kio

klimitediodevice.h

00001 /* This file is part of the KDE libraries
00002    Copyright (C) 2001, 2002 David Faure <david@mandrakesoft.com>
00003 
00004    This library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Library General Public
00006    License version 2 as published by the Free Software Foundation.
00007 
00008    This library is distributed in the hope that it will be useful,
00009    but WITHOUT ANY WARRANTY; without even the implied warranty of
00010    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00011    Library General Public License for more details.
00012 
00013    You should have received a copy of the GNU Library General Public License
00014    along with this library; see the file COPYING.LIB.  If not, write to
00015    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
00016    Boston, MA 02110-1301, USA.
00017 */
00018 
00019 #ifndef klimitediodevice_h
00020 #define klimitediodevice_h
00021 
00022 #include <kdebug.h>
00023 #include <qiodevice.h>
00031 class KIO_EXPORT KLimitedIODevice : public QIODevice
00032 {
00033 public:
00041     KLimitedIODevice( QIODevice *dev, int start, int length )
00042         : m_dev( dev ), m_start( start ), m_length( length )
00043     {
00044         //kdDebug(7005) << "KLimitedIODevice::KLimitedIODevice start=" << start << " length=" << length << endl;
00045         setType( IO_Direct ); // we support sequential too, but then atEnd() tries getch/ungetch !
00046         open( IO_ReadOnly );
00047     }
00048     virtual ~KLimitedIODevice() {}
00049 
00050     virtual bool open( int m ) {
00051         //kdDebug(7005) << "KLimitedIODevice::open m=" << m << endl;
00052         if ( m & IO_ReadOnly ) {
00053             /*bool ok = false;
00054             if ( m_dev->isOpen() )
00055                 ok = ( m_dev->mode() == IO_ReadOnly );
00056             else
00057                 ok = m_dev->open( m );
00058             if ( ok )*/
00059                 m_dev->at( m_start ); // No concurrent access !
00060         }
00061         else
00062             kdWarning(7005) << "KLimitedIODevice::open only supports IO_ReadOnly!" << endl;
00063         setState( IO_Open );
00064         setMode( m );
00065         return true;
00066     }
00067     virtual void close() {}
00068     virtual void flush() {}
00069 
00070     virtual Offset size() const { return m_length; }
00071 
00072     virtual Q_LONG readBlock ( char * data, Q_ULONG maxlen )
00073     {
00074         maxlen = QMIN( maxlen, m_length - at() ); // Apply upper limit
00075         return m_dev->readBlock( data, maxlen );
00076     }
00077     virtual Q_LONG writeBlock ( const char *, Q_ULONG ) { return -1; } // unsupported
00078     virtual int putch( int ) { return -1; } // unsupported
00079 
00080     virtual int getch() {
00081         char c[2];
00082         if ( readBlock(c, 1) == -1)
00083             return -1;
00084         else
00085             return c[0];
00086     }
00087     virtual int ungetch( int c ) { return m_dev->ungetch(c); } // ## apply lower limit ?
00088     virtual Offset at() const { return m_dev->at() - m_start; }
00089     virtual bool at( Offset pos ) {
00090         Q_ASSERT( pos <= m_length );
00091         pos = QMIN( pos, m_length ); // Apply upper limit
00092         return m_dev->at( m_start + pos );
00093     }
00094     virtual bool atEnd() const { return m_dev->atEnd() || m_dev->at() >= m_start + m_length; }
00095 private:
00096     QIODevice* m_dev;
00097     Q_ULONG m_start;
00098     Q_ULONG m_length;
00099 };
00100 
00101 #endif
kio

klimitediodevice.h

kio

API Reference
