[PVFS-developers] Manager unable to open log file

[Rob Ross]

Hey,

I applied a fix using the dup2() approach.

Rob

On Fri, 30 Jul 2004, Rob Ross wrote:

> I agree that this could be a problem.  I think that the right solution 
> would probably be to open() /dev/null as you suggest and dup2() the FDs 
> into the right spots.  The mgr could just blow up if it couldn't open 
> /dev/null for some reason.
> 
> Regards,
> 
> Rob
> 
> On Fri, 30 Jul 2004, Stuart White wrote:
> 
> > In mgr.c, code exists that opens the log file.  (line 365 in
> > 1.6.3-pre2)
> > 
> >    if ((logfd = open(logname, logflags, 0700)) == -1) {
> > #endif
> >       ERR("couldn't create logfile...continuing...\n");
> >       close(0); close(1); close(2);
> >    }
> > 		
> > If the open() of the log file fails, stdin, stdout, and stderr are
> > closed, and then execution simply continues.
> > 
> > This seems dangerous to me.  Because stdout and stderr are closed,
> > their file descriptors will be re-used when opening metadata files. 
> > Lots of debugging code exists in the manager that fprintf's to stderr. 
> > If stderr's file descriptor has been recycled and used for a metadata
> > file, these debug fprintf's will corrupt the contents of the metadata
> > files.
> > 
> > In my version of PVFS, I changed this case to simply error out if the
> > open() of the log file failed.  However, I'm not submitting a patch for
> > that because, it seems this is a judgement call for how one wants to
> > handle this situation.  Another option would be to open /dev/null and
> > call dup2() redirecting stdout and stderr to /dev/null.
> > 
> > In any case, it seems something different should be done.  I ask you
> > guys to take a look at this and implement whatever correction you deem
> > appropriate.
> > 
> > As always, feedback is appreciated!  Thanks!
> > 
> > 
> > 
> > 		
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