Xref: utzoo comp.unix.questions:12846 comp.lang.c:17627
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!ames!pasteur!ucbvax!decwrl!labrea!rutgers!att!homxb!hound!rkl1
From: rkl1@hound.UUCP (K.LAUX)
Newsgroups: comp.unix.questions,comp.lang.c
Subject: Re: lockfile/unix/c
Keywords: c, unix, lockf
Message-ID: <3012@hound.UUCP>
Date: 13 Apr 89 15:59:30 GMT
References: <6307@homxc.ATT.COM>
Organization: AT&T Bell Laboratories, Holmdel
Lines: 19

In article <6307@homxc.ATT.COM>, iluvu@homxc.ATT.COM (S.RAVIKUMAR) writes:
| I tried to restrict access to a shared resource between
| processes using the unix system call "lockf". The piece of code
| is as follows:
| 
| 	fd = open(FILENAME, O_CREAT, 0666);
| 	lockf(fd, F_LOCK, (long)0);
| 
| "lockf" always returns with an error and errno is set to "Bad
| file descriptor". Any help or suggestions are welcome.

	Sounds like the open call is returning an error.  You should check
for this before issuing the lockf call.

	Also, after opening a file with O_CREAT, I close the file, then
reopen it with another open call, because O_CREAT will only let you
write to the file, and I usually need read/write permission.

--rkl