/****************************************************************************
** SPDX-License-Identifier: BSD-3-Clause
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** This file is part of the Qt Solutions component.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
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** modification, are permitted provided that the following conditions are
** met:
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**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
**     of its contributors may be used to endorse or promote products derived
**     from this software without specific prior written permission.
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****************************************************************************/

#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>

#include "LockedFile.h"

bool LockedFile::lock(LockMode mode, bool block)
{
	if (!isOpen()) {
		qWarning("QtLockedFile::lock(): file is not opened");
		return false;
	}

	if (mode == NoLock)
		return unlock();

	if (mode == m_lock_mode)
		return true;

	if (m_lock_mode != NoLock)
		unlock();

	struct flock fl;
	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 0;
	fl.l_type = (mode == ReadLock) ? F_RDLCK : F_WRLCK;
	int cmd = block ? F_SETLKW : F_SETLK;
	int ret = fcntl(handle(), cmd, &fl);

	if (ret == -1) {
		if (errno != EINTR && errno != EAGAIN)
			qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
		return false;
	}

	m_lock_mode = mode;
	return true;
}

bool LockedFile::unlock()
{
	if (!isOpen()) {
		qWarning("QtLockedFile::unlock(): file is not opened");
		return false;
	}

	if (!isLocked())
		return true;

	struct flock fl;
	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 0;
	fl.l_type = F_UNLCK;
	int ret = fcntl(handle(), F_SETLKW, &fl);

	if (ret == -1) {
		qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
		return false;
	}

	m_lock_mode = NoLock;
	return true;
}

LockedFile::~LockedFile()
{
	if (isOpen())
		unlock();
}
