Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[John Levon]

On Wed, Aug 01, 2007 at 09:53:17AM -0700, Xen patchbot-unstable wrote:

> +
> +		/* Get ourselves a nice xenstored crash if these are used. */
> +		stdin = NULL;
> +		stdout = NULL;
> +		stderr = NULL;

You cannot assign to std* on Solaris, this becomes:

 (&__iob[0]) = 0;
 (&__iob[1]) = 0;
 (&__iob[2]) = 0;

which obviously won't compile.

regards,
john

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[Keir Fraser]

On 1/8/07 19:03, "John Levon" <levon@movementarian.org> wrote:

>> +
>> +  /* Get ourselves a nice xenstored crash if these are used. */
>> +  stdin = NULL;
>> +  stdout = NULL;
>> +  stderr = NULL;
> 
> You cannot assign to std* on Solaris, this becomes:
> 
>  (&__iob[0]) = 0;
>  (&__iob[1]) = 0;
>  (&__iob[2]) = 0;
> 
> which obviously won't compile.

Okay, I'll fix this by redirecting xprintf() to trace() and get rid of the
NULL assignments.

 -- Keir

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[John Levon]

On Wed, Aug 01, 2007 at 07:12:22PM +0100, Keir Fraser wrote:

> > You cannot assign to std* on Solaris, this becomes:
> > 
> >  (&__iob[0]) = 0;
> >  (&__iob[1]) = 0;
> >  (&__iob[2]) = 0;
> 
> Okay, I'll fix this by redirecting xprintf() to trace() and get rid of the
> NULL assignments.

Thanks!

BTW, you mentioned a new 3.1 release some time soon. Is there something
we can usefully be doing to help this happen? (Certainly me doing some
testing of 3.1 at all would help...)

The bug fixes I care most about offhand are the ones that finish
implementing the xen api.

regards,
john

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[Alan Cox]

> Okay, I'll fix this by redirecting xprintf() to trace() and get rid of the
> NULL assignments.

You are guaranteed to be able to freopen() stdin/stdout/stderr and that
is a portable C feature. This means you can divert the stdin/out/err to a
log file to catch such accidents or at least avoid future problems by
firing them down /dev/null.

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[Daniel P. Berrange]

On Wed, Aug 01, 2007 at 07:03:23PM +0100, John Levon wrote:
> On Wed, Aug 01, 2007 at 09:53:17AM -0700, Xen patchbot-unstable wrote:
> 
> > +
> > +		/* Get ourselves a nice xenstored crash if these are used. */
> > +		stdin = NULL;
> > +		stdout = NULL;
> > +		stderr = NULL;
> 
> You cannot assign to std* on Solaris, this becomes:
> 
>  (&__iob[0]) = 0;
>  (&__iob[1]) = 0;
>  (&__iob[2]) = 0;
> 
> which obviously won't compile.

Yep, rather than closing FD's and setting the FILE* to NULL, the daeon
code should re-open /dev/null for stdin/out/err which is the traditional
approach for most UNIX daemons.

        if (dofork) {
                int devnull;
                devnull = open(_PATH_DEVNULL, O_RDWR);
                close(STDIN_FILENO);
                close(STDOUT_FILENO);
                close(STDERR_FILENO);
                dup2(devnull, STDIN_FILENO);
                dup2(devnull, STDOUT_FILENO);
                dup2(devnull, STDERR_FILENO);
                close(devnull);
        }

(With error checking on open/close/dup2 of ccourse)

Regards,
Dan.
-- 
|=- Red Hat, Engineering, Emerging Technologies, Boston.  +1 978 392 2496 -=|
|=-           Perl modules: http://search.cpan.org/~danberr/              -=|
|=-               Projects: http://freshmeat.net/~danielpb/               -=|
|=-  GnuPG: 7D3B9505   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505  -=| 

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[Keir Fraser]

Good idea. Can't use _PATH_DEVNULL easily though, since it'll break Solaris
again (no paths.h). Hardcoding /dev/null is not so bad -- the console daemon
does this already.

 -- Keir

On 1/8/07 19:20, "Daniel P. Berrange" <berrange@redhat.com> wrote:

> Yep, rather than closing FD's and setting the FILE* to NULL, the daeon
> code should re-open /dev/null for stdin/out/err which is the traditional
> approach for most UNIX daemons.
> 
>         if (dofork) {
>                 int devnull;
>                 devnull = open(_PATH_DEVNULL, O_RDWR);
>                 close(STDIN_FILENO);
>                 close(STDOUT_FILENO);
>                 close(STDERR_FILENO);
>                 dup2(devnull, STDIN_FILENO);
>                 dup2(devnull, STDOUT_FILENO);
>                 dup2(devnull, STDERR_FILENO);
>                 close(devnull);
>         }

Re: Re: [Xen-changelog] [xen-unstable] xenstored: Do not write to stderr if we are daemonised!

[John Levon]

On Wed, Aug 01, 2007 at 07:32:59PM +0100, Keir Fraser wrote:

> Good idea. Can't use _PATH_DEVNULL easily though, since it'll break Solaris
> again (no paths.h). Hardcoding /dev/null is not so bad -- the console daemon
> does this already.

I'm somewhat bemused as to the purpose of _PATH_DEVNULL - is this
different on Hurd or something?

regards
john