Make sure that _FileInputStream._fillBuffer is not entered again before it finishes.

runtime/bin/file_impl.dart

Index: runtime/bin/file_impl.dart
diff --git a/runtime/bin/file_impl.dart b/runtime/bin/file_impl.dart
index 5671f358949e1d2fd3990bbb461f8ab6f8559d8f..8b1b5ec4a694d45a740a6c1e9d0b802acf5ce7bb 100644
--- a/runtime/bin/file_impl.dart
+++ b/runtime/bin/file_impl.dart
@@ -65,8 +65,11 @@ class _FileInputStream extends _BaseDataInputStream implements InputStream {
       _closeFile();
       return;
     }
+    if (_activeFillBufferCall) return;

[Ivan Posva, 2012/06/12 15:56:52]

Comment about buffer filling in flight please.

+    _activeFillBufferCall = true;
     if (_data.length != size) {
       _data = new Uint8List(size);
+      _position = _data.length;

[Bill Hesse, 2012/06/12 15:18:10]

This was probably the cause of a bug.  It could cause a negative value for
available().

[Ivan Posva, 2012/06/12 15:56:52]

This is very confusing. Please add a comment explaining what this does.
Basically you are signaling nothing available yet.

     }
     var future = _openedFile.readList(_data, 0, _data.length);
     future.then((read) {
@@ -75,12 +78,18 @@ class _FileInputStream extends _BaseDataInputStream implements InputStream {
         _data = _data.getRange(0, read);
       }
       _position = 0;
+      _activeFillBufferCall = false;
 
       if (_fileLength == _filePosition) {
         _closeFile();
       }
       _checkScheduleCallbacks();
     });
+    future.handleException((e) {
+      _activeFillBufferCall = false;
+      _reportError(e);
+      return true;
+    });
   }
 
   int available() {
@@ -135,6 +144,7 @@ class _FileInputStream extends _BaseDataInputStream implements InputStream {
   int _position;
   int _filePosition;
   int _fileLength;
+  bool _activeFillBufferCall = false;
 }