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 // ============================================================================
  27
  28 namespace {
  29
  30 const sal_uInt8 VBASTREAM_SIGNATURE         = 1;
  31
  32 const sal_uInt16 VBACHUNK_SIGMASK           = 0x7000;
  33 const sal_uInt16 VBACHUNK_SIG               = 0x3000;
  34 const sal_uInt16 VBACHUNK_COMPRESSED        = 0x8000;
  35 const sal_uInt16 VBACHUNK_LENMASK           = 0x0FFF;
  36
  37 } // namespace
  38
  39 // ============================================================================
  40
  41 VbaInputStream::VbaInputStream( BinaryInputStream& rInStrm ) :
  42     BinaryStreamBase( false ),
  43     mpInStrm( &rInStrm ),
  44     mnChunkPos( 0 )
  45 {
  46     maChunk.reserve( 4096 );
  47
  48     sal_uInt8 nSig = rInStrm.readuInt8();
  49     OSL_ENSURE( nSig == VBASTREAM_SIGNATURE, "VbaInputStream::VbaInputStream - wrong signature" );
  50     mbEof = mbEof || rInStrm.isEof() || (nSig != VBASTREAM_SIGNATURE);
  51 }
  52
  53 sal_Int64 VbaInputStream::size() const
  54 {
  55     return -1;
  56 }
  57
  58 sal_Int64 VbaInputStream::tell() const
  59 {
  60     return -1;
  61 }
  62
  63 void VbaInputStream::seek( sal_Int64 )
  64 {
  65 }
  66
  67 void VbaInputStream::close()
  68 {
  69     mpInStrm = 0;
  70     mbEof = true;
  71 }
  72
  73 sal_Int32 VbaInputStream::readData( StreamDataSequence& orData, sal_Int32 nBytes, size_t nAtomSize )
  74 {
  75     sal_Int32 nRet = 0;
  76     if( !mbEof )
  77     {
  78         orData.realloc( ::std::max< sal_Int32 >( nBytes, 0 ) );
  79         if( nBytes > 0 )
  80         {
  81             nRet = readMemory( orData.getArray(), nBytes, nAtomSize );
  82             if( nRet < nBytes )
  83                 orData.realloc( nRet );
  84         }
  85     }
  86     return nRet;
  87 }
  88
  89 sal_Int32 VbaInputStream::readMemory( void* opMem, sal_Int32 nBytes, size_t /*nAtomSize*/ )
  90 {
  91     sal_Int32 nRet = 0;
  92     sal_uInt8* opnMem = reinterpret_cast< sal_uInt8* >( opMem );
  93     while( (nBytes > 0) && updateChunk() )
  94     {
  95         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
  96         sal_Int32 nReadBytes = ::std::min( nBytes, nChunkLeft );
  97         memcpy( opnMem, &*(maChunk.begin() + mnChunkPos), nReadBytes );
  98         opnMem += nReadBytes;
  99         mnChunkPos += static_cast< size_t >( nReadBytes );
 100         nBytes -= nReadBytes;
 101         nRet += nReadBytes;
 102     }
 103     return nRet;
 104 }
 105
 106 void VbaInputStream::skip( sal_Int32 nBytes, size_t /*nAtomSize*/ )
 107 {
 108     while( (nBytes > 0) && updateChunk() )
 109     {
 110         sal_Int32 nChunkLeft = static_cast< sal_Int32 >( maChunk.size() - mnChunkPos );
 111         sal_Int32 nSkipBytes = ::std::min( nBytes, nChunkLeft );
 112         mnChunkPos += static_cast< size_t >( nSkipBytes );
 113         nBytes -= nSkipBytes;
 114     }
 115 }
 116
 117 // private --------------------------------------------------------------------
 118
 119 bool VbaInputStream::updateChunk()
 120 {
 121     if( mbEof || (mnChunkPos < maChunk.size()) ) return !mbEof;
 122     // try to read next chunk header, this may trigger EOF
 123     sal_uInt16 nHeader = mpInStrm->readuInt16();
 124
 125     mbEof = mpInStrm->isEof();
 126     if( mbEof ) return false;
 127
 128     // check header signature
 129     bool bIgnoreBrokenSig = !( (nHeader & VBACHUNK_SIGMASK) == VBACHUNK_SIG );
 130
 131     // decode length of chunk data and compression flag
 132     bool bCompressed = getFlag( nHeader, VBACHUNK_COMPRESSED );
 133     sal_uInt16 nChunkLen = (nHeader & VBACHUNK_LENMASK) + 1;
 134     OSL_ENSURE( bCompressed || (nChunkLen == 4096), "VbaInputStream::updateChunk - invalid uncompressed chunk size" );
 135
 136     // From the amazing bit detective work of Valek Filippov<frob@gnome.org>
 137     // this tweak and the one at the bottom of the method to seek to the
 138     // start of the next chunk we can read those strange broken
 139     // ( I guess from a MSO bug ) commpessed streams > 4k
 140
 141     if ( bIgnoreBrokenSig )
 142     {
 143         bCompressed = true;
 144         nChunkLen = 4094;
 145     }
 146
 147     sal_Int64 target = mpInStrm->tell() + nChunkLen;
 148     if( bCompressed )
 149     {
 150         maChunk.clear();
 151         sal_uInt8 nBitCount = 4;
 152         sal_uInt16 nChunkPos = 0;
 153         while( !mbEof && !mpInStrm->isEof() && (nChunkPos < nChunkLen) )
 154         {
 155             sal_uInt8 nTokenFlags = mpInStrm->readuInt8();
 156             ++nChunkPos;
 157             for( int nBit = 0; !mbEof && !mpInStrm->isEof() && (nBit < 8) && (nChunkPos < nChunkLen); ++nBit, nTokenFlags >>= 1 )
 158             {
 159                 if( nTokenFlags & 1 )
 160                 {
 161                     sal_uInt16 nCopyToken = mpInStrm->readuInt16();
 162                     nChunkPos = nChunkPos + 2;
 163                     // update bit count used for offset/length in the token
 164                     while( static_cast< size_t >( 1 << nBitCount ) < maChunk.size() ) ++nBitCount;
 165                     // extract length from lower (16-nBitCount) bits, plus 3
 166                     sal_uInt16 nLength = extractValue< sal_uInt16 >( nCopyToken, 0, 16 - nBitCount ) + 3;
 167                     // extract offset from high nBitCount bits, plus 1
 168                     sal_uInt16 nOffset = extractValue< sal_uInt16 >( nCopyToken, 16 - nBitCount, nBitCount ) + 1;
 169                     mbEof = (nOffset > maChunk.size()) || (maChunk.size() + nLength > 4096);
 170                     OSL_ENSURE( !mbEof, "VbaInputStream::updateChunk - invalid offset or size in copy token" );
 171                     if( !mbEof )
 172                     {
 173                         // append data to buffer
 174                         maChunk.resize( maChunk.size() + nLength );
 175                         sal_uInt8* pnTo = &*(maChunk.end() - nLength);
 176                         const sal_uInt8* pnEnd = pnTo + nLength;
 177                         const sal_uInt8* pnFrom = pnTo - nOffset;
 178                         // offset may be less than length, effectively duplicating source data several times
 179                         size_t nRunLen = ::std::min< size_t >( nLength, nOffset );
 180                         while( pnTo < pnEnd )
 181                         {
 182                             size_t nStepLen = ::std::min< size_t >( nRunLen, pnEnd - pnTo );
 183                             memcpy( pnTo, pnFrom, nStepLen );
 184                             pnTo += nStepLen;
 185                         }
 186                     }
 187                 }
 188                 // we suspect this will never be called
 189                 else
 190                 {
 191                     maChunk.resize( maChunk.size() + 1 );
 192                     *mpInStrm >> maChunk.back();
 193                     ++nChunkPos;
 194                 }
 195             }
 196         }
 197     }
 198     else
 199     {
 200         maChunk.resize( nChunkLen );
 201         mpInStrm->readMemory( &maChunk.front(), nChunkLen );
 202     }
 203     // decompression sometimes leaves the stream pos offset 1 place ( at
 204     // least ) past or before the expected stream pos.
 205     // here we make sure we are on the chunk boundry
 206     mpInStrm->seek( target );
 207     mnChunkPos = 0;
 208     return !mbEof;
 209 }
 210
 211 // ============================================================================
 212
 213 } // namespace ole
 214 } // namespace oox
 215
 216 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */