"if" and "of" with the exception that the communicate with a rump
kernel instead of the host kernel.
For example, to write stdout to /tmp/file.txt in a rump kernel namespace:
dd rof=/tmp/file.txt
copy /file1 to /file2 inside a rump kernel:
dd rif=/file1 rof=/file2
copy a snippet from /dev/rmd0d on the rump kernel to the host fs:
dd rif=/dev/rmd0d of=save seek=1000 count=3
Eat that, usermode OS.
(I'll document the operands one I have some manpage to refer to
for rump client use).
If stdout is a tty, use vis(3) to print any filenames to prevent garbage
from being printed if the filename contains control- or other non-printable
characters.
While here, sprinkle some EXIT_FAILURE and NOTREACHED where appropriate.
