CRC checks for files

Question

I'm working with a small FAT16 filesystem, and I want to generate CRC values for indidual XML files which store configuration information. In case the data changes or is corrupted, I want to be able to check the CRC to determine that the file is still in it's original state.

The question is, how do I put the CRC value into the file, without changing the CRC value of the file itself? I can think of a couple solutions, but I think there must be a fairly standard solution for this issue.

Answer 1

You could append the CRC value to the end of the file. Then, when computing the CRC value later for checking, omit the last four bytes.

Answer 2

Define a header, generate the CRC of everything except the header then put the value in the header.