Fix for JsPointerToString and JsCreateString #6669

bin/NativeTests/JsRTApiTest.cpp

@@ -165,6 +165,13 @@ namespace JsRTApiTest
  JsValueRef value2 = JS_INVALID_REFERENCE;
  REQUIRE(JsPointerToString(_u("value1"), wcslen(_u("value1")), &value2) == JsNoError);
 
+ // Test JsPointerToString and JsCreateString on NULL inputs
+ JsValueRef nullStr;
+ REQUIRE(JsPointerToString(NULL, 0, &nullStr) == JsNoError);
+
+ JsValueRef nullFname;
+ REQUIRE(JsCreateString(NULL, 0, &nullFname) == JsNoError);
+
  REQUIRE(JsSetProperty(object, name1, value1, true) == JsNoError);
  REQUIRE(JsSetProperty(object, name2, value2, true) == JsNoError);
 

lib/Jsrt/ChakraCommonWindows.h

@@ -323,7 +323,12 @@
  /// Creates a string value from a string pointer.
  /// </summary>
  /// <remarks>
- /// Requires an active script context.
+ /// <para>
+ /// Requires an active script context.
+ /// </para>
+ /// <para>
+ /// Providing length of 0 will ignore input string pointer and return a Js empty string.
+ /// </para>
  /// </remarks>
  /// <param name="stringValue">The string pointer to convert to a string value.</param>
  /// <param name="stringLength">The length of the string to convert.</param>
@@ -333,7 +338,7 @@
  /// </returns>
  CHAKRA_API
  JsPointerToString(
- _In_reads_(stringLength) const wchar_t *stringValue,
+ _In_reads_opt_(stringLength) const wchar_t *stringValue,
  _In_ size_t stringLength,
  _Out_ JsValueRef *value);
 

lib/Jsrt/ChakraCore.h

@@ -505,6 +505,9 @@ typedef bool (CHAKRA_CALLBACK * JsSerializedLoadScriptCallback)
 /// <para>
 /// Input string can be either ASCII or Utf8
 /// </para>
+/// <para>
+/// Providing length of 0 will ignore input string pointer and return a Js empty string.
+/// </para>
 /// </remarks>
 /// <param name="content">Pointer to string memory.</param>
 /// <param name="length">Number of bytes within the string</param>
@@ -514,7 +517,7 @@ typedef bool (CHAKRA_CALLBACK * JsSerializedLoadScriptCallback)
 /// </returns>
 CHAKRA_API
  JsCreateString(
- _In_ const char *content,
+ _In_opt_ const char *content,
  _In_ size_t length,
  _Out_ JsValueRef *value);
 

lib/Jsrt/Core/JsrtCore.cpp

@@ -868,10 +868,15 @@ static void CastCopy(const SrcChar* src, DstChar* dst, size_t count)
 }
 
 CHAKRA_API JsCreateString(
- _In_ const char *content,
+ _In_opt_ const char *content,
  _In_ size_t length,
  _Out_ JsValueRef *value)
 {
+ if (length == 0)
+ {
+ content = "";
+ }
+
  PARAM_NOT_NULL(content);
  PARAM_NOT_NULL(value);
  *value = JS_INVALID_REFERENCE;

lib/Jsrt/Jsrt.cpp

@@ -1229,20 +1229,28 @@ CHAKRA_API JsGetStringLength(_In_ JsValueRef value, _Out_ int *length)
  END_JSRT_NO_EXCEPTION
 }
 
-CHAKRA_API JsPointerToString(_In_reads_(stringLength) const WCHAR *stringValue, _In_ size_t stringLength, _Out_ JsValueRef *string)
+CHAKRA_API JsPointerToString(_In_reads_opt_(stringLength) const WCHAR *stringValue, _In_ size_t stringLength, _Out_ JsValueRef *string)
 {
  return ContextAPINoScriptWrapper([&](Js::ScriptContext *scriptContext, TTDRecorder& _actionEntryPopper) -> JsErrorCode {
  PERFORM_JSRT_TTD_RECORD_ACTION(scriptContext, RecordJsRTCreateString, stringValue, stringLength);
-
- PARAM_NOT_NULL(stringValue);
- PARAM_NOT_NULL(string);
-
- if (!Js::IsValidCharCount(stringLength))
- {
- Js::JavascriptError::ThrowOutOfMemoryError(scriptContext);
- }
-
- *string = Js::JavascriptString::NewCopyBuffer(stringValue, static_cast<charcount_t>(stringLength), scriptContext);
+
+ PARAM_NOT_NULL(string);
+
+ if (stringLength == 0)
+ {
+ *string = scriptContext->GetLibrary()->GetEmptyString();
+ }
+ else
+ {
+ PARAM_NOT_NULL(stringValue);
+
+
+ if (!Js::IsValidCharCount(stringLength))
+ {
+ Js::JavascriptError::ThrowOutOfMemoryError(scriptContext);
+ }
+ *string = Js::JavascriptString::NewCopyBuffer(stringValue, static_cast<charcount_t>(stringLength), scriptContext);
+ }
 
  PERFORM_JSRT_TTD_RECORD_ACTION_RESULT(scriptContext, string);