RE: Bug in _VFPRINTF_R

["Matt Gessner" <mgessner at Avidyne dot com>]

First, apologies because the first email I posted in response was sent before I finished editing it.

> 
> I'm sorry Eric, but I gave you a specific example :
>     printf("%.*s\n",len,(char *)NULL) /* len = 0 */
> 
> and not printf("%s", (char *)NULL)
> 

Actually, you did NOT use that as your example.

You posted:

*******************************************************************
Hi,

In newlib printf, snprintf (perhaps others string functions) use 
_VFPRINTF_R.
So if you call :   
    printf("%.*s\n",len,(char *)NULL)   
    snprintf(ptr, 40, "%.*s", len, (char *)NULL)
You obtain :
    (null)
    ptr = "(null)"

*******************************************************************

Never did you mention anywhere that len == 0.

That drastically changes the meaning of the code you originally posted, and while I don't have the code in front of me, the len == 0 case is not going to be processed in the precise section where you originally posted your change.

FWIW, I think your suggested behaviour makes sense, for snprintf, but not for printf.

> In my example, I think the result should be empty an not (null)
> 
> Samuel
> 
> Eric Blake a écrit :
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > According to Samuel Vinson on 9/15/2007 1:35 AM:
> >
> >> I never see that with different libc implementation, I used
> >> (linux/gcc/libc/glibc, windows/msvcrt, solaris/libc...)
> >>
> >
> > It may not match msvcrt or solaris libc, but it does match glibc - I'm
> not
> > sure how you tested it.
> >
> >
> >> Perhaps POSIX and C99 allow your choice, but this is not portable in
> >> different platforms.
> >>
> >
> > This is not portable, period.  Calling printf("%s", (char*)NULL) invokes
> > undefined behavior, and is a bug in your program, not in newlib.
> >
> > - --
> > Don't work too hard, make some time for fun as well!
> >
> > Eric Blake             ebb9@byu.net
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> >