Re: [Xen-devel] [PATCH] libxl: prevent xl from running if xend is running.

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Ian Campbell writes ("Re: [Xen-devel] [PATCH] libxl: prevent xl from running if 
xend    is running."):
> On Tue, 2012-04-24 at 14:17 +0100, Ian Jackson wrote:
> > Can we somehow limit this to commands that actually change things ?
> > Having xl as a diagnostic tool even for xend-based systems is useful.
> 
> Perhaps a new flag in xl_cmdtable.h? Overriden by -f or -N (dry run).

Yes, something like that.

> > > +        if (!access(locks[i], F_OK) && !force_execution) {
> > > +            fprintf(stderr, "xend is running, which prevents xl from 
> > > working "
> > > +                            "correctly. If you still want to force the "
> > > +                            "execution of xl please use the -f 
> > > option\n");
> > > +            exit(2);
> > > +        }
> > 
> > If access fails with an unexpected error code (EACCES? EIO?) this will
> > blunder on.
> 
> It'll fail whether the error code is expected or not, won't it?

I think if access fails with EIO, it will return -1, and the if
condition will not be satisfied (!-1 = 0), so the fprintf and exit
will not be taken.

Ian.

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