Read files in chunks, not relaying on size.

sdk/lib/io/file_impl.dart

 // Copyright (c) 2013, 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.
 
 part of dart.io;
 
+// Read the file in blocks of size 64k.
+const int _BLOCK_SIZE = 64 * 1024;
+
 
 class _FileStream extends Stream<List<int>> {
   // Stream controller.
   StreamController<List<int>> _controller;
 
-  // Read the file in blocks of size 64k.
-  final int _blockSize = 64 * 1024;
-
   // Information about the underlying file.
   String _path;
   RandomAccessFile _openedFile;
   int _position;
 
   // Has the stream been paused or unsubscribed?
   bool _paused = false;
   bool _unsubscribed = false;
 
   // Is there a read currently in progress?
@@ skipping 44 matching lines @@
     _openedFile.length()
       .then((length) {
         if (_position >= length) {
           _readInProgress = false;
           if (!_unsubscribed) {
             _closeFile().then((_) { _controller.close(); });
             _unsubscribed = true;
           }
           return null;
         } else {
-          return _openedFile.read(_blockSize);
+          return _openedFile.read(_BLOCK_SIZE);
         }
       })
       .then((block) {
         _readInProgress = false;
         if (block == null || _unsubscribed) {
           return;
         }
         _position += block.length;
         if (_paused) {
           _currentBlock = block;
@@ skipping 406 matching lines @@
       },
       onError: (e) {
         completer.completeError(e);
       },
       unsubscribeOnError: true);
     return completer.future;
   }
 
   List<int> readAsBytesSync() {
     var opened = openSync();
-    var length = opened.lengthSync();
-    var result = new Uint8List(length);
-    var read = opened.readListSync(result, 0, length);
-    if (read != length) {
-      throw new FileIOException("Failed to read file");
+    var chunks = new _BufferList();
+    var data;
+    while ((data = opened.readSync(_BLOCK_SIZE)).length > 0) {
+      chunks.add(data);
     }
     opened.closeSync();
-    return result;
+    return chunks.readBytes();
   }
 
   Future<String> readAsString({Encoding encoding: Encoding.UTF_8}) {
     _ensureFileService();
     return readAsBytes().then((bytes) {
       return _decodeString(bytes, encoding);
     });
   }
 
   String readAsStringSync({Encoding encoding: Encoding.UTF_8}) {
@@ skipping 521 matching lines @@
           new FileIOException("File closed '$_path'"));
     });
     return completer.future;
   }
 
   final String _path;
   int _id;
 
   SendPort _fileService;
 }