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/* Copyright (C) 2002-2005 RealVNC Ltd. All Rights Reserved.
* Copyright 2014-2020 Pierre Ossman for Cendio AB
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*/
//
// rdr::InStream marshalls data from a buffer stored in RDR (RFB Data
// Representation).
//
#ifndef __RDR_INSTREAM_H__
#define __RDR_INSTREAM_H__
#include <rdr/types.h>
#include <rdr/Exception.h>
#include <string.h> // for memcpy
// Check that callers are using InStream properly,
// useful when writing new protocol handling
#undef RFB_INSTREAM_CHECK
namespace rdr {
class InStream {
public:
virtual ~InStream() {}
// avail() returns the number of bytes that are currenctly directly
// available from the stream.
inline size_t avail() {
#ifdef RFB_INSTREAM_CHECK
checkedBytes = end - ptr;
#endif
return end - ptr;
}
// hasData() ensures there is at least "length" bytes of buffer data,
// possibly trying to fetch more data if there isn't enough right away
inline bool hasData(size_t length) {
#ifdef RFB_INSTREAM_CHECK
checkedBytes = 0;
#endif
if (length > (size_t)(end - ptr)) {
if (restorePoint != NULL) {
bool ret;
size_t restoreDiff;
restoreDiff = ptr - restorePoint;
ptr = restorePoint;
ret = overrun(length + restoreDiff);
restorePoint = ptr;
ptr += restoreDiff;
if (!ret)
return false;
} else {
if (!overrun(length))
return false;
}
}
#ifdef RFB_INSTREAM_CHECK
checkedBytes = length;
#endif
return true;
}
inline bool hasDataOrRestore(size_t length) {
if (hasData(length))
return true;
gotoRestorePoint();
return false;
}
inline void setRestorePoint() {
#ifdef RFB_INSTREAM_CHECK
if (restorePoint != NULL)
throw Exception("Nested use of input stream restore point");
#endif
restorePoint = ptr;
}
inline void clearRestorePoint() {
#ifdef RFB_INSTREAM_CHECK
if (restorePoint == NULL)
throw Exception("Incorrect clearing of input stream restore point");
#endif
restorePoint = NULL;
}
inline void gotoRestorePoint() {
#ifdef RFB_INSTREAM_CHECK
if (restorePoint == NULL)
throw Exception("Incorrect activation of input stream restore point");
#endif
ptr = restorePoint;
clearRestorePoint();
}
// readU/SN() methods read unsigned and signed N-bit integers.
inline U8 readU8() { check(1); return *ptr++; }
inline U16 readU16() { check(2); int b0 = *ptr++; int b1 = *ptr++;
return b0 << 8 | b1; }
inline U32 readU32() { check(4); int b0 = *ptr++; int b1 = *ptr++;
int b2 = *ptr++; int b3 = *ptr++;
return b0 << 24 | b1 << 16 | b2 << 8 | b3; }
inline S8 readS8() { return (S8) readU8(); }
inline S16 readS16() { return (S16)readU16(); }
inline S32 readS32() { return (S32)readU32(); }
// skip() ignores a number of bytes on the stream
inline void skip(size_t bytes) {
check(bytes);
ptr += bytes;
}
// readBytes() reads an exact number of bytes.
void readBytes(void* data, size_t length) {
check(length);
memcpy(data, ptr, length);
ptr += length;
}
// readOpaqueN() reads a quantity without byte-swapping.
inline U8 readOpaque8() { return readU8(); }
inline U16 readOpaque16() { check(2); U16 r; ((U8*)&r)[0] = *ptr++;
((U8*)&r)[1] = *ptr++; return r; }
inline U32 readOpaque32() { check(4); U32 r; ((U8*)&r)[0] = *ptr++;
((U8*)&r)[1] = *ptr++; ((U8*)&r)[2] = *ptr++;
((U8*)&r)[3] = *ptr++; return r; }
// pos() returns the position in the stream.
virtual size_t pos() = 0;
// getptr() and setptr() are "dirty" methods which allow you direct access
// to the buffer. This is useful for a stream which is a wrapper around an
// some other stream API.
inline const U8* getptr(size_t length) { check(length);
#ifdef RFB_INSTREAM_CHECK
checkedBytes += length;
#endif
return ptr; }
inline void setptr(size_t length) { if (length > avail())
throw Exception("Input stream overflow");
skip(length); }
private:
const U8* restorePoint;
#ifdef RFB_INSTREAM_CHECK
size_t checkedBytes;
#endif
inline void check(size_t bytes) {
#ifdef RFB_INSTREAM_CHECK
if (bytes > checkedBytes)
throw Exception("Input stream used without underrun check");
checkedBytes -= bytes;
#endif
if (bytes > (size_t)(end - ptr))
throw Exception("InStream buffer underrun");
}
// overrun() is implemented by a derived class to cope with buffer overrun.
// It tries to ensure there are at least needed bytes of buffer data.
// Returns true if it managed to satisfy the request, or false otherwise.
virtual bool overrun(size_t needed) = 0;
protected:
InStream() : restorePoint(NULL)
#ifdef RFB_INSTREAM_CHECK
,checkedBytes(0)
#endif
{}
const U8* ptr;
const U8* end;
};
}
#endif
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