Re: libc 2.3 and RT signals broken

[Daniel Jacobowitz <dan@debian.org>]

On Tue, Oct 29, 2002 at 12:13:53PM +0900, GOTO Masanori wrote:
> At Mon, 28 Oct 2002 21:40:19 -0500,
> Daniel Jacobowitz wrote:
> > 2002-09-18  Ulrich Drepper  <drepper@redhat.com>
> > 
> >         * signal/allocrtsig.c: Move to...
> >         * sysdeps/generic/allocrtsig.c: ...here.  New file.
> > 
> > as far as I can tell.
> > 
> > The problem is something I ran into in GDB today: the location of a
> > source file overrides the normal search path.  If a file in
> > sysdeps/generic/ includes a header using "", the copy in
> > sysdeps/generic/ will win.  So we get sysdeps/generic/testrtsig.h
> > instead of the sysdeps/unix/sysv/linux/testrtsig.h, and
> > kernel_has_rtsig always returns 0.
> > 
> > So SIGRTMIN is -1.  Oops.
> > 
> > Why does allocrtsig.c have to be in sysdeps/generic?  If it does need
> > to, then we will have to duplicate it in sysdeps/unix/sysv/linux/; but
> > since nothing overrides it I don't see why it had to move out of
> > signal/.
> 
> allocrtsig.c is OK.
> 
> This patch fixes the bug. uname(&name) changes 'struct name'. But
> evaluation order is not defined (C99 says about in detail), so on i386
> gcc evaluates '__strverscmp (name.release, "2.1.70") >= 0' in first
> and name.release has no valid value.  Thus this function does not work
> well.
> 
> Please apply this patch.
> 
> Regards,
> -- gotom

Um, gotom, did you actually _try_ it?  This function is not present in
_my_ copy of /usr/lib/libc.a, we get the version in sysdeps/generic/
instead.  Which returns 0.

And C99 says:
       [#1] The following are  the  sequence  points  described  in
       5.1.2.3:
...
         -- The  end  of  the  first  operand  of   the   following
            operators:  logical  AND  &&  (6.5.13);  logical  OR ||
            (6.5.14); conditional ? (6.5.15); comma , (6.5.17).

So your patch is unnecessary.

> 
> 2002-10-29  GOTO Masanori  <gotom@debian.or.jp>
> 
> 	* sysdeps/unix/sysv/linux/testrtsig.h: Fix possibly illegal
> 	evaluation order.
> 
> --- sysdeps/unix/sysv/linux/testrtsig.h 2001-07-06 13:56:13.000000000 +0900
> +++ sysdeps/unix/sysv/linux/testrtsig.h.new     2002-10-29 12:12:20.000000000 +0900
> @@ -30,7 +30,9 @@
>    return 1;
>  #else
>    struct utsname name;
> -
> -  return uname (&name) == 0 && __strverscmp (name.release, "2.1.70") >= 0;
> +  int ret;
> +  
> +  ret = uname (&name);
> +  return ret == 0 && __strverscmp (name.release, "2.1.70") >= 0;
>  #endif
>  }
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer