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Telegram/SourceFiles/storage/storage_file_lock.h

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+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "base/basic_types.h"
+#include <QtCore/QFile>
+
+namespace Storage {
+
+class FileLock {
+public:
+	FileLock();
+
+	bool lock(QFile &file, QIODevice::OpenMode mode);
+	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 Storage