Golang: Initialize console handlers after AttachConsole or AllocConsole on Windows.

init_console_handlers_windows.go

// Used in https://github.com/SCP002/terminator.

package main

import (
	"errors"
	"os"

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

// InitConsoleHandles initializes standard IO handles for the current console.
//
// Useful to call after AttachConsole or AllocConsole.
func InitConsoleHandles() error {
	// Retrieve standard handles.
	hIn, err := windows.GetStdHandle(windows.STD_INPUT_HANDLE)
	if err != nil {
		return errors.New("Failed to retrieve standard input handler.")
	}
	hOut, err := windows.GetStdHandle(windows.STD_OUTPUT_HANDLE)
	if err != nil {
		return errors.New("Failed to retrieve standard output handler.")
	}
	hErr, err := windows.GetStdHandle(windows.STD_ERROR_HANDLE)
	if err != nil {
		return errors.New("Failed to retrieve standard error handler.")
	}

	// Wrap handles in files. /dev/ prefix just to make it conventional.
	stdInF := os.NewFile(uintptr(hIn), "/dev/stdin")
	if stdInF == nil {
		return errors.New("Failed to create a new file for standard input.")
	}
	stdOutF := os.NewFile(uintptr(hOut), "/dev/stdout")
	if stdOutF == nil {
		return errors.New("Failed to create a new file for standard output.")
	}
	stdErrF := os.NewFile(uintptr(hErr), "/dev/stderr")
	if stdErrF == nil {
		return errors.New("Failed to create a new file for standard error.")
	}

	// Set handles for standard input, output and error devices.
	err = windows.SetStdHandle(windows.STD_INPUT_HANDLE, windows.Handle(stdInF.Fd()))
	if err != nil {
		return errors.New("Failed to set standard input handler.")
	}
	err = windows.SetStdHandle(windows.STD_OUTPUT_HANDLE, windows.Handle(stdOutF.Fd()))
	if err != nil {
		return errors.New("Failed to set standard output handler.")
	}
	err = windows.SetStdHandle(windows.STD_ERROR_HANDLE, windows.Handle(stdErrF.Fd()))
	if err != nil {
		return errors.New("Failed to set standard error handler.")
	}

	// Update golang standard IO file descriptors.
	os.Stdin = stdInF
	os.Stdout = stdOutF
	os.Stderr = stdErrF

	return nil
}