previewjob.cpp

// -*- c++ -*-
/*
    This file is part of the KDE libraries
    SPDX-FileCopyrightText: 2000 David Faure <faure@kde.org>
    SPDX-FileCopyrightText: 2000 Carsten Pfeiffer <pfeiffer@kde.org>
    SPDX-FileCopyrightText: 2001 Malte Starostik <malte.starostik@t-online.de>
 
    SPDX-License-Identifier: LGPL-2.0-or-later
*/
 
#include "previewjob.h"
#include "filecopyjob.h"
#include "kiogui_debug.h"
#include "statjob.h"
 
#if defined(Q_OS_UNIX) && !defined(Q_OS_ANDROID)
#define WITH_SHM 1
#else
#define WITH_SHM 0
#endif
 
#if WITH_SHM
#include <sys/ipc.h>
#include <sys/shm.h>
#endif
 
#include <algorithm>
#include <limits>
 
#include <QDir>
#include <QFile>
#include <QImage>
#include <QPixmap>
#include <QRegularExpression>
#include <QSaveFile>
#include <QTemporaryFile>
#include <QTimer>
 
#include <QCryptographicHash>
 
#include <KConfigGroup>
#include <KMountPoint>
#include <KPluginMetaData>
#include <KService>
#include <KSharedConfig>
#include <QMimeDatabase>
#include <QStandardPaths>
#include <Solid/Device>
#include <Solid/StorageAccess>
#include <kprotocolinfo.h>
 
#include "job_p.h"
 
namespace
{
static qreal s_defaultDevicePixelRatio = 1.0;
}
 
namespace KIO
{
struct PreviewItem;
}
using namespace KIO;
 
struct KIO::PreviewItem {
    KFileItem item;
    KPluginMetaData plugin;
};
 
class KIO::PreviewJobPrivate : public KIO::JobPrivate
{
public:
    PreviewJobPrivate(const KFileItemList &items, const QSize &size)
        : initialItems(items)
        , width(size.width())
        , height(size.height())
        , cacheSize(0)
        , bScale(true)
        , bSave(true)
        , ignoreMaximumSize(false)
        , sequenceIndex(0)
        , succeeded(false)
        , maximumLocalSize(0)
        , maximumRemoteSize(0)
        , enableRemoteFolderThumbnail(false)
        , shmid(-1)
        , shmaddr(nullptr)
    {
        // https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html#DIRECTORY
        thumbRoot = QStandardPaths::writableLocation(QStandardPaths::GenericCacheLocation) + QLatin1String("/thumbnails/");
    }
 
    enum {
        STATE_STATORIG, // if the thumbnail exists
        STATE_GETORIG, // if we create it
        STATE_CREATETHUMB, // thumbnail:/ worker
        STATE_DEVICE_INFO, // additional state check to get needed device ids
    } state;
 
    KFileItemList initialItems;
    QStringList enabledPlugins;
    // Some plugins support remote URLs, <protocol, mimetypes>
    QHash<QString, QStringList> m_remoteProtocolPlugins;
    // Our todo list :)
    // We remove the first item at every step, so use std::list
    std::list<PreviewItem> items;
    // The current item
    PreviewItem currentItem;
    // The modification time of that URL
    QDateTime tOrig;
    // Path to thumbnail cache for the current size
    QString thumbPath;
    // Original URL of current item in RFC2396 format
    // (file:///path/to/a%20file instead of file:/path/to/a file)
    QByteArray origName;
    // Thumbnail file name for current item
    QString thumbName;
    // Size of thumbnail
    int width;
    int height;
    // Unscaled size of thumbnail (128, 256 or 512 if cache is enabled)
    short cacheSize;
    // Whether the thumbnail should be scaled
    bool bScale;
    // Whether we should save the thumbnail
    bool bSave;
    bool ignoreMaximumSize;
    int sequenceIndex;
    bool succeeded;
    // If the file to create a thumb for was a temp file, this is its name
    QString tempName;
    KIO::filesize_t maximumLocalSize;
    KIO::filesize_t maximumRemoteSize;
    // Manage preview for locally mounted remote directories
    bool enableRemoteFolderThumbnail;
    // Shared memory segment Id. The segment is allocated to a size
    // of extent x extent x 4 (32 bit image) on first need.
    int shmid;
    // And the data area
    uchar *shmaddr;
    // Size of the shm segment
    size_t shmsize;
    // Root of thumbnail cache
    QString thumbRoot;
    // Metadata returned from the KIO thumbnail worker
    QMap<QString, QString> thumbnailWorkerMetaData;
    qreal devicePixelRatio = s_defaultDevicePixelRatio;
    static const int idUnknown = -1;
    // Id of a device storing currently processed file
    int currentDeviceId = 0;
    // Device ID for each file. Stored while in STATE_DEVICE_INFO state, used later on.
    QMap<QString, int> deviceIdMap;
    enum CachePolicy { Prevent, Allow, Unknown } currentDeviceCachePolicy = Unknown;
 
    void getOrCreateThumbnail();
    bool statResultThumbnail();
    void createThumbnail(const QString &);
    void cleanupTempFile();
    void determineNextFile();
    void emitPreview(const QImage &thumb);
 
    void startPreview();
    void slotThumbData(KIO::Job *, const QByteArray &);
    // Checks if thumbnail is on encrypted partition different than thumbRoot
    CachePolicy canBeCached(const QString &path);
    int getDeviceId(const QString &path);
 
    Q_DECLARE_PUBLIC(PreviewJob)
 
    static QList<KPluginMetaData> loadAvailablePlugins()
    {
        static QList<KPluginMetaData> jsonMetaDataPlugins;
        if (jsonMetaDataPlugins.isEmpty()) {
            jsonMetaDataPlugins = KPluginMetaData::findPlugins(QStringLiteral("kf6/thumbcreator"));
        }
        return jsonMetaDataPlugins;
    }
};
 
void PreviewJob::setDefaultDevicePixelRatio(qreal defaultDevicePixelRatio)
{
    s_defaultDevicePixelRatio = defaultDevicePixelRatio;
}
 
PreviewJob::PreviewJob(const KFileItemList &items, const QSize &size, const QStringList *enabledPlugins)
    : KIO::Job(*new PreviewJobPrivate(items, size))
{
    Q_D(PreviewJob);
 
    if (enabledPlugins) {
        d->enabledPlugins = *enabledPlugins;
    } else {
        const KConfigGroup globalConfig(KSharedConfig::openConfig(), QStringLiteral("PreviewSettings"));
        d->enabledPlugins =
            globalConfig.readEntry("Plugins",
                                   QStringList{QStringLiteral("directorythumbnail"), QStringLiteral("imagethumbnail"), QStringLiteral("jpegthumbnail")});
    }
 
    // Return to event loop first, determineNextFile() might delete this;
    QTimer::singleShot(0, this, [d]() {
        d->startPreview();
    });
}
 
PreviewJob::~PreviewJob()
{
#if WITH_SHM
    Q_D(PreviewJob);
    if (d->shmaddr) {
        shmdt((char *)d->shmaddr);
        shmctl(d->shmid, IPC_RMID, nullptr);
    }
#endif
}
 
void PreviewJob::setScaleType(ScaleType type)
{
    Q_D(PreviewJob);
    switch (type) {
    case Unscaled:
        d->bScale = false;
        d->bSave = false;
        break;
    case Scaled:
        d->bScale = true;
        d->bSave = false;
        break;
    case ScaledAndCached:
        d->bScale = true;
        d->bSave = true;
        break;
    default:
        break;
    }
}
 
PreviewJob::ScaleType PreviewJob::scaleType() const
{
    Q_D(const PreviewJob);
    if (d->bScale) {
        return d->bSave ? ScaledAndCached : Scaled;
    }
    return Unscaled;
}
 
void PreviewJobPrivate::startPreview()
{
    Q_Q(PreviewJob);
    // Load the list of plugins to determine which MIME types are supported
    const QList<KPluginMetaData> plugins = KIO::PreviewJobPrivate::loadAvailablePlugins();
    QMap<QString, KPluginMetaData> mimeMap;
    QHash<QString, QHash<QString, KPluginMetaData>> protocolMap;
 
    for (const KPluginMetaData &plugin : plugins) {
        QStringList protocols = plugin.value(QStringLiteral("X-KDE-Protocols"), QStringList());
        const QString p = plugin.value(QStringLiteral("X-KDE-Protocol"));
        if (!p.isEmpty()) {
            protocols.append(p);
        }
        for (const QString &protocol : std::as_const(protocols)) {
            // Add supported MIME type for this protocol
            QStringList &_ms = m_remoteProtocolPlugins[protocol];
            const auto mimeTypes = plugin.mimeTypes();
            for (const QString &_m : mimeTypes) {
                protocolMap[protocol].insert(_m, plugin);
                if (!_ms.contains(_m)) {
                    _ms.append(_m);
                }
            }
        }
        if (enabledPlugins.contains(plugin.pluginId())) {
            const auto mimeTypes = plugin.mimeTypes();
            for (const QString &mimeType : mimeTypes) {
                mimeMap.insert(mimeType, plugin);
            }
        }
    }
 
    // Look for images and store the items in our todo list :)
    bool bNeedCache = false;
    for (const auto &fileItem : std::as_const(initialItems)) {
        PreviewItem item;
        item.item = fileItem;
 
        const QString mimeType = item.item.mimetype();
        KPluginMetaData plugin;
 
        // look for protocol-specific thumbnail plugins first
        auto it = protocolMap.constFind(item.item.url().scheme());
        if (it != protocolMap.constEnd()) {
            plugin = it.value().value(mimeType);
        }
 
        if (!plugin.isValid()) {
            auto pluginIt = mimeMap.constFind(mimeType);
            if (pluginIt == mimeMap.constEnd()) {
                // check MIME type inheritance, resolve aliases
                QMimeDatabase db;
                const QMimeType mimeInfo = db.mimeTypeForName(mimeType);
                if (mimeInfo.isValid()) {
                    const QStringList parentMimeTypes = mimeInfo.allAncestors();
                    for (const QString &parentMimeType : parentMimeTypes) {
                        pluginIt = mimeMap.constFind(parentMimeType);
                        if (pluginIt != mimeMap.constEnd()) {
                            break;
                        }
                    }
                }
 
                if (pluginIt == mimeMap.constEnd()) {
                    // Check the wildcards last, see BUG 453480
                    QString groupMimeType = mimeType;
                    const int slashIdx = groupMimeType.indexOf(QLatin1Char('/'));
                    if (slashIdx != -1) {
                        // Replace everything after '/' with '*'
                        groupMimeType.truncate(slashIdx + 1);
                        groupMimeType += QLatin1Char('*');
                    }
                    pluginIt = mimeMap.constFind(groupMimeType);
                }
            }
 
            if (pluginIt != mimeMap.constEnd()) {
                plugin = *pluginIt;
            }
        }
 
        if (plugin.isValid()) {
            item.plugin = plugin;
            items.push_back(item);
            if (!bNeedCache && bSave && plugin.value(QStringLiteral("CacheThumbnail"), true)) {
                const QUrl url = fileItem.targetUrl();
                if (!url.isLocalFile() || !url.adjusted(QUrl::RemoveFilename).toLocalFile().startsWith(thumbRoot)) {
                    bNeedCache = true;
                }
            }
        } else {
            Q_EMIT q->failed(fileItem);
        }
    }
 
    KConfigGroup cg(KSharedConfig::openConfig(), QStringLiteral("PreviewSettings"));
    maximumLocalSize = cg.readEntry("MaximumSize", std::numeric_limits<KIO::filesize_t>::max());
    maximumRemoteSize = cg.readEntry<KIO::filesize_t>("MaximumRemoteSize", 0);
    enableRemoteFolderThumbnail = cg.readEntry("EnableRemoteFolderThumbnail", false);
 
    if (bNeedCache) {
        const int longer = std::max(width, height);
        if (longer <= 128) {
            cacheSize = 128;
        } else if (longer <= 256) {
            cacheSize = 256;
        } else if (longer <= 512) {
            cacheSize = 512;
        } else {
            cacheSize = 1024;
        }
 
        struct CachePool {
            QString path;
            int minSize;
        };
 
        const static auto pools = {
            CachePool{QStringLiteral("/normal/"), 128},
            CachePool{QStringLiteral("/large/"), 256},
            CachePool{QStringLiteral("/x-large/"), 512},
            CachePool{QStringLiteral("/xx-large/"), 1024},
        };
 
        QString thumbDir;
        int wants = devicePixelRatio * cacheSize;
        for (const auto &p : pools) {
            if (p.minSize < wants) {
                continue;
            } else {
                thumbDir = p.path;
                break;
            }
        }
        thumbPath = thumbRoot + thumbDir;
 
        if (!QDir(thumbPath).exists()) {
            if (QDir().mkpath(thumbPath)) { // Qt5 TODO: mkpath(dirPath, permissions)
                QFile f(thumbPath);
                f.setPermissions(QFile::ReadUser | QFile::WriteUser | QFile::ExeUser); // 0700
            }
        }
    } else {
        bSave = false;
    }
 
    initialItems.clear();
    determineNextFile();
}
 
void PreviewJob::removeItem(const QUrl &url)
{
    Q_D(PreviewJob);
 
    auto it = std::find_if(d->items.cbegin(), d->items.cend(), [&url](const PreviewItem &pItem) {
        return url == pItem.item.url();
    });
    if (it != d->items.cend()) {
        d->items.erase(it);
    }
 
    if (d->currentItem.item.url() == url) {
        KJob *job = subjobs().first();
        job->kill();
        removeSubjob(job);
        d->determineNextFile();
    }
}
 
void KIO::PreviewJob::setSequenceIndex(int index)
{
    d_func()->sequenceIndex = index;
}
 
int KIO::PreviewJob::sequenceIndex() const
{
    return d_func()->sequenceIndex;
}
 
float KIO::PreviewJob::sequenceIndexWraparoundPoint() const
{
    return d_func()->thumbnailWorkerMetaData.value(QStringLiteral("sequenceIndexWraparoundPoint"), QStringLiteral("-1.0")).toFloat();
}
 
bool KIO::PreviewJob::handlesSequences() const
{
    return d_func()->thumbnailWorkerMetaData.value(QStringLiteral("handlesSequences")) == QStringLiteral("1");
}
 
void KIO::PreviewJob::setDevicePixelRatio(qreal dpr)
{
    d_func()->devicePixelRatio = dpr;
}
 
void PreviewJob::setIgnoreMaximumSize(bool ignoreSize)
{
    d_func()->ignoreMaximumSize = ignoreSize;
}
 
void PreviewJobPrivate::cleanupTempFile()
{
    if (!tempName.isEmpty()) {
        Q_ASSERT((!QFileInfo(tempName).isDir() && QFileInfo(tempName).isFile()) || QFileInfo(tempName).isSymLink());
        QFile::remove(tempName);
        tempName.clear();
    }
}
 
void PreviewJobPrivate::determineNextFile()
{
    Q_Q(PreviewJob);
    if (!currentItem.item.isNull()) {
        if (!succeeded) {
            Q_EMIT q->failed(currentItem.item);
        }
    }
    // No more items ?
    if (items.empty()) {
        q->emitResult();
        return;
    } else {
        // First, stat the orig file
        state = PreviewJobPrivate::STATE_STATORIG;
        currentItem = items.front();
        items.pop_front();
        succeeded = false;
        KIO::Job *job = KIO::stat(currentItem.item.targetUrl(), StatJob::SourceSide, KIO::StatDefaultDetails | KIO::StatInode, KIO::HideProgressInfo);
        job->addMetaData(QStringLiteral("thumbnail"), QStringLiteral("1"));
        job->addMetaData(QStringLiteral("no-auth-prompt"), QStringLiteral("true"));
        q->addSubjob(job);
    }
}
 
void PreviewJob::slotResult(KJob *job)
{
    Q_D(PreviewJob);
 
    removeSubjob(job);
    Q_ASSERT(!hasSubjobs()); // We should have only one job at a time ...
    switch (d->state) {
    case PreviewJobPrivate::STATE_STATORIG: {
        if (job->error()) { // that's no good news...
            // Drop this one and move on to the next one
            d->determineNextFile();
            return;
        }
        const KIO::UDSEntry statResult = static_cast<KIO::StatJob *>(job)->statResult();
        d->currentDeviceId = statResult.numberValue(KIO::UDSEntry::UDS_DEVICE_ID, 0);
        d->tOrig = QDateTime::fromSecsSinceEpoch(statResult.numberValue(KIO::UDSEntry::UDS_MODIFICATION_TIME, 0));
 
        bool skipCurrentItem = false;
        const KIO::filesize_t size = (KIO::filesize_t)statResult.numberValue(KIO::UDSEntry::UDS_SIZE, 0);
        const QUrl itemUrl = d->currentItem.item.mostLocalUrl();
 
        if ((itemUrl.isLocalFile() || KProtocolInfo::protocolClass(itemUrl.scheme()) == QLatin1String(":local")) && !d->currentItem.item.isSlow()) {
            skipCurrentItem = !d->ignoreMaximumSize && size > d->maximumLocalSize && !d->currentItem.plugin.value(QStringLiteral("IgnoreMaximumSize"), false);
        } else {
            // For remote items the "IgnoreMaximumSize" plugin property is not respected
            // Also we need to check if remote (but locally mounted) folder preview is enabled
            skipCurrentItem = (!d->ignoreMaximumSize && size > d->maximumRemoteSize) || (d->currentItem.item.isDir() && !d->enableRemoteFolderThumbnail);
        }
        if (skipCurrentItem) {
            d->determineNextFile();
            return;
        }
 
        bool pluginHandlesSequences = d->currentItem.plugin.value(QStringLiteral("HandleSequences"), false);
        if (!d->currentItem.plugin.value(QStringLiteral("CacheThumbnail"), true) || (d->sequenceIndex && pluginHandlesSequences)) {
            // This preview will not be cached, no need to look for a saved thumbnail
            // Just create it, and be done
            d->getOrCreateThumbnail();
            return;
        }
 
        if (d->statResultThumbnail()) {
            return;
        }
 
        d->getOrCreateThumbnail();
        return;
    }
    case PreviewJobPrivate::STATE_DEVICE_INFO: {
        KIO::StatJob *statJob = static_cast<KIO::StatJob *>(job);
        int id;
        QString path = statJob->url().toLocalFile();
        if (job->error()) {
            // We set id to 0 to know we tried getting it
            qCWarning(KIO_GUI) << "Cannot read information about filesystem under path" << path;
            id = 0;
        } else {
            id = statJob->statResult().numberValue(KIO::UDSEntry::UDS_DEVICE_ID, 0);
        }
        d->deviceIdMap[path] = id;
        d->createThumbnail(d->currentItem.item.localPath());
        return;
    }
    case PreviewJobPrivate::STATE_GETORIG: {
        if (job->error()) {
            d->cleanupTempFile();
            d->determineNextFile();
            return;
        }
 
        d->createThumbnail(static_cast<KIO::FileCopyJob *>(job)->destUrl().toLocalFile());
        return;
    }
    case PreviewJobPrivate::STATE_CREATETHUMB: {
        d->cleanupTempFile();
        d->determineNextFile();
        return;
    }
    }
}
 
bool PreviewJobPrivate::statResultThumbnail()
{
    if (thumbPath.isEmpty()) {
        return false;
    }
 
    bool isLocal;
    const QUrl url = currentItem.item.mostLocalUrl(&isLocal);
    if (isLocal) {
        const QFileInfo localFile(url.toLocalFile());
        const QString canonicalPath = localFile.canonicalFilePath();
        origName = QUrl::fromLocalFile(canonicalPath).toEncoded(QUrl::RemovePassword | QUrl::FullyEncoded);
        if (origName.isEmpty()) {
            qCWarning(KIO_GUI) << "Failed to convert" << url << "to canonical path";
            return false;
        }
    } else {
        // Don't include the password if any
        origName = currentItem.item.targetUrl().toEncoded(QUrl::RemovePassword);
    }
 
    QCryptographicHash md5(QCryptographicHash::Md5);
    md5.addData(origName);
    thumbName = QString::fromLatin1(md5.result().toHex()) + QLatin1String(".png");
 
    QImage thumb;
    QFile thumbFile(thumbPath + thumbName);
    if (!thumbFile.open(QIODevice::ReadOnly) || !thumb.load(&thumbFile, "png")) {
        return false;
    }
 
    if (thumb.text(QStringLiteral("Thumb::URI")) != QString::fromUtf8(origName)
        || thumb.text(QStringLiteral("Thumb::MTime")).toLongLong() != tOrig.toSecsSinceEpoch()) {
        return false;
    }
 
    const QString origSize = thumb.text(QStringLiteral("Thumb::Size"));
    if (!origSize.isEmpty() && origSize.toULongLong() != currentItem.item.size()) {
        // Thumb::Size is not required, but if it is set it should match
        return false;
    }
 
    // The DPR of the loaded thumbnail is unspecified (and typically irrelevant).
    // When a thumbnail is DPR-invariant, use the DPR passed in the request.
    thumb.setDevicePixelRatio(devicePixelRatio);
 
    QString thumbnailerVersion = currentItem.plugin.value(QStringLiteral("ThumbnailerVersion"));
 
    if (!thumbnailerVersion.isEmpty() && thumb.text(QStringLiteral("Software")).startsWith(QLatin1String("KDE Thumbnail Generator"))) {
        // Check if the version matches
        // The software string should read "KDE Thumbnail Generator pluginName (vX)"
        QString softwareString = thumb.text(QStringLiteral("Software")).remove(QStringLiteral("KDE Thumbnail Generator")).trimmed();
        if (softwareString.isEmpty()) {
            // The thumbnail has been created with an older version, recreating
            return false;
        }
        int versionIndex = softwareString.lastIndexOf(QLatin1String("(v"));
        if (versionIndex < 0) {
            return false;
        }
 
        QString cachedVersion = softwareString.remove(0, versionIndex + 2);
        cachedVersion.chop(1);
        uint thumbnailerMajor = thumbnailerVersion.toInt();
        uint cachedMajor = cachedVersion.toInt();
        if (thumbnailerMajor > cachedMajor) {
            return false;
        }
    }
 
    // Found it, use it
    emitPreview(thumb);
    succeeded = true;
    determineNextFile();
    return true;
}
 
void PreviewJobPrivate::getOrCreateThumbnail()
{
    Q_Q(PreviewJob);
    // We still need to load the orig file ! (This is getting tedious) :)
    const KFileItem &item = currentItem.item;
    const QString localPath = item.localPath();
    if (!localPath.isEmpty()) {
        createThumbnail(localPath);
        return;
    }
 
    // heuristics for remote URL support
    const QUrl fileUrl = item.targetUrl();
    bool supportsProtocol = false;
    if (m_remoteProtocolPlugins.value(fileUrl.scheme()).contains(item.mimetype())) {
        // There's a plugin supporting this protocol and MIME type
        supportsProtocol = true;
    } else if (m_remoteProtocolPlugins.value(QStringLiteral("KIO")).contains(item.mimetype())) {
        // Assume KIO understands any URL, ThumbCreator workers who have
        // X-KDE-Protocols=KIO will get fed the remote URL directly.
        supportsProtocol = true;
    }
 
    if (supportsProtocol) {
        createThumbnail(fileUrl.toString());
        return;
    }
    if (item.isDir()) {
        // Skip remote dirs (bug 208625)
        cleanupTempFile();
        determineNextFile();
        return;
    }
    // No plugin support access to this remote content, copy the file
    // to the local machine, then create the thumbnail
    state = PreviewJobPrivate::STATE_GETORIG;
    QTemporaryFile localFile;
 
    // Some thumbnailers, like libkdcraw, depend on the file extension being
    // correct
    const QString extension = item.suffix();
    if (!extension.isEmpty()) {
        localFile.setFileTemplate(QStringLiteral("%1.%2").arg(localFile.fileTemplate(), extension));
    }
 
    localFile.setAutoRemove(false);
    localFile.open();
    tempName = localFile.fileName();
    const QUrl currentURL = item.mostLocalUrl();
    KIO::Job *job = KIO::file_copy(currentURL, QUrl::fromLocalFile(tempName), -1, KIO::Overwrite | KIO::HideProgressInfo /* No GUI */);
    job->addMetaData(QStringLiteral("thumbnail"), QStringLiteral("1"));
    q->addSubjob(job);
}
 
PreviewJobPrivate::CachePolicy PreviewJobPrivate::canBeCached(const QString &path)
{
    // If checked file is directory on a different filesystem than its parent, we need to check it separately
    int separatorIndex = path.lastIndexOf(QLatin1Char('/'));
    // special case for root folders
    const QString parentDirPath = separatorIndex == 0 ? path : path.left(separatorIndex);
 
    int parentId = getDeviceId(parentDirPath);
    if (parentId == idUnknown) {
        return CachePolicy::Unknown;
    }
 
    bool isDifferentSystem = !parentId || parentId != currentDeviceId;
    if (!isDifferentSystem && currentDeviceCachePolicy != CachePolicy::Unknown) {
        return currentDeviceCachePolicy;
    }
    int checkedId;
    QString checkedPath;
    if (isDifferentSystem) {
        checkedId = currentDeviceId;
        checkedPath = path;
    } else {
        checkedId = getDeviceId(parentDirPath);
        checkedPath = parentDirPath;
        if (checkedId == idUnknown) {
            return CachePolicy::Unknown;
        }
    }
    // If we're checking different filesystem or haven't checked yet see if filesystem matches thumbRoot
    int thumbRootId = getDeviceId(thumbRoot);
    if (thumbRootId == idUnknown) {
        return CachePolicy::Unknown;
    }
    bool shouldAllow = checkedId && checkedId == thumbRootId;
    if (!shouldAllow) {
        Solid::Device device = Solid::Device::storageAccessFromPath(checkedPath);
        if (device.isValid()) {
            // If the checked device is encrypted, allow thumbnailing if the thumbnails are stored in an encrypted location.
            // Or, if the checked device is unencrypted, allow thumbnailing.
            if (device.as<Solid::StorageAccess>()->isEncrypted()) {
                const Solid::Device thumbRootDevice = Solid::Device::storageAccessFromPath(thumbRoot);
                shouldAllow = thumbRootDevice.isValid() && thumbRootDevice.as<Solid::StorageAccess>()->isEncrypted();
            } else {
                shouldAllow = true;
            }
        }
    }
    if (!isDifferentSystem) {
        currentDeviceCachePolicy = shouldAllow ? CachePolicy::Allow : CachePolicy::Prevent;
    }
    return shouldAllow ? CachePolicy::Allow : CachePolicy::Prevent;
}
 
int PreviewJobPrivate::getDeviceId(const QString &path)
{
    Q_Q(PreviewJob);
    auto iter = deviceIdMap.find(path);
    if (iter != deviceIdMap.end()) {
        return iter.value();
    }
    QUrl url = QUrl::fromLocalFile(path);
    if (!url.isValid()) {
        qCWarning(KIO_GUI) << "Could not get device id for file preview, Invalid url" << path;
        return 0;
    }
    state = PreviewJobPrivate::STATE_DEVICE_INFO;
    KIO::Job *job = KIO::stat(url, StatJob::SourceSide, KIO::StatDefaultDetails | KIO::StatInode, KIO::HideProgressInfo);
    job->addMetaData(QStringLiteral("no-auth-prompt"), QStringLiteral("true"));
    q->addSubjob(job);
 
    return idUnknown;
}
 
void PreviewJobPrivate::createThumbnail(const QString &pixPath)
{
    Q_Q(PreviewJob);
    state = PreviewJobPrivate::STATE_CREATETHUMB;
    QUrl thumbURL;
    thumbURL.setScheme(QStringLiteral("thumbnail"));
    thumbURL.setPath(pixPath);
 
    bool save = bSave && currentItem.plugin.value(QStringLiteral("CacheThumbnail"), true) && !sequenceIndex;
 
    bool isRemoteProtocol = currentItem.item.localPath().isEmpty();
    CachePolicy cachePolicy = isRemoteProtocol ? CachePolicy::Prevent : canBeCached(pixPath);
 
    if (cachePolicy == CachePolicy::Unknown) {
        // If Unknown is returned, creating thumbnail should be called again by slotResult
        return;
    }
 
    KIO::TransferJob *job = KIO::get(thumbURL, NoReload, HideProgressInfo);
    q->addSubjob(job);
    q->connect(job, &KIO::TransferJob::data, q, [this](KIO::Job *job, const QByteArray &data) {
        slotThumbData(job, data);
    });
 
    int thumb_width = width;
    int thumb_height = height;
    if (save) {
        thumb_width = thumb_height = cacheSize;
    }
 
    job->addMetaData(QStringLiteral("mimeType"), currentItem.item.mimetype());
    job->addMetaData(QStringLiteral("width"), QString::number(thumb_width));
    job->addMetaData(QStringLiteral("height"), QString::number(thumb_height));
    job->addMetaData(QStringLiteral("plugin"), currentItem.plugin.fileName());
    job->addMetaData(QStringLiteral("enabledPlugins"), enabledPlugins.join(QLatin1Char(',')));
    job->addMetaData(QStringLiteral("devicePixelRatio"), QString::number(devicePixelRatio));
    job->addMetaData(QStringLiteral("cache"), QString::number(cachePolicy == CachePolicy::Allow));
    if (sequenceIndex) {
        job->addMetaData(QStringLiteral("sequence-index"), QString::number(sequenceIndex));
    }
 
#if WITH_SHM
    size_t requiredSize = thumb_width * devicePixelRatio * thumb_height * devicePixelRatio * 4;
    if (shmid == -1 || shmsize < requiredSize) {
        if (shmaddr) {
            // clean previous shared memory segment
            shmdt((char *)shmaddr);
            shmaddr = nullptr;
            shmctl(shmid, IPC_RMID, nullptr);
            shmid = -1;
        }
        if (requiredSize > 0) {
            shmid = shmget(IPC_PRIVATE, requiredSize, IPC_CREAT | 0600);
            if (shmid != -1) {
                shmsize = requiredSize;
                shmaddr = (uchar *)(shmat(shmid, nullptr, SHM_RDONLY));
                if (shmaddr == (uchar *)-1) {
                    shmctl(shmid, IPC_RMID, nullptr);
                    shmaddr = nullptr;
                    shmid = -1;
                }
            }
        }
    }
    if (shmid != -1) {
        job->addMetaData(QStringLiteral("shmid"), QString::number(shmid));
    }
#endif
}
 
void PreviewJobPrivate::slotThumbData(KIO::Job *job, const QByteArray &data)
{
    thumbnailWorkerMetaData = job->metaData();
    /* clang-format off */
    const bool save = bSave
                      && !sequenceIndex
                      && currentDeviceCachePolicy == CachePolicy::Allow
                      && currentItem.plugin.value(QStringLiteral("CacheThumbnail"), true)
                      && (!currentItem.item.targetUrl().isLocalFile()
                          || !currentItem.item.targetUrl().adjusted(QUrl::RemoveFilename).toLocalFile().startsWith(thumbRoot));
    /* clang-format on */
 
    QImage thumb;
    // Keep this in sync with kio-extras|thumbnail/thumbnail.cpp
    QDataStream str(data);
    int width;
    int height;
    QImage::Format format;
    qreal imgDevicePixelRatio;
    // TODO KF6: add a version number as first parameter
    str >> width >> height >> format >> imgDevicePixelRatio;
#if WITH_SHM
    if (shmaddr != nullptr) {
        thumb = QImage(shmaddr, width, height, format).copy();
    } else {
#endif
        str >> thumb;
#if WITH_SHM
    }
#endif
    thumb.setDevicePixelRatio(imgDevicePixelRatio);
 
    if (thumb.isNull()) {
        QDataStream s(data);
        s >> thumb;
    }
 
    if (thumb.isNull()) {
        // let succeeded in false state
        // failed will get called in determineNextFile()
        return;
    }
 
    if (save) {
        thumb.setText(QStringLiteral("Thumb::URI"), QString::fromUtf8(origName));
        thumb.setText(QStringLiteral("Thumb::MTime"), QString::number(tOrig.toSecsSinceEpoch()));
        thumb.setText(QStringLiteral("Thumb::Size"), number(currentItem.item.size()));
        thumb.setText(QStringLiteral("Thumb::Mimetype"), currentItem.item.mimetype());
        QString thumbnailerVersion = currentItem.plugin.value(QStringLiteral("ThumbnailerVersion"));
        QString signature = QLatin1String("KDE Thumbnail Generator ") + currentItem.plugin.name();
        if (!thumbnailerVersion.isEmpty()) {
            signature.append(QLatin1String(" (v") + thumbnailerVersion + QLatin1Char(')'));
        }
        thumb.setText(QStringLiteral("Software"), signature);
        QSaveFile saveFile(thumbPath + thumbName);
        if (saveFile.open(QIODevice::WriteOnly)) {
            if (thumb.save(&saveFile, "PNG")) {
                saveFile.commit();
            }
        }
    }
    emitPreview(thumb);
    succeeded = true;
}
 
void PreviewJobPrivate::emitPreview(const QImage &thumb)
{
    Q_Q(PreviewJob);
    QPixmap pix;
    const qreal ratio = thumb.devicePixelRatio();
    if (thumb.width() > width * ratio || thumb.height() > height * ratio) {
        pix = QPixmap::fromImage(thumb.scaled(QSize(width * ratio, height * ratio), Qt::KeepAspectRatio, Qt::SmoothTransformation));
    } else {
        pix = QPixmap::fromImage(thumb);
    }
    pix.setDevicePixelRatio(ratio);
    Q_EMIT q->gotPreview(currentItem.item, pix);
}
 
QList<KPluginMetaData> PreviewJob::availableThumbnailerPlugins()
{
    return PreviewJobPrivate::loadAvailablePlugins();
}
 
QStringList PreviewJob::availablePlugins()
{
    QStringList result;
    const auto plugins = KIO::PreviewJobPrivate::loadAvailablePlugins();
    for (const KPluginMetaData &plugin : plugins) {
        result << plugin.pluginId();
    }
    return result;
}
 
QStringList PreviewJob::defaultPlugins()
{
    const QStringList blacklist = QStringList() << QStringLiteral("textthumbnail");
 
    QStringList defaultPlugins = availablePlugins();
    for (const QString &plugin : blacklist) {
        defaultPlugins.removeAll(plugin);
    }
 
    return defaultPlugins;
}
 
QStringList PreviewJob::supportedMimeTypes()
{
    QStringList result;
    const auto plugins = KIO::PreviewJobPrivate::loadAvailablePlugins();
    for (const KPluginMetaData &plugin : plugins) {
        result += plugin.mimeTypes();
    }
    return result;
}
 
PreviewJob *KIO::filePreview(const KFileItemList &items, const QSize &size, const QStringList *enabledPlugins)
{
    return new PreviewJob(items, size, enabledPlugins);
}
 
#include "moc_previewjob.cpp"