From 7ff7473db6ac640114f743b01a5cdba679a4d0e8 Mon Sep 17 00:00:00 2001
From: Ilya Fedin <fedin-ilja2010@ya.ru>
Date: Thu, 25 Nov 2021 05:32:31 +0400
Subject: [PATCH] Auto-check for many instance

This option was invented when single instance check wasn't adapted for -workdir. Now, -workdir can work without -many and this option is redudant, but auto-update prevention is helpful. Let's autodetect whether the binary is already running with a lock file.
---
 Telegram/SourceFiles/core/launcher.cpp |  2 --
 Telegram/SourceFiles/core/sandbox.cpp  | 47 +++++++++++++++++++-------
 Telegram/SourceFiles/core/sandbox.h    |  3 ++
 3 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/Telegram/SourceFiles/core/launcher.cpp b/Telegram/SourceFiles/core/launcher.cpp
index eda856e5b..b9b927c44 100644
--- a/Telegram/SourceFiles/core/launcher.cpp
+++ b/Telegram/SourceFiles/core/launcher.cpp
@@ -460,7 +460,6 @@ void Launcher::processArguments() {
 	auto parseMap = std::map<QByteArray, KeyFormat> {
 		{ "-debug"          , KeyFormat::NoValues },
 		{ "-freetype"       , KeyFormat::NoValues },
-		{ "-many"           , KeyFormat::NoValues },
 		{ "-key"            , KeyFormat::OneValue },
 		{ "-autostart"      , KeyFormat::NoValues },
 		{ "-fixprevious"    , KeyFormat::NoValues },
@@ -499,7 +498,6 @@ void Launcher::processArguments() {
 
 	gUseFreeType = parseResult.contains("-freetype");
 	gDebugMode = parseResult.contains("-debug");
-	gManyInstance = parseResult.contains("-many");
 	gKeyFile = parseResult.value("-key", {}).join(QString()).toLower();
 	gKeyFile = gKeyFile.replace(QRegularExpression("[^a-z0-9\\-_]"), {});
 	gLaunchMode = parseResult.contains("-autostart") ? LaunchModeAutoStart
diff --git a/Telegram/SourceFiles/core/sandbox.cpp b/Telegram/SourceFiles/core/sandbox.cpp
index a113e88aa..b8d481454 100644
--- a/Telegram/SourceFiles/core/sandbox.cpp
+++ b/Telegram/SourceFiles/core/sandbox.cpp
@@ -29,6 +29,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/effects/animations.h"
 #include "app.h"
 
+#include <QtCore/QLockFile>
 #include <QtGui/QSessionManager>
 #include <QtGui/QScreen>
 #include <qpa/qplatformscreen.h>
@@ -99,10 +100,35 @@ int Sandbox::start() {
 	if (!Core::UpdaterDisabled()) {
 		_updateChecker = std::make_unique<Core::UpdateChecker>();
 	}
-	const auto d = QFile::encodeName(QDir(cWorkingDir()).absolutePath());
-	char h[33] = { 0 };
-	hashMd5Hex(d.constData(), d.size(), h);
-	_localServerName = Platform::SingleInstanceLocalServerName(h);
+
+	{
+		const auto d = QFile::encodeName(QDir(cWorkingDir()).absolutePath());
+		char h[33] = { 0 };
+		hashMd5Hex(d.constData(), d.size(), h);
+		_localServerName = Platform::SingleInstanceLocalServerName(h);
+	}
+
+	{
+		const auto d = QFile::encodeName(cExeDir() + cExeName());
+		QByteArray h;
+		h.resize(32);
+		hashMd5Hex(d.constData(), d.size(), h.data());
+		_lockFile = std::make_unique<QLockFile>(QDir::tempPath() + '/' + h + '-' + cGUIDStr());
+		_lockFile->setStaleLockTime(0);
+		if (!_lockFile->tryLock() && _launcher->customWorkingDir()) {
+			// On Windows, QLockFile has problems detecting a stale lock
+			// if the machine's hostname contains characters outside the US-ASCII character set.
+			if constexpr (Platform::IsWindows()) {
+				// QLockFile::removeStaleLockFile returns false on Windows,
+				// when the application owning the lock is still running.
+				if (!_lockFile->removeStaleLockFile()) {
+					gManyInstance = true;
+				}
+			} else {
+				gManyInstance = true;
+			}
+		}
+	}
 
 	connect(
 		&_localSocket,
@@ -149,13 +175,8 @@ int Sandbox::start() {
 		restartHint,
 		Qt::DirectConnection);
 
-	if (cManyInstance()) {
-		LOG(("Many instance allowed, starting..."));
-		singleInstanceChecked();
-	} else {
-		LOG(("Connecting local socket to %1...").arg(_localServerName));
-		_localSocket.connectToServer(_localServerName);
-	}
+	LOG(("Connecting local socket to %1...").arg(_localServerName));
+	_localSocket.connectToServer(_localServerName);
 
 	if (QuitOnStartRequested) {
 		closeApplication();
@@ -339,12 +360,12 @@ void Sandbox::socketError(QLocalSocket::LocalSocketError e) {
 
 void Sandbox::singleInstanceChecked() {
 	if (cManyInstance()) {
-		Logs::multipleInstances();
+		LOG(("App Info: Detected another instance"));
 	}
 
 	Ui::DisableCustomScaling();
 	refreshGlobalProxy();
-	if (!Logs::started() || (!cManyInstance() && !Logs::instanceChecked())) {
+	if (!Logs::started() || !Logs::instanceChecked()) {
 		new NotStartedWindow();
 		return;
 	}
diff --git a/Telegram/SourceFiles/core/sandbox.h b/Telegram/SourceFiles/core/sandbox.h
index 7362f5554..944dee65e 100644
--- a/Telegram/SourceFiles/core/sandbox.h
+++ b/Telegram/SourceFiles/core/sandbox.h
@@ -15,6 +15,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include <QtNetwork/QLocalSocket>
 #include <QtCore/QAbstractNativeEventFilter>
 
+class QLockFile;
+
 namespace Core {
 
 class Launcher;
@@ -119,6 +121,7 @@ private:
 	QLocalServer _localServer;
 	QLocalSocket _localSocket;
 	LocalClients _localClients;
+	std::unique_ptr<QLockFile> _lockFile;
 	bool _secondInstance = false;
 	bool _started = false;
 	static bool QuitOnStartRequested;