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/*
* Copyright (C) 2020 KeePassXC Team <team@keepassxc.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 or (at your option)
* version 3 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "FileWatcher.h"
#include "core/AsyncTask.h"
#include <QCryptographicHash>
#ifdef Q_OS_LINUX
#include <sys/vfs.h>
#endif
FileWatcher::FileWatcher(QObject* parent)
: QObject(parent)
{
connect(&m_fileWatcher, SIGNAL(fileChanged(QString)), SLOT(checkFileChanged()));
connect(&m_fileChecksumTimer, SIGNAL(timeout()), SLOT(checkFileChanged()));
connect(&m_fileChangeDelayTimer, &QTimer::timeout, this, [this] { emit fileChanged(m_filePath); });
m_fileChangeDelayTimer.setSingleShot(true);
m_fileIgnoreDelayTimer.setSingleShot(true);
}
FileWatcher::~FileWatcher()
{
stop();
}
void FileWatcher::start(const QString& filePath, int checksumIntervalSeconds, int checksumSizeKibibytes)
{
stop();
#if defined(Q_OS_LINUX)
struct statfs statfsBuf;
bool forcePolling = false;
const auto NFS_SUPER_MAGIC = 0x6969;
if (!statfs(filePath.toLocal8Bit().constData(), &statfsBuf)) {
forcePolling = (statfsBuf.f_type == NFS_SUPER_MAGIC);
} else {
// if we can't get the fs type let's fall back to polling
forcePolling = true;
}
auto objectName = forcePolling ? QLatin1String("_qt_autotest_force_engine_poller") : QLatin1String("");
m_fileWatcher.setObjectName(objectName);
#endif
m_fileWatcher.addPath(filePath);
m_filePath = filePath;
// Handle file checksum
m_fileChecksumSizeBytes = checksumSizeKibibytes * 1024;
m_fileChecksum = calculateChecksum();
if (checksumIntervalSeconds > 0) {
m_fileChecksumTimer.start(checksumIntervalSeconds * 1000);
}
m_ignoreFileChange = false;
}
void FileWatcher::stop()
{
if (!m_filePath.isEmpty()) {
m_fileWatcher.removePath(m_filePath);
}
m_filePath.clear();
m_fileChecksum.clear();
m_fileChecksumTimer.stop();
m_fileChangeDelayTimer.stop();
}
void FileWatcher::pause()
{
m_ignoreFileChange = true;
m_fileChangeDelayTimer.stop();
}
void FileWatcher::resume()
{
m_ignoreFileChange = false;
// Add a short delay to start in the next event loop
if (!m_fileIgnoreDelayTimer.isActive()) {
m_fileIgnoreDelayTimer.start(0);
}
}
bool FileWatcher::shouldIgnoreChanges()
{
return m_filePath.isEmpty() || m_ignoreFileChange || m_fileIgnoreDelayTimer.isActive()
|| m_fileChangeDelayTimer.isActive();
}
bool FileWatcher::hasSameFileChecksum()
{
return calculateChecksum() == m_fileChecksum;
}
void FileWatcher::checkFileChanged()
{
if (shouldIgnoreChanges()) {
return;
}
// Prevent reentrance
m_ignoreFileChange = true;
AsyncTask::runThenCallback([=] { return calculateChecksum(); },
this,
[=](QByteArray checksum) {
if (checksum != m_fileChecksum) {
m_fileChecksum = checksum;
m_fileChangeDelayTimer.start(0);
}
m_ignoreFileChange = false;
});
}
QByteArray FileWatcher::calculateChecksum()
{
QFile file(m_filePath);
if (file.open(QFile::ReadOnly)) {
QCryptographicHash hash(QCryptographicHash::Sha256);
if (m_fileChecksumSizeBytes > 0) {
hash.addData(file.read(m_fileChecksumSizeBytes));
} else {
hash.addData(&file);
}
return hash.result();
}
// If we fail to open the file return the last known checksum, this
// prevents unnecessary merge requests on intermittent network shares
return m_fileChecksum;
}
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