CSCI 331 homework 7

This assignment must be uploaded to the Moodle submission page for Homework 7 by 11:00 PM on Friday, 5 April.

The setup

On the computer joe.cs.unca.edu there are three FAT file systems set up on the following mount points:

• /csci331/csci331big
• /csci331/csci331mid
• /csci331/csci331tny

These are all a bit hard to use because the FAT file system doesn’t really support user-ids, so the file systems can only be written by the user who mounted them. However, there is a copy of a image (the raw bits) of each file system within the directory

Your job is to use dd to make a copy of the first 512-byte sector, the BPB (BIOS Parameter Brock), of each of these images into your own directory. Then you are to use od or hexdump to print the following fields from the BPB in a readable fashion.

• BS_OEMName
• BPB_BytsPerSec
• BPB_SecPerClus
• BPB_RsvdSecCnt
• BPB_NumFATs
• BS_FilSysType

Except for the BS_FilSysType field, all of these positions are located in the same offset for both FAT16 and FAT32 file systems.

What to turn in?

I suggest you run in a copy of your running the script program to get this information.

It is fine to work in groups, but you must type in your own dd and od commands. Be careful, these are old-style Unix commands. They have a very odd syntax.

Suggested reference materials

You will need to review Microsoft’s specification of the FAT file system. The PHOBOS tutorial of the FAT file system is also useful. It’s not hard to use dd to copy the first 512 bytes of a file, and hexdump isn’t that bad. The true hackers use od though.