Change the error handling in dart:io

runtime/bin/file_impl.dart

 // 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.
 
 class _FileInputStream extends _BaseDataInputStream implements InputStream {
   _FileInputStream(String name) {
     _file = new File(name);
     _data = [];
     _position = 0;
     _file.onError = (e) {
@@ skipping 82 matching lines @@
 
 class _FileOutputStream extends _BaseOutputStream implements OutputStream {
   _FileOutputStream(String name, FileMode mode) {
     _pendingOperations = new List<List<int>>();
     var f = new File(name);
     f.open(mode, (openedFile) {
       _file = openedFile;
       _setupFileHandlers();
       _processPendingOperations();
     });
-    f.onError = (e) {
-      if (_onError != null) _onError(e);
-    };
+    f.onError = (e) => _reportError(e);
   }
 
   _FileOutputStream.fromStdio(int fd) {
     assert(1 <= fd && fd <= 2);
     _file = _File._openStdioSync(fd);
     _setupFileHandlers();
   }
 
 
   void _setupFileHandlers() {
-    _file.onError = (e) {
-      if (_onError != null) _onError(e);
-    };
+    _file.onError = (e) => _reportError(e);
     _file.onNoPendingWrites = () {
       if (!_streamMarkedClosed && _onNoPendingWrites != null) {
         _onNoPendingWrites();
       }
     };
   }
 
   bool write(List<int> buffer, [bool copyBuffer = false]) {
     var data = buffer;
     if (copyBuffer) {
@@ skipping 33 matching lines @@
   }
 
   void set onNoPendingWrites(void callback()) {
     _onNoPendingWrites = callback;
   }
 
   void set onClosed(void callback()) {
     _onClosed = callback;
   }
 
-  void set onError(void callback(Exception e)) {
-    _onError = callback;
-  }
-
   void _processPendingOperations() {
     _pendingOperations.forEach((buffer) {
       (buffer != null) ? write(buffer) : close();
     });
     _pendingOperations = null;
   }
 
   void _write(List<int> buffer, int offset, int len) {
     _file.writeList(buffer, offset, len);
   }
 
   RandomAccessFile _file;
 
   // When this is set to true the stream is marked closed. When a
   // stream is marked closed no more data can be written.
   bool _streamMarkedClosed = false;
 
   // When this is set to true the close callback has been called and
   // the stream is fully closed.
   bool _closeCallbackCalled = false;
 
   // List of pending writes that were issued before the underlying
   // file was successfully opened.
   List<List<int>> _pendingOperations;
 
   Function _onNoPendingWrites;
   Function _onClosed;
-  Function _onError;
 }
 
 
 // Helper class containing static file helper methods.
 class _FileUtils {
   static final kExistsRequest = 0;
   static final kCreateRequest = 1;
   static final kDeleteRequest = 2;
   static final kOpenRequest = 3;
   static final kFullPathRequest = 4;
@@ skipping 162 matching lines @@
 
   static int checkedWriteString(int id, String string) {
     if (string is !String) return -1;
     return writeString(id, string);
   }
 
 }
 
 // Base class for _File and _RandomAccessFile with shared functions.
 class _FileBase {
+  void _reportError(e) {
+    if (_onError != null) {
+      _onError(e);
+    } else {
+      throw e;
+    }
+  }
+
   bool _isErrorResponse(response) {
     return response is List && response[0] != _FileUtils.kSuccessResponse;
   }
 
-  bool _reportError(response, String message) {
+  void _handleErrorResponse(response, String message) {
     assert(_isErrorResponse(response));
-    if (_onError != null) {
-      switch (response[_FileUtils.kErrorResponseErrorType]) {
-        case _FileUtils.kIllegalArgumentResponse:
-          _onError(new IllegalArgumentException());
-          break;
-        case _FileUtils.kOSErrorResponse:
-          var err = new OSError(response[_FileUtils.kOSErrorResponseMessage],
-                                response[_FileUtils.kOSErrorResponseErrorCode]);
-          _onError(new FileIOException(message, err));
-          break;
-        case _FileUtils.kFileClosedResponse:
-          _onError(new FileIOException("File closed"));
-          break;
-        default:
-          _onError(new Exception("Unknown error"));
-          break;
-      }
+    switch (response[_FileUtils.kErrorResponseErrorType]) {
+      case _FileUtils.kIllegalArgumentResponse:
+        _reportError(new IllegalArgumentException());
+        break;
+      case _FileUtils.kOSErrorResponse:
+        var err = new OSError(response[_FileUtils.kOSErrorResponseMessage],
+                              response[_FileUtils.kOSErrorResponseErrorCode]);
+        _reportError(new FileIOException(message, err));
+        break;
+      case _FileUtils.kFileClosedResponse:
+        _reportError(new FileIOException("File closed"));
+        break;
+      default:
+        _reportError(new Exception("Unknown error"));
+        break;
     }
   }
 
-  void set onError(void handler(Exception e)) {
+  void set onError(void handler(e)) {
     _onError = handler;
   }
 
   Function _onError;
 }
 
 // Class for encapsulating the native implementation of files.
 class _File extends _FileBase implements File {
   // Constructor for file.
   _File(String this._name);
 
   void exists(void callback(bool exists)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kExistsRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot open file");
+        _handleErrorResponse(response, "Cannot open file");
       } else {
         callback(response);
       }
     });
   }
 
   bool existsSync() {
     return _FileUtils.checkedExists(_name);
   }
 
   void create(void callback()) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kCreateRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot create file");
+        _handleErrorResponse(response, "Cannot create file");
       } else {
         callback();
       }
     });
   }
 
   void createSync() {
     bool created = _FileUtils.checkedCreate(_name);
     if (!created) {
       throw new FileIOException("Cannot create file: $_name");
     }
   }
 
   void delete(void callback()) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kDeleteRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot delete file");
+        _handleErrorResponse(response, "Cannot delete file");
       } else {
         callback();
       }
     });
   }
 
   void deleteSync() {
     _FileUtils.checkedDelete(_name);
   }
 
   void directory(void callback(Directory dir)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kDirectoryRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot retrieve directory for file");
+        _handleErrorResponse(response, "Cannot retrieve directory for file");
       } else {
         callback(new Directory(response));
       }
     });
   }
 
   Directory directorySync() {
     _FileUtils.checkedDirectory(_name);
     return new Directory(_FileUtils.directory(_name));
   }
 
   void open(FileMode mode, void callback(RandomAccessFile file)) {
     _ensureFileService();
     if (mode != FileMode.READ &&
         mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
-      if (_onError != null) {
-        _onError(new IllegalArgumentException());
-        return;
-      }
+      _reportError(new IllegalArgumentException());
+      return;
     }
     List request = new List(3);
     request[0] = _FileUtils.kOpenRequest;
     request[1] = _name;
     request[2] = mode._mode;  // Direct int value for serialization.
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot open file");
+        _handleErrorResponse(response, "Cannot open file");
       } else {
         callback(new _RandomAccessFile(response, _name));
       }
     });
   }
 
   void length(void callback(int length)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kLengthFromNameRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot retrieve length of file");
+        _handleErrorResponse(response, "Cannot retrieve length of file");
       } else {
         callback(response);
       }
     });
   }
 
   int lengthSync() {
     var result = _FileUtils.checkedLengthFromName(_name);
     if (result is OSError) {
       throw new FileIOException("Cannot retrieve length of file", result);
@@ skipping 21 matching lines @@
     return new _RandomAccessFile(id, "");
   }
 
   void fullPath(void callback(String result)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kFullPathRequest;
     request[1] = _name;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "Cannot retrieve full path");
+        _handleErrorResponse(response, "Cannot retrieve full path");
       } else {
         callback(response);
       }
     });
   }
 
   String fullPathSync() {
     return _FileUtils.checkedFullPath(_name);
   }
 
@@ skipping 14 matching lines @@
     _ensureFileService();
     var chunks = new _BufferList();
     var stream = openInputStream();
     stream.onClosed = () {
       callback(chunks.readBytes(chunks.length));
     };
     stream.onData = () {
       var chunk = stream.read();
       chunks.add(chunk);
     };
-    stream.onError = (e) {
-      if (_onError != null) {
-        _onError(e);
-      }
-    };
+    stream.onError = (e) => _reportError(e);
   }
 
   List<int> readAsBytesSync() {
     var opened = openSync();
     var length = opened.lengthSync();
     var result = new ByteArray(length);
     var read = opened.readListSync(result, 0, length);
     if (read != length) {
       throw new FileIOException("Failed to read file");
     }
     opened.closeSync();
     return result;
   }
 
   void readAsText(Encoding encoding, void callback(String text)) {
     _ensureFileService();
     var decoder = _StringDecoders.decoder(encoding);
     readAsBytes((bytes) {
       try {
         decoder.write(bytes);
       } catch (var e) {
-        if (_onError != null) {
-          _onError(e);
-          return;
-        }
+        _reportError(e);
+        return;
       }
       callback(decoder.decoded);
     });
   }
 
   String readAsTextSync([Encoding encoding = Encoding.UTF_8]) {
     var decoder = _StringDecoders.decoder(encoding);
     List<int> bytes = readAsBytesSync();
     decoder.write(bytes);
     return decoder.decoded;
@@ skipping 15 matching lines @@
     return result;
   }
 
   void readAsLines(Encoding encoding, void callback(List<String> lines)) {
     _ensureFileService();
     var decoder = _StringDecoders.decoder(encoding);
     readAsBytes((bytes) {
       try {
         decoder.write(bytes);
       } catch (var e) {
-        if (_onError != null) {
-          _onError(e);
-          return;
-        }
+        _reportError(e);
+        return;
       }
       callback(_getDecodedLines(decoder));
     });
   }
 
   List<String> readAsLinesSync([Encoding encoding = Encoding.UTF_8]) {
     var decoder = _StringDecoders.decoder(encoding);
     List<int> bytes = readAsBytesSync();
     decoder.write(bytes);
     return _getDecodedLines(decoder);
@@ skipping 11 matching lines @@
 
   SendPort _fileService;
 }
 
 
 class _RandomAccessFile extends _FileBase implements RandomAccessFile {
   _RandomAccessFile(int this._id, String this._name);
 
   void close(void callback()) {
     if (_id == 0) {
-      if (_onError != null) {
-        _onError(new FileIOException("Cannot close file: $_name"));
-      }
+      _reportError(new FileIOException("Cannot close file: $_name"));
       return;
     }
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kCloseRequest;
     request[1] = _id;
     // Set the id_ to 0 (NULL) to ensure the no more async requests
     // can be issues for this file.
     _id = 0;
     _fileService.call(request).then((result) {
       if (result != -1) {
         _id = result;
         callback();
-      } else if (_onError != null) {
-        _onError(new FileIOException("Cannot close file: $_name"));
+      } else {
+        _reportError(new FileIOException("Cannot close file: $_name"));
       }
     });
   }
 
   void closeSync() {
     var id = _FileUtils.close(_id);
     if (id == -1) {
       throw new FileIOException("Cannot close file: $_name");
     }
     _id = id;
   }
 
   void readByte(void callback(int byte)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kReadByteRequest;
     request[1] = _id;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "readByte failed");
+        _handleErrorResponse(response, "readByte failed");
       } else {
         callback(response);
       }
     });
   }
 
   int readByteSync() {
     _checkNotClosed();
     var result = _FileUtils.readByte(_id);
     if (result is OSError) {
       throw new FileIOException("readByte failed", result);
     }
     return result;
   }
 
   void readList(List<int> buffer, int offset, int bytes,
                 void callback(int read)) {
     _ensureFileService();
     if (buffer is !List || offset is !int || bytes is !int) {
-      if (_onError != null) {
-        _onError(new FileIOException("Invalid arguments to readList"));
-      }
+      _reportError(new FileIOException("Invalid arguments to readList"));
       return;
     };
     List request = new List(3);
     request[0] = _FileUtils.kReadListRequest;
     request[1] = _id;
     request[2] = bytes;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "readList failed");
+        _handleErrorResponse(response, "readList failed");
       } else {
         var read = response[1];
         var data = response[2];
         buffer.setRange(offset, read, data);
         callback(read);
       }
     });
   }
 
   int readListSync(List<int> buffer, int offset, int bytes) {
@@ skipping 10 matching lines @@
     var result = _FileUtils.readList(_id, buffer, offset, bytes);
     if (result is OSError) {
       throw new FileIOException("readList failed", result);
     }
     return result;
   }
 
   void writeByte(int value) {
     _ensureFileService();
     if (value is !int) {
-      if (_onError != null) {
-        _onError(new FileIOException("Invalid argument to writeByte"));
-      }
+      _reportError(new FileIOException("Invalid argument to writeByte"));
       return;
     }
     List request = new List(3);
     request[0] = _FileUtils.kWriteByteRequest;
     request[1] = _id;
     request[2] = value;
     _writeEnqueued();
     _fileService.call(request).then((response) {
       _writeCompleted();
       if (_isErrorResponse(response)) {
-        _reportError(response, "writeByte failed");
+        _handleErrorResponse(response, "writeByte failed");
       }
     });
   }
 
   int writeByteSync(int value) {
     _checkNotClosed();
     if (value is !int) {
       throw new FileIOException("Invalid argument to writeByte");
     }
     var result = _FileUtils.writeByte(_id, value);
     if (result is OSError) {
       throw new FileIOException("writeByte failed", result);
     }
     return result;
   }
 
   void writeList(List<int> buffer, int offset, int bytes) {
     _ensureFileService();
     if (buffer is !List || offset is !int || bytes is !int) {
-      if (_onError != null) {
-        _onError(new FileIOException("Invalid arguments to writeList"));
-      }
+      _reportError(new FileIOException("Invalid arguments to writeList"));
       return;
     }
 
     List result =
         _FileUtils.ensureFastAndSerializableBuffer(buffer, offset, bytes);
     List outBuffer = result[0];
     int outOffset = result[1];
 
     List request = new List(5);
     request[0] = _FileUtils.kWriteListRequest;
     request[1] = _id;
     request[2] = outBuffer;
     request[3] = outOffset;
     request[4] = bytes;
     _writeEnqueued();
     _fileService.call(request).then((response) {
       _writeCompleted();
       if (_isErrorResponse(response)) {
-        _reportError(response, "writeList failed");
+        _handleErrorResponse(response, "writeList failed");
       }
     });
   }
 
   int writeListSync(List<int> buffer, int offset, int bytes) {
     _checkNotClosed();
     if (buffer is !List || offset is !int || bytes is !int) {
       throw new FileIOException("Invalid arguments to writeList");
     }
     if (bytes == 0) return 0;
@@ skipping 12 matching lines @@
   void writeString(String string, [Encoding encoding = Encoding.UTF_8]) {
     _ensureFileService();
     List request = new List(3);
     request[0] = _FileUtils.kWriteStringRequest;
     request[1] = _id;
     request[2] = string;
     _writeEnqueued();
     _fileService.call(request).then((response) {
       _writeCompleted();
       if (_isErrorResponse(response)) {
-        _reportError(response, "writeString failed");
+        _handleErrorResponse(response, "writeString failed");
       }
     });
   }
 
   int writeStringSync(String string, [Encoding encoding = Encoding.UTF_8]) {
     _checkNotClosed();
     var result = _FileUtils.checkedWriteString(_id, string);
     if (result is OSError) {
       throw new FileIOException("writeString failed", result);
     }
     return result;
   }
 
   void position(void callback(int position)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kPositionRequest;
     request[1] = _id;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "position failed");
+        _handleErrorResponse(response, "position failed");
       } else {
         callback(response);
       }
     });
   }
 
   int positionSync() {
     _checkNotClosed();
     var result = _FileUtils.position(_id);
     if (result is OSError) {
       throw new FileIOException("position failed", result);
     }
     return result;
   }
 
   void setPosition(int position, void callback()) {
     _ensureFileService();
     List request = new List(3);
     request[0] = _FileUtils.kSetPositionRequest;
     request[1] = _id;
     request[2] = position;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "setPosition failed");
+        _handleErrorResponse(response, "setPosition failed");
       } else {
         callback();
       }
     });
   }
 
   void setPositionSync(int position) {
     _checkNotClosed();
     var result = _FileUtils.setPosition(_id, position);
     if (result is OSError) {
       throw new FileIOException("setPosition failed", result);
     }
   }
 
   void truncate(int length, void callback()) {
     _ensureFileService();
     List request = new List(3);
     request[0] = _FileUtils.kTruncateRequest;
     request[1] = _id;
     request[2] = length;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "truncate failed");
+        _handleErrorResponse(response, "truncate failed");
       } else {
         callback();
       }
     });
   }
 
   void truncateSync(int length) {
     _checkNotClosed();
     var result = _FileUtils.truncate(_id, length);
     if (result is OSError) {
       throw new FileIOException("truncate failed", result);
     }
   }
 
   void length(void callback(int length)) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kLengthRequest;
     request[1] = _id;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "length failed");
+        _handleErrorResponse(response, "length failed");
       } else {
         callback(response);
       }
     });
   }
 
   int lengthSync() {
     _checkNotClosed();
     var result = _FileUtils.length(_id);
     if (result is OSError) {
       throw new FileIOException("length failed", result);
     }
     return result;
   }
 
   void flush(void callback()) {
     _ensureFileService();
     List request = new List(2);
     request[0] = _FileUtils.kFlushRequest;
     request[1] = _id;
     _fileService.call(request).then((response) {
       if (_isErrorResponse(response)) {
-        _reportError(response, "flush failed");
+        _handleErrorResponse(response, "flush failed");
       } else {
         callback();
       }
     });
   }
 
   void flushSync() {
     _checkNotClosed();
     var result = _FileUtils.flush(_id);
     if (result is OSError) {
@@ skipping 42 matching lines @@
   String _name;
   int _id;
   int _pendingWrites = 0;
 
   SendPort _fileService;
 
   Timer _noPendingWriteTimer;
 
   Function _onNoPendingWrites;
 }