udf.c

VLC媒体播放程序

    do
    {
        if( !UDFReadLB( partition.dvdhandle, i_lba++, 1, pi_lb ) )
        {
            i_tag_id = 0;
        }
        else
        {
            UDFDescriptor( pi_lb , &i_tag_id );
        }

        if( i_tag_id == 261 )
        {
            UDFFileEntry( pi_lb, pi_file_type, p_file, partition );
            return 1;
        }

    } while( ( i_lba <= partition.i_start + icb.i_location +
               ( icb.i_length - 1 ) / DVD_LB_SIZE ) && ( i_tag_id != 261 ) );

    return 0;
}

/*****************************************************************************
 * UDFScanDir: serach filename in dir
 *****************************************************************************
 * Dir: Location of directory to scan
 * FileName: Name of file to look for
 * FileICB: Location of ICB of the found file
 * return 1 on success, 0 on error;
 *****************************************************************************/
static int UDFScanDir( struct ad_s dir, char * psz_filename,
                       struct ad_s * p_file_icb, struct partition_s partition )
{
    uint8_t  pi_lb[2*DVD_LB_SIZE];
    uint32_t i_lba;
    uint16_t i_tag_id;
    uint8_t  i_file_char;
    char     psz_temp[DVD_LB_SIZE];
    unsigned int p;

    /* Scan dir for ICB of file */
    i_lba = partition.i_start + dir.i_location;
#if 0
    do
    {
        if( !UDFReadLB( partition.dvdhandle, i_lba++, 1, pi_lb ) )
        {
            i_tag_id = 0;
        }
        else
        {
            p=0;
            while( p < DVD_LB_SIZE )
            {
                UDFDescriptor( &pi_lb[p], &i_tag_id );

                if( i_tag_id == 257 )
                {
                    p += UDFFileIdentifier( &pi_lb[p], &i_file_char,
                                            psz_temp, p_file_icb, partition );
                    if( !strcasecmp( psz_filename, psz_temp ) )
                    {
                        return 1;
                    }
                }
                else
                {
                    p = DVD_LB_SIZE;
                }
            }
        }

    } while( i_lba <=
      partition.i_start + dir.i_location + ( dir.i_length - 1 ) / DVD_LB_SIZE );

#else

    if( UDFReadLB( partition.dvdhandle, i_lba, 2, pi_lb ) <= 0 ) {
        return 0;
    }

    p = 0;
    while( p < dir.i_length )
    {
        if( p > DVD_LB_SIZE )
        {
            ++i_lba;
            p -= DVD_LB_SIZE;
            dir.i_length -= DVD_LB_SIZE;
            if( UDFReadLB( partition.dvdhandle, i_lba, 2, pi_lb ) <= 0 )
            {
                return 0;
            }
        }

        UDFDescriptor( &pi_lb[p], &i_tag_id );

        if( i_tag_id == 257 )
        {
            p += UDFFileIdentifier( &pi_lb[p], &i_file_char,
                                    psz_temp, p_file_icb, partition );
            if( !strcasecmp( psz_filename, psz_temp ) )
            {
                return 1;
            }
        }
        else
        {
            return 0;
        }
    }

#endif
    return 0;
}

/*****************************************************************************
 * UDFFindPartition: looks for a partition on the disc
 *****************************************************************************
 *   partnum: number of the partition, starting at 0
 *   part: structure to fill with the partition information
 *   return 1 if partition found, 0 on error;
 *****************************************************************************/
static int UDFFindPartition( int i_part_nb, struct partition_s *p_partition )
{
    uint8_t     pi_lb[DVD_LB_SIZE];
    uint8_t     pi_anchor[DVD_LB_SIZE];
    uint16_t    i_tag_id;
    uint32_t    i_lba;
    uint32_t    i_MVDS_location;
    uint32_t    i_MVDS_length;
    uint32_t    i_last_sector;
    vlc_bool_t  b_term;
    vlc_bool_t  b_vol_valid;
    int         i;

    /* Find Anchor */
    i_last_sector = 0;

    /* try #1, prime anchor */
    i_lba = 256;
    b_term = 0;

    /* Search anchor loop */
    while( 1 )
    {
        if( UDFReadLB( p_partition->dvdhandle, i_lba, 1, pi_anchor ) )
        {
            UDFDescriptor( pi_anchor, &i_tag_id );
        }
        else
        {
            i_tag_id = 0;
        }

        if( i_tag_id != 2 )
        {
            /* not an anchor? */
            if( b_term )
            {
                /* final try failed */
                return 0;
            }

            if( i_last_sector )
            {
                /* we already found the last sector
                 * try #3, alternative backup anchor */
                i_lba = i_last_sector;

                /* but that's just about enough, then! */
                b_term = 1;
            }
            else
            {
                /* TODO: find last sector of the disc (this is optional) */
                if( i_last_sector )
                {
                    /* try #2, backup anchor */
                    i_lba = i_last_sector - 256;
                }
                else
                {
                    /* unable to find last sector */
                    return 0;
                }
            }
        }
        else
        {
            /* it is an anchor! continue... */
            break;
        }
    }

    /* main volume descriptor */
    UDFExtentAD( &pi_anchor[16], &i_MVDS_length, &i_MVDS_location );

    p_partition->b_valid = 0;
    b_vol_valid = 0;
    p_partition->pi_volume_desc[0] = '\0';

    i = 1;
    /* Find Volume Descriptor */
    do
    {
        i_lba = i_MVDS_location;

        do
        {
            if( !UDFReadLB( p_partition->dvdhandle, i_lba++, 1, pi_lb ) )
            {
                i_tag_id = 0;
            }
            else
            {
                UDFDescriptor( pi_lb, &i_tag_id );
            }

            if( ( i_tag_id == 5 ) && ( !p_partition->b_valid ) )
            {
                /* Partition Descriptor */
                UDFPartition( pi_lb,
                              &p_partition->i_flags,
                              &p_partition->i_number,
                              p_partition->pi_contents,
                              &p_partition->i_start,
                              &p_partition->i_length );
                p_partition->b_valid = ( i_part_nb == p_partition->i_number );
            }
            else if( ( i_tag_id == 6 ) && ( !b_vol_valid) )
            {
                /* Logical Volume Descriptor */
                if( UDFLogVolume( pi_lb , p_partition->pi_volume_desc ) )
                {
                /* TODO: sector size wrong! */
                }
                else
                {
                    b_vol_valid = 1;
                }
            }

        } while( ( i_lba <= i_MVDS_location +
                   ( i_MVDS_length - 1 ) / DVD_LB_SIZE )
                 && ( i_tag_id != 8 )
                 && ( ( !p_partition->b_valid ) || ( !b_vol_valid ) ) );

        if( ( !p_partition->b_valid ) || ( !b_vol_valid ) )
        {
            /* backup volume descriptor */
            UDFExtentAD( &pi_anchor[24], &i_MVDS_length, &i_MVDS_location );
        }
    } while( i-- && ( ( !p_partition->b_valid ) || ( !b_vol_valid ) ) );

    /* we only care for the partition, not the volume */
    return( p_partition->b_valid);
}


/*****************************************************************************
 * DVDUDFFindFile: looks for a file on the UDF disc/imagefile
 *****************************************************************************
 * Path has to be the absolute pathname on the UDF filesystem,
 * starting with '/'.
 * returns absolute LB number, or 0 on error
 *****************************************************************************/
uint32_t DVDUDFFindFile( dvdcss_handle dvdhandle, char * psz_path )
{
    struct partition_s  partition;
    struct ad_s         root_icb;
    struct ad_s         file;
    struct ad_s         icb;
    uint32_t            i_lba;
    uint16_t            i_tag_id;
    uint8_t             pi_lb[DVD_LB_SIZE];
    uint8_t             i_file_type;
    char                psz_tokenline[DVD_LB_SIZE] = "";
    char *              psz_token;
    int                 i_partition;

    strcat( psz_tokenline, psz_path );

    /* Init file descriptor of UDF filesystem (== DVD) */
    partition.dvdhandle = dvdhandle;

    /* Find partition 0, standard partition for DVD-Video */
    i_partition = 0;
    if( !UDFFindPartition( i_partition, &partition ) )
    {
#if 0
        intf_ErrMsg( "dvd error: partition 0 not found" );
#endif
        return 0;
    }

    /* Find root dir ICB */
    i_lba = partition.i_start;

    do
    {
        if( !UDFReadLB( dvdhandle, i_lba++, 1, pi_lb ) )
        {
            i_tag_id = 0;
        }
        else
        {
            UDFDescriptor( pi_lb, &i_tag_id );
        }

        if( i_tag_id == 256 )
        {
            /* File Set Descriptor */
            UDFAD( &pi_lb[400], &root_icb, UDFADlong, partition );
        }

    } while( ( i_lba < partition.i_start + partition.i_length )
          && ( i_tag_id != 8) && ( i_tag_id != 256 ) );

    if( i_tag_id != 256 )
    {
#if 0
        intf_ErrMsg( "dvd error: bad UDF descriptor" );
#endif
        return 0;
    }
    if( root_icb.i_partition != i_partition )
    {
#if 0
        intf_ErrMsg( "dvd error: bad UDF partition" );
#endif
        return 0;
    }

    /* Find root dir */
    if( !UDFMapICB( root_icb, &i_file_type, &file, partition ) )
    {
#if 0
        intf_ErrMsg( "dvd error: can't find root dir" );
#endif
        return 0;
    }

    /* root dir should be dir */
    if( i_file_type != 4 )
    {
#if 0
        intf_ErrMsg( "dvd error: root dir error" );
#endif
        return 0;
    }

    /* Tokenize filepath */
    psz_token = strtok( psz_tokenline, "/" );
    while( psz_token )
    {
        if( !UDFScanDir( file, psz_token, &icb, partition ) )
        {
#if 0
            intf_ErrMsg( "dvd error: scan dir error" );
#endif
            return 0;
        }

        if( !UDFMapICB ( icb, &i_file_type, &file, partition ) )
        {
#if 0
            intf_ErrMsg( "dvd error: ICB error" );
#endif
            return 0;
        }

        psz_token = strtok( NULL, "/" );
    }

    return partition.i_start + file.i_location;
}