tg_windows5.12.6/Telegram/lib_base/base/file_lock.h

// This file is part of Desktop App Toolkit,
// a set of libraries for developing nice desktop applications.
//
// For license and copyright information please follow this link:
// https://github.com/desktop-app/legal/blob/master/LEGAL
//
#pragma once

#include "base/basic_types.h"
#include <QtCore/QFile>

namespace base {

class FileLock {
public:
	FileLock();

	bool lock(QFile &file, QIODevice::OpenMode mode);
	[[nodiscard]] bool locked() const;
	void unlock();

	static constexpr auto kSkipBytes = size_type(4);

	~FileLock();

private:
	class Lock;
	struct Descriptor;
	struct LockingPid;

	static constexpr auto kLockOffset = index_type(0);
	static constexpr auto kLockLimit = kSkipBytes;

	std::unique_ptr<Lock> _lock;

};

} // namespace base