ZlibInStream.cxx
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//
// Copyright (C) 2002 RealVNC Ltd. All Rights Reserved.
//
// 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.
#include "ZlibInStream.h"
#include "Exception.h"
#include "../zlib/zlib.h"
using namespace rdr;
enum { DEFAULT_BUF_SIZE = 16384 };
ZlibInStream::ZlibInStream(int bufSize_)
: underlying(0), bufSize(bufSize_ ? bufSize_ : DEFAULT_BUF_SIZE), offset(0),
bytesIn(0)
{
zs = new z_stream;
zs->zalloc = Z_NULL;
zs->zfree = Z_NULL;
zs->opaque = Z_NULL;
zs->next_in = Z_NULL;
zs->avail_in = 0;
if (inflateInit(zs) != Z_OK) {
delete zs;
throw Exception("ZlibInStream: inflateInit failed");
}
ptr = end = start = new U8[bufSize];
}
ZlibInStream::~ZlibInStream()
{
delete [] start;
inflateEnd(zs);
delete zs;
}
void ZlibInStream::setUnderlying(InStream* is, int bytesIn_)
{
underlying = is;
bytesIn = bytesIn_;
ptr = end = start;
}
int ZlibInStream::pos()
{
return offset + ptr - start;
}
void ZlibInStream::reset()
{
ptr = end = start;
if (!underlying) return;
while (bytesIn > 0) {
decompress();
end = start; // throw away any data
}
underlying = 0;
}
int ZlibInStream::overrun(int itemSize, int nItems)
{
if (itemSize > bufSize)
throw Exception("ZlibInStream overrun: max itemSize exceeded");
if (!underlying)
throw Exception("ZlibInStream overrun: no underlying stream");
if (end - ptr != 0)
memmove(start, ptr, end - ptr);
offset += ptr - start;
end -= ptr - start;
ptr = start;
while (end - ptr < itemSize) {
decompress();
}
if (itemSize * nItems > end - ptr)
nItems = (end - ptr) / itemSize;
return nItems;
}
// decompress() calls the decompressor once. Note that this won't necessarily
// generate any output data - it may just consume some input data.
void ZlibInStream::decompress()
{
zs->next_out = (U8*)end;
zs->avail_out = start + bufSize - end;
underlying->check(1);
zs->next_in = (U8*)underlying->getptr();
zs->avail_in = underlying->getend() - underlying->getptr();
if ((int)zs->avail_in > bytesIn)
zs->avail_in = bytesIn;
int rc = inflate(zs, Z_SYNC_FLUSH);
if (rc != Z_OK) {
throw Exception("ZlibInStream: inflate failed");
}
bytesIn -= zs->next_in - underlying->getptr();
end = zs->next_out;
underlying->setptr(zs->next_in);
}