Ensure to close file-stream on all errors.

sdk/lib/io/file_impl.dart

Index: sdk/lib/io/file_impl.dart
diff --git a/sdk/lib/io/file_impl.dart b/sdk/lib/io/file_impl.dart
index 2057234ac7af8da9ca6804232adac3834fb75a92..a7c145099f8eb3cb6d1eaf38d13d9b5d7a2d806e 100644
--- a/sdk/lib/io/file_impl.dart
+++ b/sdk/lib/io/file_impl.dart
@@ -76,7 +76,12 @@ class _FileStream extends Stream<List<int>> {
     if (_end != null) {
       readBytes = min(readBytes, _end - _position);
       if (readBytes < 0) {
-        throw new RangeError("Bad end position: $_end");
+        if (!_unsubscribed) {
+          _controller.addError(new RangeError("Bad end position: $_end"));
+          _closeFile().then((_) { _controller.close(); });

[kustermann, 2013/05/21 11:23:57]

I don't know if the Future returned by '_closeFile()' can complete with an
error?

[Anders Johnsen, 2013/05/21 11:37:27]

I'm quite sure it can't. Can't come to think of any scenario at least.

+          _unsubscribed = true;
+        }
+        return;
       }
     }
     _openedFile.read(readBytes)
@@ -107,6 +112,13 @@ class _FileStream extends Stream<List<int>> {
   }
 
   void _start() {
+    if (_position == null) {
+      _position = 0;
+    } else if (_position < 0) {
+      _controller.addError(new RangeError("Bad start position: $_position"));
+      _controller.close();
+      return;
+    }
     Future<RandomAccessFile> openFuture;
     if (_path != null) {
       openFuture = new File(_path).open(mode: FileMode.READ);
@@ -116,13 +128,8 @@ class _FileStream extends Stream<List<int>> {
     openFuture
       .then((RandomAccessFile opened) {
         _openedFile = opened;
-        if (_position == null) {
-          _position = 0;
-        }
         if (_position > 0) {
           return opened.setPosition(_position);
-        } else if (_position < 0) {
-          throw new RangeError("Bad start position: $_position");
         }
       })
       .then((_) => _readBlock())