Handle multipart MIME parsing with no parts

pkg/mime/lib/src/bound_multipart_stream.dart

 // Copyright (c) 2014, 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.
 library mime.bound_multipart_stream;
 
 import 'dart:async';
 import 'dart:convert';
 
 import 'mime_shared.dart';
 import 'char_code.dart';
@@ skipping 36 matching lines @@
                                         bool cancelOnError}) {
     return _stream.listen(onData,
                           onDone: onDone,
                           onError: onError,
                           cancelOnError: cancelOnError);
   }
 }
 
 class BoundMultipartStream {
    static const int _START = 0;
-   static const int _FIRST_BOUNDARY_ENDING = 111;
-   static const int _FIRST_BOUNDARY_END = 112;
    static const int _BOUNDARY_ENDING = 1;
    static const int _BOUNDARY_END = 2;
    static const int _HEADER_START = 3;
    static const int _HEADER_FIELD = 4;
    static const int _HEADER_VALUE_START = 5;
    static const int _HEADER_VALUE = 6;
    static const int _HEADER_VALUE_FOLDING_OR_ENDING = 7;
    static const int _HEADER_VALUE_FOLD_OR_END = 8;
    static const int _HEADER_ENDING = 9;
    static const int _CONTENT = 10;
@@ skipping 111 matching lines @@
        if (_index < 0) {
          byte = _boundary[boundaryPrefix + _index];
        } else {
          byte = _buffer[_index];
        }
        switch (_state) {
          case _START:
            if (byte == _boundary[_boundaryIndex]) {
              _boundaryIndex++;
              if (_boundaryIndex == _boundary.length) {
-               _state = _FIRST_BOUNDARY_ENDING;
+               _state = _BOUNDARY_ENDING;
                _boundaryIndex = 0;
              }
            } else {
              // Restart matching of the boundary.
              _index = _index - _boundaryIndex;
              _boundaryIndex = 0;
            }
            break;
 
-         case _FIRST_BOUNDARY_ENDING:
-           if (byte == CharCode.CR) {
-             _state = _FIRST_BOUNDARY_END;
-           } else {
-             _expectWhitespace(byte);
-           }
-           break;
-
-         case _FIRST_BOUNDARY_END:
-           _expectByteValue(byte, CharCode.LF);
-           _state = _HEADER_START;
-           break;
-
          case _BOUNDARY_ENDING:
            if (byte == CharCode.CR) {
              _state = _BOUNDARY_END;
            } else if (byte == CharCode.DASH) {
              _state = _LAST_BOUNDARY_DASH2;
            } else {
              _expectWhitespace(byte);
            }
            break;
 
          case _BOUNDARY_END:
            _expectByteValue(byte, CharCode.LF);
-           _multipartController.close();
-           _multipartController = null;
+           if (_multipartController != null) {
+             _multipartController.close();
+             _multipartController = null;
+           }
            _state = _HEADER_START;
            break;
 
          case _HEADER_START:
            _headers = new Map<String, String>();
            if (byte == CharCode.CR) {
              _state = _HEADER_ENDING;
            } else {
              // Start of new header field.
              _headerField.add(_toLowerCase(byte));
@@ skipping 101 matching lines @@
          case _LAST_BOUNDARY_ENDING:
            if (byte == CharCode.CR) {
              _state = _LAST_BOUNDARY_END;
            } else {
              _expectWhitespace(byte);
            }
            break;
 
          case _LAST_BOUNDARY_END:
            _expectByteValue(byte, CharCode.LF);
-           _multipartController.close();
-           _multipartController = null;
+           if (_multipartController != null) {
+             _multipartController.close();
+             _multipartController = null;
+           }
            _state = _DONE;
            break;
 
          default:
            // Should be unreachable.
            assert(false);
            break;
        }
 
        // Move to the next byte.
        _index++;
      }
 
      // Report any known content.
      if (_state == _CONTENT && contentStartIndex != null) {
        reportData();
      }
 
      // Resume if at end.
      if (_index == _buffer.length) {
        _buffer = null;
        _index = null;
        _resumeStream();
      }
    }
 }