expression.AsStringView(), &resolveNodeRS,
                                       dwFlag, nullptr)) {
-    return CJS_Return(runtime->NewNull());
+    return CJS_Return::Success(runtime->NewNull());
   }
 
   if (resolveNodeRS.dwFlags == XFA_ResolveNode_RSType_Nodes) {
@@ -59,30 +59,32 @@ CJS_Return CJX_Tree::resolveNode(
     CFXJSE_Value* value =
         GetDocument()->GetScriptContext()->GetJSValueFromMap(pObject);
     if (!value)
-      return CJS_Return(runtime->NewNull());
+      return CJS_Return::Success(runtime->NewNull());
 
-    return CJS_Return(value->DirectGetValue().Get(runtime->GetIsolate()));
+    return CJS_Return::Success(
+        value->DirectGetValue().Get(runtime->GetIsolate()));
   }
 
   const XFA_SCRIPTATTRIBUTEINFO* lpAttributeInfo =
       resolveNodeRS.pScriptAttribute;
   if (!lpAttributeInfo ||
       lpAttributeInfo->eValueType != XFA_ScriptType::Object) {
-    return CJS_Return(runtime->NewNull());
+    return CJS_Return::Success(runtime->NewNull());
   }
 
   auto pValue = pdfium::MakeUnique<CFXJSE_Value>(pScriptContext->GetIsolate());
   CJX_Object* jsObject = resolveNodeRS.objects.front()->JSObject();
   (jsObject->*(lpAttributeInfo->callback))(pValue.get(), false,
                                            lpAttributeInfo->attribute);
-  return CJS_Return(pValue->DirectGetValue().Get(runtime->GetIsolate()));
+  return CJS_Return::Success(
+      pValue->DirectGetValue().Get(runtime->GetIsolate()));
 }
 
 CJS_Return CJX_Tree::resolveNodes(
     CFX_V8* runtime,
     const std::vector<v8::Local<v8::Value>>& params) {
   if (params.size() != 1)
-    return CJS_Return(JSGetStringFromID(JSMessage::kParamError));
+    return CJS_Return::Failure(JSMessage::kParamError);
 
   CXFA_Object* refNode = GetXFAObject();
   if (refNode->GetElementType() == XFA_Element::Xfa)
@@ -90,7 +92,7 @@ CJS_Return CJX_Tree::resolveNodes(
 
   CFXJSE_Engine* pScriptContext = GetDocument()->GetScriptContext();
   if (!pScriptContext)
-    return CJS_Return();
+    return CJS_Return::Success();
 
   auto pValue = pdfium::MakeUnique<CFXJSE_Value>(pScriptContext->GetIsolate());
   ResolveNodeList(pValue.get(), runtime->ToWideString(params[0]),
@@ -98,7 +100,8 @@ CJS_Return CJX_Tree::resolveNodes(
                       XFA_RESOLVENODE_Properties | XFA_RESOLVENODE_Parent |
                       XFA_RESOLVENODE_Siblings,
                   ToNode(refNode));
-  return CJS_Return(pValue->DirectGetValue().Get(runtime->GetIsolate()));
+  return CJS_Return::Success(
+      pValue->DirectGetValue().Get(runtime->GetIsolate()));
 }
 
 void CJX_Tree::all(CFXJSE_Value* pValue,