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From: generous@dgis.daitc.mil (Curtis Generous)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: is it a socket or is it not?
Keywords: workaround, fstat, bug
Message-ID: <8@dgis.daitc.mil>
Date: 29 Jul 89 17:49:15 GMT
Followup-To: comp.unix.questions
Organization: DTIC Special Projects Office (DTIC-SPO), Alexandria VA
Lines: 23

What's a good method of determining whether a file descriptor
is a socket or not?  The fstat(2) call does not work well on sockets
(and it even says so in the man page :-)

This is what I would like to do but doesn't work:

    if (fstat(fildes, &statb) == 0) {
	if ((statb.st_mode &= S_IFMT) == S_IFSOCK)
	    sockflag++;
    }

Is there a better/cleaner way?  Do you go through the list of possibles
and work by elimination (S_IFREG, S_IFDIR, ...)?  Can I assume that fstat(2)
will _always_ return a zeroed buffer as mentioned in the BUGS of the man page?

The OS is More/BSD 4.3 on a VAX 780, but I think this spans many BSD derivatives

--curtis
-- 
Curtis C. Generous
DTIC Special Projects Office (DTIC-SPO)
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