Use ByteArray's native for Socket and File.

runtime/platform/utils.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 PLATFORM_UTILS_H_
 #define PLATFORM_UTILS_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 
@@ skipping 136 matching lines @@
     if (IsDecimalDigit(c)) return c - '0';
     if (('A' <= c) && (c <= 'F')) return 10 + (c - 'A');
     return 10 + (c - 'a');
   }
 
   static char IntToHexDigit(int i) {
     ASSERT(0 <= i && i < 16);
     if (i < 10) return static_cast<char>('0' + i);
     return static_cast<char>('A' + (i - 10));
   }
+
+  // Perform a range check, checking if
+  //    offset + count <= length
+  // without the risk of integer overflow.
+  static inline bool RangeCheck(intptr_t offset,
+                                intptr_t count,
+                                intptr_t length) {
+    return offset >= 0 &&
+           count >= 0 &&
+           length >= 0 &&
+           count <= (length - offset);
+  }
 };
 
 }  // namespace dart
 
 #endif  // PLATFORM_UTILS_H_