Trojan Horses

[The Grey Wolf]

In article <18578 at rpp386.cactus.org> jfh at rpp386.cactus.org (John F. Haugh II) writes:
# In article <1990Oct7.155203.13283 at hq.demos.su> avg at hq.demos.su (Vadim G. Antonov) writes:
# 
# >	2) All processes, associated with a TTY should be killed
# >	   (as SIGHUP does) andprotected processes should be
# >	   RE-ASSOCIATED with an unique TTY-id (which actually
# >	   does not exist).
# 
# Killed is a tad strong.  The only real requirement is that unauthorized
# access to the device be revoked.  You can do this simply by marking a
# file table entry which references the device as "stale" and returning
# an error on any attempt (other than close, I suppose ...) to use that
# descriptor.

I believe this is what the vhangup() call does.  Or used to.  I don't know
what has taken its place, but I have heard rumours of the demise of this
call...

# John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
# Ma Bell: (512) 832-8832                           Domain: jfh at rpp386.cactus.org
# "SCCS, the source motel!  Programs check in and never check out!"
# 		-- Ken Thompson

I wonder, incidentally, why does close() return something?  Is it just that
it's a system call?  What checks for close()'s return value?  I could see it
being used for security checks and such, I suppose (verifying that "fd %d
had to be closed -- CHECK THIS").

-- 
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