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**
** Copyright (C) 2015 The Qt Company Ltd.
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** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
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** accordance with the commercial license agreement provided with the
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** Alternatively, this file may be used under the terms of the GNU Lesser
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#include "qresource.h"
#include "qresource_p.h"
#include "qresource_iterator_p.h"
#include "qset.h"
#include "qmutex.h"
#include "qdebug.h"
#include "qlocale.h"
#include "qglobal.h"
#include "qvector.h"
#include "qdatetime.h"
#include "qbytearray.h"
#include "qstringlist.h"
#include <qshareddata.h>
#include <qplatformdefs.h>
#include "private/qabstractfileengine_p.h"

#ifdef Q_OS_UNIX
# include "private/qcore_unix_p.h"
#endif

//#define DEBUG_RESOURCE_MATCH

QT_BEGIN_NAMESPACE


class QStringSplitter
{
public:
    QStringSplitter(const QString &s)
        : m_string(s), m_data(m_string.constData()), m_len(s.length()), m_pos(0)
    {
        m_splitChar = QLatin1Char('/');
    }

    inline bool hasNext() {
        while (m_pos < m_len && m_data[m_pos] == m_splitChar)
            ++m_pos;
        return m_pos < m_len;
    }

    inline QStringRef next() {
        int start = m_pos;
        while (m_pos < m_len && m_data[m_pos] != m_splitChar)
            ++m_pos;
        return QStringRef(&m_string, start, m_pos - start);
    }

    QString m_string;
    const QChar *m_data;
    QChar m_splitChar;
    int m_len;
    int m_pos;
};


//resource glue
class QResourceRoot
{
    enum Flags
    {
        Compressed = 0x01,
        Directory = 0x02
    };
    const uchar *tree, *names, *payloads;
    inline int findOffset(int node) const { return node * 14; } //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(0), names(0), payloads(0) {}
    inline QResourceRoot(const uchar *t, const uchar *n, const uchar *d) { setSource(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; }
    inline bool isCompressed(int node) const { return flags(node) & Compressed; }
    const uchar *data(int node, qint64 *size) const;
    QStringList children(int node) const;
    virtual QString mappingRoot() const { return QString(); }
    bool mappingRootSubdir(const QString &path, QString *match=0) const;
    inline bool operator==(const QResourceRoot &other) const
    { return tree == other.tree && names == other.names && payloads == other.payloads; }
    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(const uchar *t, const uchar *n, const uchar *d) {
        tree = t;
        names = n;
        payloads = d;
    }
};

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(QLatin1String("//")))
        path.remove(0, 1);
    return path;
}

Q_DECLARE_TYPEINFO(QResourceRoot, Q_MOVABLE_TYPE);

Q_GLOBAL_STATIC_WITH_ARGS(QMutex, resourceMutex, (QMutex::Recursive))

typedef QList<QResourceRoot*> ResourceList;
Q_GLOBAL_STATIC(ResourceList, resourceList)

Q_GLOBAL_STATIC(QStringList, resourceSearchPaths)

/*!
    \class QResource
    \inmodule QtCore
    \brief The QResource class provides an interface for reading directly from resources.

    \ingroup io

    \reentrant
    \since 4.2

    QResource is an object that represents a set of data (and possibly
    children) relating to a single resource entity. QResource gives direct
    access to the bytes in their raw format. In this way direct access
    allows reading data without buffer copying or indirection. Indirection
    is often useful when interacting with the resource entity as if it is a
    file, this can be achieved with QFile. The data and children behind a
    QResource are normally compiled into an application/library, but it is
    also possible to load a resource at runtime. When loaded at run time
    the resource file will be loaded as one big set of data and then given
    out in pieces via references into the resource tree.

    A QResource can either be loaded with an absolute path, either treated
    as a file system rooted with a \c{/} character, or in resource notation
    rooted with a \c{:} character. A relative resource can also be opened
    which will be found in the list of paths returned by QDir::searchPaths().

    A QResource that is representing a file will have data backing it, this
    data can possibly be compressed, in which case qUncompress() must be
    used to access the real data; this happens implicitly when accessed
    through a QFile. A QResource that is representing a directory will have
    only children and no data.

    \section1 Dynamic Resource Loading

    A resource can be left out of an application's binary and loaded when
    it is needed at run-time by using the registerResource() function. The
    resource file passed into registerResource() must be a binary resource
    as created by rcc. Further information about binary resources can be
    found in \l{The Qt Resource System} documentation.

    This can often be useful when loading a large set of application icons
    that may change based on a setting, or that can be edited by a user and
    later recreated. The resource is immediately loaded into memory, either
    as a result of a single file read operation, or as a memory mapped file.

    This approach can prove to be a significant performance gain as only a
    single file will be loaded, and pieces of data will be given out via the
    path requested in setFileName().

    The unregisterResource() function removes a reference to a particular
    file. If there are QResource objects that currently reference resources related
    to the unregistered file, they will continue to be valid but the resource
    file itself will be removed from the resource roots, and thus no further
    QResource can be created pointing into this resource data. The resource
    itself will be unmapped from memory when the last QResource that points
    to it is destroyed.

    \sa {The Qt Resource System}, QFile, QDir, QFileInfo
*/

class QResourcePrivate {
public:
    inline QResourcePrivate(QResource *_q) : q_ptr(_q) { clear(); }
    inline ~QResourcePrivate() { clear(); }

    void ensureInitialized() const;
    void ensureChildren() const;

    bool load(const QString &file);
    void clear();

    QLocale locale;
    QString fileName, absoluteFilePath;
    QList<QResourceRoot*> related;
    uint container : 1;
    mutable uint compressed : 1;
    mutable qint64 size;
    mutable const uchar *data;
    mutable QStringList children;

    QResource *q_ptr;
    Q_DECLARE_PUBLIC(QResource)
};

void
QResourcePrivate::clear()
{
    absoluteFilePath.clear();
    compressed = 0;
    data = 0;
    size = 0;
    children.clear();
    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();
    QMutexLocker 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);
                    compressed = res->isCompressed(node);
                } else {
                    data = 0;
                    size = 0;
                    compressed = 0;
                }
            } 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 = 0;
            size = 0;
            compressed = 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 == QLatin1String(":"))
        that->fileName += QLatin1Char('/');
    that->absoluteFilePath = fileName;
    if(!that->absoluteFilePath.startsWith(QLatin1Char(':')))
        that->absoluteFilePath.prepend(QLatin1Char(':'));

    QString path = fileName;
    if(path.startsWith(QLatin1Char(':')))
        path = path.mid(1);

    if(path.startsWith(QLatin1Char('/'))) {
        that->load(path);
    } else {
        QMutexLocker lock(resourceMutex());
        QStringList searchPaths = *resourceSearchPaths();
        searchPaths << QLatin1String("");
        for(int i = 0; i < searchPaths.size(); ++i) {
            const QString searchPath(searchPaths.at(i) + QLatin1Char('/') + path);
            if(that->load(searchPath)) {
                that->absoluteFilePath = QLatin1Char(':') + searchPath;
                break;
            }
        }
    }
}

void
QResourcePrivate::ensureChildren() const
{
    ensureInitialized();
    if(!children.isEmpty() || !container || related.isEmpty())
        return;

    QString path = absoluteFilePath, k;
    if(path.startsWith(QLatin1Char(':')))
        path = path.mid(1);
    QSet<QString> kids;
    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.contains(k)) {
                children += k;
                kids.insert(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.contains(k)) {
                        children += k;
                        kids.insert(k);
                    }
                }
            }
        }
    }
}

/*!
    Constructs a QResource pointing to \a file. \a locale is used to
    load a specific localization of a resource data.

    \sa QFileInfo, QDir::searchPaths(), setFileName(), setLocale()
*/

QResource::QResource(const QString &file, const QLocale &locale) : d_ptr(new QResourcePrivate(this))
{
    Q_D(QResource);
    d->fileName = file;
    d->locale = locale;
}

/*!
    Releases the resources of the QResource object.
*/
QResource::~QResource()
{
}

/*!
    Sets a QResource to only load the localization of resource to for \a
    locale. If a resource for the specific locale is not found then the
    C locale is used.

    \sa setFileName()
*/

void QResource::setLocale(const QLocale &locale)
{
    Q_D(QResource);
    d->clear();
    d->locale = locale;
}

/*!
    Returns the locale used to locate the data for the QResource.
*/

QLocale QResource::locale() const
{
    Q_D(const QResource);
    return d->locale;
}

/*!
    Sets a QResource to point to \a file. \a file can either be absolute,
    in which case it is opened directly, if relative then the file will be
    tried to be found in QDir::searchPaths().

    \sa absoluteFilePath()
*/

void QResource::setFileName(const QString &file)
{
    Q_D(QResource);
    d->clear();
    d->fileName = file;
}

/*!
    Returns the full path to the file that this QResource represents as it
    was passed.

    \sa absoluteFilePath()
*/

QString QResource::fileName() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->fileName;
}

/*!
    Returns the real path that this QResource represents, if the resource
    was found via the QDir::searchPaths() it will be indicated in the path.

    \sa fileName()
*/

QString QResource::absoluteFilePath() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->absoluteFilePath;
}

/*!
    Returns \c true if the resource really exists in the resource hierarchy,
    false otherwise.

*/

bool QResource::isValid() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return !d->related.isEmpty();
}

/*!
    \fn bool QResource::isFile() const

    Returns \c true if the resource represents a file and thus has data
    backing it, false if it represents a directory.

    \sa isDir()
*/


/*!
    Returns \c true if the resource represents a file and the data backing it
    is in a compressed format, false otherwise.

    \sa data(), isFile()
*/

bool QResource::isCompressed() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->compressed;
}

/*!
    Returns the size of the data backing the resource.

    \sa data(), isFile()
*/

qint64 QResource::size() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->size;
}

/*!
    Returns direct access to a read only segment of data that this resource
    represents. If the resource is compressed the data returns is
    compressed and qUncompress() must be used to access the data. If the
    resource is a directory 0 is returned.

    \sa size(), isCompressed(), isFile()
*/

const uchar *QResource::data() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->data;
}

/*!
    Returns \c true if the resource represents a directory and thus may have
    children() in it, false if it represents a file.

    \sa isFile()
*/

bool QResource::isDir() const
{
    Q_D(const QResource);
    d->ensureInitialized();
    return d->container;
}

/*!
    Returns a list of all resources in this directory, if the resource
    represents a file the list will be empty.

    \sa isDir()
*/

QStringList QResource::children() const
{
    Q_D(const QResource);
    d->ensureChildren();
    return d->children;
}

/*!
  \obsolete

  Use QDir::addSearchPath() with a prefix instead.

  Adds \a path to the search paths searched in to find resources that are
  not specified with an absolute path. The \a path must be an absolute
  path (start with \c{/}).

  The default search path is to search only in the root (\c{:/}). The last
  path added will be consulted first upon next QResource creation.
*/
void
QResource::addSearchPath(const QString &path)
{
    if (!path.startsWith(QLatin1Char('/'))) {
        qWarning("QResource::addResourceSearchPath: Search paths must be absolute (start with /) [%s]",
                 path.toLocal8Bit().data());
        return;
    }
    QMutexLocker lock(resourceMutex());
    resourceSearchPaths()->prepend(path);
}

/*!
  \obsolete

  Use QDir::searchPaths() instead.

  Returns the current search path list. This list is consulted when
  creating a relative resource.

  \sa QDir::addSearchPath(), QDir::setSearchPaths()
*/

QStringList
QResource::searchPaths()
{
    QMutexLocker lock(resourceMutex());
    return *resourceSearchPaths();
}

inline uint QResourceRoot::hash(int node) const
{
    if(!node) //root
        return 0;
    const int offset = findOffset(node);
    int name_offset = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                      (tree[offset+2] << 8) + (tree[offset+3] << 0);
    name_offset += 2; //jump past name length
    return (names[name_offset+0] << 24) + (names[name_offset+1] << 16) +
           (names[name_offset+2] << 8) + (names[name_offset+3] << 0);
}
inline QString QResourceRoot::name(int node) const
{
    if(!node) // root
        return QString();
    const int offset = findOffset(node);

    QString ret;
    int name_offset = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                      (tree[offset+2] << 8) + (tree[offset+3] << 0);
    const short name_length = (names[name_offset+0] << 8) +
                              (names[name_offset+1] << 0);
    name_offset += 2;
    name_offset += 4; //jump past hash

    ret.resize(name_length);
    QChar *strData = ret.data();
    for(int i = 0; i < name_length*2; i+=2) {
        QChar c(names[name_offset+i+1], names[name_offset+i]);
        *strData = c;
        ++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 = QLatin1Char('/');
            } else {
                if(!root.endsWith(QLatin1Char('/')))
                    root += QLatin1Char('/');
                if(path.size() >= root.size() && path.startsWith(root))
                    path = path.mid(root.length()-1);
                if(path.isEmpty())
                    path = QLatin1Char('/');
            }
        }
    }
#ifdef DEBUG_RESOURCE_MATCH
    qDebug() << "!!!!" << "START" << path << locale.country() << locale.language();
#endif

    if(path == QLatin1String("/"))
        return 0;

    //the root node is always first
    int child_count = (tree[6] << 24) + (tree[7] << 16) +
                      (tree[8] << 8) + (tree[9] << 0);
    int child       = (tree[10] << 24) + (tree[11] << 16) +
                      (tree[12] << 8) + (tree[13] << 0);

    //now iterate up the tree
    int node = -1;

    QStringSplitter splitter(path);
    while (child_count && splitter.hasNext()) {
        QStringRef 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 short flags = (tree[offset+0] << 8) +
                                        (tree[offset+1] << 0);
                    offset += 2;

                    if(!splitter.hasNext()) {
                        if(!(flags & Directory)) {
                            const short country = (tree[offset+0] << 8) +
                                                  (tree[offset+1] << 0);
                            offset += 2;

                            const short language = (tree[offset+0] << 8) +
                                                   (tree[offset+1] << 0);
                            offset += 2;
#ifdef DEBUG_RESOURCE_MATCH
                            qDebug() << "    " << "LOCALE" << country << language;
#endif
                            if(country == locale.country() && language == locale.language()) {
#ifdef DEBUG_RESOURCE_MATCH
                                qDebug() << "!!!!" << "FINISHED" << __LINE__ << sub_node;
#endif
                                return sub_node;
                            } else if((country == QLocale::AnyCountry && language == locale.language()) ||
                                      (country == QLocale::AnyCountry && 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 = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                                  (tree[offset+2] << 8) + (tree[offset+3] << 0);
                    offset += 4;
                    child = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                            (tree[offset+2] << 8) + (tree[offset+3] << 0);
                    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 (tree[offset+0] << 8) + (tree[offset+1] << 0);
}
const uchar *QResourceRoot::data(int node, qint64 *size) const
{
    if(node == -1) {
        *size = 0;
        return 0;
    }
    int offset = findOffset(node) + 4; //jump past name

    const short flags = (tree[offset+0] << 8) + (tree[offset+1] << 0);
    offset += 2;

    offset += 4; //jump past locale

    if(!(flags & Directory)) {
        const int data_offset = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                                (tree[offset+2] << 8) + (tree[offset+3] << 0);
        const uint data_length = (payloads[data_offset+0] << 24) + (payloads[data_offset+1] << 16) +
                                 (payloads[data_offset+2] << 8) + (payloads[data_offset+3] << 0);
        const uchar *ret = payloads+data_offset+4;
        *size = data_length;
        return ret;
    }
    *size = 0;
    return 0;
}
QStringList QResourceRoot::children(int node) const
{
    if(node == -1)
        return QStringList();
    int offset = findOffset(node) + 4; //jump past name

    const short flags = (tree[offset+0] << 8) + (tree[offset+1] << 0);
    offset += 2;

    QStringList ret;
    if(flags & Directory) {
        const int child_count = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                                (tree[offset+2] << 8) + (tree[offset+3] << 0);
        offset += 4;
        const int child_off = (tree[offset+0] << 24) + (tree[offset+1] << 16) +
                              (tree[offset+2] << 8) + (tree[offset+3] << 0);
        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()) {
        const QVector<QStringRef> root_segments = root.splitRef(QLatin1Char('/'), QString::SkipEmptyParts),
                                  path_segments = path.splitRef(QLatin1Char('/'), QString::SkipEmptyParts);
        if(path_segments.size() <= root_segments.size()) {
            int matched = 0;
            for(int i = 0; i < path_segments.size(); ++i) {
                if(root_segments[i] != path_segments[i])
                    break;
                ++matched;
            }
            if(matched == path_segments.size()) {
                if(match && root_segments.size() > matched)
                    *match = root_segments.at(matched).toString();
                return true;
            }
        }
    }
    return false;
}

Q_CORE_EXPORT bool qRegisterResourceData(int version, const unsigned char *tree,
                                         const unsigned char *name, const unsigned char *data)
{
    QMutexLocker lock(resourceMutex());
    if(version == 0x01 && resourceList()) {
        bool found = false;
        QResourceRoot res(tree, name, data);
        for(int i = 0; i < resourceList()->size(); ++i) {
            if(*resourceList()->at(i) == res) {
                found = true;
                break;
            }
        }
        if(!found) {
            QResourceRoot *root = new QResourceRoot(tree, name, data);
            root->ref.ref();
            resourceList()->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)
{
    QMutexLocker lock(resourceMutex());
    if(version == 0x01 && resourceList()) {
        QResourceRoot res(tree, name, data);
        for(int i = 0; i < resourceList()->size(); ) {
            if(*resourceList()->at(i) == res) {
                QResourceRoot *root = resourceList()->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(0) { }
    inline ~QDynamicBufferResourceRoot() { }
    inline const uchar *mappingBuffer() const { return buffer; }
    virtual QString mappingRoot() const Q_DECL_OVERRIDE { return root; }
    virtual ResourceRootType type() const Q_DECL_OVERRIDE { return Resource_Buffer; }

    // size == -1 means "unknown"
    bool registerSelf(const uchar *b, int 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 = (b[offset+0] << 24) + (b[offset+1] << 16) +
                         (b[offset+2] << 8) + (b[offset+3] << 0);
        offset += 4;

        const int tree_offset = (b[offset+0] << 24) + (b[offset+1] << 16) +
                                (b[offset+2] << 8) + (b[offset+3] << 0);
        offset += 4;

        const int data_offset = (b[offset+0] << 24) + (b[offset+1] << 16) +
                                (b[offset+2] << 8) + (b[offset+3] << 0);
        offset += 4;

        const int name_offset = (b[offset+0] << 24) + (b[offset+1] << 16) +
                                (b[offset+2] << 8) + (b[offset+3] << 0);
        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;

        if(version == 0x01) {
            buffer = b;
            setSource(b+tree_offset, b+name_offset, b+data_offset);
            return true;
        }
        return false;
    }
};

#if defined(Q_OS_UNIX) && !defined (Q_OS_NACL) && !defined(Q_OS_INTEGRITY)
#define QT_USE_MMAP
#endif

// most of the headers below are already included in qplatformdefs.h
// also this lacks Large File support but that's probably irrelevant
#if defined(QT_USE_MMAP)
// for mmap
QT_BEGIN_INCLUDE_NAMESPACE
#include <sys/mman.h>
#include <errno.h>
QT_END_INCLUDE_NAMESPACE
#endif



class QDynamicFileResourceRoot: public QDynamicBufferResourceRoot
{
    QString fileName;
    // for mmap'ed files, this is what needs to be unmapped.
    uchar *unmapPointer;
    unsigned int unmapLength;

public:
    inline QDynamicFileResourceRoot(const QString &_root) : QDynamicBufferResourceRoot(_root), unmapPointer(0), unmapLength(0) { }
    ~QDynamicFileResourceRoot() {
#if defined(QT_USE_MMAP)
        if (unmapPointer) {
            munmap((char*)unmapPointer, unmapLength);
            unmapPointer = 0;
            unmapLength = 0;
        } else
#endif
        {
            delete [] mappingBuffer();
        }
    }
    QString mappingFile() const { return fileName; }
    virtual ResourceRootType type() const Q_DECL_OVERRIDE { return Resource_File; }

    bool registerSelf(const QString &f) {
        bool fromMM = false;
        uchar *data = 0;
        unsigned int data_len = 0;

#ifdef QT_USE_MMAP

#ifndef MAP_FILE
#define MAP_FILE 0
#endif
#ifndef MAP_FAILED
#define MAP_FAILED -1
#endif

        int fd = QT_OPEN(QFile::encodeName(f), O_RDONLY,
#if defined(Q_OS_WIN)
                         _S_IREAD | _S_IWRITE
#else
                         0666
#endif
            );
        if (fd >= 0) {
            QT_STATBUF st;
            if (!QT_FSTAT(fd, &st)) {
                uchar *ptr;
                ptr = reinterpret_cast<uchar *>(
                    mmap(0, st.st_size,             // any address, whole file
                         PROT_READ,                 // read-only memory
                         MAP_FILE | MAP_PRIVATE,    // swap-backed map from file
                         fd, 0));                   // from offset 0 of fd
                if (ptr && ptr != reinterpret_cast<uchar *>(MAP_FAILED)) {
                    data = ptr;
                    data_len = st.st_size;
                    fromMM = true;
                }
            }
            ::close(fd);
        }
#endif // QT_USE_MMAP
        if(!data) {
            QFile file(f);
            if (!file.exists())
                return false;
            data_len = file.size();
            data = new uchar[data_len];

            bool ok = false;
            if (file.open(QIODevice::ReadOnly))
                ok = (data_len == (uint)file.read((char*)data, data_len));
            if (!ok) {
                delete [] data;
                data = 0;
                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(QLatin1Char(':')))
            r = r.mid(1);
        if(!r.isEmpty())
            r = QDir::cleanPath(r);
    }
    return r;
}


/*!
   \fn bool QResource::registerResource(const QString &rccFileName, const QString &mapRoot)

   Registers the resource with the given \a rccFileName at the location in the
   resource tree specified by \a mapRoot, and returns \c true if the file is
   successfully opened; otherwise returns \c false.

   \sa unregisterResource()
*/

bool
QResource::registerResource(const QString &rccFilename, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
    if(!r.isEmpty() && r[0] != QLatin1Char('/')) {
        qWarning("QDir::registerResource: Registering a resource [%s] must be rooted in an absolute path (start with /) [%s]",
                 rccFilename.toLocal8Bit().data(), resourceRoot.toLocal8Bit().data());
        return false;
    }

    QDynamicFileResourceRoot *root = new QDynamicFileResourceRoot(r);
    if(root->registerSelf(rccFilename)) {
        root->ref.ref();
        QMutexLocker lock(resourceMutex());
        resourceList()->append(root);
        return true;
    }
    delete root;
    return false;
}

/*!
  \fn bool QResource::unregisterResource(const QString &rccFileName, const QString &mapRoot)

  Unregisters the resource with the given \a rccFileName at the location in
  the resource tree specified by \a mapRoot, and returns \c true if the
  resource is successfully unloaded and no references exist for the
  resource; otherwise returns \c false.

  \sa registerResource()
*/

bool
QResource::unregisterResource(const QString &rccFilename, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);

    QMutexLocker 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) {
                resourceList()->removeAt(i);
                if(!root->ref.deref()) {
                    delete root;
                    return true;
                }
                return false;
            }
        }
    }
    return false;
}


/*!
   \fn bool QResource::registerResource(const uchar *rccData, const QString &mapRoot)
   \since 4.3

   Registers the resource with the given \a rccData at the location in the
   resource tree specified by \a mapRoot, and returns \c true if the file is
   successfully opened; otherwise returns \c false.

   \warning The data must remain valid throughout the life of any QFile
   that may reference the resource data.

   \sa unregisterResource()
*/

bool
QResource::registerResource(const uchar *rccData, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);
    if(!r.isEmpty() && r[0] != QLatin1Char('/')) {
        qWarning("QDir::registerResource: Registering a resource [%p] must be rooted in an absolute path (start with /) [%s]",
                 rccData, resourceRoot.toLocal8Bit().data());
        return false;
    }

    QDynamicBufferResourceRoot *root = new QDynamicBufferResourceRoot(r);
    if (root->registerSelf(rccData, -1)) {
        root->ref.ref();
        QMutexLocker lock(resourceMutex());
        resourceList()->append(root);
        return true;
    }
    delete root;
    return false;
}

/*!
  \fn bool QResource::unregisterResource(const uchar *rccData, const QString &mapRoot)
  \since 4.3

  Unregisters the resource with the given \a rccData at the location in the
  resource tree specified by \a mapRoot, and returns \c true if the resource is
  successfully unloaded and no references exist into the resource; otherwise returns \c false.

  \sa registerResource()
*/

bool
QResource::unregisterResource(const uchar *rccData, const QString &resourceRoot)
{
    QString r = qt_resource_fixResourceRoot(resourceRoot);

    QMutexLocker 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) {
                resourceList()->removeAt(i);
                if(!root->ref.deref()) {
                    delete root;
                    return true;
                }
                return false;
            }
        }
    }
    return false;
}

//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);
    qint64 offset;
    QResource resource;
    QByteArray uncompressed;
protected:
    QResourceFileEnginePrivate() : offset(0) { }
};

bool QResourceFileEngine::mkdir(const QString &, bool) const
{
    return false;
}

bool QResourceFileEngine::rmdir(const QString &, bool) const
{
    return false;
}

bool QResourceFileEngine::setSize(qint64)
{
    return false;
}

QStringList QResourceFileEngine::entryList(QDir::Filters filters, const QStringList &filterNames) const
{
    return QAbstractFileEngine::entryList(filters, filterNames);
}

bool QResourceFileEngine::caseSensitive() const
{
    return true;
}

QResourceFileEngine::QResourceFileEngine(const QString &file) :
    QAbstractFileEngine(*new QResourceFileEnginePrivate)
{
    Q_D(QResourceFileEngine);
    d->resource.setFileName(file);
    if(d->resource.isCompressed() && d->resource.size()) {
#ifndef QT_NO_COMPRESS
        d->uncompressed = qUncompress(d->resource.data(), d->resource.size());
#else
        Q_ASSERT(!"QResourceFileEngine::open: Qt built without support for compression");
#endif
    }
}

QResourceFileEngine::~QResourceFileEngine()
{
}

void QResourceFileEngine::setFileName(const QString &file)
{
    Q_D(QResourceFileEngine);
    d->resource.setFileName(file);
}

bool QResourceFileEngine::open(QIODevice::OpenMode flags)
{
    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.isValid())
       return false;
    return true;
}

bool QResourceFileEngine::close()
{
    Q_D(QResourceFileEngine);
    d->offset = 0;
    d->uncompressed.clear();
    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->resource.isCompressed())
        memcpy(data, d->uncompressed.constData()+d->offset, len);
    else
        memcpy(data, d->resource.data()+d->offset, len);
    d->offset += len;
    return len;
}

qint64 QResourceFileEngine::write(const char *, qint64)
{
    return -1;
}

bool QResourceFileEngine::remove()
{
    return false;
}

bool QResourceFileEngine::copy(const QString &)
{
    return false;
}

bool QResourceFileEngine::rename(const QString &)
{
    return false;
}

bool QResourceFileEngine::link(const QString &)
{
    return false;
}

qint64 QResourceFileEngine::size() const
{
    Q_D(const QResourceFileEngine);
    if(!d->resource.isValid())
        return 0;
    if(d->resource.isCompressed())
        return d->uncompressed.size();
    return d->resource.size();
}

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;
}

bool QResourceFileEngine::isSequential() const
{
    return false;
}

QAbstractFileEngine::FileFlags QResourceFileEngine::fileFlags(QAbstractFileEngine::FileFlags type) const
{
    Q_D(const QResourceFileEngine);
    QAbstractFileEngine::FileFlags ret = 0;
    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() == QLatin1String(":/"))
            ret |= RootFlag;
    }
    return ret;
}

bool QResourceFileEngine::setPermissions(uint)
{
    return false;
}

QString QResourceFileEngine::fileName(FileName file) const
{
    Q_D(const QResourceFileEngine);
    if(file == BaseName) {
        int slash = d->resource.fileName().lastIndexOf(QLatin1Char('/'));
        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 int slash = path.lastIndexOf(QLatin1Char('/'));
        if (slash == -1)
            return QLatin1String(":");
        else if (slash <= 1)
            return QLatin1String(":/");
        return path.left(slash);

    } else if(file == CanonicalName || file == CanonicalPathName) {
        const QString absoluteFilePath = d->resource.absoluteFilePath();
        if(file == CanonicalPathName) {
            const int slash = absoluteFilePath.lastIndexOf(QLatin1Char('/'));
            if (slash != -1)
                return absoluteFilePath.left(slash);
        }
        return absoluteFilePath;
    }
    return d->resource.fileName();
}

bool QResourceFileEngine::isRelativePath() const
{
    return false;
}

uint QResourceFileEngine::ownerId(FileOwner) const
{
    static const uint nobodyID = (uint) -2;
    return nobodyID;
}

QString QResourceFileEngine::owner(FileOwner) const
{
    return QString();
}

QDateTime QResourceFileEngine::fileTime(FileTime) const
{
    return QDateTime();
}

/*!
    \internal
*/
QAbstractFileEngine::Iterator *QResourceFileEngine::beginEntryList(QDir::Filters filters,
                                                                   const QStringList &filterNames)
{
    return new QResourceFileEngineIterator(filters, filterNames);
}

/*!
    \internal
*/
QAbstractFileEngine::Iterator *QResourceFileEngine::endEntryList()
{
    return 0;
}

bool QResourceFileEngine::extension(Extension extension, const ExtensionOption *option, ExtensionReturn *output)
{
    Q_D(QResourceFileEngine);
    if (extension == MapExtension) {
        const MapExtensionOption *options = (const MapExtensionOption*)(option);
        MapExtensionReturn *returnValue = static_cast<MapExtensionReturn*>(output);
        returnValue->address = d->map(options->offset, options->size, options->flags);
        return (returnValue->address != 0);
    }
    if (extension == UnMapExtension) {
        const UnMapExtensionOption *options = (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);
    if (offset < 0 || size <= 0 || !resource.isValid() || offset + size > resource.size()) {
        q->setError(QFile::UnspecifiedError, QString());
        return 0;
    }
    uchar *address = const_cast<uchar *>(resource.data());
    return (address + offset);
}

bool QResourceFileEnginePrivate::unmap(uchar *ptr)
{
    Q_UNUSED(ptr);
    return true;
}

QT_END_NAMESPACE
