Re: [PATCH v2 1/4] lib/vsprintf: Print time64_t in human readable format

[Alexandre Belloni <alexandre.belloni@bootlin.com>]

On 01/10/2019 16:47:14+0300, Andy Shevchenko wrote:
> There are users which print time and date represented by content of
> time64_t type in human readable format.
> 
> Instead of open coding that each time introduce %ptT[dt][r] specifier.
> 
> Few test cases for %ptT specifier has been added as well.
> 
> Cc: Hans Verkuil <hverkuil@xs4all.nl>
> Cc: Mathias Nyman <mathias.nyman@intel.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Cc: Jonathan Hunter <jonathanh@nvidia.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
>  Documentation/core-api/printk-formats.rst | 22 ++++++++--------
>  lib/test_printf.c                         | 13 +++++++---
>  lib/vsprintf.c                            | 31 +++++++++++++++++++++--
>  3 files changed, 51 insertions(+), 15 deletions(-)
> 
> diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> index ecbebf4ca8e7..83f452e45f3f 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -428,21 +428,23 @@ Examples::
>  
>  Passed by reference.
>  
> -Time and date (struct rtc_time)
> --------------------------------
> +Time and date
> +-------------
>  
>  ::
>  
> -	%ptR		YYYY-mm-ddTHH:MM:SS
> -	%ptRd		YYYY-mm-dd
> -	%ptRt		HH:MM:SS
> -	%ptR[dt][r]
> +	%pt[RT]			YYYY-mm-ddTHH:MM:SS
> +	%pt[RT]d		YYYY-mm-dd
> +	%pt[RT]t		HH:MM:SS
> +	%pt[RT][dt][r]
>  
> -For printing date and time as represented by struct rtc_time structure in
> -human readable format.
> +For printing date and time as represented by
> +	R  struct rtc_time structure
> +	T  time64_t type
> +in human readable format.
>  
> -By default year will be incremented by 1900 and month by 1. Use %ptRr (raw)
> -to suppress this behaviour.
> +By default year will be incremented by 1900 and month by 1.
> +Use %pt[RT]r (raw) to suppress this behaviour.
>  
>  Passed by reference.
>  
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 5d94cbff2120..16fb668685dd 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -476,7 +476,7 @@ struct_va_format(void)
>  }
>  
>  static void __init
> -struct_rtc_time(void)
> +time_and_date(void)
>  {
>  	/* 1543210543 */
>  	const struct rtc_time tm = {
> @@ -487,14 +487,21 @@ struct_rtc_time(void)
>  		.tm_mon = 10,
>  		.tm_year = 118,
>  	};
> +	/* 2019-01-04T15:32:23 */
> +	time64_t t = 1546615943;
>  
> -	test("(%ptR?)", "%pt", &tm);
> +	test("(%pt?)", "%pt", &tm);
>  	test("2018-11-26T05:35:43", "%ptR", &tm);
>  	test("0118-10-26T05:35:43", "%ptRr", &tm);
>  	test("05:35:43|2018-11-26", "%ptRt|%ptRd", &tm, &tm);
>  	test("05:35:43|0118-10-26", "%ptRtr|%ptRdr", &tm, &tm);
>  	test("05:35:43|2018-11-26", "%ptRttr|%ptRdtr", &tm, &tm);
>  	test("05:35:43 tr|2018-11-26 tr", "%ptRt tr|%ptRd tr", &tm, &tm);
> +
> +	test("2019-01-04T15:32:23", "%ptT", &t);
> +	test("0119-00-04T15:32:23", "%ptTr", &t);
> +	test("15:32:23|2019-01-04", "%ptTt|%ptTd", &t, &t);
> +	test("15:32:23|0119-00-04", "%ptTtr|%ptTdr", &t, &t);
>  }
>  
>  static void __init
> @@ -610,7 +617,7 @@ test_pointer(void)
>  	uuid();
>  	dentry();
>  	struct_va_format();
> -	struct_rtc_time();
> +	time_and_date();
>  	struct_clk();
>  	bitmap();
>  	netdev_features();
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index e78017a3e1bd..e4bc380deb62 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -33,6 +33,7 @@
>  #include <linux/dcache.h>
>  #include <linux/cred.h>
>  #include <linux/rtc.h>
> +#include <linux/time.h>
>  #include <linux/uuid.h>
>  #include <linux/of.h>
>  #include <net/addrconf.h>
> @@ -1780,6 +1781,29 @@ char *rtc_str(char *buf, char *end, const struct rtc_time *tm,
>  	return buf;
>  }
>  
> +static noinline_for_stack
> +char *time64_str(char *buf, char *end, const time64_t time,
> +		 struct printf_spec spec, const char *fmt)
> +{
> +	struct rtc_time rtc_time;
> +	struct tm tm;
> +
> +	time64_to_tm(time, 0, &tm);
> +
> +	rtc_time.tm_sec = tm.tm_sec;
> +	rtc_time.tm_min = tm.tm_min;
> +	rtc_time.tm_hour = tm.tm_hour;
> +	rtc_time.tm_mday = tm.tm_mday;
> +	rtc_time.tm_mon = tm.tm_mon;
> +	rtc_time.tm_year = tm.tm_year;
> +	rtc_time.tm_wday = tm.tm_wday;
> +	rtc_time.tm_yday = tm.tm_yday;
> +
> +	rtc_time.tm_isdst = 0;
> +
> +	return rtc_str(buf, end, &rtc_time, spec, fmt);
> +}
> +
>  static noinline_for_stack
>  char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
>  		    const char *fmt)
> @@ -1787,8 +1811,10 @@ char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
>  	switch (fmt[1]) {
>  	case 'R':
>  		return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt);
> +	case 'T':
> +		return time64_str(buf, end, *(const time64_t *)ptr, spec, fmt);
>  	default:
> -		return error_string(buf, end, "(%ptR?)", spec);
> +		return error_string(buf, end, "(%pt?)", spec);
>  	}
>  }
>  
> @@ -2088,8 +2114,9 @@ static char *kobject_string(char *buf, char *end, void *ptr,
>   * - '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][r]' For time and date as represented:
> + * - 't[RT][dt][r]' For time and date as represented by:
>   *      R    struct rtc_time
> + *      T    time64_t
>   * - '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
> -- 
> 2.23.0
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com