[PATCH] Do not abort compilation when dump file is /dev/*

[Bernhard Reutner-Fischer]

On Fri, 19 Nov 2021 10:35:26 +0100 (CET)
Richard Biener via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:

> On Fri, 19 Nov 2021, Alexandre Oliva wrote:
> 
> > On Nov 18, 2021, Richard Biener <rguenther@suse.de> wrote:
> >   
> > > IMHO a more reasonable thing to do would be to not treat
> > > -o /dev/null as a source for -dumpdir and friends.  Alex?  
> > 
> > +1
> > 
> > I think we already have some special-casing for /dev/null somewhere.  
> 
> Grepping finds me the following in system.h which is already checked
> for in gcc.c in a few places indeed.
> 
> /* Provide a default for the HOST_BIT_BUCKET.
>    This suffices for POSIX-like hosts.  */
> 
> #ifndef HOST_BIT_BUCKET
> #define HOST_BIT_BUCKET "/dev/null"
> #endif
> 
> 
> > > You did the last re-org, where'd we put such special casing?  
> > 
> > I think we're missing something like this, to avoid messing with dumpdir
> > with -o /dev/null.  We already use the same function when computing
> > outbase just below this.  
> 
> Ah yeah, not_actual_file_p should do the trick indeed.  Giuliano, can
> you update the patch like below?  I think we should still adjust
> documentation as you did.

But that wouldn't cater for the general problem that the dumpdir is not
writable, no? Why not just simply check access W_OK of the dumpdir?

Otherwise a dumpdir /dev/full or anyother such path will cause the same
thing i guess.

thanks,
> 
> > diff --git a/gcc/gcc.c b/gcc/gcc.c
> > index 506c2acc282d6..a986728fb91d6 100644
> > --- a/gcc/gcc.c
> > +++ b/gcc/gcc.c
> > @@ -5098,7 +5098,8 @@ process_command (unsigned int decoded_options_count,
> >  
> >    bool explicit_dumpdir = dumpdir;
> >  
> > -  if (!save_temps_overrides_dumpdir && explicit_dumpdir)
> > +  if ((!save_temps_overrides_dumpdir && explicit_dumpdir)
> > +      || (output_file != NULL && not_actual_file_p (output_file)))
> >      {
> >        /* Do nothing.  */
> >      }
> >