Re: [PATCH v6 01/20] lib/vsprintf: Print time and date in human readable format via %pt

[Andy Shevchenko]

On Tue, Dec 04, 2018 at 11:23:11PM +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][r] specifier.
> 

Petr, is it now looks good to you? Can you give a tag?

Alexandre, it looks like Petr's Ack is missed and we would be fine to
eventually proceed with it if you have no more comments. What do you think?

> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@xxxxxxxxxxx>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Cc: Guan Xuetao <gxt@xxxxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Jonathan Hunter <jonathanh@xxxxxxxxxx>
> Cc: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
> Cc: Petr Mladek <pmladek@xxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
>  Documentation/core-api/printk-formats.rst |  18 ++++
>  lib/test_printf.c                         |  61 ++++++++++++-
>  lib/vsprintf.c                            | 100 ++++++++++++++++++++++
>  3 files changed, 176 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
> index ff48b55040ef..a7fae4538946 100644
> --- a/Documentation/core-api/printk-formats.rst
> +++ b/Documentation/core-api/printk-formats.rst
> @@ -412,6 +412,24 @@ Examples::
>  
>  Passed by reference.
>  
> +Time and date (struct rtc_time)
> +-------------------------------
> +
> +::
> +
> +	%ptR		YYYY-mm-ddTHH:MM:SS
> +	%ptRd		YYYY-mm-dd
> +	%ptRt		HH:MM:SS
> +	%ptR[dt][r]
> +
> +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.
> +
> +Passed by reference.
> +
>  struct clk
>  ----------
>  
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 53527ea822b5..659b6cc0d483 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -9,6 +9,7 @@
>  #include <linux/module.h>
>  #include <linux/printk.h>
>  #include <linux/random.h>
> +#include <linux/rtc.h>
>  #include <linux/slab.h>
>  #include <linux/string.h>
>  
> @@ -249,12 +250,11 @@ plain_format(void)
>  #endif	/* BITS_PER_LONG == 64 */
>  
>  static int __init
> -plain_hash(void)
> +plain_hash_to_buffer(const void *p, char *buf, size_t len)
>  {
> -	char buf[PLAIN_BUF_SIZE];
>  	int nchars;
>  
> -	nchars = snprintf(buf, PLAIN_BUF_SIZE, "%p", PTR);
> +	nchars = snprintf(buf, len, "%p", p);
>  
>  	if (nchars != PTR_WIDTH)
>  		return -1;
> @@ -265,6 +265,20 @@ plain_hash(void)
>  		return 0;
>  	}
>  
> +	return 0;
> +}
> +
> +
> +static int __init
> +plain_hash(void)
> +{
> +	char buf[PLAIN_BUF_SIZE];
> +	int ret;
> +
> +	ret = plain_hash_to_buffer(PTR, buf, PLAIN_BUF_SIZE);
> +	if (ret)
> +		return ret;
> +
>  	if (strncmp(buf, PTR_STR, PTR_WIDTH) == 0)
>  		return -1;
>  
> @@ -294,6 +308,23 @@ plain(void)
>  	}
>  }
>  
> +static void __init
> +test_hashed(const char *fmt, const void *p)
> +{
> +	char buf[PLAIN_BUF_SIZE];
> +	int ret;
> +
> +	/*
> +	 * No need to increase failed test counter since this is assumed
> +	 * to be called after plain().
> +	 */
> +	ret = plain_hash_to_buffer(p, buf, PLAIN_BUF_SIZE);
> +	if (ret)
> +		return;
> +
> +	test(buf, fmt, p);
> +}
> +
>  static void __init
>  symbol_ptr(void)
>  {
> @@ -418,6 +449,29 @@ struct_va_format(void)
>  {
>  }
>  
> +static void __init
> +struct_rtc_time(void)
> +{
> +	/* 1543210543 */
> +	const struct rtc_time tm = {
> +		.tm_sec = 43,
> +		.tm_min = 35,
> +		.tm_hour = 5,
> +		.tm_mday = 26,
> +		.tm_mon = 10,
> +		.tm_year = 118,
> +	};
> +
> +	test_hashed("%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);
> +}
> +
>  static void __init
>  struct_clk(void)
>  {
> @@ -529,6 +583,7 @@ 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..3add92329bae 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 +1564,87 @@ 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 r)
> +{
> +	int year = tm->tm_year + (r ? 0 : 1900);
> +	int mon = tm->tm_mon + (r ? 0 : 1);
> +
> +	buf = number(buf, end, year, default_dec04_spec);
> +	if (buf < end)
> +		*buf = '-';
> +	buf++;
> +
> +	buf = number(buf, end, mon, default_dec02_spec);
> +	if (buf < end)
> +		*buf = '-';
> +	buf++;
> +
> +	return number(buf, end, tm->tm_mday, default_dec02_spec);
> +}
> +
> +static noinline_for_stack
> +char *time_str(char *buf, char *end, const struct rtc_time *tm, bool r)
> +{
> +	buf = number(buf, end, tm->tm_hour, default_dec02_spec);
> +	if (buf < end)
> +		*buf = ':';
> +	buf++;
> +
> +	buf = number(buf, end, tm->tm_min, default_dec02_spec);
> +	if (buf < end)
> +		*buf = ':';
> +	buf++;
> +
> +	return number(buf, end, tm->tm_sec, default_dec02_spec);
> +}
> +
> +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 raw = false;
> +	int count = 2;
> +
> +	switch (fmt[count]) {
> +	case 'd':
> +		have_t = false;
> +		count++;
> +		break;
> +	case 't':
> +		have_d = false;
> +		count++;
> +		break;
> +	}
> +
> +	raw = fmt[count] == 'r';
> +
> +	if (have_d)
> +		buf = date_str(buf, end, tm, raw);
> +	if (have_d && have_t) {
> +		/* Respect ISO 8601 */
> +		if (buf < end)
> +			*buf = 'T';
> +		buf++;
> +	}
> +	if (have_t)
> +		buf = time_str(buf, end, tm, raw);
> +
> +	return buf;
> +}
> +
> +static noinline_for_stack
> +char *time_and_date(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 +1924,8 @@ 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][r]' 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 +2050,8 @@ 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 time_and_date(buf, end, ptr, spec, fmt);
>  	case 'C':
>  		return clock(buf, end, ptr, spec, fmt);
>  	case 'D':
> -- 
> 2.19.2
> 

-- 
With Best Regards,
Andy Shevchenko