C program which copies floppy (FAT12)

rakestraw · 08-02-2006, 01:26 PM

Hi there!

I write one simple C program, which reads a content of diskette and than write it to another...BUT, i need to do it that program will copy just used sectors and that's sectors will stay on same place (addresses).

Please, give me some advices how to make that...cause my problem is, i don't know how to start. I know some FAT12 basics...but i don't know how to use it in a program.

Tnx!

cdhgee · 08-03-2006, 10:09 AM

You don't need to write one...it already exists.

It's called dd and it does a block-by-block copy from any device to any device. For example:

Code:

dd if=/dev/floppy1 of=/dev/floppy2

will copy the entire contents of floppy1 to floppy2, irrespective of size, filesystem format, etc.

rakestraw · 08-03-2006, 11:22 AM

yeah I know...but, I need it to write for Faculty task...can I get source dd program...I'll check out, but I don't know if is it writen in C or if it does only this task...

Hko · 08-03-2006, 12:58 PM

Quote:

Originally Posted by rakestraw

can I get source dd program...I'll check out, but I don't know if is it writen in C or if it does only this task...

"dd" is written in C for sure.
"dd" is part of the GNU coreutils package which you can download from ftp://mirrors.usc.edu/pub/gnu/coreutils/

To copy the floppy, I think just copying /dev/fd0 will do. To skip unused sectors, you'll need to read and parse the File Allocation Table (FAT). Search the web on how to get that information from /dev/fd0.

rakestraw · 08-04-2006, 03:00 AM

Tnx!
Yes i work with /dev/fd0.
I was allready workink with readig Boot sectors to calculate the start of a FAT, but i didn't know if that's right way...
I found site, where is written about "File Allocation Table Entry Cluster Values" and how to read them...smth about shiffting en reversing...

I also find that info:
Number of FATs: 2
Sectors per FAT: 9
Total Sectors: 2,880
Sectors per Cluster: 1

Somehow i need to walk through this 2880 sectors, check if they are unused and skip them...