/**************************************************************************** ** $Id$ ** ** Implementation of QBuffer class ** ** Created : 930812 ** ** Copyright (C) 1992-2002 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. ** ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for ** information about Qt Commercial License Agreements. ** See http://www.trolltech.com/qpl/ for QPL licensing information. ** See http://www.trolltech.com/gpl/ for GPL licensing information. ** ** Contact info@trolltech.com if any conditions of this licensing are ** not clear to you. ** **********************************************************************/ #include "qbuffer.h" #include <stdlib.h> /*! \class QBuffer qbuffer.h \reentrant \brief The QBuffer class is an I/O device that operates on a QByteArray. \ingroup io \ingroup collection QBuffer is used to read and write to a memory buffer. It is normally used with a QTextStream or a QDataStream. QBuffer has an associated QByteArray which holds the buffer data. The size() of the buffer is automatically adjusted as data is written. The constructor \c QBuffer(QByteArray) creates a QBuffer using an existing byte array. The byte array can also be set with setBuffer(). Writing to the QBuffer will modify the original byte array because QByteArray is \link shclass.html explicitly shared.\endlink Use open() to open the buffer before use and to set the mode (read-only, write-only, etc.). close() closes the buffer. The buffer must be closed before reopening or calling setBuffer(). A common way to use QBuffer is through \l QDataStream or \l QTextStream, which have constructors that take a QBuffer parameter. For convenience, there are also QDataStream and QTextStream constructors that take a QByteArray parameter. These constructors create and open an internal QBuffer. Note that QTextStream can also operate on a QString (a Unicode string); a QBuffer cannot. You can also use QBuffer directly through the standard QIODevice functions readBlock(), writeBlock() readLine(), at(), getch(), putch() and ungetch(). \sa QFile, QDataStream, QTextStream, QByteArray, \link shclass.html Shared Classes\endlink */ /*! Constructs an empty buffer. */ QBuffer::QBuffer() { setFlags( IO_Direct ); a_inc = 16; // initial increment a_len = 0; ioIndex = 0; } /*! Constructs a buffer that operates on \a buf. If you open the buffer in write mode (\c IO_WriteOnly or \c IO_ReadWrite) and write something into the buffer, \a buf will be modified. Example: \code QCString str = "abc"; QBuffer b( str ); b.open( IO_WriteOnly ); b.at( 3 ); // position at the 4th character (the terminating \0) b.writeBlock( "def", 4 ); // write "def" including the terminating \0 b.close(); // Now, str == "abcdef" with a terminating \0 \endcode \sa setBuffer() */ QBuffer::QBuffer( QByteArray buf ) : a(buf) { setFlags( IO_Direct ); a_len = a.size(); a_inc = (a_len > 512) ? 512 : a_len; // initial increment if ( a_inc < 16 ) a_inc = 16; ioIndex = 0; } /*! Destroys the buffer. */ QBuffer::~QBuffer() { } /*! Replaces the buffer's contents with \a buf and returns TRUE. Does nothing (and returns FALSE) if isOpen() is TRUE. Note that if you open the buffer in write mode (\c IO_WriteOnly or IO_ReadWrite) and write something into the buffer, \a buf is also modified because QByteArray is an explicitly shared class. \sa buffer(), open(), close() */ bool QBuffer::setBuffer( QByteArray buf ) { if ( isOpen() ) { #if defined(QT_CHECK_STATE) qWarning( "QBuffer::setBuffer: Buffer is open" ); #endif return FALSE; } a = buf; a_len = a.size(); a_inc = (a_len > 512) ? 512 : a_len; // initial increment if ( a_inc < 16 ) a_inc = 16; ioIndex = 0; return TRUE; } /*! \fn QByteArray QBuffer::buffer() const Returns this buffer's byte array. \sa setBuffer() */ /*! \reimp Opens the buffer in mode \a m. Returns TRUE if successful; otherwise returns FALSE. The buffer must be opened before use. The mode parameter \a m must be a combination of the following flags. \list \i \c IO_ReadOnly opens the buffer in read-only mode. \i \c IO_WriteOnly opens the buffer in write-only mode. \i \c IO_ReadWrite opens the buffer in read/write mode. \i \c IO_Append sets the buffer index to the end of the buffer. \i \c IO_Truncate truncates the buffer. \endlist \sa close(), isOpen() */ bool QBuffer::open( int m ) { if ( isOpen() ) { // buffer already open #if defined(QT_CHECK_STATE) qWarning( "QBuffer::open: Buffer already open" ); #endif return FALSE; } setMode( m ); if ( m & IO_Truncate ) { // truncate buffer a.resize( 0 ); a_len = 0; } if ( m & IO_Append ) { // append to end of buffer ioIndex = a.size(); } else { ioIndex = 0; } a_inc = 16; setState( IO_Open ); setStatus( 0 ); return TRUE; } /*! \reimp Closes an open buffer. \sa open() */ void QBuffer::close() { if ( isOpen() ) { setFlags( IO_Direct ); ioIndex = 0; a_inc = 16; } } /*! \reimp The flush function does nothing for a QBuffer. */ void QBuffer::flush() { return; } /*! \fn QIODevice::Offset QBuffer::at() const \reimp */ /*! \fn QIODevice::Offset QBuffer::size() const \reimp */ /*! \reimp */ bool QBuffer::at( Offset pos ) { #if defined(QT_CHECK_STATE) if ( !isOpen() ) { qWarning( "QBuffer::at: Buffer is not open" ); return FALSE; } #endif if ( pos > a_len ) { #if defined(QT_CHECK_RANGE) #if defined(QT_LARGEFILE_SUPPORT) && defined(QT_ABI_64BITOFFSET) qWarning( "QBuffer::at: Index %llu out of range", pos ); #else qWarning( "QBuffer::at: Index %lu out of range", pos ); #endif #endif return FALSE; } ioIndex = pos; return TRUE; } /*! \reimp */ Q_LONG QBuffer::readBlock( char *p, Q_ULONG len ) { #if defined(QT_CHECK_STATE) if ( !p ) { qWarning( "QBuffer::readBlock: Null pointer error" ); return -1; } if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::readBlock: Buffer not open" ); return -1; } if ( !isReadable() ) { // reading not permitted qWarning( "QBuffer::readBlock: Read operation not permitted" ); return -1; } #endif if ( ioIndex + len > a.size() ) { // overflow if ( ioIndex >= a.size() ) { return 0; } else { len = a.size() - ioIndex; } } memcpy( p, a.data()+ioIndex, len ); ioIndex += len; return len; } /*! \overload Q_LONG QBuffer::writeBlock( const QByteArray& data ) This convenience function is the same as calling \c{writeBlock( data.data(), data.size() )} with \a data. */ /*! Writes \a len bytes from \a p into the buffer at the current index position, overwriting any characters there and extending the buffer if necessary. Returns the number of bytes actually written. Returns -1 if an error occurred. \sa readBlock() */ Q_LONG QBuffer::writeBlock( const char *p, Q_ULONG len ) { if ( len == 0 ) return 0; #if defined(QT_CHECK_NULL) if ( p == 0 ) { qWarning( "QBuffer::writeBlock: Null pointer error" ); return -1; } #endif #if defined(QT_CHECK_STATE) if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::writeBlock: Buffer not open" ); return -1; } if ( !isWritable() ) { // writing not permitted qWarning( "QBuffer::writeBlock: Write operation not permitted" ); return -1; } #endif if ( ioIndex + len >= a_len ) { // overflow Q_ULONG new_len = a_len + a_inc*((ioIndex+len-a_len)/a_inc+1); if ( !a.resize( new_len ) ) { // could not resize #if defined(QT_CHECK_NULL) qWarning( "QBuffer::writeBlock: Memory allocation error" ); #endif setStatus( IO_ResourceError ); return -1; } a_inc *= 2; // double increment a_len = new_len; a.shd->len = ioIndex + len; } memcpy( a.data()+ioIndex, p, len ); ioIndex += len; if ( a.shd->len < ioIndex ) a.shd->len = ioIndex; // fake (not alloc'd) length return len; } /*! \reimp */ Q_LONG QBuffer::readLine( char *p, Q_ULONG maxlen ) { #if defined(QT_CHECK_NULL) if ( p == 0 ) { qWarning( "QBuffer::readLine: Null pointer error" ); return -1; } #endif #if defined(QT_CHECK_STATE) if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::readLine: Buffer not open" ); return -1; } if ( !isReadable() ) { // reading not permitted qWarning( "QBuffer::readLine: Read operation not permitted" ); return -1; } #endif if ( maxlen == 0 ) return 0; Q_ULONG start = ioIndex; char *d = a.data() + ioIndex; maxlen--; // make room for 0-terminator if ( a.size() - ioIndex < maxlen ) maxlen = a.size() - ioIndex; while ( maxlen-- ) { if ( (*p++ = *d++) == '\n' ) break; } *p = '\0'; ioIndex = d - a.data(); return ioIndex - start; } /*! \reimp */ int QBuffer::getch() { #if defined(QT_CHECK_STATE) if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::getch: Buffer not open" ); return -1; } if ( !isReadable() ) { // reading not permitted qWarning( "QBuffer::getch: Read operation not permitted" ); return -1; } #endif if ( ioIndex+1 > a.size() ) { // overflow setStatus( IO_ReadError ); return -1; } return uchar(*(a.data()+ioIndex++)); } /*! \reimp Writes the character \a ch into the buffer at the current index position, overwriting any existing character and extending the buffer if necessary. Returns \a ch, or -1 if an error occurred. \sa getch(), ungetch() */ int QBuffer::putch( int ch ) { #if defined(QT_CHECK_STATE) if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::putch: Buffer not open" ); return -1; } if ( !isWritable() ) { // writing not permitted qWarning( "QBuffer::putch: Write operation not permitted" ); return -1; } #endif if ( ioIndex + 1 >= a_len ) { // overflow char buf[1]; buf[0] = (char)ch; if ( writeBlock(buf,1) != 1 ) return -1; // write error } else { *(a.data() + ioIndex++) = (char)ch; if ( a.shd->len < ioIndex ) a.shd->len = ioIndex; } return ch; } /*! \reimp */ int QBuffer::ungetch( int ch ) { #if defined(QT_CHECK_STATE) if ( !isOpen() ) { // buffer not open qWarning( "QBuffer::ungetch: Buffer not open" ); return -1; } if ( !isReadable() ) { // reading not permitted qWarning( "QBuffer::ungetch: Read operation not permitted" ); return -1; } #endif if ( ch != -1 ) { if ( ioIndex ) ioIndex--; else ch = -1; } return ch; }