qresource.cpp

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// Copyright (C) 2019 The Qt Company Ltd.
// Copyright (C) 2020 Intel Corporation.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qresource.h"
#include "qresource_p.h"
#include "qresource_iterator_p.h"
#include "qset.h"
#include <private/qlocking_p.h>
#include "qdebug.h"
#include "qlocale.h"
#include "qglobal.h"
#include "qlist.h"
#include "qdatetime.h"
#include "qbytearray.h"
#include "qstringlist.h"
#include "qendian.h"
#include <qshareddata.h>
#include <qplatformdefs.h>
#include <qendian.h>
#include "private/qabstractfileengine_p.h"
#include "private/qduplicatetracker_p.h"
#include "private/qnumeric_p.h"
#include "private/qsimd_p.h"
#include "private/qtools_p.h"
#include "private/qsystemerror_p.h"
 
#ifndef QT_NO_COMPRESS
#  include <zconf.h>
#  include <zlib.h>
#endif
#if QT_CONFIG(zstd)
#  include <zstd.h>
#endif
 
#if defined(Q_OS_UNIX) && !defined(Q_OS_NACL) && !defined(Q_OS_INTEGRITY)
#  define QT_USE_MMAP
#  include <sys/mman.h>
#endif
 
//#define DEBUG_RESOURCE_MATCH
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
// Symbols used by code generated by RCC.
// They cause compilation errors if the RCC content couldn't
// be interpreted by this QtCore version.
#if defined(__ELF__) || defined(__APPLE__)  // same as RCC generates
#  define RCC_FEATURE_SYMBOL(feature)   \
    extern Q_CORE_EXPORT const quint8 qt_resourceFeature ## feature; \
    const quint8 qt_resourceFeature ## feature = 0;
#else
#  define RCC_FEATURE_SYMBOL(feature)   \
    Q_CORE_EXPORT quint8 qResourceFeature ## feature() { return 0; }
#endif
 
#ifndef QT_NO_COMPRESS
RCC_FEATURE_SYMBOL(Zlib)
#endif
#if QT_CONFIG(zstd)
RCC_FEATURE_SYMBOL(Zstd)
#endif
 
#undef RCC_FEATURE_SYMBOL
 
class QStringSplitter
{
public:
    explicit QStringSplitter(QStringView sv)
        : m_data(sv.data()), m_len(sv.size())
    {
    }
 
    inline bool hasNext()
    {
        while (m_pos < m_len && m_data[m_pos] == m_splitChar)
            ++m_pos;
        return m_pos < m_len;
    }
 
    inline QStringView next()
    {
        const qsizetype start = m_pos;
        while (m_pos < m_len && m_data[m_pos] != m_splitChar)
            ++m_pos;
        return QStringView(m_data + start, m_pos - start);
    }
 
    const QChar *m_data;
    qsizetype m_len;
    qsizetype m_pos = 0;
    QChar m_splitChar = u'/';
};
 
// resource glue
class QResourceRoot
{
public:
    enum Flags {
        // must match rcc.h
        Compressed = 0x01,
        Directory = 0x02,
        CompressedZstd = 0x04
    };
 
private:
    const uchar *tree, *names, *payloads;
    int version;
    inline int findOffset(int node) const { return node * (14 + (version >= 0x02 ? 8 : 0)); } //sizeof each tree element
    uint hash(int node) const;
    QString name(int node) const;
    short flags(int node) const;
public:
    mutable QAtomicInt ref;
 
    inline QResourceRoot(): tree(nullptr), names(nullptr), payloads(nullptr), version(0) {}
    inline QResourceRoot(int version, const uchar *t, const uchar *n, const uchar *d) { setSource(version, t, n, d); }
    virtual ~QResourceRoot() { }
    int findNode(const QString &path, const QLocale &locale=QLocale()) const;
    inline bool isContainer(int node) const { return flags(node) & Directory; }
    QResource::Compression compressionAlgo(int node)
    {
        uint compressionFlags = flags(node) & (Compressed | CompressedZstd);
        if (compressionFlags == Compressed)
            return QResource::ZlibCompression;
        if (compressionFlags == CompressedZstd)
            return QResource::ZstdCompression;
        return QResource::NoCompression;
    }
    const uchar *data(int node, qint64 *size) const;
    quint64 lastModified(int node) const;
    QStringList children(int node) const;
    virtual QString mappingRoot() const { return QString(); }
    bool mappingRootSubdir(const QString &path, QString *match = nullptr) const;
    inline bool operator==(const QResourceRoot &other) const
    { return tree == other.tree && names == other.names && payloads == other.payloads && version == other.version; }
    inline bool operator!=(const QResourceRoot &other) const
    { return !operator==(other); }
    enum ResourceRootType { Resource_Builtin, Resource_File, Resource_Buffer };
    virtual ResourceRootType type() const { return Resource_Builtin; }
 
protected:
    inline void setSource(int v, const uchar *t, const uchar *n, const uchar *d) {
        tree = t;
        names = n;
        payloads = d;
        version = v;
    }
};
 
static QString cleanPath(const QString &_path)
{
    QString path = QDir::cleanPath(_path);
    // QDir::cleanPath does not remove two trailing slashes under _Windows_
    // due to support for UNC paths. Remove those manually.
    if (path.startsWith("//"_L1))
        path.remove(0, 1);
    return path;
}
 
Q_DECLARE_TYPEINFO(QResourceRoot, Q_RELOCATABLE_TYPE);
 
typedef QList<QResourceRoot*> ResourceList;
struct QResourceGlobalData
{
    QRecursiveMutex resourceMutex;
    ResourceList resourceList;
};
Q_GLOBAL_STATIC(QResourceGlobalData, resourceGlobalData)
 
static inline QRecursiveMutex &resourceMutex()
{ return resourceGlobalData->resourceMutex; }
 
static inline ResourceList *resourceList()
{ return &resourceGlobalData->resourceList; }
 
class QResourcePrivate {
public:
    inline QResourcePrivate(QResource *_q) : q_ptr(_q) { clear(); }
    inline ~QResourcePrivate() { clear(); }
 
    void ensureInitialized() const;
    void ensureChildren() const;
    qint64 uncompressedSize() const Q_DECL_PURE_FUNCTION;
    qsizetype decompress(char *buffer, qsizetype bufferSize) const;
 
    bool load(const QString &file);
    void clear();
 
    QLocale locale;
    QString fileName, absoluteFilePath;
    QList<QResourceRoot *> related;
    mutable qint64 size;
    mutable quint64 lastModified;
    mutable const uchar *data;
    mutable QStringList children;
    mutable quint8 compressionAlgo;
    bool container;
    /* 2 or 6 padding bytes */
 
    QResource *q_ptr;
    Q_DECLARE_PUBLIC(QResource)
};
 
void QResourcePrivate::clear()
{
    absoluteFilePath.clear();
    compressionAlgo = QResource::NoCompression;
    data = nullptr;
    size = 0;
    children.clear();
    lastModified = 0;
    container = 0;
    for (int i = 0; i < related.size(); ++i) {
        QResourceRoot *root = related.at(i);
        if (!root->ref.deref())
            delete root;
    }
    related.clear();
}
 
bool QResourcePrivate::load(const QString &file)
{
    related.clear();
    const auto locker = qt_scoped_lock(resourceMutex());
    const ResourceList *list = resourceList();
    QString cleaned = cleanPath(file);
    for (int i = 0; i < list->size(); ++i) {
        QResourceRoot *res = list->at(i);
        const int node = res->findNode(cleaned, locale);
        if (node != -1) {
            if (related.isEmpty()) {
                container = res->isContainer(node);
                if (!container) {
                    data = res->data(node, &size);
                    compressionAlgo = res->compressionAlgo(node);
                } else {
                    data = nullptr;
                    size = 0;
                    compressionAlgo = QResource::NoCompression;
                }
                lastModified = res->lastModified(node);
            } else if (res->isContainer(node) != container) {
                qWarning("QResourceInfo: Resource [%s] has both data and children!",
                         file.toLatin1().constData());
            }
            res->ref.ref();
            related.append(res);
        } else if (res->mappingRootSubdir(file)) {
            container = true;
            data = nullptr;
            size = 0;
            compressionAlgo = QResource::NoCompression;
            lastModified = 0;
            res->ref.ref();
            related.append(res);
        }
    }
    return !related.isEmpty();
}
 
void QResourcePrivate::ensureInitialized() const
{
    if (!related.isEmpty())
        return;
    QResourcePrivate *that = const_cast<QResourcePrivate *>(this);
    if (fileName == ":"_L1)
        that->fileName += u'/';
    that->absoluteFilePath = fileName;
    if (!that->absoluteFilePath.startsWith(u':'))
        that->absoluteFilePath.prepend(u':');
 
    QStringView path(fileName);
    if (path.startsWith(u':'))
        path = path.mid(1);
 
    if (path.startsWith(u'/')) {
        that->load(path.toString());
    } else {
        // Should we search QDir::searchPath() before falling back to root ?
        const QString searchPath(u'/' + path);
        if (that->load(searchPath))
            that->absoluteFilePath = u':' + searchPath;
    }
}
 
void QResourcePrivate::ensureChildren() const
{
    ensureInitialized();
    if (!children.isEmpty() || !container || related.isEmpty())
        return;
 
    QString path = absoluteFilePath, k;
    if (path.startsWith(u':'))
        path = path.mid(1);
    QDuplicateTracker<QString> kids(related.size());
    QString cleaned = cleanPath(path);
    for (int i = 0; i < related.size(); ++i) {
        QResourceRoot *res = related.at(i);
        if (res->mappingRootSubdir(path, &k) && !k.isEmpty()) {
            if (!kids.hasSeen(k))
                children += k;
        } else {
            const int node = res->findNode(cleaned);
            if (node != -1) {
                QStringList related_children = res->children(node);
                for (int kid = 0; kid < related_children.size(); ++kid) {
                    k = related_children.at(kid);
                    if (!kids.hasSeen(k))
                        children += k;
                }
            }
        }
    }
}
 
qint64 QResourcePrivate::uncompressedSize() const
{
    switch (compressionAlgo) {
    case QResource::NoCompression:
        return size;
 
    case QResource::ZlibCompression:
#ifndef QT_NO_COMPRESS
        if (size_t(size) >= sizeof(quint32))
            return qFromBigEndian<quint32>(data);
#else
        Q_ASSERT(!"QResource: Qt built without support for Zlib compression");
        Q_UNREACHABLE();
#endif
        break;
 
    case QResource::ZstdCompression: {
#if QT_CONFIG(zstd)
        size_t n = ZSTD_getFrameContentSize(data, size);
        return ZSTD_isError(n) ? -1 : qint64(n);
#else
        // This should not happen because we've refused to load such resource
        Q_ASSERT(!"QResource: Qt built without support for Zstd compression");
        Q_UNREACHABLE();
#endif
    }
    }
    return -1;
}
 
qsizetype QResourcePrivate::decompress(char *buffer, qsizetype bufferSize) const
{
    Q_ASSERT(data);
#if defined(QT_NO_COMPRESS) && !QT_CONFIG(zstd)
    Q_UNUSED(buffer);
    Q_UNUSED(bufferSize);
#endif
 
    switch (compressionAlgo) {
    case QResource::NoCompression:
        Q_UNREACHABLE();
        break;
 
    case QResource::ZlibCompression: {
#ifndef QT_NO_COMPRESS
        uLong len = uLong(bufferSize);
        int res = ::uncompress(reinterpret_cast<Bytef *>(buffer), &len, data + sizeof(quint32),
                               uLong(size - sizeof(quint32)));
        if (res != Z_OK) {
            qWarning("QResource: error decompressing zlib content (%d)", res);
            return -1;
        }
        return len;
#else
        Q_UNREACHABLE();
#endif
    }
 
    case QResource::ZstdCompression: {
#if QT_CONFIG(zstd)
        size_t usize = ZSTD_decompress(buffer, bufferSize, data, size);
        if (ZSTD_isError(usize)) {
            qWarning("QResource: error decompressing zstd content: %s", ZSTD_getErrorName(usize));
            return -1;
        }
        return usize;
#else
        Q_UNREACHABLE();
#endif
    }
    }
 
    return -1;
}
 
QResource::QResource(const QString &file, const QLocale &locale) : d_ptr(new QResourcePrivate(this))
{
    Q_D(QResource);
    d->fileName = file;
    d->locale = locale;
}
 
QResource::~QResource()
{
}
 
void QResource::setLocale(const QLocale &locale)
{
    Q_D(QResource);
    d->clear();
    d->locale = locale;
}
 
QLocale QResource::locale() const
{
    Q_D(const QResource);
    return d->locale;
}
 
void QResource::setFileName(const QString &file)
{
    Q_D(QResource);
    d->clear();
    d->fileName = file;
}
 
QString QResource::fileName() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->fileName;
}
 
QString QResource::absoluteFilePath() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->absoluteFilePath;
}
 
bool QResource::isValid() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return !d->related.isEmpty();
}
 
QResource::Compression QResource::compressionAlgorithm() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return Compression(d->compressionAlgo);
}
 
qint64 QResource::size() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->size;
}
 
qint64 QResource::uncompressedSize() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->uncompressedSize();
}
 
const uchar *QResource::data() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->data;
}
 
QByteArray QResource::uncompressedData() const
{
    Q_D(const QResource);
    qint64 n = uncompressedSize();
    if (n < 0)
        return QByteArray();
    if (n > std::numeric_limits<QByteArray::size_type>::max()) {
        qWarning("QResource: compressed content does not fit into a QByteArray; use QFile instead");
        return QByteArray();
    }
    if (d->compressionAlgo == NoCompression)
        return QByteArray::fromRawData(reinterpret_cast<const char *>(d->data), n);
 
    // decompress
    QByteArray result(n, Qt::Uninitialized);
    n = d->decompress(result.data(), n);
    if (n < 0)
        result.clear();
    else
        result.truncate(n);
    return result;
}
 
QDateTime QResource::lastModified() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->lastModified ? QDateTime::fromMSecsSinceEpoch(d->lastModified) : QDateTime();
}
 
bool QResource::isDir() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->container;
}
 
QStringList QResource::children() const
{
    Q_D(const QResource);
    d->ensureChildren();
    return d->children;
}
 
inline uint QResourceRoot::hash(int node) const
{
    if (!node) // root
        return 0;
    const int offset = findOffset(node);
    qint32 name_offset = qFromBigEndian<qint32>(tree + offset);
    name_offset += 2; // jump past name length
    return qFromBigEndian<quint32>(names + name_offset);
}
inline QString QResourceRoot::name(int node) const
{
    if (!node) // root
        return QString();
    const int offset = findOffset(node);
 
    QString ret;
    qint32 name_offset = qFromBigEndian<qint32>(tree + offset);
    quint16 name_length = qFromBigEndian<qint16>(names + name_offset);
    name_offset += 2;
    name_offset += 4; // jump past hash
 
    ret.resize(name_length);
    QChar *strData = ret.data();
    qFromBigEndian<char16_t>(names + name_offset, name_length, strData);
    return ret;
}
 
int QResourceRoot::findNode(const QString &_path, const QLocale &locale) const
{
    QString path = _path;
    {
        QString root = mappingRoot();
        if (!root.isEmpty()) {
            if (root == path) {
                path = u'/';
            } else {
                if (!root.endsWith(u'/'))
                    root += u'/';
                if (path.size() >= root.size() && path.startsWith(root))
                    path = path.mid(root.size() - 1);
                if (path.isEmpty())
                    path = u'/';
            }
        }
    }
#ifdef DEBUG_RESOURCE_MATCH
    qDebug() << "!!!!" << "START" << path << locale.territory() << locale.language();
#endif
 
    if (path == "/"_L1)
        return 0;
 
    // the root node is always first
    qint32 child_count = qFromBigEndian<qint32>(tree + 6);
    qint32 child       = qFromBigEndian<qint32>(tree + 10);
 
    // now iterate up the tree
    int node = -1;
 
    QStringSplitter splitter(path);
    while (child_count && splitter.hasNext()) {
        QStringView segment = splitter.next();
 
#ifdef DEBUG_RESOURCE_MATCH
        qDebug() << "  CHILDREN" << segment;
        for (int j = 0; j < child_count; ++j) {
            qDebug() << "   " << child + j << " :: " << name(child + j);
        }
#endif
        const uint h = qt_hash(segment);
 
        // do the binary search for the hash
        int l = 0, r = child_count - 1;
        int sub_node = (l + r + 1) / 2;
        while (r != l) {
            const uint sub_node_hash = hash(child + sub_node);
            if (h == sub_node_hash)
                break;
            else if (h < sub_node_hash)
                r = sub_node - 1;
            else
                l = sub_node;
            sub_node = (l + r + 1) / 2;
        }
        sub_node += child;
 
        // now do the "harder" compares
        bool found = false;
        if (hash(sub_node) == h) {
            while (sub_node > child && hash(sub_node - 1) == h) // backup for collisions
                --sub_node;
            for (; sub_node < child + child_count && hash(sub_node) == h;
                 ++sub_node) { // here we go...
                if (name(sub_node) == segment) {
                    found = true;
                    int offset = findOffset(sub_node);
#ifdef DEBUG_RESOURCE_MATCH
                    qDebug() << "  TRY" << sub_node << name(sub_node) << offset;
#endif
                    offset += 4; // jump past name
 
                    const qint16 flags = qFromBigEndian<qint16>(tree + offset);
                    offset += 2;
 
                    if (!splitter.hasNext()) {
                        if (!(flags & Directory)) {
                            const qint16 territory = qFromBigEndian<qint16>(tree + offset);
                            offset += 2;
 
                            const qint16 language = qFromBigEndian<qint16>(tree + offset);
                            offset += 2;
#ifdef DEBUG_RESOURCE_MATCH
                            qDebug() << "    " << "LOCALE" << country << language;
#endif
                            if (territory == locale.territory() && language == locale.language()) {
#ifdef DEBUG_RESOURCE_MATCH
                                qDebug() << "!!!!" << "FINISHED" << __LINE__ << sub_node;
#endif
                                return sub_node;
                            } else if ((territory == QLocale::AnyTerritory
                                        && language == locale.language())
                                       || (territory == QLocale::AnyTerritory
                                           && language == QLocale::C
                                           && node == -1)) {
                                node = sub_node;
                            }
                            continue;
                        } else {
#ifdef DEBUG_RESOURCE_MATCH
                            qDebug() << "!!!!" << "FINISHED" << __LINE__ << sub_node;
#endif
 
                            return sub_node;
                        }
                    }
 
                    if (!(flags & Directory))
                        return -1;
 
                    child_count = qFromBigEndian<qint32>(tree + offset);
                    offset += 4;
                    child = qFromBigEndian<qint32>(tree + offset);
                    break;
                }
            }
        }
        if (!found)
            break;
    }
#ifdef DEBUG_RESOURCE_MATCH
    qDebug() << "!!!!" << "FINISHED" << __LINE__ << node;
#endif
    return node;
}
short QResourceRoot::flags(int node) const
{
    if (node == -1)
        return 0;
    const int offset = findOffset(node) + 4; // jump past name
    return qFromBigEndian<qint16>(tree + offset);
}
const uchar *QResourceRoot::data(int node, qint64 *size) const
{
    if (node == -1) {
        *size = 0;
        return nullptr;
    }
    int offset = findOffset(node) + 4; // jump past name
 
    const qint16 flags = qFromBigEndian<qint16>(tree + offset);
    offset += 2;
 
    offset += 4; // jump past locale
 
    if (!(flags & Directory)) {
        const qint32 data_offset = qFromBigEndian<qint32>(tree + offset);
        const quint32 data_length = qFromBigEndian<quint32>(payloads + data_offset);
        const uchar *ret = payloads + data_offset + 4;
        *size = data_length;
        return ret;
    }
    *size = 0;
    return nullptr;
}
 
quint64 QResourceRoot::lastModified(int node) const
{
    if (node == -1 || version < 0x02)
        return 0;
 
    const int offset = findOffset(node) + 14;
 
    return qFromBigEndian<quint64>(tree + offset);
}
 
QStringList QResourceRoot::children(int node) const
{
    if (node == -1)
        return QStringList();
    int offset = findOffset(node) + 4; // jump past name
 
    const qint16 flags = qFromBigEndian<qint16>(tree + offset);
    offset += 2;
 
    QStringList ret;
    if (flags & Directory) {
        const qint32 child_count = qFromBigEndian<qint32>(tree + offset);
        offset += 4;
        const qint32 child_off = qFromBigEndian<qint32>(tree + offset);
        ret.reserve(child_count);
        for (int i = child_off; i < child_off + child_count; ++i)
            ret << name(i);
    }
    return ret;
}
bool QResourceRoot::mappingRootSubdir(const QString &path, QString *match) const
{
    const QString root = mappingRoot();
    if (root.isEmpty())
        return false;
 
    QStringSplitter rootIt(root);
    QStringSplitter pathIt(path);
    while (rootIt.hasNext()) {
        if (pathIt.hasNext()) {
            if (rootIt.next() != pathIt.next()) // mismatch
                return false;
        } else {
            // end of path, but not of root:
            if (match)
                *match = rootIt.next().toString();
            return true;
        }
    }
    // end of root
    return !pathIt.hasNext();
}
 
Q_CORE_EXPORT bool qRegisterResourceData(int version, const unsigned char *tree,
                                         const unsigned char *name, const unsigned char *data)
{
    if (resourceGlobalData.isDestroyed())
        return false;
    const auto locker = qt_scoped_lock(resourceMutex());
    ResourceList *list = resourceList();
    if (version >= 0x01 && version <= 0x3) {
        bool found = false;
        QResourceRoot res(version, tree, name, data);
        for (int i = 0; i < list->size(); ++i) {
            if (*list->at(i) == res) {
                found = true;
                break;
            }
        }
        if (!found) {
            QResourceRoot *root = new QResourceRoot(version, tree, name, data);
            root->ref.ref();
            list->append(root);
        }
        return true;
    }
    return false;
}
 
Q_CORE_EXPORT bool qUnregisterResourceData(int version, const unsigned char *tree,
                                           const unsigned char *name, const unsigned char *data)
{
    if (resourceGlobalData.isDestroyed())
        return false;
 
    const auto locker = qt_scoped_lock(resourceMutex());
    if (version >= 0x01 && version <= 0x3) {
        QResourceRoot res(version, tree, name, data);
        ResourceList *list = resourceList();
        for (int i = 0; i < list->size();) {
            if (*list->at(i) == res) {
                QResourceRoot *root = list->takeAt(i);
                if (!root->ref.deref())
                    delete root;
            } else {
                ++i;
            }
        }
        return true;
    }
    return false;
}
 
// run time resource creation
 
class QDynamicBufferResourceRoot : public QResourceRoot
{
    QString root;
    const uchar *buffer;
 
public:
    inline QDynamicBufferResourceRoot(const QString &_root) : root(_root), buffer(nullptr) { }
    inline ~QDynamicBufferResourceRoot() { }
    inline const uchar *mappingBuffer() const { return buffer; }
    QString mappingRoot() const override { return root; }
    ResourceRootType type() const override { return Resource_Buffer; }
 
    // size == -1 means "unknown"
    bool registerSelf(const uchar *b, qsizetype size)
    {
        // 5 int "pointers"
        if (size >= 0 && size < 20)
            return false;
 
        // setup the data now
        int offset = 0;
 
        // magic number
        if (b[offset + 0] != 'q' || b[offset + 1] != 'r' || b[offset + 2] != 'e'
            || b[offset + 3] != 's') {
            return false;
        }
        offset += 4;
 
        const int version = qFromBigEndian<qint32>(b + offset);
        offset += 4;
 
        const int tree_offset = qFromBigEndian<qint32>(b + offset);
        offset += 4;
 
        const int data_offset = qFromBigEndian<qint32>(b + offset);
        offset += 4;
 
        const int name_offset = qFromBigEndian<qint32>(b + offset);
        offset += 4;
 
        quint32 file_flags = 0;
        if (version >= 3) {
            file_flags = qFromBigEndian<qint32>(b + offset);
            offset += 4;
        }
 
        // Some sanity checking for sizes. This is _not_ a security measure.
        if (size >= 0 && (tree_offset >= size || data_offset >= size || name_offset >= size))
            return false;
 
        // And some sanity checking for features
        quint32 acceptableFlags = 0;
#ifndef QT_NO_COMPRESS
        acceptableFlags |= Compressed;
#endif
        if (QT_CONFIG(zstd))
            acceptableFlags |= CompressedZstd;
        if (file_flags & ~acceptableFlags)
            return false;
 
        if (version >= 0x01 && version <= 0x03) {
            buffer = b;
            setSource(version, b + tree_offset, b + name_offset, b + data_offset);
            return true;
        }
        return false;
    }
};
 
class QDynamicFileResourceRoot : public QDynamicBufferResourceRoot
{
    QString fileName;
    // for mmap'ed files, this is what needs to be unmapped.
    uchar *unmapPointer;
    qsizetype unmapLength;
 
public:
    QDynamicFileResourceRoot(const QString &_root)
        : QDynamicBufferResourceRoot(_root), unmapPointer(nullptr), unmapLength(0)
    { }
    ~QDynamicFileResourceRoot() {
#if defined(QT_USE_MMAP)
        if (unmapPointer) {
            munmap(reinterpret_cast<char *>(unmapPointer), unmapLength);
            unmapPointer = nullptr;
            unmapLength = 0;
        } else
#endif
        {
            delete[] mappingBuffer();
        }
    }
    QString mappingFile() const { return fileName; }
    ResourceRootType type() const override { return Resource_File; }
 
    bool registerSelf(const QString &f);
};
 
#ifndef MAP_FILE
#  define MAP_FILE 0
#endif
#ifndef MAP_FAILED
#  define MAP_FAILED reinterpret_cast<void *>(-1)
#endif
 
bool QDynamicFileResourceRoot::registerSelf(const QString &f)
{
    bool fromMM = false;
    uchar *data = nullptr;
    qsizetype data_len = 0;
 
#if defined(QT_USE_MMAP)
    int fd = QT_OPEN(QFile::encodeName(f), O_RDONLY);
    if (fd >= 0) {
        QT_STATBUF st;
        if (!QT_FSTAT(fd, &st) && st.st_size <= std::numeric_limits<qsizetype>::max()) {
            int protection = PROT_READ;                 // read-only memory
            int flags = MAP_FILE | MAP_PRIVATE;         // swap-backed map from file
            void *ptr = QT_MMAP(nullptr, st.st_size,    // any address, whole file
                                protection, flags,
                                fd, 0);                 // from offset 0 of fd
            if (ptr != MAP_FAILED) {
                data = static_cast<uchar *>(ptr);
                data_len = st.st_size;
                fromMM = true;
            }
        }
        QT_CLOSE(fd);
    }
#endif // QT_USE_MMAP
    if (!data) {
        QFile file(f);
        bool ok = false;
        if (file.open(QIODevice::ReadOnly)) {
            qint64 fsize = file.size();
            if (fsize <= std::numeric_limits<qsizetype>::max()) {
                data_len = file.size();
                data = new uchar[data_len];
                ok = (data_len == file.read(reinterpret_cast<char *>(data), data_len));
            }
        }
        if (!ok) {
            delete[] data;
            data = nullptr;
            data_len = 0;
            return false;
        }
        fromMM = false;
    }
    if (data && QDynamicBufferResourceRoot::registerSelf(data, data_len)) {
        if (fromMM) {
            unmapPointer = data;
            unmapLength = data_len;
        }
        fileName = f;
        return true;
    }
    return false;
}
 
static QString qt_resource_fixResourceRoot(QString r)
{
    if (!r.isEmpty()) {
        if (r.startsWith(u':'))
            r = r.mid(1);
        if (!r.isEmpty())
            r = QDir::cleanPath(r);
    }
    return r;
}
 
bool QResource::registerResource(const QString &rccFilename, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
    if (!r.isEmpty() && r[0] != u'/') {
        qWarning("QDir::registerResource: Registering a resource [%ls] must be rooted in an "
                 "absolute path (start with /) [%ls]",
                 qUtf16Printable(rccFilename), qUtf16Printable(resourceRoot));
        return false;
    }
 
    QDynamicFileResourceRoot *root = new QDynamicFileResourceRoot(r);
    if (root->registerSelf(rccFilename)) {
        root->ref.ref();
        const auto locker = qt_scoped_lock(resourceMutex());
        resourceList()->append(root);
        return true;
    }
    delete root;
    return false;
}
 
bool QResource::unregisterResource(const QString &rccFilename, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
 
    const auto locker = qt_scoped_lock(resourceMutex());
    ResourceList *list = resourceList();
    for (int i = 0; i < list->size(); ++i) {
        QResourceRoot *res = list->at(i);
        if (res->type() == QResourceRoot::Resource_File) {
            QDynamicFileResourceRoot *root = reinterpret_cast<QDynamicFileResourceRoot *>(res);
            if (root->mappingFile() == rccFilename && root->mappingRoot() == r) {
                list->removeAt(i);
                if (!root->ref.deref()) {
                    delete root;
                    return true;
                }
                return false;
            }
        }
    }
    return false;
}
 
bool QResource::registerResource(const uchar *rccData, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
    if (!r.isEmpty() && r[0] != u'/') {
        qWarning("QDir::registerResource: Registering a resource [%p] must be rooted in an "
                 "absolute path (start with /) [%ls]",
                 rccData, qUtf16Printable(resourceRoot));
        return false;
    }
 
    QDynamicBufferResourceRoot *root = new QDynamicBufferResourceRoot(r);
    if (root->registerSelf(rccData, -1)) {
        root->ref.ref();
        const auto locker = qt_scoped_lock(resourceMutex());
        resourceList()->append(root);
        return true;
    }
    delete root;
    return false;
}
 
bool QResource::unregisterResource(const uchar *rccData, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
 
    const auto locker = qt_scoped_lock(resourceMutex());
    ResourceList *list = resourceList();
    for (int i = 0; i < list->size(); ++i) {
        QResourceRoot *res = list->at(i);
        if (res->type() == QResourceRoot::Resource_Buffer) {
            QDynamicBufferResourceRoot *root = reinterpret_cast<QDynamicBufferResourceRoot *>(res);
            if (root->mappingBuffer() == rccData && root->mappingRoot() == r) {
                list->removeAt(i);
                if (!root->ref.deref()) {
                    delete root;
                    return true;
                }
                return false;
            }
        }
    }
    return false;
}
 
#if !defined(QT_BOOTSTRAPPED)
// resource engine
class QResourceFileEnginePrivate : public QAbstractFileEnginePrivate
{
protected:
    Q_DECLARE_PUBLIC(QResourceFileEngine)
private:
    uchar *map(qint64 offset, qint64 size, QFile::MemoryMapFlags flags);
    bool unmap(uchar *ptr);
    void uncompress() const;
    qint64 offset;
    QResource resource;
    mutable QByteArray uncompressed;
protected:
    QResourceFileEnginePrivate() : offset(0) { }
};
 
bool QResourceFileEngine::caseSensitive() const
{
    return true;
}
 
QResourceFileEngine::QResourceFileEngine(const QString &file) :
    QAbstractFileEngine(*new QResourceFileEnginePrivate)
{
    Q_D(QResourceFileEngine);
    d->resource.setFileName(file);
}
 
QResourceFileEngine::~QResourceFileEngine()
{
}
 
void QResourceFileEngine::setFileName(const QString &file)
{
    Q_D(QResourceFileEngine);
    d->resource.setFileName(file);
}
 
bool QResourceFileEngine::open(QIODevice::OpenMode flags,
                               std::optional<QFile::Permissions> permissions)
{
    Q_UNUSED(permissions);
 
    Q_D(QResourceFileEngine);
    if (d->resource.fileName().isEmpty()) {
        qWarning("QResourceFileEngine::open: Missing file name");
        return false;
    }
    if (flags & QIODevice::WriteOnly)
        return false;
    if (d->resource.compressionAlgorithm() != QResource::NoCompression) {
        d->uncompress();
        if (d->uncompressed.isNull()) {
            d->errorString = QSystemError::stdString(EIO);
            return false;
        }
    }
    if (!d->resource.isValid()) {
        d->errorString = QSystemError::stdString(ENOENT);
        return false;
    }
    return true;
}
 
bool QResourceFileEngine::close()
{
    Q_D(QResourceFileEngine);
    d->offset = 0;
    return true;
}
 
bool QResourceFileEngine::flush()
{
    return true;
}
 
qint64 QResourceFileEngine::read(char *data, qint64 len)
{
    Q_D(QResourceFileEngine);
    if (len > size() - d->offset)
        len = size() - d->offset;
    if (len <= 0)
        return 0;
    if (!d->uncompressed.isNull())
        memcpy(data, d->uncompressed.constData() + d->offset, len);
    else
        memcpy(data, d->resource.data() + d->offset, len);
    d->offset += len;
    return len;
}
 
qint64 QResourceFileEngine::size() const
{
    Q_D(const QResourceFileEngine);
    return d->resource.isValid() ? d->resource.uncompressedSize() : 0;
}
 
qint64 QResourceFileEngine::pos() const
{
    Q_D(const QResourceFileEngine);
    return d->offset;
}
 
bool QResourceFileEngine::atEnd() const
{
    Q_D(const QResourceFileEngine);
    if (!d->resource.isValid())
        return true;
    return d->offset == size();
}
 
bool QResourceFileEngine::seek(qint64 pos)
{
    Q_D(QResourceFileEngine);
    if (!d->resource.isValid())
        return false;
 
    if (d->offset > size())
        return false;
    d->offset = pos;
    return true;
}
 
QAbstractFileEngine::FileFlags QResourceFileEngine::fileFlags(QAbstractFileEngine::FileFlags type) const
{
    Q_D(const QResourceFileEngine);
    QAbstractFileEngine::FileFlags ret;
    if (!d->resource.isValid())
        return ret;
 
    if (type & PermsMask)
        ret |= QAbstractFileEngine::FileFlags(ReadOwnerPerm | ReadUserPerm | ReadGroupPerm
                                              | ReadOtherPerm);
    if (type & TypesMask) {
        if (d->resource.isDir())
            ret |= DirectoryType;
        else
            ret |= FileType;
    }
    if (type & FlagsMask) {
        ret |= ExistsFlag;
        if (d->resource.absoluteFilePath() == ":/"_L1)
            ret |= RootFlag;
    }
    return ret;
}
 
QString QResourceFileEngine::fileName(FileName file) const
{
    Q_D(const QResourceFileEngine);
    if (file == BaseName) {
        const qsizetype slash = d->resource.fileName().lastIndexOf(u'/');
        if (slash == -1)
            return d->resource.fileName();
        return d->resource.fileName().mid(slash + 1);
    } else if (file == PathName || file == AbsolutePathName) {
        const QString path = (file == AbsolutePathName) ? d->resource.absoluteFilePath()
                                                        : d->resource.fileName();
        const qsizetype slash = path.lastIndexOf(u'/');
        if (slash == -1)
            return ":"_L1;
        else if (slash <= 1)
            return ":/"_L1;
        return path.left(slash);
 
    } else if (file == CanonicalName || file == CanonicalPathName) {
        const QString absoluteFilePath = d->resource.absoluteFilePath();
        if (file == CanonicalPathName) {
            const qsizetype slash = absoluteFilePath.lastIndexOf(u'/');
            if (slash != -1)
                return absoluteFilePath.left(slash);
        }
        return absoluteFilePath;
    }
    return d->resource.fileName();
}
 
uint QResourceFileEngine::ownerId(FileOwner) const
{
    static const uint nobodyID = static_cast<uint>(-2);
    return nobodyID;
}
 
QDateTime QResourceFileEngine::fileTime(FileTime time) const
{
    Q_D(const QResourceFileEngine);
    if (time == ModificationTime)
        return d->resource.lastModified();
    return QDateTime();
}
 
QAbstractFileEngine::Iterator *QResourceFileEngine::beginEntryList(QDir::Filters filters,
                                                                   const QStringList &filterNames)
{
    return new QResourceFileEngineIterator(filters, filterNames);
}
 
QAbstractFileEngine::Iterator *QResourceFileEngine::endEntryList()
{
    return nullptr;
}
 
bool QResourceFileEngine::extension(Extension extension, const ExtensionOption *option, ExtensionReturn *output)
{
    Q_D(QResourceFileEngine);
    if (extension == MapExtension) {
        const auto *options = static_cast<const MapExtensionOption *>(option);
        auto *returnValue = static_cast<MapExtensionReturn *>(output);
        returnValue->address = d->map(options->offset, options->size, options->flags);
        return (returnValue->address != nullptr);
    }
    if (extension == UnMapExtension) {
        const auto *options = static_cast<const UnMapExtensionOption *>(option);
        return d->unmap(options->address);
    }
    return false;
}
 
bool QResourceFileEngine::supportsExtension(Extension extension) const
{
    return (extension == UnMapExtension || extension == MapExtension);
}
 
uchar *QResourceFileEnginePrivate::map(qint64 offset, qint64 size, QFile::MemoryMapFlags flags)
{
    Q_Q(QResourceFileEngine);
    Q_UNUSED(flags);
 
    qint64 max = resource.uncompressedSize();
    qint64 end;
    if (offset < 0 || size <= 0 || !resource.isValid() ||
            qAddOverflow(offset, size, &end) || end > max) {
        q->setError(QFile::UnspecifiedError, QString());
        return nullptr;
    }
 
    const uchar *address = resource.data();
    if (resource.compressionAlgorithm() != QResource::NoCompression) {
        uncompress();
        if (uncompressed.isNull())
            return nullptr;
        address = reinterpret_cast<const uchar *>(uncompressed.constData());
    }
 
    return const_cast<uchar *>(address) + offset;
}
 
bool QResourceFileEnginePrivate::unmap(uchar *ptr)
{
    Q_UNUSED(ptr);
    return true;
}
 
void QResourceFileEnginePrivate::uncompress() const
{
    if (resource.compressionAlgorithm() == QResource::NoCompression
            || !uncompressed.isEmpty() || resource.size() == 0)
        return;     // nothing to do
    uncompressed = resource.uncompressedData();
}
 
#endif // !defined(QT_BOOTSTRAPPED)
 
QT_END_NAMESPACE