412 lines
14 KiB
C++
412 lines
14 KiB
C++
/*
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SPDX-FileCopyrightText: 2017-2020 Andrius Štikonas <andrius@stikonas.eu>
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SPDX-FileCopyrightText: 2018 Huzaifa Faruqui <huzaifafaruqui@gmail.com>
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SPDX-FileCopyrightText: 2018 Caio Jordão Carvalho <caiojcarvalho@gmail.com>
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SPDX-FileCopyrightText: 2018-2019 Harald Sitter <sitter@kde.org>
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SPDX-FileCopyrightText: 2018 Simon Depiets <sdepiets@gmail.com>
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SPDX-FileCopyrightText: 2019 Shubham Jangra <aryan100jangid@gmail.com>
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SPDX-FileCopyrightText: 2020 David Edmundson <kde@davidedmundson.co.uk>
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SPDX-License-Identifier: GPL-3.0-or-later
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*/
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#include "externalcommandhelper.h"
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#include "externalcommand_whitelist.h"
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#include <filesystem>
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#include <QtDBus>
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#include <QCoreApplication>
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#include <QDebug>
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#include <QElapsedTimer>
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#include <QFile>
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#include <QString>
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#include <QVariant>
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#include <KLocalizedString>
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#include <PolkitQt1/Authority>
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#include <PolkitQt1/Subject>
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#include <polkitqt1-version.h>
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/** Initialize ExternalCommandHelper Daemon and prepare DBus interface
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*
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* This helper runs in the background until all applications using it exit.
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* If helper is not busy then it exits when the client services gets
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* unregistered. In case the client crashes, the helper waits
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* for the current job to finish before exiting, to avoid leaving partially moved data.
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*
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* This helper starts DBus interface where it listens to command execution requests.
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* New clients connecting to the helper have to authenticate using Polkit.
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*/
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ExternalCommandHelper::ExternalCommandHelper()
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{
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if (!QDBusConnection::systemBus().registerObject(QStringLiteral("/Helper"), this, QDBusConnection::ExportAllSlots | QDBusConnection::ExportAllSignals)) {
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::exit(-1);
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}
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if (!QDBusConnection::systemBus().registerService(QStringLiteral("org.kde.kpmcore.helperinterface"))) {
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::exit(-1);
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}
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// we know this service must be registered already as DBus policy blocks calls from anyone else
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m_serviceWatcher = new QDBusServiceWatcher(this);
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m_serviceWatcher->setConnection(QDBusConnection ::systemBus());
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m_serviceWatcher->setWatchMode(QDBusServiceWatcher::WatchForUnregistration);
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connect(m_serviceWatcher, &QDBusServiceWatcher::serviceUnregistered, qApp, [this](const QString &service) {
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m_serviceWatcher->removeWatchedService(service);
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if (m_serviceWatcher->watchedServices().isEmpty()) {
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qApp->quit();
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}
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});
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}
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/** Reads the given number of bytes from the sourceDevice into the given buffer.
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@param sourceDevice device or file to read from
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@param buffer buffer to store the bytes read in
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@param offset offset where to begin reading
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@param size the number of bytes to read
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@return true on success
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*/
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bool ExternalCommandHelper::readData(const QString& sourceDevice, QByteArray& buffer, const qint64 offset, const qint64 size)
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{
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QFile device(sourceDevice);
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if (!device.open(QIODevice::ReadOnly | QIODevice::Unbuffered)) {
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qCritical() << xi18n("Could not open device <filename>%1</filename> for reading.", sourceDevice);
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return false;
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}
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if (!device.seek(offset)) {
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qCritical() << xi18n("Could not seek position %1 on device <filename>%2</filename>.", offset, sourceDevice);
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return false;
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}
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buffer = device.read(size);
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if (size != buffer.size()) {
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qCritical() << xi18n("Could not read from device <filename>%1</filename>.", sourceDevice);
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return false;
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}
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return true;
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}
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/** Writes the data from buffer to a given device.
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@param targetDevice device or file to write to
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@param buffer the data that we write
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@param offset offset where to begin writing
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@return true on success
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*/
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bool ExternalCommandHelper::writeData(const QString &targetDevice, const QByteArray& buffer, const qint64 offset)
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{
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QFile device(targetDevice);
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auto flags = QIODevice::WriteOnly | QIODevice::Unbuffered;
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if (!device.open(flags)) {
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qCritical() << xi18n("Could not open device <filename>%1</filename> for writing.", targetDevice);
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return false;
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}
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if (!device.seek(offset)) {
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qCritical() << xi18n("Could not seek position %1 on device <filename>%2</filename>.", offset, targetDevice);
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return false;
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}
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if (device.write(buffer) != buffer.size()) {
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qCritical() << xi18n("Could not write to device <filename>%1</filename>.", targetDevice);
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return false;
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}
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return true;
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}
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/** Creates a new file with given contents.
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@param filePath file to write to
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@param fileContents the data that we write
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@return true on success
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*/
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bool ExternalCommandHelper::CreateFile(const QString &filePath, const QByteArray& fileContents)
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{
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if (!isCallerAuthorized()) {
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return false;
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}
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// Do not allow using this helper for writing to arbitrary location
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if ( !filePath.contains(QStringLiteral("/etc/fstab")) )
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return false;
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QFile device(filePath);
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auto flags = QIODevice::WriteOnly | QIODevice::Unbuffered;
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if (!device.open(flags)) {
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qCritical() << xi18n("Could not open file <filename>%1</filename> for writing.", filePath);
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return false;
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}
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if (device.write(fileContents) != fileContents.size()) {
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qCritical() << xi18n("Could not write to file <filename>%1</filename>.", filePath);
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return false;
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}
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return true;
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}
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// If targetDevice is empty then return QByteArray with data that was read from disk.
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QVariantMap ExternalCommandHelper::CopyBlocks(const QString& sourceDevice, const qint64 sourceOffset, const qint64 sourceLength, const QString& targetDevice, const qint64 targetOffset, const qint64 blockSize)
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{
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if (!isCallerAuthorized()) {
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return {};
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}
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// Avoid division by zero further down
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if (!blockSize) {
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return {};
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}
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// Prevent some out of memory situations
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if (blockSize > 100 * MiB) {
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return {};
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}
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QVariantMap reply;
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reply[QStringLiteral("success")] = true;
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// This enum specified whether individual blocks are moved left or right
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// When partition is moved to the left, we start with the leftmost block,
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// and move it further left, then second leftmost block and so on.
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// But when we move partition to the right, we start with rightmost block.
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// To account for this difference, we introduce CopyDirection variable which takes
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// care of some of the differences between these two cases.
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enum CopyDirection : qint8 {
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Left = 1,
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Right = -1,
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};
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qint8 copyDirection = targetOffset > sourceOffset ? CopyDirection::Right : CopyDirection::Left;
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// Let readOffset (r) and writeOffset (w) be the offsets of the first block that we move.
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// When we move data to the left:
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// ______target______ ______source______
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// r <- w=================
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qint64 readOffset = sourceOffset;
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qint64 writeOffset = targetOffset;
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// When we move data to the right, we start moving data from the last block
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// ______source______ ______target______
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// =================r -> w
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if (copyDirection == CopyDirection::Right) {
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readOffset = sourceOffset + sourceLength - blockSize;
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writeOffset = targetOffset + sourceLength - blockSize;
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}
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const qint64 blocksToCopy = sourceLength / blockSize;
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const qint64 lastBlock = sourceLength % blockSize;
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qint64 bytesWritten = 0;
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qint64 blocksCopied = 0;
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QByteArray buffer;
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int percent = 0;
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QElapsedTimer timer;
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timer.start();
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QString reportText = xi18nc("@info:progress", "Copying %1 blocks (%2 bytes) from %3 to %4, direction: %5.", blocksToCopy,
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sourceLength, readOffset, writeOffset, copyDirection == CopyDirection::Left ? i18nc("direction: left", "left")
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: i18nc("direction: right", "right"));
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Q_EMIT report(reportText);
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bool rval = true;
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while (blocksCopied < blocksToCopy) {
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if (!(rval = readData(sourceDevice, buffer, readOffset + blockSize * blocksCopied * copyDirection, blockSize)))
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break;
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if (!(rval = writeData(targetDevice, buffer, writeOffset + blockSize * blocksCopied * copyDirection)))
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break;
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bytesWritten += buffer.size();
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if (++blocksCopied * 100 / blocksToCopy != percent) {
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percent = blocksCopied * 100 / blocksToCopy;
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if (percent % 5 == 0 && timer.elapsed() > 1000) {
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const qint64 mibsPerSec = (blocksCopied * blockSize / 1024 / 1024) / (timer.elapsed() / 1000);
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const qint64 estSecsLeft = (100 - percent) * timer.elapsed() / percent / 1000;
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reportText = xi18nc("@info:progress", "Copying %1 MiB/second, estimated time left: %2", mibsPerSec, QTime(0, 0).addSecs(estSecsLeft).toString());
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Q_EMIT report(reportText);
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}
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Q_EMIT progress(percent);
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}
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}
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// copy the remainder
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if (rval && lastBlock > 0) {
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Q_ASSERT(lastBlock < blockSize);
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const qint64 lastBlockReadOffset = copyDirection == CopyDirection::Left ? readOffset + blockSize * blocksCopied : sourceOffset;
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const qint64 lastBlockWriteOffset = copyDirection == CopyDirection::Left ? writeOffset + blockSize * blocksCopied : targetOffset;
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reportText = xi18nc("@info:progress", "Copying remainder of block size %1 from %2 to %3.", lastBlock, lastBlockReadOffset, lastBlockWriteOffset);
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Q_EMIT report(reportText);
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rval = readData(sourceDevice, buffer, lastBlockReadOffset, lastBlock);
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if (rval) {
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rval = writeData(targetDevice, buffer, lastBlockWriteOffset);
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}
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if (rval) {
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Q_EMIT progress(100);
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bytesWritten += buffer.size();
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}
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}
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reportText = xi18ncp("@info:progress argument 2 is a string such as 7 bytes (localized accordingly)", "Copying 1 block (%2) finished.", "Copying %1 blocks (%2) finished.", blocksCopied, i18np("1 byte", "%1 bytes", bytesWritten));
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Q_EMIT report(reportText);
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reply[QStringLiteral("success")] = rval;
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return reply;
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}
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QByteArray ExternalCommandHelper::ReadData(const QString& device, const qint64 offset, const qint64 length)
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{
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if (!isCallerAuthorized()) {
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return {};
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}
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if (length > MiB) {
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return {};
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}
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if (!std::filesystem::is_block_file(device.toStdString())) {
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qWarning() << "Not a block device";
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return {};
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}
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QByteArray buffer;
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bool rval = readData(device, buffer, offset, length);
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if (rval) {
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return buffer;
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}
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return QByteArray();
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}
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bool ExternalCommandHelper::WriteData(const QByteArray& buffer, const QString& targetDevice, const qint64 targetOffset)
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{
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if (!isCallerAuthorized()) {
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return false;
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}
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// Do not allow using this helper for writing to arbitrary location
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if ( targetDevice.left(5) != QStringLiteral("/dev/") )
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return false;
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return writeData(targetDevice, buffer, targetOffset);
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}
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QVariantMap ExternalCommandHelper::RunCommand(const QString& command, const QStringList& arguments, const QByteArray& input, const int processChannelMode)
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{
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if (!isCallerAuthorized()) {
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return {};
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}
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QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
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QVariantMap reply;
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reply[QStringLiteral("success")] = true;
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if (command.isEmpty()) {
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reply[QStringLiteral("success")] = false;
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return reply;
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}
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// Compare with command whitelist
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QString basename = command.mid(command.lastIndexOf(QLatin1Char('/')) + 1);
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if (allowedCommands.find(basename) == allowedCommands.end()) { // TODO: C++20: replace with contains
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qInfo() << command <<" command is not one of the whitelisted command";
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reply[QStringLiteral("success")] = false;
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return reply;
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}
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// connect(&cmd, &QProcess::readyReadStandardOutput, this, &ExternalCommandHelper::onReadOutput);
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QProcess cmd;
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cmd.setEnvironment( { QStringLiteral("LVM_SUPPRESS_FD_WARNINGS=1") } );
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cmd.setProcessChannelMode(static_cast<QProcess::ProcessChannelMode>(processChannelMode));
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cmd.start(command, arguments);
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cmd.write(input);
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cmd.closeWriteChannel();
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cmd.waitForFinished(-1);
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QByteArray output = cmd.readAllStandardOutput();
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reply[QStringLiteral("output")] = output;
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reply[QStringLiteral("exitCode")] = cmd.exitCode();
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return reply;
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}
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void ExternalCommandHelper::onReadOutput()
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{
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/* const QByteArray s = cmd.readAllStandardOutput();
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if(output.length() > 10*1024*1024) { // prevent memory overflow for badly corrupted file systems
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if (report())
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report()->line() << xi18nc("@info:status", "(Command is printing too much output)");
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return;
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}
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output += s;
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if (report())
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*report() << QString::fromLocal8Bit(s);*/
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}
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bool ExternalCommandHelper::isCallerAuthorized()
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{
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if (!calledFromDBus()) {
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return false;
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}
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// Cache successful authentication requests, so that clients don't need
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// to authenticate multiple times during long partitioning operations.
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// auth_admin_keep is not used intentionally because with current architecture
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// it might lead to data loss if user cancels sfdisk partition boundary adjustment
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// after partition data was moved.
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if (m_serviceWatcher->watchedServices().contains(message().service())) {
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return true;
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}
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PolkitQt1::SystemBusNameSubject subject(message().service());
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PolkitQt1::Authority *authority = PolkitQt1::Authority::instance();
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PolkitQt1::Authority::Result result;
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QEventLoop e;
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connect(authority, &PolkitQt1::Authority::checkAuthorizationFinished, &e, [&e, &result](PolkitQt1::Authority::Result _result) {
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result = _result;
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e.quit();
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});
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authority->checkAuthorization(QStringLiteral("org.kde.kpmcore.externalcommand.init"), subject, PolkitQt1::Authority::AllowUserInteraction);
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e.exec();
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if (authority->hasError()) {
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qDebug() << "Encountered error while checking authorization, error code:" << authority->lastError() << authority->errorDetails();
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authority->clearError();
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}
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switch (result) {
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case PolkitQt1::Authority::Yes:
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// track who called into us so we can close when all callers have gone away
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m_serviceWatcher->addWatchedService(message().service());
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return true;
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default:
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sendErrorReply(QDBusError::AccessDenied);
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if (m_serviceWatcher->watchedServices().isEmpty())
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qApp->quit();
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return false;
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}
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}
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int main(int argc, char ** argv)
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{
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QCoreApplication app(argc, argv);
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ExternalCommandHelper helper;
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app.exec();
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}
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