一个关于virtual cd-rom的问题！

在对付保护光盘时， 他采用了一种技术在扇区标准之间加入一个byte，然后后面的数据后移，我要读它就需要还原成标准格式，必须去掉哪个庸余的字节，然后把后边的数据都前移一个byte.
我现在用的是Direct Buffer方式 fdo->Flags|=DO_DIRECT_IO;读取数据，然而系统一个PAGE_SIZE 是4K,而光盘扇区一个是2K,所以我一次读取最小粒度是4K,而这包含了两个光盘扇区，和中间的一个庸余字节，当我用Retcopymemery()，这个这样我就page falut exception。
所以我想在读的时候如何能够不对中间那个byte读。

各位有什么指点？

是2048+1+2048吗?

高手！是的呀，就是这样的情况有办法解决吗？中间哪个字节是不要的，删除它该如何做？如何操作才能修改被直接锁定的4k页内的数据呢？



谢谢谢谢，希望指教，如果知道，跟您作揖了<<<<<

if you develop your own cdrom driver(like virtual cdrom), of course you can do what you want .

if you only want read this type of media in a common cdrom or exist virtual cdrom, ou need to make a filter driver, realize you filter driver irp_mj_read dispatch routine like following way:

1.analysis read request (if it data mode 1, offset,size will be aligned to 2048 , if data mode  , it should be 2336)
2.change orignal request to lba  or msf(raw data is 2352 alignment, commonly you need not get subcode area)
3.allocate new irp/mdl and set device io control to IOCTL_CDROM_RAW_READ (build scsi command and set opcode to scsi_op_read_cd  is better, but a little difficult)
4. send it to lower driver
5. get data if success, copy what you want back to user buffer. (when copy , of course you can skip that dummy one byte)
6. free mdl, your allocated irp and complete original request

in 9x/Me, it should be a layer driver.
in 2k/xp, it\'s only a common filer driver.