Re: [HACKERS] flock patch breaks things here - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] flock patch breaks things here
Date
Msg-id 199808310436.AAA07618@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] flock patch breaks things here  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [HACKERS] flock patch breaks things here  (dg@informix.com (David Gould))
Re: [HACKERS] flock patch breaks things here  ("Billy G. Allie" <Bill.Allie@mug.org>)
List pgsql-hackers
> The Hermit Hacker <scrappy@hub.org> writes:
> > either way, moving the pid file (or
> > socket, for that matter) from /tmp should be listed as a security related
> > requirement for v6.4 :)
>
> Huh?  There is no pid file being generated in /tmp (or anywhere else)
> at the moment.  If we do add one, it should not go into /tmp for the
> reasons I gave before.
>
> Where the Unix-domain socket file lives is an entirely separate issue.
>
> If we move the socket out of /tmp then we have just kicked away all the
> work we did to preserve backwards compatibility of the FE/BE protocol
> with existing clients.  Being able to talk to a 1.0 client isn't much
> good if you aren't listening where he's going to try to contact you.
> So I think I have to vote in favor of leaving the socket where it is.

I have been thinking about this.  First, we can easily use fopen(r+) to
check to see if the file exists, and if it does read the pid and do a
kill -0 to see if it is running.  If no one else does it, I will take it
on.

Second, where to put the pid file.  There is reason to put in /tmp,
because it will get cleared in a reboot, and because it is locking the
port number 5432.  There is also reason to put it in /data because you
can't have more than one postmaster running on a single data directory.

So, we really want to lock both places.  If this is going to make it
easier for people to run more than one postmaster, because it will
prevent/warn administrators when they try and put two postmasters in the
same data dir or port, I say create the pid lock files both places, and
give the admin a clear description of what he is doing wrong in each
case.


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