Fix length computation in Dart_StringToUTF8.

vm/dart_api_impl.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 1625 matching lines @@
   CHECK_LENGTH(length, String::kMaxElements);
   return Api::NewHandle(isolate,
                         String::NewExternal(utf16_array, length, peer, cback));
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToCString(Dart_Handle object,
                                              const char** cstr) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
+  if (cstr == NULL) {
+    RETURN_NULL_ERROR(cstr);
+  }
   const String& str_obj = Api::UnwrapStringHandle(isolate, object);
   if (str_obj.IsNull()) {
     RETURN_TYPE_ERROR(isolate, object, String);
   }
   intptr_t string_length = Utf8::Length(str_obj);
   char* res = Api::TopScope(isolate)->zone()->Alloc<char>(string_length + 1);
   if (res == NULL) {
     return Api::NewError("Unable to allocate memory");
   }
   const char* string_value = str_obj.ToCString();
   memmove(res, string_value, string_length + 1);
   ASSERT(res[string_length] == '\0');
   *cstr = res;
   return Api::Success(isolate);
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToUTF8(Dart_Handle str,
-                                          uint8_t* utf8_array,
+                                          uint8_t** utf8_array,
                                           intptr_t* length) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
+  if (utf8_array == NULL) {
+    RETURN_NULL_ERROR(utf8_array);
+  }
+  if (length == NULL) {
+    RETURN_NULL_ERROR(length);
+  }
   const String& str_obj = Api::UnwrapStringHandle(isolate, str);
   if (str_obj.IsNull()) {
     RETURN_TYPE_ERROR(isolate, str, String);
   }
-  intptr_t str_len = str_obj.Length();
-  if (str_len > *length) {
-    return Api::NewError("Input array is not large enough to hold the result");
+  intptr_t str_len = Utf8::Length(str_obj);
+  *utf8_array = Api::TopScope(isolate)->zone()->Alloc<uint8_t>(str_len);
+  if (*utf8_array == NULL) {
+    return Api::NewError("Unable to allocate memory");
   }
-  str_obj.ToUTF8(utf8_array, str_len);
-  *length= str_len;
+  str_obj.ToUTF8(*utf8_array, str_len);
+  *length = str_len;
   return Api::Success(isolate);
 }
 
 
 DART_EXPORT Dart_Handle Dart_StringToUTF16(Dart_Handle str,
                                            uint16_t* utf16_array,
                                            intptr_t* length) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   const String& str_obj = Api::UnwrapStringHandle(isolate, str);
@@ skipping 2793 matching lines @@
   }
   {
     NoGCScope no_gc;
     RawObject* raw_obj = obj.raw();
     isolate->heap()->SetPeer(raw_obj, peer);
   }
   return Api::Success(isolate);
 }
 
 }  // namespace dart