[syslinux] Read disk with open()/read()?

[Gordon Schumacher]

Is there already a way to read directly from the disk, perhaps via 
INT22/19h, using the COM32 open()/read() functions?

If not, I'd like to propose adding the ability to do something like:
int fd = open("//", O_RDONLY);
to allow reading from the raw disk.

I am working on building a COM32 module out of the checkisomd5 tool from 
isomd5sum, but I need a way to
access the raw disk in order to do that.