Re: [PATCH v3 01/20] lib/vsprintf: Print time and date in human readable format via %pt

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Nov 20, 2018 at 11:27:57PM +0100, Alexandre Belloni wrote:
> Hello,
> 
> (Please update my email address).

I will follow all recommendations.
New version coming soon...

Thanks for review!

> 
> On 13/11/2018 19:17:10+0200, Andy Shevchenko wrote:
> > There are users which print time and date represented by content of
> > struct rtc_time in human readable format.
> > 
> > Instead of open coding that each time introduce %ptR[dt][rv] specifier.
> > 
> > Note, users have to select PRINTK_PEXT_TIMEDATE option in a Kconfig.
> > 
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> > Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> > Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > Cc: Jason Wessel <jason.wessel@windriver.com>
> > Cc: Jonathan Corbet <corbet@lwn.net>
> > Cc: Jonathan Hunter <jonathanh@nvidia.com>
> > Cc: Krzysztof Kozlowski <krzk@kernel.org>
> > Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> > Cc: Thierry Reding <thierry.reding@gmail.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > ---
> >  Documentation/core-api/printk-formats.rst |  20 ++++
> >  lib/test_printf.c                         |   6 +
> >  lib/vsprintf.c                            | 140 ++++++++++++++++++++++
> >  3 files changed, 166 insertions(+)
> > 
> > diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> > index ff48b55040ef..8342a65eab0b 100644
> > --- a/Documentation/core-api/printk-formats.rst
> > +++ b/Documentation/core-api/printk-formats.rst
> > @@ -412,6 +412,26 @@ Examples::
> >  
> >  Passed by reference.
> >  
> > +Time and date (struct rtc_time)
> > +-------------------------------
> > +
> > +::
> > +
> > +	%ptR		YYYY-mm-dd HH:MM:SS
> > +	%ptRd		YYYY-mm-dd
> > +	%ptRt		HH:MM:SS
> > +	%ptR[dt][rv]
> > +
> > +For printing date and time as represented by struct rtc_time structure in
> > +human readable format.
> > +
> > +By default year will be incremented by 1900 and month by 1. Use %ptRr (raw)
> > +to suppress this behaviour. On the other hand when %ptRv is applied
> > +validation mechanism will be in use, i.e. numbers out of range will be
> > +replaced by ** or ****.
> > +
> > +Passed by reference.
> > +
> >  struct clk
> >  ----------
> >  
> > diff --git a/lib/test_printf.c b/lib/test_printf.c
> > index 53527ea822b5..97b7d14961d6 100644
> > --- a/lib/test_printf.c
> > +++ b/lib/test_printf.c
> > @@ -418,6 +418,11 @@ struct_va_format(void)
> >  {
> >  }
> >  
> > +static void __init
> > +struct_rtc_time(void)
> > +{
> > +}
> > +
> >  static void __init
> >  struct_clk(void)
> >  {
> > @@ -529,6 +534,7 @@ test_pointer(void)
> >  	uuid();
> >  	dentry();
> >  	struct_va_format();
> > +	struct_rtc_time();
> >  	struct_clk();
> >  	bitmap();
> >  	netdev_features();
> > diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> > index 37a54a6dd594..8455cbda8d6c 100644
> > --- a/lib/vsprintf.c
> > +++ b/lib/vsprintf.c
> > @@ -30,6 +30,7 @@
> >  #include <linux/ioport.h>
> >  #include <linux/dcache.h>
> >  #include <linux/cred.h>
> > +#include <linux/rtc.h>
> >  #include <linux/uuid.h>
> >  #include <linux/of.h>
> >  #include <net/addrconf.h>
> > @@ -822,6 +823,20 @@ static const struct printf_spec default_dec_spec = {
> >  	.precision = -1,
> >  };
> >  
> > +static const struct printf_spec default_dec02_spec = {
> > +	.base = 10,
> > +	.field_width = 2,
> > +	.precision = -1,
> > +	.flags = ZEROPAD,
> > +};
> > +
> > +static const struct printf_spec default_dec04_spec = {
> > +	.base = 10,
> > +	.field_width = 4,
> > +	.precision = -1,
> > +	.flags = ZEROPAD,
> > +};
> > +
> >  static noinline_for_stack
> >  char *resource_string(char *buf, char *end, struct resource *res,
> >  		      struct printf_spec spec, const char *fmt)
> > @@ -1549,6 +1564,127 @@ char *address_val(char *buf, char *end, const void *addr, const char *fmt)
> >  	return special_hex_number(buf, end, num, size);
> >  }
> >  
> > +static noinline_for_stack
> > +char *date_str(char *buf, char *end, const struct rtc_time *tm, bool v, bool r)
> > +{
> > +	int year = tm->tm_year + (r ? 0 : 1900);
> > +	int mon = tm->tm_mon + (r ? 0 : 1);
> > +
> > +	if (unlikely(v && (unsigned int)tm->tm_year > 200))
> > +		buf = string(buf, end, "****", default_str_spec);
> 
> I think you should drop the validation option. This is only used in a
> deprecated ABI and is mostly wrong as many RTCs will still be valid
> after 2100.
> 
> > +	else
> > +		buf = number(buf, end, year, default_dec04_spec);
> > +
> > +	if (buf < end)
> > +		*buf = '-';
> > +	buf++;
> > +
> > +	if (unlikely(v && (unsigned int)tm->tm_mon > 11))
> > +		buf = string(buf, end, "**", default_str_spec);
> > +	else
> > +		buf = number(buf, end, mon, default_dec02_spec);
> > +
> > +	if (buf < end)
> > +		*buf = '-';
> > +	buf++;
> > +
> > +	if (unlikely(v && (unsigned int)tm->tm_mday > 31))
> > +		buf = string(buf, end, "**", default_str_spec);
> 
> Same here, this doesn't protect February, April, June, September and
> November. There is one RTC that think that 31st of November is valid.
> 
> > +	else
> > +		buf = number(buf, end, tm->tm_mday, default_dec02_spec);
> > +
> > +	return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *time_str(char *buf, char *end, const struct rtc_time *tm, bool v, bool r)
> > +{
> > +	if (unlikely(v && (unsigned int)tm->tm_hour > 24))
> > +		buf = string(buf, end, "**", default_str_spec);
> > +	else
> > +		buf = number(buf, end, tm->tm_hour, default_dec02_spec);
> > +
> > +	if (buf < end)
> > +		*buf = ':';
> > +	buf++;
> > +
> > +	if (unlikely(v && (unsigned int)tm->tm_min > 59))
> > +		buf = string(buf, end, "**", default_str_spec);
> > +	else
> > +		buf = number(buf, end, tm->tm_min, default_dec02_spec);
> > +
> > +	if (buf < end)
> > +		*buf = ':';
> > +	buf++;
> > +
> > +	if (unlikely(v && (unsigned int)tm->tm_sec > 59))
> > +		buf = string(buf, end, "**", default_str_spec);
> 
> Some RTCs will consider 60 valid. So, really, instead of fixing all of
> those, I'd just get rid of the validation option.
> 
> > +	else
> > +		buf = number(buf, end, tm->tm_sec, default_dec02_spec);
> > +
> > +	return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *rtc_str(char *buf, char *end, const struct rtc_time *tm, const char *fmt)
> > +{
> > +	bool have_t = true, have_d = true;
> > +	bool validate = false;
> > +	bool raw = false;
> > +	int count = 2;
> > +	bool found;
> > +
> > +	switch (fmt[count]) {
> > +	case 'd':
> > +		have_t = false;
> > +		count++;
> > +		break;
> > +	case 't':
> > +		have_d = false;
> > +		count++;
> > +		break;
> > +	}
> > +
> > +	found = true;
> > +	do {
> > +		switch (fmt[count++]) {
> > +		case 'r':
> > +			raw = true;
> > +			break;
> > +		case 'v':
> > +			validate = true;
> > +			break;
> > +		default:
> > +			found = false;
> > +			break;
> > +		}
> > +	} while (found);
> > +
> > +	if (have_d)
> > +		buf = date_str(buf, end, tm, validate, raw);
> > +	if (have_d && have_t) {
> > +		if (buf < end)
> > +			*buf = ' ';
> 
> I'd go for ISO 8601 and use a 'T' here.
> 
> > +		buf++;
> > +	}
> > +	if (have_t)
> > +		buf = time_str(buf, end, tm, validate, raw);
> > +
> > +	return buf;
> > +}
> > +
> > +static noinline_for_stack
> > +char *timeanddate(char *buf, char *end, void *ptr, struct printf_spec spec,
> > +		  const char *fmt)
> > +{
> > +	switch (fmt[1]) {
> > +	case 'R':
> > +		return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt);
> > +	default:
> > +		return ptr_to_id(buf, end, ptr, spec);
> > +	}
> > +}
> > +
> >  static noinline_for_stack
> >  char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
> >  	    const char *fmt)
> > @@ -1828,6 +1964,8 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
> >   * - 'd[234]' For a dentry name (optionally 2-4 last components)
> >   * - 'D[234]' Same as 'd' but for a struct file
> >   * - 'g' For block_device name (gendisk + partition number)
> > + * - 't[R][dt][rv]' For time and date as represented:
> > + *      R    struct rtc_time
> >   * - 'C' For a clock, it prints the name (Common Clock Framework) or address
> >   *       (legacy clock framework) of the clock
> >   * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
> > @@ -1952,6 +2090,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
> >  		return address_val(buf, end, ptr, fmt);
> >  	case 'd':
> >  		return dentry_name(buf, end, ptr, spec, fmt);
> > +	case 't':
> > +		return timeanddate(buf, end, ptr, spec, fmt);
> >  	case 'C':
> >  		return clock(buf, end, ptr, spec, fmt);
> >  	case 'D':
> > -- 
> > 2.19.1
> > 
> 
> -- 
> Alexandre Belloni, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

-- 
With Best Regards,
Andy Shevchenko