kio Library API Documentation

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., 59 Temple Place - Suite 330,
00016    Boston, MA 02111-1307, USA.
00017 */
00018 
00019 #ifndef klimitediodevice_h
00020 #define klimitediodevice_h
00021 
00029 class KLimitedIODevice : public QIODevice
00030 {
00031 public:
00036     KLimitedIODevice( QIODevice *dev, int start, int length )
00037         : m_dev( dev ), m_start( start ), m_length( length )
00038     {
00039         //kdDebug(7005) << "KLimitedIODevice::KLimitedIODevice start=" << start << " length=" << length << endl;
00040         setType( IO_Direct ); // we support sequential too, but then atEnd() tries getch/ungetch !
00041         open( IO_ReadOnly );
00042     }
00043     virtual ~KLimitedIODevice() {}
00044 
00045     virtual bool open( int m ) {
00046         //kdDebug(7005) << "KLimitedIODevice::open m=" << m << endl;
00047         if ( m & IO_ReadOnly ) {
00048             /*bool ok = false;
00049             if ( m_dev->isOpen() )
00050                 ok = ( m_dev->mode() == IO_ReadOnly );
00051             else
00052                 ok = m_dev->open( m );
00053             if ( ok )*/
00054                 m_dev->at( m_start ); // No concurrent access !
00055         }
00056         else
00057             kdWarning(7005) << "KLimitedIODevice::open only supports IO_ReadOnly!" << endl;
00058         setState( IO_Open );
00059         setMode( m );
00060         return true;
00061     }
00062     virtual void close() {}
00063     virtual void flush() {}
00064 
00065     virtual Offset size() const { return m_length; }
00066 
00067     virtual Q_LONG readBlock ( char * data, Q_ULONG maxlen )
00068     {
00069         maxlen = QMIN( maxlen, m_length - at() ); // Apply upper limit
00070         return m_dev->readBlock( data, maxlen );
00071     }
00072     virtual Q_LONG writeBlock ( const char *, Q_ULONG ) { return -1; } // unsupported
00073     virtual int putch( int ) { return -1; } // unsupported
00074 
00075     virtual int getch() {
00076         char c[2];
00077         if ( readBlock(c, 1) == -1)
00078             return -1;
00079         else
00080             return c[0];
00081     }
00082     virtual int ungetch( int c ) { return m_dev->ungetch(c); } // ## apply lower limit ?
00083     virtual Offset at() const { return m_dev->at() - m_start; }
00084     virtual bool at( Offset pos ) {
00085         Q_ASSERT( pos <= m_length );
00086         pos = QMIN( pos, m_length ); // Apply upper limit
00087         return m_dev->at( m_start + pos );
00088     }
00089     virtual bool atEnd() const { return m_dev->at() >= m_start + m_length; }
00090 private:
00091     QIODevice* m_dev;
00092     Q_ULONG m_start;
00093     Q_ULONG m_length;
00094 };
00095 
00096 #endif
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This file is part of the documentation for kdelibs Version 3.1.5.
Documentation copyright © 1996-2002 the KDE developers.
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