nfsd, rpcbind: add -P option to support pidfile path

[khng]

Summary

The -P option, when specified opens a pidfile to a given path.

Sponsored by: Juniper Networks, Inc.

[khng]

Add comments.

[rmacklem]

I'll leave the minor nits up to you.
Are you a committer or do you need me
to do it?

usr.sbin/nfsd/nfsd.c

456

I think I'd call this a LOG_ERR, since the pidfile
wasn't set up correctly.

usr.sbin/rpcbind/rpcbind.c

260

Same as above. Minor nit, but I'd call this
a LOG_ERR.

846

The string argument is in alphabetical order
with upper case before lower case, so I'd put
"P" after "N".
(Again, a minor nit.)

[khng]

In D50624#1158182, @rmacklem wrote:

I'll leave the minor nits up to you.
Are you a committer or do you need me
to do it?

No worries, I am a committer.

[khng]

By the way, given that rpcbind and nfsd will install a default pidfile to /var/run even without specifying -P: shall we document that somewhere in RELNOTES and the commit message, or do we make the errno == EEXIST case a warn() call instead of errx()? I am thinking of that because some people might spin up multiple nfsd in their setup without using the rc.d/nfsd script, and with different bound IP for each nfsd spun.

[rmacklem]

In D50624#1158192, @khng wrote:

By the way, given that rpcbind and nfsd will install a default pidfile to /var/run even without specifying -P: shall we document that somewhere in RELNOTES and the commit message, or do we make the errno == EEXIST case a warn() call instead of errx()? I am thinking of that because some people might spin up multiple nfsd in their setup without using the rc.d/nfsd script, and with different bound IP for each nfsd spun.

If they spin up multiple instances of the nfsd, it will be badly broken.
The only case where a system can run multiple instances of nfsd is
when each of them is in a separate vnet prison.

As such, it should be a fatal error for nfsd, imho.

[khng]

Addressed.