Re: another stdio patch for UnixWare

[Tim Rice]

Hi Bruno,

On Sun, 11 Oct 2020, Bruno Haible wrote:

> Tim Rice wrote:
> > ./gnulib-tool --create-testdir --dir=/var/tmp --with-tests \
> >     --single-configure --avoid=havelib-tests fseterr freadable fwritable \
> >     fbufmode freading fwriting freadptr freadseek freadahead fpurge fseeko
> >     ftello fpending fflush 
> 
> Yes, this is the way to test these modules.
> 
> > and the attached patch, I am down to 2 failures in the stdio tests.
> 
> Hmm, there are three things I find suspicious:
> 
> 1) __freadable is defined in a way that is inconsistent with Gnulib:
>    #define __freadable(p) (__freading(p) && __fpending(p))
>    [in Gnulib, a stream that is not reading nor writing is considered
>    to be readable]
>    but you don't ensure that freadable doesn't get defined other than
>    __freadable.
> 
> 2) Likewise for __fwritable, which is defined in a way inconsistent with 
> Gnulib:
>    #define __fwritable(p) (__fwriting(p) && __fpending(p) < __fbufsiz(p))

Indeed. And after the post with the defines I found tests for
for __freadable and __fwritable were failing.
It looks like we just need to check for _IOREAD, _IORW, _IOWRT flags.
Sorry I didn't update the post with the defines. This is what I'm working
with now which does pass __freadable and __fwritable tests.

#define __freadable(p) ((void)sizeof(__filbuf(p)), ((FILE *)(p))->__flag & 
(_IOREAD | _IORW))
#define __fwritable(p) ((void)sizeof(__filbuf(p)), ((FILE *)(p))->__flag & 
(_IOWRT | _IORW))

> 3) In freadahead.c you add:
>    return __fpending(fp_);
>    But __fpending looks at the pending output, whereas freadahead shall look
>    at the available input. Should be different things, no?

I had that change for so long I had to research why it was done that way.
Looking back at a 2009 an e-mail from one of the SCO engineers, I see
"... using the __fpending(), which in our libc.so.1 will work for
both input or output files."

> 
> Bruno
> 

-- 
Tim Rice                                Multitalents
tim@multitalents.net