C# - .NET 4.0 이하에서 Console.IsInputRedirected 구현

예전에 netcat 프로그램을 만들면서,

C# - 간단하게 만들어 보는 리눅스의 nc(netcat) 프로그램
; https://www.sysnet.pe.kr/2/0/12311

Console.IsInputRedirected Property
; https://learn.microsoft.com/en-us/dotnet/api/system.console.isinputredirected

[DllImport("kernel32.dll")]
internal static extern int GetFileType(SafeFileHandle handle);

[DllImport("kernel32.dll", SetLastError = true)]
internal static extern bool GetConsoleMode(IntPtr hConsoleHandle, out int mode);

[SecuritySafeCritical]
private static bool IsHandleRedirected(IntPtr ioHandle)
{
    SafeFileHandle handle = new SafeFileHandle(ioHandle, ownsHandle: false);
    int fileType = Win32Native.GetFileType(handle);
    if ((fileType & 2) != 2)
    {
        return true;
    }

    int mode;
    bool consoleMode = Win32Native.GetConsoleMode(ioHandle, out mode);
    return !consoleMode;
}

public static bool IsInputRedirected
{
    [SecuritySafeCritical]
    get
    {
        // ...[생략]...
        return IsHandleRedirected(ConsoleInputHandle);
    }
}

private static IntPtr ConsoleInputHandle
{
    [SecurityCritical]
    get
    {
        if (_consoleInputHandle == IntPtr.Zero)
        {
            _consoleInputHandle = Win32Native.GetStdHandle(-10);
        }

        return _consoleInputHandle;
    }
}

using Microsoft.Win32.SafeHandles;
using System;
using System.Runtime.InteropServices;
using System.Security;

class Program
{
    static void Main(string[] args)
    {
        // .NET 4.5 or later
        Console.WriteLine(Console.IsInputRedirected);

        // .NET 4.0 or below
        Console.WriteLine(ConsoleHelper.IsInputHandleRedirected());
    }
}

// Utilities/netcat/ConsoleHelper.cs 
// https://github.com/stjeong/Utilities/blob/master/netcat/ConsoleHelper.cs
class ConsoleHelper
{
    [DllImport("kernel32.dll")]
    internal static extern int GetFileType(SafeFileHandle handle);

    [DllImport("kernel32.dll")]
    private static extern IntPtr GetStdHandle(StdHandle std);

    [DllImport("kernel32.dll", SetLastError = true)]
    internal static extern bool GetConsoleMode(IntPtr hConsoleHandle, out int mode);

    private enum StdHandle { Stdin = -10, Stdout = -11, Stderr = -12 };

    [SecuritySafeCritical]
    public static bool IsInputHandleRedirected()
    {
        IntPtr ioHandle = GetStdHandle(StdHandle.Stdin);

        SafeFileHandle handle = new SafeFileHandle(ioHandle, ownsHandle: false);
        int fileType = GetFileType(handle);
        if ((fileType & 2) != 2)
        {
            return true;
        }

        bool consoleMode = GetConsoleMode(ioHandle, out _);
        return !consoleMode;
    }
}

/* 출력 결과
C:\temp> dir . | ConsoleApp1.exe
True
True

C:\temp> ConsoleApp1.exe
False
False
*/