Don't double-escape in strings in the VM Service, and don't use \u0000 to determine the string lengt

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 5568 matching lines @@
   }
 
   bool IsExternal() const {
     return RawObject::IsExternalStringClassId(raw()->GetClassId());
   }
 
   void* GetPeer() const;
 
   void ToUTF8(uint8_t* utf8_array, intptr_t array_len) const;
 
-  // Produces a quoted, escaped, (possibly) truncated string.
-  const char* ToUserCString(intptr_t max_len) const;
+  // Creates a UTF-8, NUL-terminated string in the current zone. The size of the
+  // created string in UTF-8 code units (bytes) is answered in 'length'; this
+  // can be longer than strlen of the result when the string has internal NULs.
+  // For the truncating version, 'max_length' is in UTF-16 code units, and will
+  // be rounded down if necessary to prevent splitting a surrogate pair.
+  const char* ToCString(intptr_t *length) const;
+  const char* ToCStringTruncated(intptr_t max_len,
+                                 bool* did_truncate,
+                                 intptr_t *length) const;
 
   // Copies the string characters into the provided external array
   // and morphs the string object into an external string object.
   // The remaining unused part of the original string object is marked as
   // an Array object or a regular Object so that it can be traversed during
   // garbage collection.
   RawString* MakeExternal(void* array,
                           intptr_t length,
                           void* peer,
                           Dart_PeerFinalizer cback) const;
@@ skipping 125 matching lines @@
   }
 
   template<typename HandleType, typename ElementType, typename CallbackType>
   static void ReadFromImpl(SnapshotReader* reader,
                            String* str_obj,
                            intptr_t len,
                            intptr_t tags,
                            CallbackType new_symbol,
                            Snapshot::Kind kind);
 
-  intptr_t EscapedString(char* buffer, int max_len) const;
-  intptr_t EscapedStringLen(intptr_t tooLong) const;
-
   FINAL_HEAP_OBJECT_IMPLEMENTATION(String, Instance);
 
   friend class Class;
   friend class Symbols;
   friend class StringSlice;  // SetHash
   template<typename CharType> friend class CharArray;  // SetHash
   friend class ConcatString;  // SetHash
   friend class OneByteString;
   friend class TwoByteString;
   friend class ExternalOneByteString;
@@ skipping 1700 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_