Re: fcntl always fails to delete lock file, and PID is always -6464

On Sun, 3 Oct 2010 22:05:12 -0700
Garrett Cooper <gcooper_at_FreeBSD.org> wrote:
> On Sun, Oct 3, 2010 at 8:37 PM, Daichi GOTO <daichi_at_ongs.co.jp> wrote:
> > It looks very strange. fcntl() always fails to delete lock file
> > and command.l_pid is always -6464. This issue is disclosed in
> > porting Google's Japanese input system called "mozc".
> >
> >  details follow:
> >    http://code.google.com/p/mozc/issues/detail?id=40
> >
> > % uname -a
> > FreeBSD parancell.ongs.co.jp 9.0-CURRENT FreeBSD 9.0-CURRENT #6 r213257: Thu Sep 30 10:30:06 JST 2010     root_at_parancell.ongs.co.jp:/usr/obj/usr/src/sys/PARANCELL  amd64
> > %
> >
> > My home directory on NFS server.  Does anyone have any ideas?
> 
> 
>     I see some bad assumptions in the code:
> 
>     const int result = ::fcntl(*fd, F_SETLK, &command);
>     if (-1 == result) {  // failed
>       ::close(*fd);
>       LOG(WARNING) << "already locked";
>       return false;   // another server is already running
>     }
> 
>     If the developer actually coded to POSIX expectations, he/she
> would be checking for EACCES/EAGAIN; there are a myriad of other

It was EAGAIN, when I checked.  And -6464 is very strange....
It should be -1 when it fails with EGAIN according to FreeBSD 
fcntl(2) manual.

Repeat is easy:
  # cd /usr/ports/japanese/mozc-server/
  # rm files/patch-server_mozc_server.cc
  # make WITH_DEBUG_CODE=yes install clean

  % mozc_server
  ^C    --> in this timing, lock files should be deleted, but not working.
  % mozc_server  --> so server will not run and finish soon
  %

  % cat ~/.mozc/mozc_server.log

> issues that might be occurring with the software, as per my copy of
> SUSv4 (see the ERRORS section of fcntl). I would print out the
> strerror for that case.
>     Providing a backtrace of the application's execution and the
> architecture and what version of FreeBSD you're using would be
> helpful.
> Thanks,
> -Garrett

-- 
Daichi GOTO
CEO | ONGS Inc.
81-42-316-7945 | daichi_at_ongs.co.jp | http://www.ongs.co.jp
LinkedIn: http://linkedin.com/in/daichigoto