The assignment is to write a setuid program that has most of the
characteristics of a print spooler.  This program must be secure
against many different attacks, including attempts to "print" files
not accessible to the user.  At the same, it must "print" each legitimate
file.  (Note that you will not actually be printing anything.)

Here are the specific requirements.  The setuid program should read
a list of filenames from stdin.  For each such file, it should (if the
file is readable by the actual user) run the command /usr/bin/md5sum
on that file.  The output of the command should be written to a file
writable only by the owner of the setuid program, and in particular not
writable by the invoker.  You may *not* use the MD5 library procedures;
you *must* use the external command.

Pay careful attention to your selection of test data.

You will be given access to a second account to use for this assignment.
Use your regular account to create the program and make it setuid;
use the second account for testing.

Deliverables
The tar file you turn in will include the program, the input from
a test run, and the output from that run.  You'll be graded on the
overall quality of the program, its resistance to the various attacks
we've discussed in class --- this assignment is designed to stress
several different points --- and your selection of test data.