mirror of
https://github.com/FirebirdSQL/firebird.git
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116 lines
2.2 KiB
C++
116 lines
2.2 KiB
C++
/*
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* The contents of this file are subject to the Initial
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* Developer's Public License Version 1.0 (the "License");
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* you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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* http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_idpl.
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*
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* Software distributed under the License is distributed AS IS,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied.
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* See the License for the specific language governing rights
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* and limitations under the License.
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*
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* The Original Code was created by Adriano dos Santos Fernandes
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* for the Firebird Open Source RDBMS project.
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*
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* Copyright (c) 2009 Adriano dos Santos Fernandes <adrianosf@uol.com.br>
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* and all contributors signed below.
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*
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* All Rights Reserved.
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* Contributor(s): ______________________________________.
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*/
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#ifndef JRD_BLR_READER_H
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#define JRD_BLR_READER_H
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#include "iberror.h"
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namespace Jrd {
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class BlrReader
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{
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public:
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BlrReader(const UCHAR* buffer, unsigned maxLen)
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: start(buffer),
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end(buffer + maxLen),
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pos(buffer)
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{
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// ASF: A big maxLen like MAX_ULONG could overflow the pointer size and
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// points to something before start. In this case, we set the end to the
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// max possible address.
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if (end < start)
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end = ((UCHAR*) 0) - 1;
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}
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BlrReader()
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: start(NULL),
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end(NULL),
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pos(NULL)
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{
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}
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public:
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const UCHAR* getPos() const
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{
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fb_assert(pos);
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return pos;
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}
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void setPos(const UCHAR* newPos)
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{
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fb_assert(newPos >= start && newPos < end);
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pos = newPos;
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}
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void seekBackward(unsigned n)
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{
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setPos(getPos() - n);
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}
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void seekForward(unsigned n)
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{
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setPos(getPos() + n);
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}
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unsigned getOffset() const
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{
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return getPos() - start;
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}
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UCHAR peekByte() const
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{
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fb_assert(pos);
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if (pos >= end)
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(Firebird::Arg::Gds(isc_invalid_blr) << Firebird::Arg::Num(getOffset())).raise();
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return *pos;
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}
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UCHAR getByte()
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{
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UCHAR byte = peekByte();
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++pos;
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return byte;
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}
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USHORT getWord()
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{
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const UCHAR low = getByte();
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const UCHAR high = getByte();
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return high * 256 + low;
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}
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private:
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const UCHAR* start;
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const UCHAR* end;
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const UCHAR* pos;
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};
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} // namespace
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#endif // JRD_BLR_READER_H
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