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3282836baf
Move the checks around to avoid missing cases where we might access memory that is no longer valid. Also avoid touching the underlying stream implicitly (e.g. via the destructor) as it might also no longer be valid. A malicious server could theoretically use this for remote code execution in the client. Issue found by Pavel Cheremushkin from Kaspersky Lab
458 lines
10 KiB
C++
458 lines
10 KiB
C++
/* Copyright (C) 2000-2003 Constantin Kaplinsky. All Rights Reserved.
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* Copyright 2004-2005 Cendio AB.
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* Copyright 2009-2015 Pierre Ossman for Cendio AB
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* Copyright (C) 2011 D. R. Commander. All Rights Reserved.
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This software 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#include <assert.h>
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#include <rdr/InStream.h>
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#include <rdr/MemInStream.h>
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#include <rdr/OutStream.h>
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#include <rfb/ConnParams.h>
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#include <rfb/Exception.h>
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#include <rfb/PixelBuffer.h>
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#include <rfb/TightConstants.h>
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#include <rfb/TightDecoder.h>
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using namespace rfb;
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static const int TIGHT_MAX_WIDTH = 2048;
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static const int TIGHT_MIN_TO_COMPRESS = 12;
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#define BPP 8
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#include <rfb/tightDecode.h>
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#undef BPP
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#define BPP 16
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#include <rfb/tightDecode.h>
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#undef BPP
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#define BPP 32
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#include <rfb/tightDecode.h>
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#undef BPP
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TightDecoder::TightDecoder() : Decoder(DecoderPartiallyOrdered)
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{
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}
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TightDecoder::~TightDecoder()
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{
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}
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void TightDecoder::readRect(const Rect& r, rdr::InStream* is,
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const ConnParams& cp, rdr::OutStream* os)
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{
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rdr::U8 comp_ctl;
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comp_ctl = is->readU8();
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os->writeU8(comp_ctl);
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comp_ctl >>= 4;
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// "Fill" compression type.
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if (comp_ctl == tightFill) {
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if (cp.pf().is888())
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os->copyBytes(is, 3);
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else
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os->copyBytes(is, cp.pf().bpp/8);
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return;
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}
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// "JPEG" compression type.
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if (comp_ctl == tightJpeg) {
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rdr::U32 len;
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len = readCompact(is);
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os->writeOpaque32(len);
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os->copyBytes(is, len);
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return;
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}
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// Quit on unsupported compression type.
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if (comp_ctl > tightMaxSubencoding)
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throw Exception("TightDecoder: bad subencoding value received");
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// "Basic" compression type.
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int palSize = 0;
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if (r.width() > TIGHT_MAX_WIDTH)
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throw Exception("TightDecoder: too large rectangle (%d pixels)", r.width());
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// Possible palette
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if ((comp_ctl & tightExplicitFilter) != 0) {
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rdr::U8 filterId;
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filterId = is->readU8();
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os->writeU8(filterId);
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switch (filterId) {
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case tightFilterPalette:
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palSize = is->readU8() + 1;
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os->writeU8(palSize - 1);
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if (cp.pf().is888())
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os->copyBytes(is, palSize * 3);
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else
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os->copyBytes(is, palSize * cp.pf().bpp/8);
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break;
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case tightFilterGradient:
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if (cp.pf().bpp == 8)
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throw Exception("TightDecoder: invalid BPP for gradient filter");
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break;
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case tightFilterCopy:
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break;
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default:
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throw Exception("TightDecoder: unknown filter code received");
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}
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}
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size_t rowSize, dataSize;
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if (palSize != 0) {
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if (palSize <= 2)
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rowSize = (r.width() + 7) / 8;
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else
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rowSize = r.width();
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} else if (cp.pf().is888()) {
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rowSize = r.width() * 3;
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} else {
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rowSize = r.width() * cp.pf().bpp/8;
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}
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dataSize = r.height() * rowSize;
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if (dataSize < TIGHT_MIN_TO_COMPRESS)
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os->copyBytes(is, dataSize);
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else {
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rdr::U32 len;
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len = readCompact(is);
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os->writeOpaque32(len);
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os->copyBytes(is, len);
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}
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}
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bool TightDecoder::doRectsConflict(const Rect& rectA,
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const void* bufferA,
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size_t buflenA,
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const Rect& rectB,
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const void* bufferB,
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size_t buflenB,
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const ConnParams& cp)
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{
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rdr::U8 comp_ctl_a, comp_ctl_b;
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assert(buflenA >= 1);
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assert(buflenB >= 1);
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comp_ctl_a = *(const rdr::U8*)bufferA;
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comp_ctl_b = *(const rdr::U8*)bufferB;
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// Resets or use of zlib pose the same problem, so merge them
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if ((comp_ctl_a & 0x80) == 0x00)
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comp_ctl_a |= 1 << ((comp_ctl_a >> 4) & 0x03);
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if ((comp_ctl_b & 0x80) == 0x00)
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comp_ctl_b |= 1 << ((comp_ctl_b >> 4) & 0x03);
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if (((comp_ctl_a & 0x0f) & (comp_ctl_b & 0x0f)) != 0)
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return true;
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return false;
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}
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void TightDecoder::decodeRect(const Rect& r, const void* buffer,
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size_t buflen, const ConnParams& cp,
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ModifiablePixelBuffer* pb)
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{
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const rdr::U8* bufptr;
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const PixelFormat& pf = cp.pf();
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rdr::U8 comp_ctl;
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bufptr = (const rdr::U8*)buffer;
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assert(buflen >= 1);
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comp_ctl = *bufptr;
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bufptr += 1;
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buflen -= 1;
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// Reset zlib streams if we are told by the server to do so.
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for (int i = 0; i < 4; i++) {
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if (comp_ctl & 1) {
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zis[i].reset();
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}
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comp_ctl >>= 1;
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}
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// "Fill" compression type.
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if (comp_ctl == tightFill) {
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if (pf.is888()) {
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rdr::U8 pix[4];
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assert(buflen >= 3);
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pf.bufferFromRGB(pix, bufptr, 1);
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pb->fillRect(pf, r, pix);
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} else {
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assert(buflen >= (size_t)pf.bpp/8);
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pb->fillRect(pf, r, bufptr);
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}
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return;
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}
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// "JPEG" compression type.
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if (comp_ctl == tightJpeg) {
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rdr::U32 len;
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int stride;
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rdr::U8 *buf;
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JpegDecompressor jd;
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assert(buflen >= 4);
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memcpy(&len, bufptr, 4);
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bufptr += 4;
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buflen -= 4;
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// We always use direct decoding with JPEG images
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buf = pb->getBufferRW(r, &stride);
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jd.decompress(bufptr, len, buf, stride, r, pb->getPF());
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pb->commitBufferRW(r);
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return;
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}
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// Quit on unsupported compression type.
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assert(comp_ctl <= tightMaxSubencoding);
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// "Basic" compression type.
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int palSize = 0;
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rdr::U8 palette[256 * 4];
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bool useGradient = false;
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if ((comp_ctl & tightExplicitFilter) != 0) {
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rdr::U8 filterId;
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assert(buflen >= 1);
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filterId = *bufptr;
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bufptr += 1;
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buflen -= 1;
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switch (filterId) {
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case tightFilterPalette:
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assert(buflen >= 1);
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palSize = *bufptr + 1;
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bufptr += 1;
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buflen -= 1;
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if (pf.is888()) {
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rdr::U8 tightPalette[palSize * 3];
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assert(buflen >= sizeof(tightPalette));
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memcpy(tightPalette, bufptr, sizeof(tightPalette));
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bufptr += sizeof(tightPalette);
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buflen -= sizeof(tightPalette);
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pf.bufferFromRGB(palette, tightPalette, palSize);
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} else {
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size_t len;
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len = palSize * pf.bpp/8;
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assert(buflen >= len);
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memcpy(palette, bufptr, len);
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bufptr += len;
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buflen -= len;
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}
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break;
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case tightFilterGradient:
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useGradient = true;
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break;
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case tightFilterCopy:
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break;
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default:
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assert(false);
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}
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}
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// Determine if the data should be decompressed or just copied.
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size_t rowSize, dataSize;
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rdr::U8* netbuf;
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netbuf = NULL;
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if (palSize != 0) {
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if (palSize <= 2)
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rowSize = (r.width() + 7) / 8;
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else
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rowSize = r.width();
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} else if (pf.is888()) {
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rowSize = r.width() * 3;
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} else {
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rowSize = r.width() * pf.bpp/8;
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}
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dataSize = r.height() * rowSize;
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if (dataSize < TIGHT_MIN_TO_COMPRESS)
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assert(buflen >= dataSize);
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else {
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rdr::U32 len;
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int streamId;
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rdr::MemInStream* ms;
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assert(buflen >= 4);
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memcpy(&len, bufptr, 4);
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bufptr += 4;
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buflen -= 4;
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assert(buflen >= len);
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streamId = comp_ctl & 0x03;
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ms = new rdr::MemInStream(bufptr, len);
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zis[streamId].setUnderlying(ms, len);
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// Allocate buffer and decompress the data
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netbuf = new rdr::U8[dataSize];
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zis[streamId].readBytes(netbuf, dataSize);
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zis[streamId].flushUnderlying();
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zis[streamId].setUnderlying(NULL, 0);
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delete ms;
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bufptr = netbuf;
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buflen = dataSize;
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}
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// Time to decode the actual data
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bool directDecode;
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rdr::U8* outbuf;
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int stride;
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if (pb->getPF().equal(pf)) {
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// Decode directly into the framebuffer (fast path)
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directDecode = true;
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} else {
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// Decode into an intermediate buffer and use pixel translation
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directDecode = false;
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}
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if (directDecode)
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outbuf = pb->getBufferRW(r, &stride);
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else {
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outbuf = new rdr::U8[r.area() * (pf.bpp/8)];
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stride = r.width();
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}
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if (palSize == 0) {
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// Truecolor data
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if (useGradient) {
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if (pf.is888())
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FilterGradient24(bufptr, pf, (rdr::U32*)outbuf, stride, r);
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else {
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switch (pf.bpp) {
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case 8:
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assert(false);
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break;
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case 16:
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FilterGradient(bufptr, pf, (rdr::U16*)outbuf, stride, r);
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break;
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case 32:
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FilterGradient(bufptr, pf, (rdr::U32*)outbuf, stride, r);
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break;
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}
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}
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} else {
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// Copy
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rdr::U8* ptr = outbuf;
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const rdr::U8* srcPtr = bufptr;
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int w = r.width();
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int h = r.height();
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if (pf.is888()) {
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while (h > 0) {
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pf.bufferFromRGB(ptr, srcPtr, w);
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ptr += stride * pf.bpp/8;
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srcPtr += w * 3;
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h--;
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}
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} else {
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while (h > 0) {
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memcpy(ptr, srcPtr, w * pf.bpp/8);
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ptr += stride * pf.bpp/8;
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srcPtr += w * pf.bpp/8;
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h--;
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}
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}
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}
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} else {
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// Indexed color
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switch (pf.bpp) {
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case 8:
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FilterPalette((const rdr::U8*)palette, palSize,
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bufptr, (rdr::U8*)outbuf, stride, r);
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break;
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case 16:
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FilterPalette((const rdr::U16*)palette, palSize,
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bufptr, (rdr::U16*)outbuf, stride, r);
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break;
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case 32:
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FilterPalette((const rdr::U32*)palette, palSize,
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bufptr, (rdr::U32*)outbuf, stride, r);
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break;
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}
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}
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if (directDecode)
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pb->commitBufferRW(r);
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else {
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pb->imageRect(pf, r, outbuf);
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delete [] outbuf;
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}
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delete [] netbuf;
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}
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rdr::U32 TightDecoder::readCompact(rdr::InStream* is)
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{
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rdr::U8 b;
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rdr::U32 result;
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b = is->readU8();
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result = (int)b & 0x7F;
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if (b & 0x80) {
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b = is->readU8();
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result |= ((int)b & 0x7F) << 7;
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if (b & 0x80) {
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b = is->readU8();
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result |= ((int)b & 0xFF) << 14;
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}
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}
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return result;
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}
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