From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v1 1/4] lib/vsprintf: Allow to override date and time separator Date: Tue, 11 May 2021 17:56:56 +0300 Message-ID: References: <20210510150413.59356-1-andriy.shevchenko@linux.intel.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Petr Mladek Cc: JC Kuo , Joe Perches , Sumit Garg , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kgdb-bugreport-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Steven Rostedt , Sergey Senozhatsky , Rasmus Villemoes , Jonathan Corbet , Mathias Nyman , Greg Kroah-Hartman , Thierry Reding , Jonathan Hunter , Ryusuke Konishi , Jason Wessel , Daniel Thompson , Douglas Anderson 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