/******************************************************************************** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.**** This file is part of the QtCore module of the Qt Toolkit.**** This file may be used under the terms of the GNU General Public** License version 2.0 as published by the Free Software Foundation** and appearing in the file LICENSE.GPL included in the packaging of** this file.  Please review the following information to ensure GNU** General Public Licensing requirements will be met:** http://www.trolltech.com/products/qt/opensource.html**** If you are unsure which license is appropriate for your use, please** review the following information:** http://www.trolltech.com/products/qt/licensing.html or contact the** sales department at sales@trolltech.com.**** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.******************************************************************************/#include "qdatastream.h"#ifndef QT_NO_DATASTREAM#include "qbuffer.h"#include "qstring.h"#include <stdio.h>#include <ctype.h>#include <stdlib.h>/*!    \class QDataStream    \reentrant    \brief The QDataStream class provides serialization of binary data    to a QIODevice.    \ingroup io    \mainclass    A data stream is a binary stream of encoded information which is    100% independent of the host computer's operating system, CPU or    byte order. For example, a data stream that is written by a PC    under Windows can be read by a Sun SPARC running Solaris.    You can also use a data stream to read/write \l{raw}{raw    unencoded binary data}. If you want a "parsing" input stream, see    QTextStream.    The QDataStream class implements the serialization of C++'s basic    data types, like \c char, \c short, \c int, \c{char *}, etc.    Serialization of more complex data is accomplished by breaking up    the data into primitive units.    A data stream cooperates closely with a QIODevice. A QIODevice    represents an input/output medium one can read data from and write    data to. The QFile class is an example of an I/O device.    Example (write binary data to a stream):    \code        QFile file("file.dat");        file.open(QIODevice::WriteOnly);        QDataStream out(&file);   // we will serialize the data into the file        out << "the answer is";   // serialize a string        out << (qint32)42;        // serialize an integer    \endcode    Example (read binary data from a stream):    \code        QFile file("file.dat");        file.open(QIODevice::ReadOnly);        QDataStream in(&file);    // read the data serialized from the file        QString str;        qint32 a;        in >> str >> a;           // extract "the answer is" and 42    \endcode    Each item written to the stream is written in a predefined binary    format that varies depending on the item's type. Supported Qt    types include QBrush, QColor, QDateTime, QFont, QPixmap, QString,    QVariant and many others. For the complete list of all Qt types    supporting data streaming see the \l{Format of the QDataStream    operators}.    For integers it is best to always cast to a Qt integer type for    writing, and to read back into the same Qt integer type. This    ensures that you get integers of the size you want and insulates    you from compiler and platform differences.    To take one example, a \c{char *} string is written as a 32-bit    integer equal to the length of the string including the '\\0' byte,    followed by all the characters of the string including the    '\\0' byte. When reading a \c{char *} string, 4 bytes are read to    create the 32-bit length value, then that many characters for the    \c {char *} string including the '\\0' terminator are read.    The initial I/O device is usually set in the constructor, but can be    changed with setDevice(). If you've reached the end of the data    (or if there is no I/O device set) atEnd() will return true.    \section1 Versioning    QDataStream's binary format has evolved since Qt 1.0, and is    likely to continue evolving to reflect changes done in Qt. When    inputting or outputting complex types, it's very important to    make sure that the same version of the stream (version()) is used    for reading and writing. If you need both forward and backward    compatibility, you can hardcode the version number in the    application:    \code        stream.setVersion(QDataStream::Qt_4_0);    \endcode    If you are producing a new binary data format, such as a file    format for documents created by your application, you could use a    QDataStream to write the data in a portable format. Typically, you    would write a brief header containing a magic string and a version    number to give yourself room for future expansion. For example:    \code        QFile file("file.xxx");        file.open(QIODevice::WriteOnly);        QDataStream out(&file);        // Write a header with a "magic number" and a version        out << (quint32)0xA0B0C0D0;        out << (qint32)123;        out.setVersion(QDataStream::Qt_4_0);        // Write the data        out << lots_of_interesting_data;    \endcode    Then read it in with:    \code        QFile file("file.xxx");        file.open(QIODevice::ReadOnly);        QDataStream in(&file);        // Read and check the header        quint32 magic;        in >> magic;        if (magic != 0xA0B0C0D0)            return XXX_BAD_FILE_FORMAT;        // Read the version        qint32 version;        in >> version;        if (version < 100)            return XXX_BAD_FILE_TOO_OLD;        if (version > 123)            return XXX_BAD_FILE_TOO_NEW;        if (version <= 110)            in.setVersion(QDataStream::Qt_3_2);        else            in.setVersion(QDataStream::Qt_4_0);        // Read the data        in >> lots_of_interesting_data;        if (version >= 120)            in >> data_new_in_XXX_version_1_2;        in >> other_interesting_data;    \endcode    You can select which byte order to use when serializing data. The    default setting is big endian (MSB first). Changing it to little    endian breaks the portability (unless the reader also changes to    little endian). We recommend keeping this setting unless you have    special requirements.    \target raw    \section1 Reading and writing raw binary data    You may wish to read/write your own raw binary data to/from the    data stream directly. Data may be read from the stream into a    preallocated \c{char *} using readRawData(). Similarly data can be    written to the stream using writeRawData(). Note that any    encoding/decoding of the data must be done by you.    A similar pair of functions is readBytes() and writeBytes(). These    differ from their \e raw counterparts as follows: readBytes()    reads a quint32 which is taken to be the length of the data to be    read, then that number of bytes is read into the preallocated    \c{char *}; writeBytes() writes a quint32 containing the length of the    data, followed by the data. Note that any encoding/decoding of    the data (apart from the length quint32) must be done by you.    \sa QTextStream QVariant*//*!    \enum QDataStream::ByteOrder    The byte order used for reading/writing the data.    \value BigEndian Most significant byte first (the default)    \value LittleEndian Less significant byte first*//*!    \enum QDataStream::Status    This enum describes the current status of the data stream.    \value Ok               The data stream is operating normally.    \value ReadPastEnd      The data stream has read past the end of the                            data in the underlying device.    \value ReadCorruptData  The data stream has read corrupt data.*//*****************************************************************************  QDataStream member functions *****************************************************************************/#ifndef QT_NO_DEBUG#undef  CHECK_STREAM_PRECOND#define CHECK_STREAM_PRECOND(retVal) \    if (!dev) { \        qWarning("QDataStream: No device"); \        return retVal; \    }#else#define CHECK_STREAM_PRECOND(retVal)#endifenum {    DefaultStreamVersion = QDataStream::Qt_4_2};// ### 4.0: when streaming invalid QVariants, just the type should// be written, no "data" after it/*!    Constructs a data stream that has no I/O device.    \sa setDevice()*/QDataStream::QDataStream(){    dev = 0;    owndev = false;    byteorder = BigEndian;    ver = DefaultStreamVersion;    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;    q_status = Ok;}/*!    Constructs a data stream that uses the I/O device \a d.    \warning If you use QSocket or QSocketDevice as the I/O device \a d    for reading data, you must make sure that enough data is available    on the socket for the operation to successfully proceed;    QDataStream does not have any means to handle or recover from    short-reads.    \sa setDevice(), device()*/QDataStream::QDataStream(QIODevice *d){    dev = d;                                // set device    owndev = false;    byteorder = BigEndian;                        // default byte order    ver = DefaultStreamVersion;    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;    q_status = Ok;}#ifdef QT3_SUPPORT/*!    \fn QDataStream::QDataStream(QByteArray *array, int mode)    \compat    Constructs a data stream that operates on the given \a array. The    \a mode specifies how the byte array is to be used, and is    usually either QIODevice::ReadOnly or QIODevice::WriteOnly.*/QDataStream::QDataStream(QByteArray *a, int mode){    QBuffer *buf = new QBuffer(a);    buf->open(QIODevice::OpenMode(mode));    dev = buf;    owndev = true;    byteorder = BigEndian;    ver = DefaultStreamVersion;    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;    q_status = Ok;}#endif/*!    \fn QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode mode)    Constructs a data stream that operates on a byte array, \a a. The    \a mode describes how the device is to be used.    Alternatively, you can use QDataStream(const QByteArray &) if you    just want to read from a byte array.    Since QByteArray is not a QIODevice subclass, internally a QBuffer    is created to wrap the byte array.*/QDataStream::QDataStream(QByteArray *a, QIODevice::OpenMode flags){    QBuffer *buf = new QBuffer(a);    buf->open(flags);    dev = buf;    owndev = true;    byteorder = BigEndian;    ver = DefaultStreamVersion;    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;    q_status = Ok;}/*!    Constructs a read-only data stream that operates on byte array \a a.    Use QDataStream(QByteArray*, int) if you want to write to a byte    array.    Since QByteArray is not a QIODevice subclass, internally a QBuffer    is created to wrap the byte array.*/QDataStream::QDataStream(const QByteArray &a){    QBuffer *buf = new QBuffer;    buf->setData(a);    buf->open(QIODevice::ReadOnly);    dev = buf;    owndev = true;    byteorder = BigEndian;    ver = DefaultStreamVersion;    noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian;    q_status = Ok;}/*!    Destroys the data stream.    The destructor will not affect the current I/O device, unless it is    an internal I/O device (e.g. a QBuffer) processing a QByteArray    passed in the \e constructor, in which case the internal I/O device    is destroyed.*/QDataStream::~QDataStream(){    if (owndev)        delete dev;}/*!    \fn QIODevice *QDataStream::device() const    Returns the I/O device currently set.    \sa setDevice(), unsetDevice()*//*!    void QDataStream::setDevice(QIODevice *d)    Sets the I/O device to \a d.    \sa device(), unsetDevice()*/void QDataStream::setDevice(QIODevice *d){    if (owndev) {        delete dev;        owndev = false;    }    dev = d;}/*!    Unsets the I/O device. This is the same as calling setDevice(0).    \sa device(), setDevice()*/void QDataStream::unsetDevice(){    setDevice(0);}/*!    \fn bool QDataStream::atEnd() const    Returns true if the I/O device has reached the end position (end of    the stream or file) or if there is no I/O device set; otherwise    returns false.    \sa QIODevice::atEnd()*/bool QDataStream::atEnd() const{    return dev ? dev->atEnd() : true;}/*!    Returns the status of the data stream.    \sa Status setStatus() resetStatus()*/QDataStream::Status QDataStream::status() const{    return q_status;}/*!    Resets the status of the data stream.    \sa Status status() setStatus()*/void QDataStream::resetStatus(){    q_status = Ok;}/*!    Sets the status of the data stream to the \a status given.    \sa Status status() resetStatus()*/void QDataStream::setStatus(Status status){    if (q_status == Ok)        q_status = status;}/*!\fn bool QDataStream::eof() const    Use atEnd() instead.*//*!    \fn int QDataStream::byteOrder() const    Returns the current byte order setting -- either BigEndian or    LittleEndian.    \sa setByteOrder()*//*!    Sets the serialization byte order to \a bo.    The \a bo parameter can be QDataStream::BigEndian or    QDataStream::LittleEndian.    The default setting is big endian. We recommend leaving this    setting unless you have special requirements.    \sa byteOrder()*/void QDataStream::setByteOrder(ByteOrder bo){    byteorder = bo;    if (QSysInfo::ByteOrder == QSysInfo::BigEndian)        noswap = (byteorder == BigEndian);    else        noswap = (byteorder == LittleEndian);}/*!    \fn bool QDataStream::isPrintableData() const    In Qt 4, this function always returns false.    \sa setPrintableData()*//*!    \fn void QDataStream::setPrintableData(bool enable)    In Qt 3, this function enabled output in a human-readable    format if \a enable was false.    In Qt 4, QDataStream no longer provides a human-readable output.    This function does nothing.*//*!    \enum QDataStream::Version    This enum provides symbolic synonyms for the data serialization    format version numbers.    \value Qt_1_0 Version 1 (Qt 1.x)    \value Qt_2_0 Version 2 (Qt 2.0)    \value Qt_2_1 Version 3 (Qt 2.1, 2.2, 2.3)    \value Qt_3_0 Version 4 (Qt 3.0)    \value Qt_3_1 Version 5 (Qt 3.1, 3.2)    \value Qt_3_3 Version 6 (Qt 3.3)    \value Qt_4_0 Version 7 (Qt 4.0, Qt 4.1)    \value Qt_4_1 Version 7 (Qt 4.0, Qt 4.1)    \value Qt_4_2 Version 8 (Qt 4.2)    \sa setVersion(), version()*//*!    \fn int QDataStream::version() const    Returns the version number of the data serialization format.    \sa setVersion(), Version*//*!    \fn void QDataStream::setVersion(int v)    Sets the version number of the data serialization format to \a v.    You don't \e have to set a version if you are using the current    version of Qt, but for your own custom binary formats we    recommend that you do; see \l{Versioning} in the Detailed    Description.    In order to accommodate new functionality, the datastream    serialization format of some Qt classes has changed in some    versions of Qt. If you want to read data that was created by an    earlier version of Qt, or write data that can be read by a    program that was compiled with an earlier version of Qt, use this    function to modify the serialization format used by QDataStream.    \table    \header \i Qt Version       \i QDataStream Version    \row \i Qt 4.2              \i 8    \row \i Qt 4.0              \i 7    \row \i Qt 3.3              \i 6    \row \i Qt 3.1, 3.2         \i 5    \row \i Qt 3.0              \i 4    \row \i Qt 2.1, 2.2, 2.3    \i 3    \row \i Qt 2.0              \i 2    \row \i Qt 1.x              \i 1    \endtable    The \l Version enum provides symbolic constants for the different    versions of Qt. For example:    \code        QDataStream out(file);        out.setVersion(QDataStream::Qt_4_0);    \endcode    \sa version(), Version*//*****************************************************************************  QDataStream read functions *****************************************************************************//*!    \fn QDataStream &QDataStream::operator>>(quint8 &i)    \overload    Reads an unsigned byte from the stream into \a i, and returns a    reference to the stream.*//*!    Reads a signed byte from the stream into \a i, and returns a    reference to the stream.*/QDataStream &QDataStream::operator>>(qint8 &i){    i = 0;    CHECK_STREAM_PRECOND(*this)    char c;    if (!dev->getChar(&c))        setStatus(ReadPastEnd);    else        i = qint8(c);    return *this;}/*!    \fn QDataStream &QDataStream::operator>>(quint16 &i)    \overload