On Tue, May 11, 2021 at 04:14:56PM +0200, Petr Mladek wrote:
> On Mon 2021-05-10 18:04:10, Andy Shevchenko wrote:
> > ISO 8601 defines 'T' as a separator between date and time. Though,
> > some ABIs use time and date with ' ' separator instead.
> >
> > Add a flavour to the %pt specifier to override default separator.
...
> > %pt[RT] YYYY-mm-ddTHH:MM:SS
> > + %pt[RT]s YYYY-mm-dd HH:MM:SS
> > %pt[RT]d YYYY-mm-dd
> > %pt[RT]t HH:MM:SS
> > - %pt[RT][dt][r]
> > + %pt[RT][dt][rs]
>
> Sigh, we do not have clear rules what [xy] means. It might be:
>
> + always use one of them
> + optionally use one of them
> + always use any of them
> + optionally use any of them
>
> %pt[RT][dt][rs] is a great mix:
>
> + R or T is required, the rest is optional
> + 'd' or 't' can be used but both together are not supported
> + any variant of 'r' and 's' is supported including various ordering
>
> Honestly, I do not know about any magic solution that might make it
> easier to understand these monster modifiers.
>
> Well, what about using the following at least in this case:
>
> %pt[RT][dt][r][s]
>
> It might help to understand that both 'r' and 's' can be used at the
> same time.
This is the case, yes, thanks for catching it.
> An attempt to distinguishing all the possibilities might be:
>
> %pt{RT}[{dt}][r][s]
>
> where [] means that it is optional and {} means one of them must be
> chosen. But I am not sure if it really makes the life easier. Anyway,
> this would be for another patch that updates the entire printk-formats.rst.
No, this is not the case, the d and t can go in any combinations: none, d, t,
dt, or td.
>
> > For printing date and time as represented by::
> >
> > @@ -528,6 +529,9 @@ in human readable format.
> > By default year will be incremented by 1900 and month by 1.
> > Use %pt[RT]r (raw) to suppress this behaviour.
> >
> > +The %pt[RT]s (space) will override ISO 8601 by using ' ' instead of 'T'
> > +between date and time. It won't have any effect when date or time is omitted.
...
> > + do {
> > + switch (fmt[count++]) {
> > + case 'r':
> > + raw = true;
> > + break;
> > + case 's':
> > + space = true;
> > + break;
> > + default:
> > + found = false;
> > + break;
> > + }
> > + } while (found);
> >
> > if (have_d)
> > buf = date_str(buf, end, tm, raw);
> > if (have_d && have_t) {
> > /* Respect ISO 8601 */
>
> The comment is slightly misleding now. What about something like?
>
> /* 'T' by ISO 8601. */
>
> Or maybe call the variable: iso_8601, remove the comment, and
> invert the logic:
Okay, I will think how to improve, thanks!
> bool iso_8601 = true;
>
> case 's':
> iso_8601 = false;
> break;
>
> *buf = iso_8601 ? 'T' : ' ';
>
> > if (buf < end)
> > - *buf = 'T';
> > + *buf = space ? ' ' : 'T';
> > buf++;
> > }
--
With Best Regards,
Andy Shevchenko
