OS.cs

//     _                _      _  ____   _                           _____
//    / \    _ __  ___ | |__  (_)/ ___| | |_  ___   __ _  _ __ ___  |  ___|__ _  _ __  _ __ ___
//   / _ \  | '__|/ __|| '_ \ | |\___ \ | __|/ _ \ / _` || '_ ` _ \ | |_  / _` || '__|| '_ ` _ \
//  / ___ \ | |  | (__ | | | || | ___) || |_|  __/| (_| || | | | | ||  _|| (_| || |   | | | | | |
// /_/   \_\|_|   \___||_| |_||_||____/  \__|\___| \__,_||_| |_| |_||_|   \__,_||_|   |_| |_| |_|
// |
// Copyright 2015-2021 Łukasz "JustArchi" Domeradzki
// Contact: JustArchi@JustArchi.net
// |
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// |
// http://www.apache.org/licenses/LICENSE-2.0
// |
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Security.Cryptography;
using System.Security.Principal;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using ArchiSteamFarm.Localization;
using ArchiSteamFarm.Storage;
using ArchiSteamFarm.Web;

namespace ArchiSteamFarm.Core;

internal static class OS {
	// We need to keep this one assigned and not calculated on-demand
	internal static readonly string ProcessFileName = Environment.ProcessPath ?? throw new InvalidOperationException(nameof(ProcessFileName));

	internal static DateTime ProcessStartTime {
#if NETFRAMEWORK
		get => RuntimeMadness.ProcessStartTime.ToUniversalTime();
#else
		get {
			using Process process = Process.GetCurrentProcess();

			return process.StartTime.ToUniversalTime();
		}
#endif
	}

	internal static string Version {
		get {
			if (!string.IsNullOrEmpty(BackingVersion)) {
				// ReSharper disable once RedundantSuppressNullableWarningExpression - required for .NET Framework
				return BackingVersion!;
			}

			string framework = RuntimeInformation.FrameworkDescription.Trim();

			if (framework.Length == 0) {
				framework = "Unknown Framework";
			}

#if NETFRAMEWORK
			string runtime = RuntimeInformation.OSArchitecture.ToString();
#else
			string runtime = RuntimeInformation.RuntimeIdentifier.Trim();

			if (runtime.Length == 0) {
				runtime = "Unknown Runtime";
			}
#endif

			string description = RuntimeInformation.OSDescription.Trim();

			if (description.Length == 0) {
				description = "Unknown OS";
			}

			BackingVersion = $"{framework}; {runtime}; {description}";

			return BackingVersion;
		}
	}

	private static string? BackingVersion;
	private static Mutex? SingleInstance;

	internal static void CoreInit(bool systemRequired) {
		if (OperatingSystem.IsWindows()) {
			if (systemRequired) {
				WindowsKeepSystemActive();
			}

			if (!Console.IsOutputRedirected) {
				// Normally we should use UTF-8 console encoding as it's the most correct one for our case, and we already use it on other OSes such as Linux
				// However, older Windows versions, mainly 7/8.1 can't into UTF-8 without appropriate console font, and expecting from users to change it manually is unwanted
				// As irrational as it can sound, those versions actually can work with unicode encoding instead, as they magically map it into proper chars despite of incorrect font
				// See https://github.com/JustArchiNET/ArchiSteamFarm/issues/1289 for more details
				Console.OutputEncoding = OperatingSystem.IsWindowsVersionAtLeast(10) ? Encoding.UTF8 : Encoding.Unicode;

				// Quick edit mode will freeze when user start selecting something on the console until the selection is cancelled
				// Users are very often doing it accidentally without any real purpose, and we want to avoid this common issue which causes the whole process to hang
				// See http://stackoverflow.com/questions/30418886/how-and-why-does-quickedit-mode-in-command-prompt-freeze-applications for more details
				WindowsDisableQuickEditMode();
			}
		}
	}

	internal static string GetOsResourceName(string objectName) {
		if (string.IsNullOrEmpty(objectName)) {
			throw new ArgumentNullException(nameof(objectName));
		}

		return $"{SharedInfo.AssemblyName}-{objectName}";
	}

	internal static void Init(GlobalConfig.EOptimizationMode optimizationMode) {
		if (!Enum.IsDefined(typeof(GlobalConfig.EOptimizationMode), optimizationMode)) {
			throw new ArgumentNullException(nameof(optimizationMode));
		}

		switch (optimizationMode) {
			case GlobalConfig.EOptimizationMode.MaxPerformance:
				// No specific tuning required for now, ASF is optimized for max performance by default
				break;
			case GlobalConfig.EOptimizationMode.MinMemoryUsage:
				// We can disable regex cache which will slightly lower memory usage (for a huge performance hit)
				Regex.CacheSize = 0;

				break;
			default:
				throw new ArgumentOutOfRangeException(nameof(optimizationMode));
		}
	}

	internal static bool IsRunningAsRoot() {
		if (OperatingSystem.IsWindows()) {
			using WindowsIdentity identity = WindowsIdentity.GetCurrent();

			return identity.IsSystem || new WindowsPrincipal(identity).IsInRole(WindowsBuiltInRole.Administrator);
		}

		if (OperatingSystem.IsFreeBSD() || OperatingSystem.IsLinux() || OperatingSystem.IsMacOS()) {
			return NativeMethods.GetEUID() == 0;
		}

		// We can't determine whether user is running as root or not, so fallback to that not happening
		return false;
	}

	internal static async Task<bool> RegisterProcess() {
		if (SingleInstance != null) {
			return false;
		}

		// The only purpose of using hashing here is to cut on a potential size of the resource name - paths can be really long, and we almost certainly have some upper limit on the resource name we can allocate
		// At the same time it'd be the best if we avoided all special characters, such as '/' found e.g. in base64, as we can't be sure that it's not a prohibited character in regards to native OS implementation
		// Because of that, SHA256 is sufficient for our case, as it generates alphanumeric characters only, and is barely 256-bit long. We don't need any kind of complex cryptography or collision detection here, any hashing will do, and the shorter the better
		string uniqueName = $"Global\\{GetOsResourceName(nameof(SingleInstance))}-{Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(Directory.GetCurrentDirectory())))}";

		Mutex? singleInstance = null;

		for (byte i = 0; i < WebBrowser.MaxTries; i++) {
			if (i > 0) {
				await Task.Delay(1000).ConfigureAwait(false);
			}

			singleInstance = new Mutex(true, uniqueName, out bool result);

			if (result) {
				break;
			}

			singleInstance.Dispose();
			singleInstance = null;
		}

		if (singleInstance == null) {
			return false;
		}

		SingleInstance = singleInstance;

		return true;
	}

	[SupportedOSPlatform("FreeBSD")]
	[SupportedOSPlatform("Linux")]
	[SupportedOSPlatform("MacOS")]
	internal static void UnixSetFileAccess(string path, EUnixPermission permission) {
		if (string.IsNullOrEmpty(path)) {
			throw new ArgumentNullException(nameof(path));
		}

		if (!OperatingSystem.IsFreeBSD() && !OperatingSystem.IsLinux() && !OperatingSystem.IsMacOS()) {
			throw new PlatformNotSupportedException();
		}

		if (!File.Exists(path) && !Directory.Exists(path)) {
			ASF.ArchiLogger.LogGenericError(string.Format(CultureInfo.CurrentCulture, Strings.WarningFailedWithError, $"!{nameof(path)}"));

			return;
		}

		// Chmod() returns 0 on success, -1 on failure
		if (NativeMethods.Chmod(path, (int) permission) != 0) {
			ASF.ArchiLogger.LogGenericError(string.Format(CultureInfo.CurrentCulture, Strings.WarningFailedWithError, Marshal.GetLastWin32Error()));
		}
	}

	internal static void UnregisterProcess() {
		if (SingleInstance == null) {
			return;
		}

		// We should release the mutex here, but that can be done only from the same thread due to thread affinity
		// Instead, we'll dispose the mutex which should automatically release it by the CLR
		SingleInstance.Dispose();
		SingleInstance = null;
	}

	internal static bool VerifyEnvironment() {
#if NETFRAMEWORK
		// This is .NET Framework build, we support that one only on mono for platforms not supported by .NET Core

		// We're not going to analyze source builds, as we don't know what changes the author has made, assume they have a point
		if (SharedInfo.BuildInfo.IsCustomBuild) {
			return true;
		}

		// All windows variants have valid .NET Core build, and generic-netf is supported only on mono
		if (OperatingSystem.IsWindows() || !RuntimeMadness.IsRunningOnMono) {
			return false;
		}

		return RuntimeInformation.OSArchitecture switch {
			// Sadly we can't tell a difference between ARMv6 and ARMv7 reliably, we'll believe that this linux-arm user knows what he's doing and he's indeed in need of generic-netf on ARMv6
			Architecture.Arm => true,

			// Apart from real x86, this also covers all unknown architectures, such as sparc, ppc64, and anything else Mono might support, we're fine with that
			Architecture.X86 => true,

			// Everything else is covered by .NET Core
			_ => false
		};
#else

		// This is .NET Core build, we support all scenarios
		return true;
#endif
	}

	[SupportedOSPlatform("Windows")]
	private static void WindowsDisableQuickEditMode() {
		if (!OperatingSystem.IsWindows()) {
			throw new PlatformNotSupportedException();
		}

		IntPtr consoleHandle = NativeMethods.GetStdHandle(NativeMethods.StandardInputHandle);

		if (!NativeMethods.GetConsoleMode(consoleHandle, out uint consoleMode)) {
			ASF.ArchiLogger.LogGenericError(Strings.WarningFailed);

			return;
		}

		consoleMode &= ~NativeMethods.EnableQuickEditMode;

		if (!NativeMethods.SetConsoleMode(consoleHandle, consoleMode)) {
			ASF.ArchiLogger.LogGenericError(Strings.WarningFailed);
		}
	}

	[SupportedOSPlatform("Windows")]
	private static void WindowsKeepSystemActive() {
		if (!OperatingSystem.IsWindows()) {
			throw new PlatformNotSupportedException();
		}

		// This function calls unmanaged API in order to tell Windows OS that it should not enter sleep state while the program is running
		// If user wishes to enter sleep mode, then he should use ShutdownOnFarmingFinished or manage ASF process with third-party tool or script
		// See https://docs.microsoft.com/windows/win32/api/winbase/nf-winbase-setthreadexecutionstate for more details
		NativeMethods.EExecutionState result = NativeMethods.SetThreadExecutionState(NativeMethods.AwakeExecutionState);

		// SetThreadExecutionState() returns NULL on failure, which is mapped to 0 (EExecutionState.None) in our case
		if (result == NativeMethods.EExecutionState.None) {
			ASF.ArchiLogger.LogGenericError(string.Format(CultureInfo.CurrentCulture, Strings.WarningFailedWithError, result));
		}
	}

	[Flags]
	[SupportedOSPlatform("FreeBSD")]
	[SupportedOSPlatform("Linux")]
	[SupportedOSPlatform("MacOS")]
	internal enum EUnixPermission : ushort {
		OtherExecute = 0x1,
		OtherWrite = 0x2,
		OtherRead = 0x4,
		GroupExecute = 0x8,
		GroupWrite = 0x10,
		GroupRead = 0x20,
		UserExecute = 0x40,
		UserWrite = 0x80,
		UserRead = 0x100,
		Combined777 = UserRead | UserWrite | UserExecute | GroupRead | GroupWrite | GroupExecute | OtherRead | OtherWrite | OtherExecute
	}

	private static class NativeMethods {
		[SupportedOSPlatform("Windows")]
		internal const EExecutionState AwakeExecutionState = EExecutionState.SystemRequired | EExecutionState.AwayModeRequired | EExecutionState.Continuous;

		[SupportedOSPlatform("Windows")]
		internal const uint EnableQuickEditMode = 0x0040;

		[SupportedOSPlatform("Windows")]
		internal const sbyte StandardInputHandle = -10;

#pragma warning disable CA2101 // False positive, we can't use unicode charset on Unix, and it uses UTF-8 by default anyway
		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("libc", EntryPoint = "chmod", SetLastError = true)]
		[SupportedOSPlatform("FreeBSD")]
		[SupportedOSPlatform("Linux")]
		[SupportedOSPlatform("MacOS")]
		internal static extern int Chmod(string path, int mode);
#pragma warning restore CA2101 // False positive, we can't use unicode charset on Unix, and it uses UTF-8 by default anyway

		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("kernel32.dll")]
		[SupportedOSPlatform("Windows")]
		internal static extern bool GetConsoleMode(IntPtr hConsoleHandle, out uint lpMode);

		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("libc", EntryPoint = "geteuid", SetLastError = true)]
		[SupportedOSPlatform("FreeBSD")]
		[SupportedOSPlatform("Linux")]
		[SupportedOSPlatform("MacOS")]
		internal static extern uint GetEUID();

		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("kernel32.dll")]
		[SupportedOSPlatform("Windows")]
		internal static extern IntPtr GetStdHandle(int nStdHandle);

		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("kernel32.dll")]
		[SupportedOSPlatform("Windows")]
		internal static extern bool SetConsoleMode(IntPtr hConsoleHandle, uint dwMode);

		[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
		[DllImport("kernel32.dll")]
		[SupportedOSPlatform("Windows")]
		internal static extern EExecutionState SetThreadExecutionState(EExecutionState executionState);

		[Flags]
		[SupportedOSPlatform("Windows")]
		internal enum EExecutionState : uint {
			None = 0,
			SystemRequired = 0x00000001,
			AwayModeRequired = 0x00000040,
			Continuous = 0x80000000
		}
	}
}