Re: Dillo and Irix

On Thu, Sep 18, 2014 at 12:44:33PM -0300, Jorge Arellano Cid wrote:
> On Tue, Sep 16, 2014 at 06:29:27AM +0000, eocene wrote:
> > 
> > In the typical vsnprintf() (i.e., following the c99 standard), if you
> > have space for 10 bytes and you want to write 20 bytes (including '\0'),
> > you return 19, whereas irix returns 9.
> > 
> > Some options:
> > 
> > 1. It's possible to make irix and the standard run with a change like
> > 
> > diff -r 5f63e28334b2 dlib/dlib.c
> > --- a/dlib/dlib.c       Tue Sep 16 00:21:49 2014 +0000
> > +++ b/dlib/dlib.c       Tue Sep 16 04:59:20 2014 +0000
> > @@ -406,11 +406,11 @@
> >           va_copy(argp2, argp);
> >           n = vsnprintf(ds->str + ds->len, ds->sz - ds->len, format, argp2);
> >           va_end(argp2);
> > -         if (n > -1 && n < ds->sz - ds->len) {
> > +         if (n > -1 && n+1 < ds->sz - ds->len) {
> >              ds->len += n;      /* Success! */
> >              break;
> >           } else if (n > -1) {  /* glibc >= 2.1 */
> > -            n_sz = ds->len + n + 1;
> > +            n_sz = ds->len + n + 2;
> >           } else {              /* old glibc */
> >              n_sz = ds->sz * 2;
> >           }
> > 
> > ...although it would need tweaking to waste less running time.
> > 
> > But of course even if dillo is partly about retrocomputing, it'll be
> > 99% linux+bsd retrocomputing and 1% other-stuff retrocomputing, so...
> > 
> > 2. Throw an ifdef at it. Dillo has never had many ifdefs, and I'd thought
> > they were discouraged, but maybe the changes needed for all of that stuff
> > at the bottom of Compatibility.html like
> > 
> > SGI O2 running IRIX
> > Tru64 (OSF1) 4.0 on Alpha 
> > QNX RTP 6.1/x86 (with occasional memory faults out of GTK+) 
> > AIX 4.3 (with some tweaks) 
> > Atari-based 68k-systems running MiNT 
> > Microsoft Windows using Cygwin 
> > RISC OS
> > 
> > ...just didn't make it back into mainline dillo1?
> > 
> > 3. We could always borrow fltk's vsnprintf(), which is about 250 lines.
> > 
> > 
> > I lean toward giving it an ifdef.
> 
> 
>   Me too, it clearly is an IRIX issue and the #ifdef would make it
> cristal clear (compared to a soln. using fltk's vsnprintf() for
> instance).
> 
>   +1

  A bit more elaboration:

  I'd add an my_vsnprintf() in dlibc and make dStr_vsprintfa() use it,
and make it like:

my_vsnprintf()
{
#if IRIX
  /* compute required length by using IRIX's rules */
#else
  /* use vsnprintf(), no problem */
#fi
}

  To avoid autoconf, the IRIX test can be placed in the same
function with a static int:

static int IRIX = -1;
if (IRIX == -1) {
  /* very simple snprintf() test here */
  IRIX = test ? 1 : 0;
}


-- 
  Cheers
  Jorge.-