BepInEx/BepInEx.Core/Console/Windows/WindowsConsoleDriver.cs

using System;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using BepInEx.ConsoleUtil;
using HarmonyLib;
using Microsoft.Win32.SafeHandles;
using UnityInjector.ConsoleUtil;

namespace BepInEx
{
    internal class WindowsConsoleDriver : IConsoleDriver
    {
        // Apparently on some versions of Unity (e.g. 2018.4) using old mono causes crashes on game close if
        // IntPtr overload is used for file streams (check #139).
        // On the other hand, not all Unity games come with SafeFileHandle overload for FileStream
        // As such, we're trying to use SafeFileHandle when it's available and go back to IntPtr overload if not available
        private static readonly ConstructorInfo FileStreamCtor = new[]
        {
            AccessTools.Constructor(typeof(FileStream), new[] { typeof(SafeFileHandle), typeof(FileAccess) }),
            AccessTools.Constructor(typeof(FileStream), new[] { typeof(IntPtr), typeof(FileAccess) })
        }.FirstOrDefault(m => m != null);

        public TextWriter StandardOut { get; private set; }
        public TextWriter ConsoleOut { get; private set; }

        public bool ConsoleActive { get; private set; }
        public bool ConsoleIsExternal => true;

        public void Initialize(bool alreadyActive)
        {
            ConsoleActive = alreadyActive || Console.WindowWidth != 0 && Console.WindowHeight != 0;
            
            if (ConsoleActive)
            {
                // We're in a .NET framework / XNA environment; console *is* stdout
                ConsoleOut = Console.Out;
                StandardOut = new StreamWriter(Console.OpenStandardOutput());
            }
            else
            {
                StandardOut = Console.Out;
            }
        }

        public void CreateConsole(uint codepage)
        {
            ConsoleWindow.Attach();

            // Make sure of ConsoleEncoding helper class because on some Monos
            // Encoding.GetEncoding throws NotImplementedException on most codepages
            // NOTE: We don't set Console.OutputEncoding because it resets any existing Console.Out writers
            ConsoleEncoding.ConsoleCodePage = codepage;

            // If stdout exists, write to it, otherwise make it the same as console out
            // Not sure if this is needed? Does the original Console.Out still work?
            var stdout = GetOutHandle();
            if (stdout == IntPtr.Zero)
            {
                StandardOut = TextWriter.Null;
                ConsoleOut = TextWriter.Null;
                return;
            }

            var originalOutStream = OpenFileStream(stdout);
            StandardOut = new StreamWriter(originalOutStream, Utility.UTF8NoBom)
            {
                AutoFlush = true
            };

            var consoleOutStream = OpenFileStream(ConsoleWindow.ConsoleOutHandle);
            // Can't use Console.OutputEncoding because it can be null (i.e. not preference by user)
            ConsoleOut = new StreamWriter(consoleOutStream, ConsoleEncoding.OutputEncoding)
            {
                AutoFlush = true
            };
            ConsoleActive = true;
        }

        public void PreventClose() => ConsoleWindow.PreventClose();

        public void DetachConsole()
        {
            ConsoleWindow.Detach();

            ConsoleOut.Close();
            ConsoleOut = null;

            ConsoleActive = false;
        }

        public void SetConsoleColor(ConsoleColor color)
        {
            SafeConsole.ForegroundColor = color;
            Kon.ForegroundColor = color;
        }

        public void SetConsoleTitle(string title) => ConsoleWindow.Title = title;

        private static FileStream OpenFileStream(IntPtr handle)
        {
            var fileHandle = new SafeFileHandle(handle, false);
            var ctorParams = AccessTools.ActualParameters(FileStreamCtor,
                                                          new object[]
                                                          {
                                                              fileHandle, fileHandle.DangerousGetHandle(),
                                                              FileAccess.Write
                                                          });
            return (FileStream) Activator.CreateInstance(typeof(FileStream), ctorParams);
        }

        private IntPtr GetOutHandle()
        {
            switch (ConsoleManager.ConfigConsoleOutRedirectType.Value)
            {
                case ConsoleManager.ConsoleOutRedirectType.ConsoleOut:
                    return ConsoleWindow.ConsoleOutHandle;
                case ConsoleManager.ConsoleOutRedirectType.StandardOut:
                    return ConsoleWindow.OriginalStdoutHandle;
                case ConsoleManager.ConsoleOutRedirectType.Auto:
                default:
                    return ConsoleWindow.OriginalStdoutHandle != IntPtr.Zero
                               ? ConsoleWindow.OriginalStdoutHandle
                               : ConsoleWindow.ConsoleOutHandle;
            }
        }
    }
}