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From: pj@sam.wpd.sgi.com (Paul Jackson)
Newsgroups: comp.sys.sgi
Subject: Re: File locking problems
Message-ID: <1991Jun13.233213.14609@dragon.wpd.sgi.com>
Date: 13 Jun 91 23:32:13 GMT
References: <9106131834.AA08574@sct60a.sunyct.edu>
Sender: news@dragon.wpd.sgi.com (CNews Account)
Reply-To: pj@sgi.com
Organization: Silicon Graphics, Research & Development
Lines: 16

In article <9106131834.AA08574@sct60a.sunyct.edu>, sweetmr@SCT60A.SUNYCT.EDU (michael
sweet) writes:
|> ... lockf(2) function doesn't seem to work properly
|>   if (fd = open("config_file", O_RDWR, 02644) < 0)
|>     ....
|>   if (lockf(fd, F_TLOCK, 0L) < 0)

Change the open line to have parentheses around (fd = open(...)).
Your current code sets fd to be the result of the boolean (open(...) < 0),
which if the open succeeds is false.  So fd is 0 (for false) and lockf(0,...)
succeeds.
-- 

				I won't rest till it's the best ...
				Software Production Engineer
				Paul Jackson (pj@wpd.sgi.com), x1373