oox/source/ole/vbainputstream.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #include <oox/ole/vbainputstream.hxx>
  21 #include <osl/diagnose.h>
  22
  23 namespace oox::ole {
  24
  25 namespace {
  26
  27 const sal_uInt8 VBASTREAM_SIGNATURE         = 1;
  28
  29 const sal_uInt16 VBACHUNK_SIGMASK           = 0x7000;
  30 const sal_uInt16 VBACHUNK_SIG               = 0x3000;
  31 const sal_uInt16 VBACHUNK_COMPRESSED        = 0x8000;
  32 const sal_uInt16 VBACHUNK_LENMASK           = 0x0FFF;
  33
  34 } // namespace
  35
  36 VbaInputStream::VbaInputStream( BinaryInputStream& rInStrm ) :
  37     BinaryStreamBase( false ),
  38     mpInStrm( &rInStrm ),
  39     mnChunkPos( 0 )
  40 {
  41     maChunk.reserve( 4096 );
  42
  43     sal_uInt8 nSig = rInStrm.readuInt8();
  44     OSL_ENSURE( nSig == VBASTREAM_SIGNATURE, "VbaInputStream::VbaInputStream - wrong signature" );
  45     mbEof = mbEof || rInStrm.isEof() || (nSig != VBASTREAM_SIGNATURE);
  46 }
  47
  48 sal_Int64 VbaInputStream::size() const
  49 {
  50     return -1;
  51 }
  52
  53 sal_Int64 VbaInputStream::tell() const
  54 {
  55     return -1;
  56 }
  57
  58 void VbaInputStream::seek( sal_Int64 )
  59 {
  60 }
  61
  62 void VbaInputStream::close()
  63 {
  64     mpInStrm = nullptr;
  65     mbEof = true;
  66 }
  67
  68 sal_Int32 VbaInputStream::readData( StreamDataSequence& orData, sal_Int32 nBytes, size_t nAtomSize )
  69 {
  70     sal_Int32 nRet = 0;
  71     if( !mbEof )
  72     {
  73         orData.realloc( ::std::max< sal_Int32 >( nBytes, 0 ) );
  74         if( nBytes > 0 )
  75         {
  76             nRet = readMemory( orData.getArray(), nBytes, nAtomSize );
  77             if( nRet < nBytes )
  78                 orData.realloc( nRet );
  79         }
  80     }
  81     return nRet;
  82 }
  83
  84 sal_Int32 VbaInputStream::readMemory( void* opMem, sal_Int32 nBytes, size_t /*nAtomSize*/ )
  85 {
  86     sal_Int32 nRet = 0;
  87     sal_uInt8* opnMem = static_cast< sal_uInt8* >( opMem );
  88     while( (nBytes > 0) && updateChunk() )
  89     {
  90         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
  91         sal_Int32 nReadBytes = ::std::min( nBytes, nChunkLeft );
  92         memcpy( opnMem, &*(maChunk.begin() + mnChunkPos), nReadBytes );
  93         opnMem += nReadBytes;
  94         mnChunkPos += static_cast< size_t >( nReadBytes );
  95         nBytes -= nReadBytes;
  96         nRet += nReadBytes;
  97     }
  98     return nRet;
  99 }
 100
 101 void VbaInputStream::skip( sal_Int32 nBytes, size_t /*nAtomSize*/ )
 102 {
 103     while( (nBytes > 0) && updateChunk() )
 104     {
 105         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
 106         sal_Int32 nSkipBytes = ::std::min( nBytes, nChunkLeft );
 107         mnChunkPos += static_cast< size_t >( nSkipBytes );
 108         nBytes -= nSkipBytes;
 109     }
 110 }
 111
 112 // private --------------------------------------------------------------------
 113
 114 bool VbaInputStream::updateChunk()
 115 {
 116     if( mbEof || (mnChunkPos < maChunk.size()) ) return !mbEof;
 117     // try to read next chunk header, this may trigger EOF
 118     sal_uInt16 nHeader = mpInStrm->readuInt16();
 119
 120     mbEof = mpInStrm->isEof();
 121     if( mbEof ) return false;
 122
 123     // check header signature
 124     bool bIgnoreBrokenSig = ( (nHeader & VBACHUNK_SIGMASK) != VBACHUNK_SIG );
 125
 126     // decode length of chunk data and compression flag
 127     bool bCompressed = getFlag( nHeader, VBACHUNK_COMPRESSED );
 128     sal_uInt16 nChunkLen = (nHeader & VBACHUNK_LENMASK) + 1;
 129     OSL_ENSURE( bCompressed || (nChunkLen == 4096), "VbaInputStream::updateChunk - invalid uncompressed chunk size" );
 130
 131     // From the amazing bit detective work of Valek Filippov<frob@gnome.org>
 132     // this tweak and the one at the bottom of the method to seek to the
 133     // start of the next chunk we can read those strange broken
 134     // ( I guess from a MSO bug ) compressed streams > 4k
 135
 136     if ( bIgnoreBrokenSig )
 137     {
 138         bCompressed = true;
 139         nChunkLen = 4094;
 140     }
 141
 142     sal_Int64 target = mpInStrm->tell() + nChunkLen;
 143     if( bCompressed )
 144     {
 145         maChunk.clear();
 146         sal_uInt8 nBitCount = 4;
 147         sal_uInt16 nChunkPos = 0;
 148         while( !mbEof && !mpInStrm->isEof() && (nChunkPos < nChunkLen) )
 149         {
 150             sal_uInt8 nTokenFlags = mpInStrm->readuInt8();
 151             ++nChunkPos;
 152             for( int nBit = 0; !mbEof && !mpInStrm->isEof() && (nBit < 8) && (nChunkPos < nChunkLen); ++nBit, nTokenFlags >>= 1 )
 153             {
 154                 if( nTokenFlags & 1 )
 155                 {
 156                     sal_uInt16 nCopyToken = mpInStrm->readuInt16();
 157                     nChunkPos = nChunkPos + 2;
 158                     // update bit count used for offset/length in the token
 159                     while( ( static_cast<size_t>(1) << nBitCount ) < maChunk.size() ) ++nBitCount;
 160                     // extract length from lower (16-nBitCount) bits, plus 3
 161                     sal_uInt16 nLength = extractValue< sal_uInt16 >( nCopyToken, 0, 16 - nBitCount ) + 3;
 162                     // extract offset from high nBitCount bits, plus 1
 163                     sal_uInt16 nOffset = extractValue< sal_uInt16 >( nCopyToken, 16 - nBitCount, nBitCount ) + 1;
 164                     mbEof = (nOffset > maChunk.size()) || (maChunk.size() + nLength > 4096);
 165                     OSL_ENSURE( !mbEof, "VbaInputStream::updateChunk - invalid offset or size in copy token" );
 166                     if( !mbEof )
 167                     {
 168                         // append data to buffer
 169                         maChunk.resize( maChunk.size() + nLength );
 170                         sal_uInt8* pnTo = &*(maChunk.end() - nLength);
 171                         const sal_uInt8* pnEnd = pnTo + nLength;
 172                         const sal_uInt8* pnFrom = pnTo - nOffset;
 173                         // offset may be less than length, effectively duplicating source data several times
 174                         size_t nRunLen = ::std::min< size_t >( nLength, nOffset );
 175                         while( pnTo < pnEnd )
 176                         {
 177                             size_t nStepLen = ::std::min< size_t >( nRunLen, pnEnd - pnTo );
 178                             memcpy( pnTo, pnFrom, nStepLen );
 179                             pnTo += nStepLen;
 180                         }
 181                     }
 182                 }
 183                 // we suspect this will never be called
 184                 else
 185                 {
 186                     maChunk.emplace_back();
 187                     maChunk.back() = mpInStrm->readuChar();
 188                     ++nChunkPos;
 189                 }
 190             }
 191         }
 192     }
 193     else
 194     {
 195         maChunk.resize( nChunkLen );
 196         mpInStrm->readMemory(maChunk.data(), nChunkLen);
 197     }
 198     // decompression sometimes leaves the stream pos offset 1 place ( at
 199     // least ) past or before the expected stream pos.
 200     // here we make sure we are on the chunk boundary
 201     mpInStrm->seek( target );
 202     mnChunkPos = 0;
 203     return !mbEof;
 204 }
 205
 206 } // namespace oox::ole
 207
 208 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */