How to disable ENABLE_LINE_INPUT in ConPTY? How to call GetConsoleMode for a PseudoConsole?

[lonnywong]

Windows Terminal version

1.12.10982.0

Windows build number

10.0.19043.0

Other Software

https://github.com/UserExistsError/conpty v0.1.0

Is it similar to https://stackoverflow.com/a/11439517/7696611 ?

Steps to reproduce

• go run conptytest.go

package main

import (
        "bufio"
        "context"
        "fmt"
        "strings"

        "github.com/UserExistsError/conpty"
)

func main() {
        cpty, err := conpty.Start("python3 -c \"import sys; s = sys.stdin.readline(); print(len(s))\"")
        if err != nil {
                fmt.Printf("Failed to spawn a pty:  %v", err)
                return
        }
        defer cpty.Close()

        go func() {
                cpty.Write([]byte(strings.Repeat("A", 3000) + "\r\n"))

                scanner := bufio.NewScanner(cpty)
                for scanner.Scan() {
                        // Should output 3001.
                        // But output 511 in cmd, output 2510 in MSYS2.
                        fmt.Printf("Output: %s\n", scanner.Text())
                }
                if err := scanner.Err(); err != nil {
                        fmt.Println(err)
                }
        }()

        if _, err := cpty.Wait(context.Background()); err != nil {
                fmt.Printf("Error: %v", err)
        }
}

Expected Behavior

Output: 3001

Actual Behavior

Output: 511

[lonnywong]

If disable ENABLE_LINE_INPUT in the child process, it works.

But I can't change the child process to disable ENABLE_LINE_INPUT.

Is there a way to disable ENABLE_LINE_INPUT in ConPTY?

• go build readline.go

package main

import (
	"bufio"
	"fmt"
	"os"

	"golang.org/x/sys/windows"
)

func main() {
	var st uint32
	if err := windows.GetConsoleMode(windows.Handle(os.Stdin.Fd()), &st); err != nil {
		fmt.Println(err)
		return
	}

	// disable ENABLE_LINE_INPUT
	raw := st &^ (windows.ENABLE_ECHO_INPUT | windows.ENABLE_LINE_INPUT)
	fmt.Printf("st: %#x, raw: %#x\n", st, raw)

	if err := windows.SetConsoleMode(windows.Handle(os.Stdin.Fd()), raw); err != nil {
		fmt.Println(err)
		return
	}

	// reset console mode
	defer func() {
		if err := windows.SetConsoleMode(windows.Handle(os.Stdin.Fd()), st); err != nil {
			fmt.Println(err)
			return
		}
	}()

	// read line
	line, err := bufio.NewReader(os.Stdin).ReadBytes('\r')
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Printf("\nLength: %d\r\n", len(line))
}

• go run conptytest.go

package main

import (
	"bufio"
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/UserExistsError/conpty"
)

func main() {
	cpty, err := conpty.Start("readline.exe") // The child process have to disable ENABLE_LINE_INPUT first
	if err != nil {
		fmt.Printf("Failed to spawn a pty:  %v", err)
		return
	}
	defer cpty.Close()

	go func() {
		time.Sleep(1 * time.Second) // Wait the child process disable ENABLE_LINE_INPUT first
		cpty.Write([]byte(strings.Repeat("A", 5000) + "\r\n"))

		scanner := bufio.NewScanner(cpty)
		for scanner.Scan() {
			fmt.Println(scanner.Text())
		}
		if err := scanner.Err(); err != nil {
			fmt.Println(err)
		}
	}()

	if _, err := cpty.Wait(context.Background()); err != nil {
		fmt.Printf("Error: %v", err)
	}
}

[zadjii-msft]

But I can't change the child process to disable ENABLE_LINE_INPUT.

Huh. I think you might be stuck here then. I don't think we provide any sort of way to call the console APIs on a conpty you create. There might be some trickery possible. You might be able to attach some other helper disable-line-input.exe to the same conpty, which just calls that API, and have it magically work. IIRC input mode is a global state, so multiple attached clients can mess with each other's state. But, I'd also caution that's definitely a hack and one we're intending to fix (#4954)

[lonnywong]

But I can't change the child process to disable ENABLE_LINE_INPUT.

Huh. I think you might be stuck here then. I don't think we provide any sort of way to call the console APIs on a conpty you create. There might be some trickery possible. You might be able to attach some other helper disable-line-input.exe to the same conpty, which just calls that API, and have it magically work. IIRC input mode is a global state, so multiple attached clients can mess with each other's state. But, I'd also caution that's definitely a hack and one we're intending to fix (#4954)

Thanks for your help.

I tried it before, it works.

I disabled the ENABLE_LINE_INPUT and create a ssh process.
But the /usr/bin/ssh in MSYS2 still can't read all the input from ConPTY.
Looks like it's another issue.

Btw, the C:\Windows\System32\OpenSSH\ssh.exe works good.