Dart file copy in Windows - file-io

Question

The File class in the dart:io library doesn't yet include copy() and move() methods.
To tide me over until they arrive, I'm trying to roll my own copy function. I'm using the code below on Windows, but it just creates a 0kb file.
void copyFile(String input, String output) {
var inFile = new File(input), outFile = new File(output);
if (outFile.existsSync()) outFile.deleteSync(); // I realize this isn't required
var inStream = null, outStream = null;
try {
inStream = inFile.openInputStream();
outStream = outFile.openOutputStream(FileMode.WRITE);
inStream.pipe(outStream);
} finally {
if (outStream != null && !outStream.closed) outStream.close();
if (inStream != null && !inStream.closed) inStream.close();
}
}
I've also tried replacing the pipe line with print(inStream.read(100).toString()); and I get null. The input file does exist (otherwise I'd get a FileIOException). Am I doing something wrong, or are input streams broken under Windows?
I'm using:
Dart Editor version 0.3.1_r17463
Dart SDK version 0.3.1.2_r17463
Edit: The following works (although it doesn't "chunk"). Am I using the streams above incorrectly?
void copyFile(String input, String output) {
var inFile = new File(input), outFile = new File(output);
if (outFile.existsSync()) outFile.deleteSync(); // I realize this isn't required
outFile.writeAsBytesSync(inFile.readAsBytesSync(), FileMode.WRITE);
}

Answer 1

With your first code snippet, you get an empty file because pipe is not a synchronous method. Thus, the copy of inputStream to outputStream has not started when the finally block is execute. By closing the streams in this finally block, you stop the pipe before it even starts. Without that finally block the copy is done correctly.
void copyFile(String input, String output) {
final inStream = new File(input).openInputStream();
final outStream = new File(output).openOutputStream(FileMode.WRITE);
inStream.pipe(outStream);
}
Finally, you don't have to worry about closing streams because pipe close streams by default once achieved. See InputStream.pipe.

Answer 2

For synchronous copy, use:
File(sourceFile).copySync(destinationFile);
For asynchronous copy, use:
File(sourceFile).copy(destinationFile);