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nuttx/libs/libc/time/lib_strftime.c
guoshichao 714926e6ea libs/libc/strftime: add modifier character support to strftime 
1. make the ltp/open_posix_testsuite/strftime 2-1.c case
2. the modification are referred to https://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html

Signed-off-by: guoshichao <guoshichao@xiaomi.com>
2023-07-24 10:34:23 -07:00

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/****************************************************************************
* libs/libc/time/lib_strftime.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <stdio.h>
#include <debug.h>
#include <nuttx/clock.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Public Constant Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
static const char * const g_abbrev_wdayname[7] =
{
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
static const char * const g_wdayname[7] =
{
"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
"Saturday"
};
static const char * const g_abbrev_monthname[12] =
{
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
static const char * const g_monthname[12] =
{
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: is_leap
*
* Description:
* determine if the given year is a leap year or not
*
* Input Parameters:
* year - a year value
*
* Returnd value:
* true if current is leap year, false is not a leap year
*/
static bool is_leap(int year)
{
return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}
/****************************************************************************
* Name: get_week_num
*
* Description:
* get the week number in a year based on iso8601 standard
*
* Input Parameters:
* time - the specified time
*
* Returnd value:
* the week numer in a year
*/
static int get_week_num(FAR const struct tm *time)
{
/* calculate the total week number in a year */
int week = (time->tm_yday + DAYSPERWEEK -
(time->tm_wday + 6) % DAYSPERWEEK) / DAYSPERWEEK;
/* if xxxx-1-1 is just passed 1-3 days after Monday
* then the previous week will calculated into this year
*/
if ((time->tm_wday + 371 - time->tm_yday - 2) % DAYSPERWEEK <= 2)
{
week++;
}
if (week == 0)
{
week = 52;
/* if xxxx-12-31 is Thursday or Friday, and the previous year is
* leap year, then the previous year has 53 weeks
*/
int dec31 = (time->tm_wday + DAYSPERWEEK - time->tm_yday - 1)
% DAYSPERWEEK;
if (dec31 == TM_THURSDAY ||
(dec31 == TM_FRIDAY && is_leap(time->tm_year % 400 - 1)))
{
week++;
}
}
else if (week == 53)
{
/* If xxxx-1.1 is not a Thursday, and not a Wednesday of a leap year,
* then this year has only 52 weeks
*/
int jan1 = (time->tm_wday + 371 - time->tm_yday) % DAYSPERWEEK;
if (jan1 != TM_THURSDAY &&
(jan1 != TM_WEDNESDAY || !is_leap(time->tm_year)))
{
week = 1;
}
}
return week;
}
/****************************************************************************
* Name: get_week_year
*
* Description:
* get the week year based on iso8601 standard
*
* Input Parameters:
* time - the specified time
*
* Returnd value:
* the year that calculated based on week number
*/
static int get_week_year(FAR const struct tm *time)
{
int week_num = get_week_num(time);
int week_year = time->tm_year + TM_YEAR_BASE;
if (time->tm_yday < 3 && week_num != 1)
{
week_year--;
}
else if (time->tm_yday > 360 && week_num == 1)
{
week_year++;
}
return week_year;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: strftime
*
* Description:
* The strftime() function formats the broken-down time tm according to
* the format specification format and places the result in the character
* array s of size max.
*
* Ordinary characters placed in the format string are copied to s without
* conversion. Conversion specifications are introduced by a '%' charac-
* ter, and terminated by a conversion specifier character, and are
* replaced in s as follows:
*
* %a The abbreviated weekday name according to the current locale.
* %A The full weekday name according to the current locale.
* %b The abbreviated month name according to the current locale.
* %B The full month name according to the current locale.
* %C The century number (year/100) as a 2-digit integer. (SU)
* %d The day of the month as a decimal number (range 01 to 31).
* %e Like %d, the day of the month as a decimal number, but a leading
* zero is replaced by a space.
* %F The full date format but with no time fields
* %g The last 2 digits of the week-based year as a decimal number
* [00,99]
* %G The full version of %g, display the full year value
* %h Equivalent to %b. (SU)
* %H The hour as a decimal number using a 24-hour clock
* (range 00 to 23).
* %I The hour as a decimal number using a 12-hour clock
* (range 01 to 12).
* %j The day of the year as a decimal number (range 001 to 366).
* %k The hour (24-hour clock) as a decimal number (range 0 to 23);
* single digits are preceded by a blank. (See also %H.) (TZ)
* %l The hour (12-hour clock) as a decimal number (range 1 to 12);
* single digits are preceded by a blank. (See also %I.) (TZ)
* %m The month as a decimal number (range 01 to 12).
* %M The minute as a decimal number (range 00 to 59).
* %n A newline character. (SU)
* %p Either "AM" or "PM" according to the given time value, or the
* corresponding strings for the current locale. Noon is treated
* as "PM" and midnight as "AM".
* %P Like %p but in lowercase: "am" or "pm" or a corresponding string
* for the current locale. (GNU)
* %r The time in a.m. and p.m. notation
* %R The time in 24-hour notation ( %H : %M ).
* %s The number of seconds since the Epoch, that is, since 1970-01-01
* 00:00:00 UTC. (TZ)
* %S The second as a decimal number (range 00 to 60). (The range is
* up to 60 to allow for occasional leap seconds.)
* %t A tab character. (SU)
* %u The weekday as a decimal number [1,7], with 1 representing
* Monday.
* %U The week number of the year as a decimal number [00,53].
* %V The week number of the year
* %w The weekday as a decimal number (range 0 to 6).
* %W The week number of the year as a decimal number [00,53].
* %x The locale's appropriate date representation, but without time.
* %X The locale's appropriate time representation, but without date.
* %y The year as a decimal number without a century (range 00 to 99).
* %Y The year as a decimal number including the century.
* %z The timezone name or abbreviation, or by no bytes if no timezone
* information exists.
* %% A literal '%' character.
*
* Returned Value:
* The strftime() function returns the number of characters placed in the
* array s, not including the terminating null byte, provided the string,
* including the terminating null byte, fits. Otherwise, it returns 0,
* and the contents of the array is undefined.
*
****************************************************************************/
size_t strftime(FAR char *s, size_t max, FAR const char *format,
FAR const struct tm *tm)
{
FAR const char *str;
FAR char *dest = s;
int chleft = max;
int value;
int len;
while (*format && chleft > 0)
{
/* Just copy regular characters */
if (*format != '%')
{
*dest++ = *format++;
chleft--;
continue;
}
/* Handle the format character */
format++;
len = 0;
process_next:
switch (*format++)
{
/* %a: A three-letter abbreviation for the day of the week. */
case 'a':
{
if (tm->tm_wday < 7)
{
str = g_abbrev_wdayname[tm->tm_wday];
len = snprintf(dest, chleft, "%s", str);
}
}
break;
/* %A: The full name for the day of the week. */
case 'A':
{
if (tm->tm_wday < 7)
{
str = g_wdayname[tm->tm_wday];
len = snprintf(dest, chleft, "%s", str);
}
}
break;
/* %h: Equivalent to %b */
case 'h':
/* %b: The abbreviated month name according to the current
* locale.
*/
case 'b':
{
if (tm->tm_mon < 12)
{
str = g_abbrev_monthname[tm->tm_mon];
len = snprintf(dest, chleft, "%s", str);
}
}
break;
/* %B: The full month name according to the current locale. */
case 'B':
{
if (tm->tm_mon < 12)
{
str = g_monthname[tm->tm_mon];
len = snprintf(dest, chleft, "%s", str);
}
}
break;
/* %C: The century number (year/100) as a 2-digit integer. */
case 'C':
{
len = snprintf(dest, chleft, "%02d", tm->tm_year / 100);
}
break;
/* %d: The day of the month as a decimal number
* (range 01 to 31).
*/
case 'd':
{
len = snprintf(dest, chleft, "%02d", tm->tm_mday);
}
break;
/* The 'E' or 'O' are modifier characters to indicate that an
* alternative format or specification should be used rather than
* the one normally used by unmodified conversion specifier.
* the following are the supported format:
* %Ec %EC %Ex %EX %Ey %EY
* %Od %oe %OH %OI %Om %OM
* %OS %Ou %OU %OV %Ow %OW %Oy
* If the alternative format or specification does not exist for
* current locale, then the behavior shall be same as the
* unmodified conversion specification, i.e the %Ec is same as %c
*/
case 'E':
case 'O':
{
goto process_next;
}
/* %e: Like %d, the day of the month as a decimal number, but
* a leading zero is replaced by a space.
*/
case 'e':
{
len = snprintf(dest, chleft, "%2d", tm->tm_mday);
}
break;
/* %F: ISO 8601 date format: "%Y-%m-%d" */
case 'F':
{
len = snprintf(dest, chleft, "%04d-%02d-%02d",
tm->tm_year + TM_YEAR_BASE, tm->tm_mon,
tm->tm_mday);
}
break;
/* %g: 2-digit year version of %G, (00-99) */
case 'g':
{
value = get_week_year(tm) % 100;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %G: ISO 8601 week based year */
case 'G':
{
len = snprintf(dest, chleft, "%04d", get_week_year(tm));
}
break;
/* %H: The hour as a decimal number using a 24-hour clock
* (range 00 to 23).
*/
case 'H':
{
len = snprintf(dest, chleft, "%02d", tm->tm_hour);
}
break;
/* %I: The hour as a decimal number using a 12-hour clock
* (range 01 to 12).
*/
case 'I':
{
len = snprintf(dest, chleft, "%02d", (tm->tm_hour % 12) != 0 ?
(tm->tm_hour % 12) : 12);
}
break;
/* %j: The day of the year as a decimal number
* (range 001 to 366).
*/
case 'j':
{
if (tm->tm_mon < 12)
{
value = clock_daysbeforemonth(tm->tm_mon,
clock_isleapyear(tm->tm_year)) + tm->tm_mday;
len = snprintf(dest, chleft, "%03d", value);
}
}
break;
/* %k: The hour (24-hour clock) as a decimal number
* (range 0 to 23);
* single digits are preceded by a blank.
*/
case 'k':
{
len = snprintf(dest, chleft, "%2d", tm->tm_hour);
}
break;
/* %l: The hour (12-hour clock) as a decimal number
* (range 1 to 12);
* single digits are preceded by a blank.
*/
case 'l':
{
len = snprintf(dest, chleft, "%2d", (tm->tm_hour % 12) != 0 ?
(tm->tm_hour % 12) : 12);
}
break;
/* %m: The month as a decimal number (range 01 to 12). */
case 'm':
{
len = snprintf(dest, chleft, "%02d", tm->tm_mon + 1);
}
break;
/* %M: The minute as a decimal number (range 00 to 59). */
case 'M':
{
len = snprintf(dest, chleft, "%02d", tm->tm_min);
}
break;
/* %n: A newline character. */
case 'n':
{
*dest = '\n';
len = 1;
}
break;
/* %p: Either "AM" or "PM" according to the given time value. */
case 'p':
{
if (tm->tm_hour >= 12)
{
str = "PM";
}
else
{
str = "AM";
}
len = snprintf(dest, chleft, "%s", str);
}
break;
/* %P: Like %p but in lowercase: "am" or "pm" */
case 'P':
{
if (tm->tm_hour >= 12)
{
str = "pm";
}
else
{
str = "am";
}
len = snprintf(dest, chleft, "%s", str);
}
break;
/* %r: 12-hour clock time */
case 'r':
{
if (tm->tm_hour >= 12)
{
str = "pm";
}
else
{
str = "am";
}
value = tm->tm_hour == 12 ?
tm->tm_hour == 12 :
tm->tm_hour % (HOURSPERDAY / 2);
len = snprintf(dest, chleft, "%02d:%02d:%02d %s",
value, tm->tm_min, tm->tm_sec, str);
}
break;
/* %R: Shortcut for %H:%M. */
case 'R':
{
len = snprintf(dest, chleft, "%02d:%02d",
tm->tm_hour, tm->tm_min);
}
break;
/* %s: The number of seconds since the Epoch, that is,
* since 1970-01-01 00:00:00 UTC.
* Hmmm... mktime argume is not 'const'.
*/
case 's':
{
struct tm tmp = *tm;
len = snprintf(dest, chleft, "%ju", (uintmax_t)mktime(&tmp));
}
break;
/* %S: The second as a decimal number (range 00 to 60).
* (The range is up to 60 to allow for occasional leap seconds.)
*/
case 'S':
{
len = snprintf(dest, chleft, "%02d", tm->tm_sec);
}
break;
/* %t: A tab character. */
case 't':
{
*dest = '\t';
len = 1;
}
break;
/* %T: Shortcut for %H:%M:%S. */
case 'T':
{
len = snprintf(dest, chleft, "%02d:%02d:%02d",
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
break;
/* %u: The day of the week as a decimal, (1-7). Monday being 1,
* Sunday being 0.
*/
case 'u':
{
value = tm->tm_wday == 0 ? 7 : tm->tm_wday;
len = snprintf(dest, chleft, "%d", value);
}
break;
/* %U: week number of the current year as a decimal number,
* (00-53). Starting with the first Sunday as the first day
* of week 01.
*/
case 'U':
{
value = (tm->tm_yday + DAYSPERWEEK - tm->tm_wday)
/ DAYSPERWEEK;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %V: ISO 8601 week number */
case 'V':
{
value = get_week_num(tm);
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %w: The weekday as a decimal number (range 0 to 6). */
case 'w':
{
len = snprintf(dest, chleft, "%d", tm->tm_wday);
}
break;
/* %W: Week number of the current year as a decimal number,
* (00-53). Starting with the first Monday as the first day
* of week 01.
*/
case 'W':
{
value = (tm->tm_yday + DAYSPERWEEK -
(tm->tm_wday + 6) % DAYSPERWEEK)
/ DAYSPERWEEK;
len = snprintf(dest, chleft, "%02d", value);
}
break;
/* %x Locale date without time */
case 'x':
{
len = snprintf(dest, chleft, "%02d/%02d/%04d",
tm->tm_mon, tm->tm_mday,
tm->tm_year + TM_YEAR_BASE);
}
break;
/* %X: Locale time without date */
case 'X':
{
len = snprintf(dest, chleft, "%02d:%02d:%02d",
tm->tm_hour, tm->tm_min, tm->tm_sec);
}
break;
/* %y: The year as a decimal number without a century
* (range 00 to 99).
*/
case 'y':
{
len = snprintf(dest, chleft, "%02d", tm->tm_year % 100);
}
break;
/* %Y: The year as a decimal number including the century. */
case 'Y':
{
len = snprintf(dest, chleft, "%04d",
tm->tm_year + TM_YEAR_BASE);
}
break;
/* %z: Numeric timezone as hour and minute offset from UTC
* "+hhmm" or "-hhmm"
*/
case 'z':
{
int hour = tm->tm_gmtoff / 3600;
int min = tm->tm_gmtoff % 3600 / 60;
int utc_val = hour * 100 + min;
len = snprintf(dest, chleft, "+%04d", utc_val);
}
break;
/* %%: A literal '%' character. */
case '%':
{
*dest = '%';
len = 1;
}
break;
}
/* Update counts and pointers */
dest += len;
chleft -= len;
}
/* We get here because either we have reached the end of the format string
* or because there is no more space in the user-provided buffer and the
* resulting string has been truncated.
*
* Is there space remaining in the user-provided buffer for the NUL
* terminator?
*/
if (chleft > 0)
{
/* Yes, append terminating NUL byte */
*dest = '\0';
/* And return the number of bytes in the resulting string (excluding
* the NUL terminator).
*/
return max - chleft;
}
/* The string was truncated and/or not properly terminated. Return
* zero.
*/
return 0;
}
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