modules/demux/mkv/Ebml_parser.cpp

   1
   2 /*****************************************************************************
   3  * EbmlParser for the matroska demuxer
   4  *****************************************************************************
   5  * Copyright (C) 2003-2004 VLC authors and VideoLAN
   6  * $Id$
   7  *
   8  * Authors: Laurent Aimar <fenrir@via.ecp.fr>
   9  *          Steve Lhomme <steve.lhomme@free.fr>
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU Lesser General Public License as published by
  13  * the Free Software Foundation; either version 2.1 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  19  * GNU Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public License
  22  * along with this program; if not, write to the Free Software Foundation,
  23  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  24  *****************************************************************************/
  25
  26 #include "Ebml_parser.hpp"
  27 #include "stream_io_callback.hpp"
  28
  29 /*****************************************************************************
  30  * Ebml Stream parser
  31  *****************************************************************************/
  32 EbmlParser::EbmlParser( EbmlStream *es, EbmlElement *el_start, demux_t *p_demux,
  33                         bool b_with_dummy ) :
  34     p_demux( p_demux ),
  35     m_es( es ),
  36     mi_level( 1 ),
  37     m_got( NULL ),
  38     mi_user_level( 1 ),
  39     mb_keep( false ),
  40     mb_dummy( b_with_dummy )
  41 {
  42     memset( m_el, 0, sizeof( *m_el ) * M_EL_MAXSIZE);
  43     m_el[0] = el_start;
  44 }
  45
  46 EbmlParser::~EbmlParser( void )
  47 {
  48     if( !mi_level )
  49     {
  50         assert( !mb_keep );
  51         delete m_el[1];
  52         return;
  53     }
  54
  55     for( int i = 1; i <= mi_level; i++ )
  56     {
  57         if( !mb_keep )
  58         {
  59             delete m_el[i];
  60         }
  61         mb_keep = false;
  62     }
  63 }
  64
  65 void EbmlParser::reconstruct( EbmlStream* es, EbmlElement* el_start, demux_t* p_demux )
  66 {
  67     this->reconstruct( es, el_start, p_demux, var_InheritBool( p_demux, "mkv-use-dummy" ) );
  68 }
  69
  70 void EbmlParser::reconstruct( EbmlStream* es, EbmlElement* el_start, demux_t* p_demux,
  71   bool b_with_dummy)
  72 {
  73     this->~EbmlParser();
  74
  75     new( static_cast<void*>( this ) ) EbmlParser(
  76       es, el_start, p_demux, b_with_dummy
  77     );
  78 }
  79
  80 void EbmlParser::Up( void )
  81 {
  82     if( mi_user_level == mi_level && m_el[mi_level] )
  83     {
  84         msg_Warn( p_demux, "MKV/Ebml Parser: Up cannot escape itself" );
  85     }
  86
  87     mi_user_level--;
  88 }
  89
  90 void EbmlParser::Down( void )
  91 {
  92     mi_user_level++;
  93     mi_level++;
  94 }
  95
  96 void EbmlParser::Keep( void )
  97 {
  98     mb_keep = true;
  99 }
 100
 101 void EbmlParser::Unkeep()
 102 {
 103     mb_keep = false;
 104 }
 105
 106 int EbmlParser::GetLevel( void ) const
 107 {
 108     return mi_user_level;
 109 }
 110
 111 void EbmlParser::Reset( demux_t *p_demux )
 112 {
 113     while ( mi_level > 0)
 114     {
 115         delete m_el[mi_level];
 116         m_el[mi_level] = NULL;
 117         mi_level--;
 118     }
 119     this->p_demux = p_demux;
 120     mi_user_level = mi_level = 1;
 121     // a little faster and cleaner
 122     m_es->I_O().setFilePointer( static_cast<KaxSegment*>(m_el[0])->GetGlobalPosition(0) );
 123 }
 124
 125
 126 static const EbmlSemanticContext & GetEbmlNoGlobal_Context();
 127 static const EbmlSemanticContext EbmlNoGlobal_Context = EbmlSemanticContext(0, NULL, NULL, *GetEbmlNoGlobal_Context, NULL);
 128 static const EbmlSemanticContext & GetEbmlNoGlobal_Context()
 129 {
 130   return EbmlNoGlobal_Context;
 131 }
 132
 133 // the Segment Context should not allow Void or CRC32 elements to avoid lookup false alarm
 134 const EbmlSemanticContext Context_KaxSegmentVLC = EbmlSemanticContext(KaxSegment_Context.GetSize(),
 135                                                                       KaxSegment_Context.MyTable,
 136                                                                       KaxSegment_Context.Parent(),
 137                                                                       GetEbmlNoGlobal_Context,
 138                                                                       KaxSegment_Context.GetMaster());
 139
 140 EbmlElement *EbmlParser::Get( int n_call )
 141 {
 142     int i_ulev = 0;
 143     EbmlElement *p_prev = NULL;
 144
 145     if( mi_user_level != mi_level )
 146     {
 147         return NULL;
 148     }
 149     if( m_got )
 150     {
 151         EbmlElement *ret = m_got;
 152         m_got = NULL;
 153
 154         return ret;
 155     }
 156
 157     p_prev = m_el[mi_level];
 158     if( p_prev )
 159         p_prev->SkipData( *m_es, EBML_CONTEXT(p_prev) );
 160
 161     // If the parent is a segment, use the segment context when creating children
 162     // (to prolong their lifetime), otherwise just continue as normal
 163     EbmlSemanticContext e_context =
 164             EBML_CTX_MASTER( EBML_CONTEXT(m_el[mi_level - 1]) ) == EBML_CTX_MASTER( Context_KaxSegmentVLC )
 165             ? Context_KaxSegmentVLC
 166             : EBML_CONTEXT(m_el[mi_level - 1]);
 167
 168     /* Ignore unknown level 0 or 1 elements */
 169     m_el[mi_level] = m_es->FindNextElement( e_context,
 170                                             i_ulev, UINT64_MAX,
 171                                             (  mb_dummy | (mi_level > 1) ), 1 );
 172     if( i_ulev > 0 )
 173     {
 174         if( p_prev )
 175         {
 176             if( !mb_keep )
 177             {
 178                 if( MKV_IS_ID( p_prev, KaxBlockVirtual ) )
 179                     static_cast<KaxBlockVirtualWorkaround*>(p_prev)->Fix(); // !! WARNING : TODO !! this is undefined-behavior
 180                 delete p_prev;
 181             }
 182             mb_keep = false;
 183         }
 184         while( i_ulev > 0 )
 185         {
 186             if( mi_level == 1 )
 187             {
 188                 mi_level = 0;
 189                 return NULL;
 190             }
 191
 192             delete m_el[mi_level - 1];
 193             m_got = m_el[mi_level -1] = m_el[mi_level];
 194             m_el[mi_level] = NULL;
 195
 196             mi_level--;
 197             i_ulev--;
 198         }
 199         return NULL;
 200     }
 201     else if( m_el[mi_level] == NULL )
 202     {
 203         msg_Dbg( p_demux,"MKV/Ebml Parser: m_el[mi_level] == NULL" );
 204     }
 205     else if( m_el[mi_level]->IsDummy() && !mb_dummy )
 206     {
 207         bool b_bad_position = false;
 208         /* We got a dummy element but don't want those...
 209          * perform a sanity check */
 210         if( !mi_level )
 211         {
 212             msg_Err(p_demux, "Got invalid lvl 0 element... Aborting");
 213             return NULL;
 214         }
 215
 216         if( mi_level > 1 &&
 217             p_prev && p_prev->IsFiniteSize() &&
 218             p_prev->GetEndPosition() != m_el[mi_level]->GetElementPosition() )
 219         {
 220             msg_Err( p_demux, "Dummy Element at unexpected position... corrupted file?" );
 221             b_bad_position = true;
 222         }
 223
 224         if( n_call < M_EL_MAXSIZE && !b_bad_position && m_el[mi_level]->IsFiniteSize() &&
 225             ( !m_el[mi_level-1]->IsFiniteSize() ||
 226               m_el[mi_level]->GetEndPosition() <= m_el[mi_level-1]->GetEndPosition() ) )
 227         {
 228             /* The element fits inside its upper element */
 229             msg_Warn( p_demux, "Dummy element found %" PRIu64 "... skipping it",
 230                       m_el[mi_level]->GetElementPosition() );
 231             return Get( ++n_call );
 232         }
 233         else
 234         {
 235             /* Too large, misplaced or M_EL_MAXSIZE successive dummy elements */
 236             msg_Err( p_demux,
 237                      "Dummy element too large or misplaced at %" PRIu64 "... skipping to next upper element",
 238                      m_el[mi_level]->GetElementPosition() );
 239
 240             if( mi_level >= 1 &&
 241                 m_el[mi_level]->GetElementPosition() >= m_el[mi_level-1]->GetEndPosition() )
 242             {
 243                 msg_Err(p_demux, "This element is outside its known parent... upping level");
 244                 delete m_el[mi_level - 1];
 245                 m_got = m_el[mi_level -1] = m_el[mi_level];
 246                 m_el[mi_level] = NULL;
 247
 248                 mi_level--;
 249                 return NULL;
 250             }
 251
 252             delete m_el[mi_level];
 253             delete p_prev;
 254
 255             m_el[mi_level] = NULL;
 256             m_el[mi_level - 1]->SkipData( *m_es, EBML_CONTEXT(m_el[mi_level - 1]) );
 257             return Get();
 258         }
 259     }
 260
 261     if( p_prev )
 262     {
 263         if( !mb_keep )
 264         {
 265             if( MKV_IS_ID( p_prev, KaxBlockVirtual ) )
 266                 static_cast<KaxBlockVirtualWorkaround*>(p_prev)->Fix();
 267             delete p_prev;
 268         }
 269         mb_keep = false;
 270     }
 271     return m_el[mi_level];
 272 }
 273
 274 bool EbmlParser::IsTopPresent( EbmlElement *el ) const
 275 {
 276     for( int i = 0; i < mi_level; i++ )
 277     {
 278         if( m_el[i] && m_el[i] == el )
 279             return true;
 280     }
 281     return false;
 282 }
 283