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From: stevens@hsi.UUCP (Richard Stevens)
Newsgroups: comp.sys.att,comp.unix.wizards
Subject: how to tell if a descriptor is a streams device ??
Keywords: streams, SVR3.2
Message-ID: <290@hsi86.hsi.UUCP>
Date: 5 Feb 89 11:21:13 GMT
Organization: Health Systems Intl., New Haven, CT
Lines: 13

Is there a "best" way to tell if a given descriptor refers to
a streams device ??  I've found that none of the simple ioctl's
listed in streamio(7) return the "Not a streams device" (errno=60)
error, which is the error message I'd like to get.  The poll(2) system
call appears to return POLLHUP (hang up) if the descriptor isn't a
streams device.  The getmsg(2) system call does give you the right
error, but you may not want to get a message.  I didn't see anything
on the stat(2) man page that would give you a clue.

	Richard Stevens
	Health Systems International, New Haven, CT
	   stevens@hsi.com
           ... { uunet | yale } ! hsi ! stevens