Cancellation of FtpConnection.ReadFromStreamAsync causes UnobservedTaskException #131
Description
In FtpConnection.ReadFromStreamAsync, readTask is started using the cancellation token passed into the method, but tcs is also created which has its result set when the cancellation token is cancelled:
protected override async Task<int> ReadFromStreamAsync(byte[] buffer, int offset, int length, CancellationToken cancellationToken)
{
var readTask = Stream
.ReadAsync(buffer, offset, length, cancellationToken);
var tcs = new TaskCompletionSource<object?>();
using var registration = cancellationToken.Register(() => tcs.TrySetResult(null));
var resultTask = await Task.WhenAny(readTask, tcs.Task)
.ConfigureAwait(false);
if (cancellationToken.IsCancellationRequested)
{
Logger?.LogTrace("Cancelled through CancellationToken");
return 0;
}
...This can cause resultTask to complete when tcs.Task is complete, and the exception from the cancellation of readTask is never observed. causing an UnobservedTaskException.