/****************************************************************************
**
**
** Implementation of QDataStream class
**
** Created : 930831
**
** Copyright (C) 1992-2000 Trolltech AS. All rights reserved.
**
** This file is part of the tools module of the Qt GUI Toolkit.
**
** This file may be distributed under the terms of the Q Public License
** as defined by Trolltech AS of Norway and appearing in the file
** LICENSE.QPL included in the packaging of this file.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** Licensees holding valid Qt Enterprise Edition or Qt Professional Edition
** licenses may use this file in accordance with the Qt Commercial License
** Agreement provided with the Software.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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** information about Qt Commercial License Agreements.
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**********************************************************************/
#include "qdatastream.h"
#ifndef QT_NO_DATASTREAM
#include "qbuffer.h"
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
// REVISED: warwick
/*!
\class QDataStream qdatastream.h
\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 operation system, CPU or byte order. A
stream that is written by a PC under DOS/Windows can be read by a
Sun SPARC running Solaris.
The QDataStream class implements serialization of primitive 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.
The programmer 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.
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 IO device.
Example (write data to a stream):
\code
QFile f( "file.dta" );
f.open( IO_WriteOnly ); // open file for writing
QDataStream s( &f ); // serialize using f
s << "the answer is"; // serialize string
s << (Q_INT32)42; // serialize integer
\endcode
Example (read data from a stream):
\code
QFile f( "file.dta" );
f.open( IO_ReadOnly ); // open file for reading
QDataStream s( &f ); // serialize using f
char *str;
Q_INT32 a;
s >> str >> a; // "the answer is" and 42
delete str; // delete string
\endcode
In the last example, if you read into a QString instead of a \c char*
you do not have to delete it.
Normally, each item written to the stream is written in a fixed binary
format.
For example, a \c char* is written as a 32-bit integer equal to the
length of the string including the NUL byte, followed by all the
characters of the string including the NUL byte. Similarly when
reading a string, 4 bytes are read to create the 32-bit length value,
then that many characters for the string including the NUL. For a complete
description of all Qt types supporting data streaming see \link
datastreamformat.html Format of the QDataStream operators \endlink .
If you want a "parsing" input stream, see QTextStream. If you just want the
data to be human-readable to aid in debugging, you can set the data
stream into printable data mode with setPrintableData(). The data is
then written slower, in a human readable bloated form that is sufficient
for debugging.
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
// Open the file.
QFile f( "file.xxx" );
f.open( IO_WriteOnly );
QDataStream s( &f );
// Write a header with a "magic number" and a version
s << 0xa0b0c0d0;
s << 123;
// Write the data
s << [lots of interesting data]
\endcode
Then read it in with:
\code
// Open the file.
QFile f( "file.xxx" );
f.open( IO_ReadOnly );
QDataStream s( &f );
// Read and check the header
Q_UINT32 magic;
s >> magic;
if ( magic != 0xa0b0c0d0 )
return XXX_BAD_FILE_FORMAT;
// Read the version
Q_INT32 version;
s >> version;
if ( version < 100 )
return XXX_BAD_FILE_TOO_OLD;
if ( version > 123 )
return XXX_BAD_FILE_TOO_NEW;
if ( version <= 110 )
s.setVersion(1);
// Read the data
s >> [lots of interesting data];
if ( version > 120 )
s >> [data new in XXX version 1.2];
s >> [other interesting data];
\endcode
\sa QTextStream QVariant
*/
/*****************************************************************************
QDataStream member functions
*****************************************************************************/
#if defined(CHECK_STATE)
#undef CHECK_STREAM_PRECOND
#define CHECK_STREAM_PRECOND if ( !dev ) { \
qWarning( "QDataStream: No device" ); \
return *this; }
#else
#define CHECK_STREAM_PRECOND
#endif
static int systemWordSize = 0;
static bool systemBigEndian;
static const int DefaultStreamVersion = 3;
// 3 is default in Qt 2.1
// 2 is the Qt 2.0.x format
// 1 is the Qt 1.x format
/*!
Constructs a data stream that has no IO device.
\sa setDevice()
*/
QDataStream::QDataStream()
{
if ( systemWordSize == 0 ) // get system features
qSysInfo( &systemWordSize, &systemBigEndian );
dev = 0; // no device set
owndev = FALSE;
byteorder = BigEndian; // default byte order
printable = FALSE;
ver = DefaultStreamVersion;
noswap = systemBigEndian;
}
/*!
Constructs a data stream that uses the IO device \a d.
\sa setDevice(), device()
*/
QDataStream::QDataStream( QIODevice *d )
{
if ( systemWordSize == 0 ) // get system features
qSysInfo( &systemWordSize, &systemBigEndian );
dev = d; // set device
owndev = FALSE;
byteorder = BigEndian; // default byte order
printable = FALSE;
ver = DefaultStreamVersion;
noswap = systemBigEndian;
}
/*!
Constructs a data stream that operates on a byte array through an
internal QBuffer device.
Example:
\code
static char bindata[] = { 231, 1, 44, ... };
QByteArray a;
a.setRawData( bindata, sizeof(bindata) ); // a points to bindata
QDataStream s( a, IO_ReadOnly ); // open on a's data
s >> [something]; // read raw bindata
a.resetRawData( bindata, sizeof(bindata) ); // finished
\endcode
The QArray::setRawData() function is not for the inexperienced.
*/
QDataStream::QDataStream( QByteArray a, int mode )
{
if ( systemWordSize == 0 ) // get system features
qSysInfo( &systemWordSize, &systemBigEndian );
dev = new QBuffer( a ); // create device
((QBuffer *)dev)->open( mode ); // open device
owndev = TRUE;
byteorder = BigEndian; // default byte order
printable = FALSE;
ver = DefaultStreamVersion;
noswap = systemBigEndian;
}
/*!
Destructs the data stream.
The destructor will not affect the current IO device, unless it
is an internal IO device processing a QByteArray passed in the constructor.
*/
QDataStream::~QDataStream()
{
if ( owndev )
delete dev;
}
/*!
\fn QIODevice *QDataStream::device() const
Returns the IO device currently set.
\sa setDevice(), unsetDevice()
*/
/*!
void QDataStream::setDevice(QIODevice *d )
Sets the IO device to \a d.
\sa device(), unsetDevice()
*/
void QDataStream::setDevice(QIODevice *d )
{
if ( owndev ) {
delete dev;
owndev = FALSE;
}
dev = d;
}
/*!
Unsets the IO 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 IO device has reached the end position (end of
stream or file) or if there is no IO device set.
Returns FALSE if the current position of the read/write head of the IO
device is somewhere before the end position.
\sa QIODevice::atEnd()
*/
/*!\fn bool QDataStream::eof() const
\obsolete
Returns TRUE if the IO device has reached the end position (end of
stream or file) or if there is no IO device set.
Returns FALSE if the current position of the read/write head of the IO
device is somewhere before the end position.
\sa QIODevice::atEnd()
*/
/*!
\fn int QDataStream::byteOrder() const
Returns the current byte order setting - either \c BigEndian or
\c LittleEndian.
\sa setByteOrder()
*/
/*!
Sets the serialization byte order to \a bo.
The \a bo parameter can be \c QDataStream::BigEndian or
\c QDataStream::LittleEndian.
The default setting is big endian. We recommend leaving this setting unless
you have special requirements.
\sa byteOrder()
*/
void QDataStream::setByteOrder( int bo )
{
byteorder = bo;
if ( systemBigEndian )
noswap = byteorder == BigEndian;
else
noswap = byteorder == LittleEndian;
}
/*!
\fn bool QDataStream::isPrintableData() const
Returns TRUE if the printable data flag has been set.
\sa setPrintableData()
*/
/*!
\fn void QDataStream::setPrintableData( bool enable )
Sets or clears the printable data flag.
If this flag is set, the write functions will generate output that
consists of printable characters (7 bit ASCII).
We recommend enabling printable data only for debugging purposes
(it is slower and creates larger output).
*/
/*!
\fn int QDataStream::version() const
Returns the version number of the data serialization format.
In Qt 2.1, this number is by default 3.
\sa setVersion()
*/
/*!
\fn void QDataStream::setVersion( int v )
Sets the version number of the data serialization format.
In order to accommodate for 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 of QDataStream.
For Qt 1.x compatibility, use \a v == 1.
For Qt 2.0.x compatibility, use \a v == 2 (Not required for reading in
Qt 2.1).
\sa version()
*/
/*****************************************************************************
QDataStream read functions
*****************************************************************************/
static Q_INT32 read_int_ascii( QDataStream *s )
{
register int n = 0;
char buf[40];
while ( TRUE ) {
buf[n] = s->device()->getch();
if ( buf[n] == '\n' || n > 38 ) // $-terminator
break;
n++;
}
buf[n] = '\0';
return (Q_INT32)atol( buf );
}
/*!
\fn QDataStream &QDataStream::operator>>( Q_UINT8 &i )
Reads an unsigned byte from the stream and returns a reference to
the stream.
*/
/*!
Reads a signed byte from the stream.
*/
QDataStream &QDataStream::operator>>( Q_INT8 &i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
i = (Q_INT8)dev->getch();
if ( i == '\\' ) { // read octal code
char buf[4];
dev->readBlock( buf, 3 );
i = (buf[2] & 0x07)+((buf[1] & 0x07) << 3)+((buf[0] & 0x07) << 6);
}
} else { // data or text
i = (Q_INT8)dev->getch();
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator>>( Q_UINT16 &i )
Reads an unsigned 16-bit integer from the stream and returns a reference to
the stream.
*/
/*!
Reads a signed 16-bit integer from the stream and returns a reference to
the stream.
*/
QDataStream &QDataStream::operator>>( Q_INT16 &i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
i = (Q_INT16)read_int_ascii( this );
} else if ( noswap ) { // no conversion needed
dev->readBlock( (char *)&i, sizeof(Q_INT16) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[2];
dev->readBlock( b, 2 );
*p++ = b[1];
*p = b[0];
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator>>( Q_UINT32 &i )
Reads an unsigned 32-bit integer from the stream and returns a reference to
the stream.
*/
/*!
Reads a signed 32-bit integer from the stream and returns a reference to
the stream.
*/
QDataStream &QDataStream::operator>>( Q_INT32 &i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
i = read_int_ascii( this );
} else if ( noswap ) { // no conversion needed
dev->readBlock( (char *)&i, sizeof(Q_INT32) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[4];
dev->readBlock( b, 4 );
*p++ = b[3];
*p++ = b[2];
*p++ = b[1];
*p = b[0];
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator>>( Q_UINT64 &i )
Reads an unsigned 64-bit integer from the stream and returns a reference to
the stream, or uses the Q_UINT32 operator if 64 bit is not available.
*/
/*!
Reads a signed 64-bit integer from the stream and returns a reference to
the stream, or uses the Q_UINT32 operator if 64 bit is not available.
*/
QDataStream &QDataStream::operator>>( Q_INT64 &i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
i = read_int_ascii( this );
} else if ( noswap ) { // no conversion needed
dev->readBlock( (char *)&i, sizeof(Q_INT64) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[sizeof(Q_INT64)];
dev->readBlock( b, sizeof(Q_INT64) );
if ( sizeof(Q_INT64) == 8 ) {
*p++ = b[7];
*p++ = b[6];
*p++ = b[5];
*p++ = b[4];
}
*p++ = b[3];
*p++ = b[2];
*p++ = b[1];
*p = b[0];
}
return *this;
}
static double read_double_ascii( QDataStream *s )
{
register int n = 0;
char buf[80];
while ( TRUE ) {
buf[n] = s->device()->getch();
if ( buf[n] == '\n' || n > 78 ) // $-terminator
break;
n++;
}
buf[n] = '\0';
return atof( buf );
}
/*!
Reads a 32-bit floating point number from the stream using the standard
IEEE754 format. Returns a reference to the stream.
*/
QDataStream &QDataStream::operator>>( float &f )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
f = (float)read_double_ascii( this );
} else if ( noswap ) { // no conversion needed
dev->readBlock( (char *)&f, sizeof(float) );
} else { // swap bytes
register uchar *p = (uchar *)(&f);
char b[4];
dev->readBlock( b, 4 );
*p++ = b[3];
*p++ = b[2];
*p++ = b[1];
*p = b[0];
}
return *this;
}
/*!
Reads a 64-bit floating point number from the stream using the standard
IEEE754 format. Returns a reference to the stream.
*/
QDataStream &QDataStream::operator>>( double &f )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
f = read_double_ascii( this );
} else if ( noswap ) { // no conversion needed
dev->readBlock( (char *)&f, sizeof(double) );
} else { // swap bytes
register uchar *p = (uchar *)(&f);
char b[8];
dev->readBlock( b, 8 );
*p++ = b[7];
*p++ = b[6];
*p++ = b[5];
*p++ = b[4];
*p++ = b[3];
*p++ = b[2];
*p++ = b[1];
*p = b[0];
}
return *this;
}
/*!
Reads the '\0'-terminated string \a s from the stream and returns
a reference to the stream.
Space for the string is allocated using \c new - the caller must
eventually call delete[] on the value.
*/
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. If the length is zero or \a s cannot be allocated, \a s is
set to 0.
The \a l parameter will be set to the length of the buffer.
The serialization format is an Q_UINT32 length specifier first, then the
data (\a l bytes).
\sa readRawBytes(), writeBytes()
*/
QDataStream &QDataStream::readBytes( char *&s, uint &l )
{
CHECK_STREAM_PRECOND
Q_UINT32 len;
*this >> len; // first read length spec
l = (uint)len;
if ( len == 0 || eof() ) {
s = 0;
return *this;
} else {
s = new char[len]; // create char array
CHECK_PTR( s );
if ( !s ) // no memory
return *this;
return readRawBytes( s, (uint)len );
}
}
/*!
Reads \a len bytes from the stream into \a s and returns a reference to
the stream.
The buffer \a s must be preallocated.
\sa readBytes(), QIODevice::readBlock(), writeRawBytes()
*/
QDataStream &QDataStream::readRawBytes( char *s, uint len )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
register Q_INT8 *p = (Q_INT8*)s;
while ( len-- )
*this >> *p++;
} else { // read data char array
dev->readBlock( s, len );
}
return *this;
}
/*****************************************************************************
QDataStream write functions
*****************************************************************************/
/*!
\fn QDataStream &QDataStream::operator<<( Q_UINT8 i )
Writes an unsigned byte to the stream and returns a reference to
the stream.
*/
/*!
Writes a signed byte to the stream.
*/
QDataStream &QDataStream::operator<<( Q_INT8 i )
{
CHECK_STREAM_PRECOND
if ( printable && (i == '\\' || !isprint(i)) ) {
char buf[6]; // write octal code
buf[0] = '\\';
buf[1] = '0' + ((i >> 6) & 0x07);
buf[2] = '0' + ((i >> 3) & 0x07);
buf[3] = '0' + (i & 0x07);
buf[4] = '\0';
dev->writeBlock( buf, 4 );
} else {
dev->putch( i );
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator<<( Q_UINT16 i )
Writes an unsigned 16-bit integer to the stream and returns a reference
to the stream.
*/
/*!
Writes a signed 16-bit integer to the stream and returns a reference to
the stream.
*/
QDataStream &QDataStream::operator<<( Q_INT16 i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
char buf[16];
sprintf( buf, "%d\n", i );
dev->writeBlock( buf, strlen(buf) );
} else if ( noswap ) { // no conversion needed
dev->writeBlock( (char *)&i, sizeof(Q_INT16) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[2];
b[1] = *p++;
b[0] = *p;
dev->writeBlock( b, 2 );
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator<<( Q_UINT32 i )
Writes an unsigned 32-bit integer to the stream and returns a reference to
the stream.
*/
/*!
Writes a signed 32-bit integer to the stream and returns a reference to
the stream.
*/
QDataStream &QDataStream::operator<<( Q_INT32 i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
char buf[16];
sprintf( buf, "%d\n", i );
dev->writeBlock( buf, strlen(buf) );
} else if ( noswap ) { // no conversion needed
dev->writeBlock( (char *)&i, sizeof(Q_INT32) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[4];
b[3] = *p++;
b[2] = *p++;
b[1] = *p++;
b[0] = *p;
dev->writeBlock( b, 4 );
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator<<( Q_UINT64 i )
Writes an unsigned 64-bit integer to the stream and returns a reference to
the stream, or uses the Q_UINT32-operator if 64 bit is not available.
*/
/*!
Writes a signed 64-bit integer to the stream and returns a reference to
the stream, or calls the Q_INT32-operator if 64 bit is not available.
*/
QDataStream &QDataStream::operator<<( Q_INT64 i )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
char buf[20];
sprintf( buf, "%ld\n", i );
dev->writeBlock( buf, strlen(buf) );
} else if ( noswap ) { // no conversion needed
dev->writeBlock( (char *)&i, sizeof(Q_INT64) );
} else { // swap bytes
register uchar *p = (uchar *)(&i);
char b[sizeof(Q_INT64)];
if ( sizeof(Q_INT64) == 8 ) {
b[7] = *p++;
b[6] = *p++;
b[5] = *p++;
b[4] = *p++;
}
b[3] = *p++;
b[2] = *p++;
b[1] = *p++;
b[0] = *p;
dev->writeBlock( b, sizeof(Q_INT64) );
}
return *this;
}
/*!
\fn QDataStream &QDataStream::operator<<( uint i )
Writes an unsigned integer to the stream as a 32-bit unsigned integer
(Q_UINT32).
Returns a reference to the stream.
*/
/*!
\fn QDataStream &QDataStream::operator<<( int i )
Writes a signed integer to the stream as a 32-bit signed integer (Q_INT32).
Returns a reference to the stream.
*/
/*!
Writes a 32-bit floating point number to the stream using the standard
IEEE754 format. Returns a reference to the stream.
*/
QDataStream &QDataStream::operator<<( float f )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
char buf[32];
sprintf( buf, "%g\n", (double)f );
dev->writeBlock( buf, strlen(buf) );
} else {
float g = f; // fixes float-on-stack problem
if ( noswap ) { // no conversion needed
dev->writeBlock( (char *)&g, sizeof(float) );
} else { // swap bytes
register uchar *p = (uchar *)(&g);
char b[4];
b[3] = *p++;
b[2] = *p++;
b[1] = *p++;
b[0] = *p;
dev->writeBlock( b, 4 );
}
}
return *this;
}
/*!
Writes a 64-bit floating point number to the stream using the standard
IEEE754 format. Returns a reference to the stream.
*/
QDataStream &QDataStream::operator<<( double f )
{
CHECK_STREAM_PRECOND
if ( printable ) { // printable data
char buf[32];
sprintf( buf, "%g\n", f );
dev->writeBlock( buf, strlen(buf) );
} else if ( noswap ) { // no conversion needed
dev->writeBlock( (char *)&f, sizeof(double) );
} else { // swap bytes
register uchar *p = (uchar *)(&f);
char b[8];
b[7] = *p++;
b[6] = *p++;
b[5] = *p++;
b[4] = *p++;
b[3] = *p++;
b[2] = *p++;
b[1] = *p++;
b[0] = *p;
dev->writeBlock( b, 8 );
}
return *this;
}
/*!
Writes the '\0'-terminated string \a s to the stream and returns
a reference to the stream.
The string is serialized using writeBytes().
*/
QDataStream &QDataStream::operator<<( const char *s )
{
if ( !s ) {
*this << (Q_UINT32)0;
return *this;
}
uint len = qstrlen( s ) + 1; // also write null terminator
*this << (Q_UINT32)len; // write length specifier
return writeRawBytes( s, len );
}
/*!
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 an Q_UINT32, followed by \a len bytes from
\a s.
\sa writeRawBytes(), readBytes()
*/
QDataStream &QDataStream::writeBytes(const char *s, uint len)
{
CHECK_STREAM_PRECOND
*this << (Q_UINT32)len; // write length specifier
if ( len )
writeRawBytes( s, len );
return *this;
}
/*!
Writes \a len bytes from \a s to the stream and returns a reference to the
stream.
\sa writeBytes(), QIODevice::writeBlock(), readRawBytes()
*/
QDataStream &QDataStream::writeRawBytes( const char *s, uint len )
{
CHECK_STREAM_PRECOND
if ( printable ) { // write printable
register char *p = (char *)s;
while ( len-- )
*this << *p++;
} else { // write data char array
dev->writeBlock( s, len );
}
return *this;
}
#endif // QT_NO_DATASTREAM