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102 lines
3.6 KiB
102 lines
3.6 KiB
/* This file is part of the KDE libraries
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Copyright (C) 2001, 2002 David Faure <david@mandrakesoft.com>
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License version 2 as published by the Free Software Foundation.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public License
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along with this library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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Boston, MA 02110-1301, USA.
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*/
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#ifndef klimitediodevice_h
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#define klimitediodevice_h
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#include <kdebug.h>
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#include <tqiodevice.h>
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/**
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* A readonly device that reads from an underlying device
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* from a given point to another (e.g. to give access to a single
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* file inside an archive).
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* @author David Faure <david@mandrakesoft.com>
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* @since 3.1
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*/
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class TDEIO_EXPORT KLimitedIODevice : public TQIODevice
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{
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public:
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/**
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* Creates a new KLimitedIODevice.
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* @param dev the underlying device, opened or not
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* This device itself auto-opens (in readonly mode), no need to open it.
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* @param start where to start reading (position in bytes)
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* @param length the length of the data to read (in bytes)
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*/
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KLimitedIODevice( TQIODevice *dev, int start, int length )
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: m_dev( dev ), m_start( start ), m_length( length )
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{
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//kdDebug(7005) << "KLimitedIODevice::KLimitedIODevice start=" << start << " length=" << length << endl;
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setType( IO_Direct ); // we support sequential too, but then atEnd() tries getch/ungetch !
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open( IO_ReadOnly );
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}
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virtual ~KLimitedIODevice() {}
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virtual bool open( int m ) {
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//kdDebug(7005) << "KLimitedIODevice::open m=" << m << endl;
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if ( m & IO_ReadOnly ) {
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/*bool ok = false;
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if ( m_dev->isOpen() )
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ok = ( m_dev->mode() == IO_ReadOnly );
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else
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ok = m_dev->open( m );
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if ( ok )*/
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m_dev->at( m_start ); // No concurrent access !
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}
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else
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kdWarning(7005) << "KLimitedIODevice::open only supports IO_ReadOnly!" << endl;
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setState( IO_Open );
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setMode( m );
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return true;
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}
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virtual void close() {}
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virtual void flush() {}
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virtual Offset size() const { return m_length; }
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virtual TQ_LONG readBlock ( char * data, TQ_ULONG maxlen )
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{
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maxlen = TQMIN( maxlen, m_length - at() ); // Apply upper limit
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return m_dev->readBlock( data, maxlen );
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}
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virtual TQ_LONG writeBlock ( const char *, TQ_ULONG ) { return -1; } // unsupported
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virtual int putch( int ) { return -1; } // unsupported
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virtual int getch() {
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char c[2];
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if ( readBlock(c, 1) == -1)
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return -1;
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else
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return c[0];
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}
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virtual int ungetch( int c ) { return m_dev->ungetch(c); } // ## apply lower limit ?
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virtual Offset at() const { return m_dev->at() - m_start; }
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virtual bool at( Offset pos ) {
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Q_ASSERT( pos <= m_length );
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pos = TQMIN( pos, m_length ); // Apply upper limit
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return m_dev->at( m_start + pos );
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}
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virtual bool atEnd() const { return m_dev->atEnd() || m_dev->at() >= m_start + m_length; }
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private:
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TQIODevice* m_dev;
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TQ_ULONG m_start;
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TQ_ULONG m_length;
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};
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#endif
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