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 {
  24 namespace ole {
  25
  26 namespace {
  27
  28 const sal_uInt8 VBASTREAM_SIGNATURE         = 1;
  29
  30 const sal_uInt16 VBACHUNK_SIGMASK           = 0x7000;
  31 const sal_uInt16 VBACHUNK_SIG               = 0x3000;
  32 const sal_uInt16 VBACHUNK_COMPRESSED        = 0x8000;
  33 const sal_uInt16 VBACHUNK_LENMASK           = 0x0FFF;
  34
  35 } // namespace
  36
  37 VbaInputStream::VbaInputStream( BinaryInputStream& rInStrm ) :
  38     BinaryStreamBase( false ),
  39     mpInStrm( &rInStrm ),
  40     mnChunkPos( 0 )
  41 {
  42     maChunk.reserve( 4096 );
  43
  44     sal_uInt8 nSig = rInStrm.readuInt8();
  45     OSL_ENSURE( nSig == VBASTREAM_SIGNATURE, "VbaInputStream::VbaInputStream - wrong signature" );
  46     mbEof = mbEof || rInStrm.isEof() || (nSig != VBASTREAM_SIGNATURE);
  47 }
  48
  49 sal_Int64 VbaInputStream::size() const
  50 {
  51     return -1;
  52 }
  53
  54 sal_Int64 VbaInputStream::tell() const
  55 {
  56     return -1;
  57 }
  58
  59 void VbaInputStream::seek( sal_Int64 )
  60 {
  61 }
  62
  63 void VbaInputStream::close()
  64 {
  65     mpInStrm = nullptr;
  66     mbEof = true;
  67 }
  68
  69 sal_Int32 VbaInputStream::readData( StreamDataSequence& orData, sal_Int32 nBytes, size_t nAtomSize )
  70 {
  71     sal_Int32 nRet = 0;
  72     if( !mbEof )
  73     {
  74         orData.realloc( ::std::max< sal_Int32 >( nBytes, 0 ) );
  75         if( nBytes > 0 )
  76         {
  77             nRet = readMemory( orData.getArray(), nBytes, nAtomSize );
  78             if( nRet < nBytes )
  79                 orData.realloc( nRet );
  80         }
  81     }
  82     return nRet;
  83 }
  84
  85 sal_Int32 VbaInputStream::readMemory( void* opMem, sal_Int32 nBytes, size_t /*nAtomSize*/ )
  86 {
  87     sal_Int32 nRet = 0;
  88     sal_uInt8* opnMem = static_cast< sal_uInt8* >( opMem );
  89     while( (nBytes > 0) && updateChunk() )
  90     {
  91         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
  92         sal_Int32 nReadBytes = ::std::min( nBytes, nChunkLeft );
  93         memcpy( opnMem, &*(maChunk.begin() + mnChunkPos), nReadBytes );
  94         opnMem += nReadBytes;
  95         mnChunkPos += static_cast< size_t >( nReadBytes );
  96         nBytes -= nReadBytes;
  97         nRet += nReadBytes;
  98     }
  99     return nRet;
 100 }
 101
 102 void VbaInputStream::skip( sal_Int32 nBytes, size_t /*nAtomSize*/ )
 103 {
 104     while( (nBytes > 0) && updateChunk() )
 105     {
 106         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
 107         sal_Int32 nSkipBytes = ::std::min( nBytes, nChunkLeft );
 108         mnChunkPos += static_cast< size_t >( nSkipBytes );
 109         nBytes -= nSkipBytes;
 110     }
 111 }
 112
 113 // private --------------------------------------------------------------------
 114
 115 bool VbaInputStream::updateChunk()
 116 {
 117     if( mbEof || (mnChunkPos < maChunk.size()) ) return !mbEof;
 118     // try to read next chunk header, this may trigger EOF
 119     sal_uInt16 nHeader = mpInStrm->readuInt16();
 120
 121     mbEof = mpInStrm->isEof();
 122     if( mbEof ) return false;
 123
 124     // check header signature
 125     bool bIgnoreBrokenSig = ( (nHeader & VBACHUNK_SIGMASK) != VBACHUNK_SIG );
 126
 127     // decode length of chunk data and compression flag
 128     bool bCompressed = getFlag( nHeader, VBACHUNK_COMPRESSED );
 129     sal_uInt16 nChunkLen = (nHeader & VBACHUNK_LENMASK) + 1;
 130     OSL_ENSURE( bCompressed || (nChunkLen == 4096), "VbaInputStream::updateChunk - invalid uncompressed chunk size" );
 131
 132     // From the amazing bit detective work of Valek Filippov<frob@gnome.org>
 133     // this tweak and the one at the bottom of the method to seek to the
 134     // start of the next chunk we can read those strange broken
 135     // ( I guess from a MSO bug ) compressed streams > 4k
 136
 137     if ( bIgnoreBrokenSig )
 138     {
 139         bCompressed = true;
 140         nChunkLen = 4094;
 141     }
 142
 143     sal_Int64 target = mpInStrm->tell() + nChunkLen;
 144     if( bCompressed )
 145     {
 146         maChunk.clear();
 147         sal_uInt8 nBitCount = 4;
 148         sal_uInt16 nChunkPos = 0;
 149         while( !mbEof && !mpInStrm->isEof() && (nChunkPos < nChunkLen) )
 150         {
 151             sal_uInt8 nTokenFlags = mpInStrm->readuInt8();
 152             ++nChunkPos;
 153             for( int nBit = 0; !mbEof && !mpInStrm->isEof() && (nBit < 8) && (nChunkPos < nChunkLen); ++nBit, nTokenFlags >>= 1 )
 154             {
 155                 if( nTokenFlags & 1 )
 156                 {
 157                     sal_uInt16 nCopyToken = mpInStrm->readuInt16();
 158                     nChunkPos = nChunkPos + 2;
 159                     // update bit count used for offset/length in the token
 160                     while( ( static_cast<size_t>(1) << nBitCount ) < maChunk.size() ) ++nBitCount;
 161                     // extract length from lower (16-nBitCount) bits, plus 3
 162                     sal_uInt16 nLength = extractValue< sal_uInt16 >( nCopyToken, 0, 16 - nBitCount ) + 3;
 163                     // extract offset from high nBitCount bits, plus 1
 164                     sal_uInt16 nOffset = extractValue< sal_uInt16 >( nCopyToken, 16 - nBitCount, nBitCount ) + 1;
 165                     mbEof = (nOffset > maChunk.size()) || (maChunk.size() + nLength > 4096);
 166                     OSL_ENSURE( !mbEof, "VbaInputStream::updateChunk - invalid offset or size in copy token" );
 167                     if( !mbEof )
 168                     {
 169                         // append data to buffer
 170                         maChunk.resize( maChunk.size() + nLength );
 171                         sal_uInt8* pnTo = &*(maChunk.end() - nLength);
 172                         const sal_uInt8* pnEnd = pnTo + nLength;
 173                         const sal_uInt8* pnFrom = pnTo - nOffset;
 174                         // offset may be less than length, effectively duplicating source data several times
 175                         size_t nRunLen = ::std::min< size_t >( nLength, nOffset );
 176                         while( pnTo < pnEnd )
 177                         {
 178                             size_t nStepLen = ::std::min< size_t >( nRunLen, pnEnd - pnTo );
 179                             memcpy( pnTo, pnFrom, nStepLen );
 180                             pnTo += nStepLen;
 181                         }
 182                     }
 183                 }
 184                 // we suspect this will never be called
 185                 else
 186                 {
 187                     maChunk.emplace_back();
 188                     maChunk.back() = mpInStrm->readuChar();
 189                     ++nChunkPos;
 190                 }
 191             }
 192         }
 193     }
 194     else
 195     {
 196         maChunk.resize( nChunkLen );
 197         mpInStrm->readMemory(maChunk.data(), nChunkLen);
 198     }
 199     // decompression sometimes leaves the stream pos offset 1 place ( at
 200     // least ) past or before the expected stream pos.
 201     // here we make sure we are on the chunk boundary
 202     mpInStrm->seek( target );
 203     mnChunkPos = 0;
 204     return !mbEof;
 205 }
 206
 207 } // namespace ole
 208 } // namespace oox
 209
 210 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */