modules/meta_engine/ID3Tag.h

   1 /*****************************************************************************
   2  * ID3Tag.h : ID3v2 Parsing Helper
   3  *****************************************************************************
   4  * Copyright (C) 2016 VLC authors and VideoLAN
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20 #ifndef ID3TAG_H
  21 #define ID3TAG_H
  22
  23 static uint32_t ID3TAG_ReadSize( const uint8_t *p_buffer, bool b_syncsafe )
  24 {
  25     if( !b_syncsafe )
  26         return GetDWBE( p_buffer );
  27     return ( (uint32_t)p_buffer[3] & 0x7F ) |
  28             (( (uint32_t)p_buffer[2] & 0x7F ) << 7) |
  29             (( (uint32_t)p_buffer[1] & 0x7F ) << 14) |
  30             (( (uint32_t)p_buffer[0] & 0x7F ) << 21);
  31 }
  32
  33 static bool ID3TAG_IsTag( const uint8_t *p_buffer, bool b_footer )
  34 {
  35     return( memcmp(p_buffer, (b_footer) ? "3DI" : "ID3", 3) == 0 &&
  36             p_buffer[3] < 0xFF &&
  37             p_buffer[4] < 0xFF &&
  38            ((GetDWBE(&p_buffer[6]) & 0x80808080) == 0) );
  39 }
  40
  41 static size_t ID3TAG_Parse( const uint8_t *p_peek, size_t i_peek,
  42                             int (*pf_callback)(uint32_t, const uint8_t *, size_t, void *), void *p_priv )
  43 {
  44     size_t i_total_size = 0;
  45     uint32_t i_ID3size = 0;
  46     if( i_peek > 10 && ID3TAG_IsTag( p_peek, false ) )
  47     {
  48         const bool b_syncsafe = p_peek[5] & 0x80;
  49         i_ID3size = ID3TAG_ReadSize( &p_peek[6], true );
  50         if( i_ID3size > i_peek - 10 )
  51             return 0;
  52         i_total_size = i_ID3size + 10;
  53         const uint8_t *p_frame = &p_peek[10];
  54         while( i_ID3size > 10 )
  55         {
  56             uint32_t i_tagname = VLC_FOURCC( p_frame[0], p_frame[1], p_frame[2], p_frame[3] );
  57             uint32_t i_framesize = ID3TAG_ReadSize( &p_frame[4], b_syncsafe ) + 10;
  58             if( i_framesize > i_ID3size )
  59                 return 0;
  60
  61             if( i_framesize > 10 &&
  62                 pf_callback( i_tagname, &p_frame[10], i_framesize - 10, p_priv ) != VLC_SUCCESS )
  63                 break;
  64
  65             p_frame += i_framesize;
  66             i_ID3size -= i_framesize;
  67         }
  68     }
  69
  70     /* Count footer if any */
  71     if( i_total_size && i_peek - i_total_size >= 10 &&
  72         ID3TAG_IsTag( &p_peek[i_total_size], true ) )
  73     {
  74         i_total_size += 10;
  75     }
  76
  77     return i_total_size;
  78 }
  79
  80 #endif // ID3TAG_H