Bug with `stdin`? about dax

[dsherret]

Yeah, that sounds correct to me. Thanks!

By the way, right now the whole way pipes work in dax is not exactly the same as in a shell. In https://github.com/denoland/deno_task_shell for example, it's implemented using real operating system level pipes (using https://crates.io/crates/os_pipe), but there's no such primitive available in Deno (ex. no pipe on Linux or anonymous pipe on Windows). So for example, doing something like command1 && command2 and having both commands read from the provided stdin won't work. It might eventually be added to Deno, but for now we have this limitation.

[pocketken]

By the way, right now the whole way pipes work in dax is not exactly the same as in a shell. In https://github.com/denoland/deno_task_shell for example, it's implemented using real operating system level pipes (using https://crates.io/crates/os_pipe), but there's no such primitive available in Deno (ex. no pipe on Linux or anonymous pipe on Windows). So for example, doing something like command1 && command2 and having both commands read from the provided stdin won't work. It might eventually be added to Deno, but for now we have this limitation.

Yeah I gathered as much as soon as I started to look through the code for deno_task_shell and (briefly) gazed down the "threading in Web Assembly" rabbit hole...

[pocketken]

Might have introduced a leak, now that I think about it:

  } finally {
    completeController.abort();
    context.signal.removeEventListener("abort", abortListener);
    p.close();
    // pre-65d20b9: p.stdin?.close();
    p.stdout?.close();
    p.stderr?.close();
  }

  async function writeStdin(stdin: ShellPipeReader, p: Deno.Process, signal: AbortSignal) {
    if (typeof stdin === "string") {
      return;
    }
    await pipeReaderToWriter(stdin, p.stdin!, signal);
    p.stdin!.close();
  }

Previously p.stdin was always closed in the finally block. After this change if typeof stdin === "string", p.stdin doesn't get closed.

I'll throw together a follow-up PR.