[Patch, Fortran] PR60286 - fix INQUIRE for write= with stdout/stdin/stderr

[Janus Weil]

Hi,

>> > Build and regtested on x86-64-gnu-linux.
>> > OK for the trunk?
>>
>> the patch looks pretty much trivial, int the sense that you just
>> hard-wire the expected values for the std* units as a special case. I
>> wonder why the 'inquire_read' and 'inquire_write' functions don't
>> actually return the correct values?
>
> One can inquire by FILE= name and by UNIT=; inquire_read() is using
> the file name - either via FILE= directly or for an opened unit
> via u->file; it then calls POSIX's access() function on the file name
> to determine the permissions. Obviously, that fails if no file
> actually exists.
>
> Thus, simply calling the function won't work - and as all three cases
> are slightly different, hardcoding the condition is simplest.
>
>
> However, I now wonder whether one should also take care of other cases,
> where no file name exists - but which could be queried. In that case,
> one could simply use the mode in which the file was opened - which
> one could do in general for files in the UNIT= mode - contrary to
> the FILE= mode. I am in particular thinking of scratch files - they
> are often opened, then deleted and only file descriptor remains.
>
>
> Namely, either unconditionally using for UNIT=:
>
> if ((cf & IOPARM_INQUIRE_HAS_READWRITE) != 0)
>   p = (u->flags.action == ACTION_READWRITE) ? yes : no;
>
> We probably still need some special case for stdin/stdout/stderr.

Do we? If the new version of the patch works correctly, then it seems
that we don't?


> Or adding as additional condition:
>   if (u->flags->status == STATUS_SCRATCH)
>     p = (u->flags.action == ACTION_READWRITE) ? yes : no;
> to also handle SCRATCH correctly.
>
>
> * Advantage of access(): Gives the true file mode by the OS.
> * Advantage of the open mode: Gives the permissions for which the
> unit was opened.

Is there actually a difference?

In any case I think INQUIRE with FILE should use the former, while
INQUIRE with UNIT should use the latter, which is apparently what your
new patch does.


> Also works in corner cases (scratch, stdout, ...).
> Simpler code.
>
> I have no idea what users prefer - but when using the unit directly,
> the OPEN's ACCTION= mode feels a bit more natural than access().
>
> Thoughts?
>
> What about the new version of the patch?

I like the new version much better, because it is more general and
even simpler. To my taste it is ok for trunk ...

Thanks,
Janus