SCO UNIX *double* device driver

[Guy Harris]

>#define fopen hvfopen
>#define fclose hvfclose
>  :              :
>
>Etc. for all required system calls, and then do in your function calls
>what you want to do.

Doesn't help very much if he doesn't have source to all programs that
might want to use the virtual disk.  Doesn't even help much if he
*does*, because the programs generally won't access the disk directly,
they'll do it through the file system; the file system just goes through
the device driver switch, rather than specifically calling the routines
from some particular driver, so a #define trick like that won't help,
even if he *does* have the source to the OS kernel....