Re: [PATCH] newlib: libc: Fix bugs in the commit 3d94e07c49b5.

On Fri, 10 Nov 2023 16:17:45 +0100
Corinna Vinschen wrote:
> On Nov 10 20:34, Takashi Yano wrote:
> > The commit 3d94e07c49b5 has a few bugs which cause testsuite failure
> > in libstdc++. This is due to excess orientation check in __srefill_r()
> > and _ungetc_r(). This patch fixes them.
> 
> Oops, _ungetc_r is used from ungetwc as well, that's not good. 
> Sorry that I missed that yesterday!
> 
> > Fixes: 3d94e07c49b5 ("newlib: libc: Fix crash on fprintf to a wide-oriented stream.")
> > Reported-by: Christophe Lyon <[email protected]>
> > Reviewed-by:
> > Signed-off-by: Takashi Yano <[email protected]>
> > ---
> >  newlib/libc/stdio/refill.c | 3 ---
> >  newlib/libc/stdio/ungetc.c | 8 ++------
> >  2 files changed, 2 insertions(+), 9 deletions(-)
> > 
> > diff --git a/newlib/libc/stdio/refill.c b/newlib/libc/stdio/refill.c
> > index c1ef7e120..cd71ed152 100644
> > --- a/newlib/libc/stdio/refill.c
> > +++ b/newlib/libc/stdio/refill.c
> > @@ -43,9 +43,6 @@ __srefill_r (struct _reent * ptr,
> >  
> >    CHECK_INIT (ptr, fp);
> >  
> > -  if (ORIENT (fp, -1) != -1)
> > -    return EOF;
> > -
> >    fp->_r = 0;			/* largely a convenience for callers */
> >  
> >    /* SysV does not make this test; take it out for compatibility */
> > diff --git a/newlib/libc/stdio/ungetc.c b/newlib/libc/stdio/ungetc.c
> > index 79914af08..5053fd6c4 100644
> > --- a/newlib/libc/stdio/ungetc.c
> > +++ b/newlib/libc/stdio/ungetc.c
> > @@ -125,12 +125,6 @@ _ungetc_r (struct _reent *rptr,
> >  
> >    _newlib_flockfile_start (fp);
> >  
> > -  if (ORIENT (fp, -1) != -1)
> > -    {
> > -      _newlib_flockfile_exit (fp);
> > -      return EOF;
> > -    }
> > -
> >    /* After ungetc, we won't be at eof anymore */
> >    fp->_flags &= ~__SEOF;
> >  
> > @@ -213,6 +207,8 @@ int
> >  ungetc (int c,
> >         register FILE *fp)
> >  {
> > +  if (ORIENT (fp, -1) != -1)
> > +    return EOF;
> >    return _ungetc_r (_REENT, c, fp);
> >  }
> >  #endif /* !_REENT_ONLY */
> > -- 
> > 2.39.0
> 
> Didn't you forget ungetwc?

Indeed. Thanks! I'll submit v2 patch.

> But then again, I checked GLibC, and there's something weird:
> ungetc does not at all set or test the orientation.
> ungetwc sets the orientation to 1, but doesn't check it.
> Puzzeling.  I wonder about the reasoning behind this.

Hmm, I'll also check that behaviour.

-- 
Takashi Yano <[email protected]>