sorry, yes I meant all 4, and the hexdump I pasted was after I zero's out the first 512 bytes to test and make sure it would detect that they were different and give me an error.

The bug was that my first 2 seeks were to the same position.

I seek to the end of the file because I do not know how big the file will be, I am dealing with block devices, not real files. All I know is the first 2 and last 2 512 bytes are supposed to be identical.

I know that there are 2 seeks in there that are not important since they seek to where it should be anyway, but I am not necessarily keeping the code as is and may put other stuff in between them, so I put the seeks in for now so I do not forget later.