Async Console Read Cannot Be Cancelled

[grochoge]

Description

After beginning an asynchronous stream read of standard input (on Windows at least) with a cancellation token, cancelling the token does not cancel the read.

Reproduction Steps

using System.Threading;
var cancel = new CancellationTokenSource();
var stdin = Console.OpenStandardInput();
var buffer = new byte[1024];
var read = stdin.ReadAsync( buffer, cancel.Token );
cancel.Cancel();
await read;

Expected behavior

Read is cancelled and a cancellation exception is thrown.

Actual behavior

The await call blocks forever.

Regression?

No response

Known Workarounds

No response

Configuration

.NET 8.0.3
Windows 10 19045.4046

Other information

A stack trace shows the program calling the regular console read method, not an asynchronous version:

 	System.Console.dll!Interop.Kernel32.ReadFile(nint handle, byte* bytes, int numBytesToRead, out int numBytesRead, nint mustBeZero) Line 412	C#
 	System.Console.dll!System.ConsolePal.WindowsConsoleStream.ReadFileNative(nint hFile, System.Span<byte> buffer, bool isPipe, out int bytesRead, bool useFileAPIs) Line 1150	C#
 	System.Console.dll!System.ConsolePal.WindowsConsoleStream.Read(System.Span<byte> buffer) Line 1108	C#
>	System.Console.dll!System.IO.ConsoleStream.Read(byte[] buffer, int offset, int count) Line 34	C#
 	[Async] Program.Main(string[] aArgs) Line 73	C#

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-console
See info in area-owners.md if you want to be subscribed.

[grochoge]

Searching further, I guess this is more of a feature request and/or a documentation bug/feature request.

The documentation states ReadAsync "monitors cancellation requests", implying that the read can be cancelled while in progress. However the actual (intended) behavior is the cancellation token is checked before reading but ReadAsync will not be cancelled after that unless the behavior is overridden in a derived class.

[reflectronic]

Console I/O cannot be canceled reliably on Windows: microsoft/terminal#12143

[alexrp]

Console I/O cannot be canceled reliably on Windows: microsoft/terminal#12143

I would very much appreciate upvotes on that issue by anyone who cares about it, by the way. It's hard to convince the team to dedicate time to it if I seem like the only person affected by it.

[adamsitnik]

Console I/O cannot be canceled reliably on Windows: microsoft/terminal#12143

I've marked it as blocking, as soon as Windows makes it possible we can give it a try (currently the handle is open for sync IO)