/**************************************************************************** ** ** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies). ** Contact: http://www.qt-project.org/legal ** ** This file is part of the QtCore module of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:LGPL21$ ** Commercial License Usage ** Licensees holding valid commercial Qt licenses may use this file in ** accordance with the commercial license agreement provided with the ** Software or, alternatively, in accordance with the terms contained in ** a written agreement between you and Digia. For licensing terms and ** conditions see http://qt.digia.com/licensing. For further information ** use the contact form at http://qt.digia.com/contact-us. ** ** GNU Lesser General Public License Usage ** Alternatively, this file may be used under the terms of the GNU Lesser ** General Public License version 2.1 or version 3 as published by the Free ** Software Foundation and appearing in the file LICENSE.LGPLv21 and ** LICENSE.LGPLv3 included in the packaging of this file. Please review the ** following information to ensure the GNU Lesser General Public License ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. ** ** In addition, as a special exception, Digia gives you certain additional ** rights. These rights are described in the Digia Qt LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qdatastream.h" #include "qdatastream_p.h" #if !defined(QT_NO_DATASTREAM) || defined(QT_BOOTSTRAPPED) #include "qbuffer.h" #include "qstring.h" #include #include #include #include "qendian.h" QT_BEGIN_NAMESPACE /*! \class QDataStream \inmodule QtCore \reentrant \brief The QDataStream class provides serialization of binary data to a QIODevice. \ingroup io 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): \snippet code/src_corelib_io_qdatastream.cpp 0 Example (read binary data from a stream): \snippet code/src_corelib_io_qdatastream.cpp 1 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 \l{Serializing Qt Data Types}. 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: \snippet code/src_corelib_io_qdatastream.cpp 2 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: \snippet code/src_corelib_io_qdatastream.cpp 3 Then read it in with: \snippet code/src_corelib_io_qdatastream.cpp 4 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. \section1 Reading and Writing Qt Collection Classes The Qt container classes can also be serialized to a QDataStream. These include QList, QLinkedList, QVector, QSet, QHash, and QMap. The stream operators are declared as non-members of the classes. \target Serializing Qt Classes \section1 Reading and Writing Other Qt Classes In addition to the overloaded stream operators documented here, any Qt classes that you might want to serialize to a QDataStream will have appropriate stream operators declared as non-member of the class: \code QDataStream &operator<<(QDataStream &, const QXxx &); QDataStream &operator>>(QDataStream &, QXxx &); \endcode For example, here are the stream operators declared as non-members of the QImage class: \code QDataStream & operator<< (QDataStream& stream, const QImage& image); QDataStream & operator>> (QDataStream& stream, QImage& image); \endcode To see if your favorite Qt class has similar stream operators defined, check the \b {Related Non-Members} section of the class's documentation page. \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 Least significant byte first */ /*! \enum QDataStream::FloatingPointPrecision The precision of floating point numbers used for reading/writing the data. This will only have an effect if the version of the data stream is Qt_4_6 or higher. \warning The floating point precision must be set to the same value on the object that writes and the object that reads the data stream. \value SinglePrecision All floating point numbers in the data stream have 32-bit precision. \value DoublePrecision All floating point numbers in the data stream have 64-bit precision. \sa setFloatingPointPrecision(), floatingPointPrecision() */ /*! \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. \value WriteFailed The data stream cannot write to the underlying device. */ /***************************************************************************** QDataStream member functions *****************************************************************************/ #undef CHECK_STREAM_PRECOND #ifndef QT_NO_DEBUG #define CHECK_STREAM_PRECOND(retVal) \ if (!dev) { \ qWarning("QDataStream: No device"); \ return retVal; \ } #else #define CHECK_STREAM_PRECOND(retVal) \ if (!dev) { \ return retVal; \ } #endif #define CHECK_STREAM_WRITE_PRECOND(retVal) \ CHECK_STREAM_PRECOND(retVal) \ if (q_status != Ok) \ return retVal; /*! Constructs a data stream that has no I/O device. \sa setDevice() */ QDataStream::QDataStream() { dev = 0; owndev = false; byteorder = BigEndian; ver = Qt_DefaultCompiledVersion; noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; q_status = Ok; } /*! Constructs a data stream that uses the I/O device \a d. \sa setDevice(), device() */ QDataStream::QDataStream(QIODevice *d) { dev = d; // set device owndev = false; byteorder = BigEndian; // default byte order ver = Qt_DefaultCompiledVersion; noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; q_status = Ok; } /*! \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); #ifndef QT_NO_QOBJECT buf->blockSignals(true); #endif buf->open(flags); dev = buf; owndev = true; byteorder = BigEndian; ver = Qt_DefaultCompiledVersion; 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; #ifndef QT_NO_QOBJECT buf->blockSignals(true); #endif buf->setData(a); buf->open(QIODevice::ReadOnly); dev = buf; owndev = true; byteorder = BigEndian; ver = Qt_DefaultCompiledVersion; 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, or 0 if no device is currently set. \sa setDevice() */ /*! void QDataStream::setDevice(QIODevice *d) Sets the I/O device to \a d, which can be 0 to unset to current I/O device. \sa device() */ void QDataStream::setDevice(QIODevice *d) { if (owndev) { delete dev; owndev = false; } dev = d; } /*! \obsolete Unsets the I/O device. Use setDevice(0) instead. */ void QDataStream::unsetDevice() { setDevice(0); } /*! \fn bool QDataStream::atEnd() const Returns \c 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 \c false. \sa QIODevice::atEnd() */ bool QDataStream::atEnd() const { return dev ? dev->atEnd() : true; } /*! Returns the floating point precision of the data stream. \since 4.6 \sa FloatingPointPrecision, setFloatingPointPrecision() */ QDataStream::FloatingPointPrecision QDataStream::floatingPointPrecision() const { return d == 0 ? QDataStream::DoublePrecision : d->floatingPointPrecision; } /*! Sets the floating point precision of the data stream to \a precision. If the floating point precision is DoublePrecision and the version of the data stream is Qt_4_6 or higher, all floating point numbers will be written and read with 64-bit precision. If the floating point precision is SinglePrecision and the version is Qt_4_6 or higher, all floating point numbers will be written and read with 32-bit precision. For versions prior to Qt_4_6, the precision of floating point numbers in the data stream depends on the stream operator called. The default is DoublePrecision. \warning This property must be set to the same value on the object that writes and the object that reads the data stream. \since 4.6 */ void QDataStream::setFloatingPointPrecision(QDataStream::FloatingPointPrecision precision) { if (d == 0) d.reset(new QDataStreamPrivate()); d->floatingPointPrecision = precision; } /*! 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. Subsequent calls to setStatus() are ignored until resetStatus() is called. \sa Status, status(), resetStatus() */ void QDataStream::setStatus(Status status) { if (q_status == Ok) q_status = status; } /*! \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); } /*! \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) \value Qt_4_3 Version 9 (Qt 4.3) \value Qt_4_4 Version 10 (Qt 4.4) \value Qt_4_5 Version 11 (Qt 4.5) \value Qt_4_6 Version 12 (Qt 4.6, Qt 4.7, Qt 4.8) \value Qt_4_7 Same as Qt_4_6. \value Qt_4_8 Same as Qt_4_6. \value Qt_4_9 Same as Qt_4_6. \value Qt_5_0 Version 13 (Qt 5.0) \value Qt_5_1 Version 14 (Qt 5.1) \value Qt_5_2 Version 15 (Qt 5.2) \value Qt_5_3 Same as Qt_5_2 \value Qt_5_4 Version 16 (Qt 5.4) \value Qt_5_5 Same as Qt_5_4 \omitvalue Qt_DefaultCompiledVersion \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, a value of the \l Version enum. 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. 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. The \l Version enum provides symbolic constants for the different versions of Qt. For example: \snippet code/src_corelib_io_qdatastream.cpp 5 \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 Reads an unsigned 16-bit integer from the stream into \a i, and returns a reference to the stream. */ /*! \overload Reads a signed 16-bit integer from the stream into \a i, and returns a reference to the stream. */ QDataStream &QDataStream::operator>>(qint16 &i) { i = 0; CHECK_STREAM_PRECOND(*this) if (dev->read((char *)&i, 2) != 2) { i = 0; setStatus(ReadPastEnd); } else { if (!noswap) { i = qbswap(i); } } return *this; } /*! \fn QDataStream &QDataStream::operator>>(quint32 &i) \overload Reads an unsigned 32-bit integer from the stream into \a i, and returns a reference to the stream. */ /*! \overload Reads a signed 32-bit integer from the stream into \a i, and returns a reference to the stream. */ QDataStream &QDataStream::operator>>(qint32 &i) { i = 0; CHECK_STREAM_PRECOND(*this) if (dev->read((char *)&i, 4) != 4) { i = 0; setStatus(ReadPastEnd); } else { if (!noswap) { i = qbswap(i); } } return *this; } /*! \fn QDataStream &QDataStream::operator>>(quint64 &i) \overload Reads an unsigned 64-bit integer from the stream, into \a i, and returns a reference to the stream. */ /*! \overload Reads a signed 64-bit integer from the stream into \a i, and returns a reference to the stream. */ QDataStream &QDataStream::operator>>(qint64 &i) { i = qint64(0); CHECK_STREAM_PRECOND(*this) if (version() < 6) { quint32 i1, i2; *this >> i2 >> i1; i = ((quint64)i1 << 32) + i2; } else { if (dev->read((char *)&i, 8) != 8) { i = qint64(0); setStatus(ReadPastEnd); } else { if (!noswap) { i = qbswap(i); } } } return *this; } /*! Reads a boolean value from the stream into \a i. Returns a reference to the stream. */ QDataStream &QDataStream::operator>>(bool &i) { qint8 v; *this >> v; i = !!v; return *this; } /*! \overload Reads a floating point number from the stream into \a f, using the standard IEEE 754 format. Returns a reference to the stream. \sa setFloatingPointPrecision() */ QDataStream &QDataStream::operator>>(float &f) { if (version() >= QDataStream::Qt_4_6 && floatingPointPrecision() == QDataStream::DoublePrecision) { double d; *this >> d; f = d; return *this; } f = 0.0f; CHECK_STREAM_PRECOND(*this) if (dev->read((char *)&f, 4) != 4) { f = 0.0f; setStatus(ReadPastEnd); } else { if (!noswap) { union { float val1; quint32 val2; } x; x.val2 = qbswap(*reinterpret_cast(&f)); f = x.val1; } } return *this; } /*! \overload Reads a floating point number from the stream into \a f, using the standard IEEE 754 format. Returns a reference to the stream. \sa setFloatingPointPrecision() */ QDataStream &QDataStream::operator>>(double &f) { if (version() >= QDataStream::Qt_4_6 && floatingPointPrecision() == QDataStream::SinglePrecision) { float d; *this >> d; f = d; return *this; } f = 0.0; CHECK_STREAM_PRECOND(*this) if (dev->read((char *)&f, 8) != 8) { f = 0.0; setStatus(ReadPastEnd); } else { if (!noswap) { union { double val1; quint64 val2; } x; x.val2 = qbswap(*reinterpret_cast(&f)); f = x.val1; } } return *this; } /*! \overload Reads the '\\0'-terminated string \a s from the stream and returns a reference to the stream. The string is deserialized using \c{readBytes()}. Space for the string is allocated using \c{new []} -- the caller must destroy it with \c{delete []}. \sa readBytes(), readRawData() */ QDataStream &QDataStream::operator>>(char *&s) { uint len = 0; return readBytes(s, len); } /*! Reads the buffer \a s from the stream and returns a reference to the stream. The buffer \a s is allocated using \c{new []}. Destroy it with the \c{delete []} operator. The \a l parameter is set to the length of the buffer. If the string read is empty, \a l is set to 0 and \a s is set to a null pointer. The serialization format is a quint32 length specifier first, then \a l bytes of data. \sa readRawData(), writeBytes() */ QDataStream &QDataStream::readBytes(char *&s, uint &l) { s = 0; l = 0; CHECK_STREAM_PRECOND(*this) quint32 len; *this >> len; if (len == 0) return *this; const quint32 Step = 1024 * 1024; quint32 allocated = 0; char *prevBuf = 0; char *curBuf = 0; do { int blockSize = qMin(Step, len - allocated); prevBuf = curBuf; curBuf = new char[allocated + blockSize + 1]; if (prevBuf) { memcpy(curBuf, prevBuf, allocated); delete [] prevBuf; } if (dev->read(curBuf + allocated, blockSize) != blockSize) { delete [] curBuf; setStatus(ReadPastEnd); return *this; } allocated += blockSize; } while (allocated < len); s = curBuf; s[len] = '\0'; l = (uint)len; return *this; } /*! Reads at most \a len bytes from the stream into \a s and returns the number of bytes read. If an error occurs, this function returns -1. The buffer \a s must be preallocated. The data is \e not encoded. \sa readBytes(), QIODevice::read(), writeRawData() */ int QDataStream::readRawData(char *s, int len) { CHECK_STREAM_PRECOND(-1) return dev->read(s, len); } /***************************************************************************** QDataStream write functions *****************************************************************************/ /*! \fn QDataStream &QDataStream::operator<<(quint8 i) \overload Writes an unsigned byte, \a i, to the stream and returns a reference to the stream. */ /*! Writes a signed byte, \a i, to the stream and returns a reference to the stream. */ QDataStream &QDataStream::operator<<(qint8 i) { CHECK_STREAM_WRITE_PRECOND(*this) if (!dev->putChar(i)) q_status = WriteFailed; return *this; } /*! \fn QDataStream &QDataStream::operator<<(quint16 i) \overload Writes an unsigned 16-bit integer, \a i, to the stream and returns a reference to the stream. */ /*! \overload Writes a signed 16-bit integer, \a i, to the stream and returns a reference to the stream. */ QDataStream &QDataStream::operator<<(qint16 i) { CHECK_STREAM_WRITE_PRECOND(*this) if (!noswap) { i = qbswap(i); } if (dev->write((char *)&i, sizeof(qint16)) != sizeof(qint16)) q_status = WriteFailed; return *this; } /*! \overload Writes a signed 32-bit integer, \a i, to the stream and returns a reference to the stream. */ QDataStream &QDataStream::operator<<(qint32 i) { CHECK_STREAM_WRITE_PRECOND(*this) if (!noswap) { i = qbswap(i); } if (dev->write((char *)&i, sizeof(qint32)) != sizeof(qint32)) q_status = WriteFailed; return *this; } /*! \fn QDataStream &QDataStream::operator<<(quint64 i) \overload Writes an unsigned 64-bit integer, \a i, to the stream and returns a reference to the stream. */ /*! \overload Writes a signed 64-bit integer, \a i, to the stream and returns a reference to the stream. */ QDataStream &QDataStream::operator<<(qint64 i) { CHECK_STREAM_WRITE_PRECOND(*this) if (version() < 6) { quint32 i1 = i & 0xffffffff; quint32 i2 = i >> 32; *this << i2 << i1; } else { if (!noswap) { i = qbswap(i); } if (dev->write((char *)&i, sizeof(qint64)) != sizeof(qint64)) q_status = WriteFailed; } return *this; } /*! \fn QDataStream &QDataStream::operator<<(quint32 i) \overload Writes an unsigned integer, \a i, to the stream as a 32-bit unsigned integer (quint32). Returns a reference to the stream. */ /*! Writes a boolean value, \a i, to the stream. Returns a reference to the stream. */ QDataStream &QDataStream::operator<<(bool i) { CHECK_STREAM_WRITE_PRECOND(*this) if (!dev->putChar(qint8(i))) q_status = WriteFailed; return *this; } /*! \overload Writes a floating point number, \a f, to the stream using the standard IEEE 754 format. Returns a reference to the stream. \sa setFloatingPointPrecision() */ QDataStream &QDataStream::operator<<(float f) { if (version() >= QDataStream::Qt_4_6 && floatingPointPrecision() == QDataStream::DoublePrecision) { *this << double(f); return *this; } CHECK_STREAM_WRITE_PRECOND(*this) float g = f; // fixes float-on-stack problem if (!noswap) { union { float val1; quint32 val2; } x; x.val1 = g; x.val2 = qbswap(x.val2); if (dev->write((char *)&x.val2, sizeof(float)) != sizeof(float)) q_status = WriteFailed; return *this; } if (dev->write((char *)&g, sizeof(float)) != sizeof(float)) q_status = WriteFailed; return *this; } /*! \overload Writes a floating point number, \a f, to the stream using the standard IEEE 754 format. Returns a reference to the stream. \sa setFloatingPointPrecision() */ QDataStream &QDataStream::operator<<(double f) { if (version() >= QDataStream::Qt_4_6 && floatingPointPrecision() == QDataStream::SinglePrecision) { *this << float(f); return *this; } CHECK_STREAM_WRITE_PRECOND(*this) if (noswap) { if (dev->write((char *)&f, sizeof(double)) != sizeof(double)) q_status = WriteFailed; } else { union { double val1; quint64 val2; } x; x.val1 = f; x.val2 = qbswap(x.val2); if (dev->write((char *)&x.val2, sizeof(double)) != sizeof(double)) q_status = WriteFailed; } return *this; } /*! \overload Writes the '\\0'-terminated string \a s to the stream and returns a reference to the stream. The string is serialized using \c{writeBytes()}. \sa writeBytes(), writeRawData() */ QDataStream &QDataStream::operator<<(const char *s) { if (!s) { *this << (quint32)0; return *this; } uint len = qstrlen(s) + 1; // also write null terminator *this << (quint32)len; // write length specifier writeRawData(s, len); return *this; } /*! Writes the length specifier \a len and the buffer \a s to the stream and returns a reference to the stream. The \a len is serialized as a quint32, followed by \a len bytes from \a s. Note that the data is \e not encoded. \sa writeRawData(), readBytes() */ QDataStream &QDataStream::writeBytes(const char *s, uint len) { CHECK_STREAM_WRITE_PRECOND(*this) *this << (quint32)len; // write length specifier if (len) writeRawData(s, len); return *this; } /*! Writes \a len bytes from \a s to the stream. Returns the number of bytes actually written, or -1 on error. The data is \e not encoded. \sa writeBytes(), QIODevice::write(), readRawData() */ int QDataStream::writeRawData(const char *s, int len) { CHECK_STREAM_WRITE_PRECOND(-1) int ret = dev->write(s, len); if (ret != len) q_status = WriteFailed; return ret; } /*! \since 4.1 Skips \a len bytes from the device. Returns the number of bytes actually skipped, or -1 on error. This is equivalent to calling readRawData() on a buffer of length \a len and ignoring the buffer. \sa QIODevice::seek() */ int QDataStream::skipRawData(int len) { CHECK_STREAM_PRECOND(-1) if (dev->isSequential()) { char buf[4096]; int sumRead = 0; while (len > 0) { int blockSize = qMin(len, (int)sizeof(buf)); int n = dev->read(buf, blockSize); if (n == -1) return -1; if (n == 0) return sumRead; sumRead += n; len -= blockSize; } return sumRead; } else { qint64 pos = dev->pos(); qint64 size = dev->size(); if (pos + len > size) len = size - pos; if (!dev->seek(pos + len)) return -1; return len; } } QT_END_NAMESPACE #endif // QT_NO_DATASTREAM