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From: drown@chaos.taylored.com (drown )
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Locking master.passwd correctly
Date: 26 Dec 1996 03:34:32 GMT
Organization: JCPenney Co., Inc.
Lines: 30
Message-ID: <59sro8$l1a@atlas.jcpenney.com>
NNTP-Posting-Host: 206.53.224.58
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:33083
Hi folks,
I've had some weird problems lately with chfn stomping over my account
creation software. It seems that chfn doesn't "see" my lock on the
master.passwd file sometimes, even though at other times it does. It seems
to be a race condition. Here's the relivant perl code for locking the
password file:
open(MPW, "</etc/master.passwd") || die "cant locate $masterpw?!?!\n";
if (!flock(MPW, 6)) {
close(MPW);
while(1) {
open(MPW, "</etc/master.passwd");
if (flock(MPW, 6)) { # Got it
last;
}
close(MPW);
sleep(5);
}
}
Seems like it should work. The strange thing is that it usually _does_ work,
it's just that every so often a user edits their info via chfn and boom,
problems. I've confirmed this by patching pwd_mkdb to log when it's called.
Any ideas what could be causing this? Am I locking the file incorrectly?
Thanks!
drown@chaos.taylored.com