Exstract content from p7s

TAsnReader.SaveContentToStream.pas

procedure TAsnReader.SaveContentToStream(stream: TStream);
var breader : TBinaryReader;
    magik, blockType, blockLength : integer;
    isEnd : boolean;
    buffer : TBytes;
begin
    m_stream.Seek(0, soBeginning);
    breader := TBinaryReader.Create(m_stream);
    magik   := breader.ReadUInt16();
    case magik of
        $8030: breader.BaseStream.Position := 50;
        $8230: breader.BaseStream.Position := 58;
        $8330: breader.BaseStream.Position := 63;
    end;

    isEnd := false;
    while (breader.BaseStream.Position < breader.BaseStream.Size) and not isEnd do begin
        blockType := breader.ReadByte();
        // eof content data
        if blockType = 0 then break;
        // content date identifier
        if $04 = blockType then begin
            blockLength := breader.ReadByte();
            case blockLength of
                $81 : blockLength := breader.ReadByte();
                $82 : begin
                    // big-endian encoding of int16
                    blockLength := (breader.ReadByte shl 8) + breader.ReadByte;
                    if blockLength < 1024 then isend := true;
                end;
                $83 : begin
                    // big-endian encoding of int24
                    blockLength := (breader.ReadByte shl 16) + (breader.ReadByte shl 8) + breader.ReadByte;;
                    if blockLength < $FFFFFF then isend := true;
                end;
            end;

            if blockLength < (breader.BaseStream.Size - breader.BaseStream.Position) then begin
                buffer := breader.ReadBytes(blockLength);
                stream.WriteData(buffer, length(buffer));
            end else begin
                isEnd:=true;
            end;
        end;
    end;
end;