Error reporting on File 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 = (String s) {
@@ skipping 233 matching lines @@
               "List element is not an integer at index $j");
         }
         outBuffer[i] = value;
         j++;
       }
     }
     return [outBuffer, outOffset];
   }
 
   static bool exists(String name) native "File_Exists";
-  static int open(String name, int mode) native "File_Open";
+  static open(String name, int mode) native "File_Open";

[Mads Ager (google), 2012/03/09 09:40:13]

Do we want 'void' here?

[Søren Gjesse, 2012/03/13 08:25:55]

No, open now returns either an int or an instance of OSError. We could write
Object.

   static bool create(String name) native "File_Create";
   static bool delete(String name) native "File_Delete";
   static String fullPath(String name) native "File_FullPath";
   static String directory(String name) native "File_Directory";
   static int close(int id) native "File_Close";
   static int readByte(int id) native "File_ReadByte";
   static int readList(int id, List<int> buffer, int offset, int bytes)
       native "File_ReadList";
   static int writeByte(int id, int value) native "File_WriteByte";
   static int writeList(int id, List<int> buffer, int offset, int bytes) {
     List result =
         _FileUtils.ensureFastAndSerializableBuffer(buffer, offset, bytes);
     List outBuffer = result[0];
     int outOffset = result[1];
     return writeListNative(id, outBuffer, outOffset, bytes);
   }
   static int writeListNative(int id, List<int> buffer, int offset, int bytes)
       native "File_WriteList";
   static int writeString(int id, String string) native "File_WriteString";
   static int position(int id) native "File_Position";
   static bool setPosition(int id, int position) native "File_SetPosition";
   static bool truncate(int id, int length) native "File_Truncate";
   static int length(int id) native "File_Length";
   static int flush(int id) native "File_Flush";
   static int openStdio(int fd) native "File_OpenStdio";
   static SendPort newServicePort() native "File_NewServicePort";
 
   static int checkedOpen(String name, int mode) {
-    if (name is !String || mode is !int) return 0;
-    return open(name, mode);
+    if (name is !String || mode is !int) {
+      throw new IllegalArgumentException();
+    };
+    var result = open(name, mode);
+    if (result is OSError) {
+      throw new FileIOException("Cannot open file", result);
+    }
+    return result; 
   }
 
   static bool checkedCreate(String name) {
     if (name is !String) return false;
     return create(name);
   }
 
   static bool checkedDelete(String name) {
     if (name is !String) return false;
     return delete(name);
@@ skipping 138 matching lines @@
       if (_onError != null) {
         _onError("Unknown file mode. Use FileMode.READ, FileMode.WRITE " +
                  "or FileMode.APPEND.");
         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).receive((id, replyTo) {
-      if (id != 0) {
+    _fileService.call(request).receive((result, replyTo) {
+      if (result is Array) {
+        if (_onError != null) {
+          _onError(new FileIOException(
+              "Cannot open file", new OSError(result[1], result[0])));
+        }
+      } else {
         callback(new _RandomAccessFile(id, _name));
-      } else if (_onError != null) {
-        _onError("Cannot open file: $_name");
       }
     });
   }
 
   RandomAccessFile openSync([FileMode mode = FileMode.READ]) {
     if (_asyncUsed) {
       throw new FileIOException(
           "Mixed use of synchronous and asynchronous API");
     }
     if (mode != FileMode.READ &&
         mode != FileMode.WRITE &&
         mode != FileMode.APPEND) {
       throw new FileIOException("Unknown file mode. Use FileMode.READ, " +
                                 "FileMode.WRITE or FileMode.APPEND.");
     }
     var id = _FileUtils.checkedOpen(_name, mode._mode);
-    if (id == 0) {
-      throw new FileIOException("Cannot open file: $_name");
-    }
+    assert(id != 0);
     return new _RandomAccessFile(id, _name);
   }
 
   static RandomAccessFile _openStdioSync(int fd) {
     var id = _FileUtils.openStdio(fd);
     if (id == 0) {
       throw new FileIOException("Cannot open stdio file for: $fd");
     }
     return new _RandomAccessFile(id, "");
   }
@@ skipping 577 matching lines @@
   bool _asyncUsed;
   int _pendingWrites = 0;
 
   SendPort _fileService;
 
   Timer _noPendingWriteTimer;
 
   Function _onNoPendingWrites;
   Function _onError;
 }