nativelibc/time/strftime.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.

	This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
*/

// Based on the CeGCC's implementation

#include <time.h>
#include <stdio.h>


/* strftime() - taken from OpenBSD.  */

#define IN_NONE 0
#define IN_SOME 1
#define IN_THIS 2
#define IN_ALL 3

#define CHAR_BIT 8
#define TYPE_BIT(type) (sizeof(type) * CHAR_BIT)
#define TYPE_SIGNED(type) (((type)-1) < 0)

#define INT_STRLEN_MAXIMUM(type) \
	((TYPE_BIT(type) - TYPE_SIGNED(type)) * 302 / 1000 + 1 + TYPE_SIGNED(type))

#define MONSPERYEAR	12
#define DAYSPERWEEK	7
#define TM_YEAR_BASE	1900
#define HOURSPERDAY	24
#define DAYSPERNYEAR	365
#define DAYSPERLYEAR	366

#define Locale (&C_time_locale)

struct lc_time {
	const char *mon[MONSPERYEAR];
	const char *month[MONSPERYEAR];
	const char *wday[DAYSPERWEEK];
	const char *weekday[DAYSPERWEEK];
	const char *X_fmt;
	const char *x_fmt;
	const char *c_fmt;
	const char *am;
	const char *pm;
	const char *date_fmt;
};

static const struct lc_time C_time_locale = {
	{ "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" },
	{ "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" },
	{ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" },
	{ "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" },

	/* X_fmt */
	"%H:%M:%S",

	/*
	 ** x_fmt
	 ** C99 requires this format.
	 ** Using just numbers (as here) makes Quakers happier;
	 ** it's also compatible with SVR4.
	 */
	"%m/%d/%y",

	/*
	 ** c_fmt
	 ** C99 requires this format.
	 ** Previously this code used "%D %X", but we now conform to C99.
	 ** Note that
	 **      "%a %b %d %H:%M:%S %Y"
	 ** is used by Solaris 2.3.
	 */
	"%a %b %e %T %Y",

	/* am */
	"AM",

	/* pm */
	"PM",

	/* date_fmt */
	"%a %b %e %H:%M:%S %Z %Y"
};


static char *_add(const char *str, char *pt, const char *ptlim) {
	while(pt < ptlim && (*pt = *str++)) pt++;
	return pt;
}


static char *_conv(const int n, const char *format, char *pt, const char *ptlim) {
	char buf[INT_STRLEN_MAXIMUM(int) + 1];

	sprintf(buf, format, n);
	return _add(buf, pt, ptlim);
}


static char *_fmt(const char *format, const struct tm *t, char *pt, const char *ptlim, int *warnp) {
	for (; *format; ++format) {
		if (*format == '%') {
start_switch:
			switch (*++format) {
				case 0:
					format--;
					break;
				case 'A':
					pt = _add((t->tm_wday < 0 || t->tm_wday >= DAYSPERWEEK) ?
						"?" : Locale->weekday[t->tm_wday], pt, ptlim);
					continue;
				case 'a':
					pt = _add((t->tm_wday < 0 || t->tm_wday >= DAYSPERWEEK) ?
						"?" : Locale->wday[t->tm_wday], pt, ptlim);
					continue;
				case 'B':
					pt = _add((t->tm_mon < 0 || t->tm_mon >= MONSPERYEAR) ?
						"?" : Locale->month[t->tm_mon], pt, ptlim);
					continue;
				case 'b':
				case 'h':
					pt = _add((t->tm_mon < 0 || t->tm_mon >= MONSPERYEAR) ?
						"?" : Locale->mon[t->tm_mon], pt, ptlim);
					continue;
				case 'C':
					/*
					 ** %C used to do a...
					 **     _fmt("%a %b %e %X %Y", t);
					 ** ...whereas now POSIX 1003.2 calls for
					 ** something completely different.
					 ** (ado, 1993-05-24)
					 */
					pt = _conv((t->tm_year + TM_YEAR_BASE) / 100, "%02d", pt, ptlim);
					continue;
				case 'c': {
					int warn2 = IN_SOME;
					pt = _fmt(Locale->c_fmt, t, pt, ptlim, warnp);
					if(warn2 == IN_ALL) warn2 = IN_THIS;
					if(warn2 > *warnp) *warnp = warn2;
					continue;
				}
				case 'D':
					pt = _fmt("%m/%d/%y", t, pt, ptlim, warnp);
					continue;
				case 'd':
					pt = _conv(t->tm_mday, "%02d", pt, ptlim);
					continue;
				case 'E':
				case 'O':
					/*
					** C99 locale modifiers.
					** The sequences
					**     %Ec %EC %Ex %EX %Ey %EY
					**     %Od %oe %OH %OI %Om %OM
					**     %OS %Ou %OU %OV %Ow %OW %Oy
					** are supposed to provide alternate
					** representations.
					*/
					goto start_switch;
				case 'e':
					pt = _conv(t->tm_mday, "%2d", pt, ptlim);
					continue;
				case 'F':
					pt = _fmt("%Y-%m-%d", t, pt, ptlim, warnp);
					continue;
				case 'H':
					pt = _conv(t->tm_hour, "%02d", pt, ptlim);
					continue;
				case 'I':
					pt = _conv((t->tm_hour % 12) ? (t->tm_hour % 12) : 12, "%02d", pt, ptlim);
					continue;
				case 'j':
					pt = _conv(t->tm_yday + 1, "%03d", pt, ptlim);
					continue;
				case 'k':
					/*
					** This used to be...
					**     _conv(t->tm_hour % 12 ?
					**             t->tm_hour % 12 : 12, 2, ' ');
					** ...and has been changed to the below to
					** match SunOS 4.1.1 and Arnold Robbins'
					** strftime version 3.0.  That is, "%k" and
					** "%l" have been swapped.
					** (ado, 1993-05-24)
					*/
					pt = _conv(t->tm_hour, "%2d", pt, ptlim);
					continue;
#ifdef KITCHEN_SINK
				case 'K':
					  /*
					   ** After all this time, still unclaimed!
					   */
					  pt = _add("kitchen sink", pt, ptlim);
					  continue;
#endif /* defined KITCHEN_SINK */
				case 'l':
					/*
					 ** This used to be...
					 **     _conv(t->tm_hour, 2, ' ');
					 ** ...and has been changed to the below to
					 ** match SunOS 4.1.1 and Arnold Robbin's
					 ** strftime version 3.0.  That is, "%k" and
					 ** "%l" have been swapped.
					 ** (ado, 1993-05-24)
					 */
					pt = _conv((t->tm_hour % 12) ? (t->tm_hour % 12) : 12, "%2d", pt, ptlim);
					continue;
				case 'M':
					pt = _conv(t->tm_min, "%02d", pt, ptlim);
					continue;
				case 'm':
					pt = _conv(t->tm_mon + 1, "%02d", pt, ptlim);
					continue;
				case 'n':
					pt = _add("\n", pt, ptlim);
					continue;
				case 'p':
					pt = _add((t->tm_hour >= (HOURSPERDAY / 2)) ?
							Locale->pm : Locale->am, pt, ptlim);
					continue;
				case 'R':
					pt = _fmt("%H:%M", t, pt, ptlim, warnp);
					continue;
				case 'r':
					pt = _fmt("%I:%M:%S %p", t, pt, ptlim, warnp);
					continue;
				case 'S':
					pt = _conv(t->tm_sec, "%02d", pt, ptlim);
					continue;
				case 's': {
					struct tm tm;
					char buf[INT_STRLEN_MAXIMUM(time_t) + 1];
					time_t mkt;

					tm = *t;
					mkt = mktime(&tm);
					if(TYPE_SIGNED(time_t)) {
						sprintf(buf, "%ld", (long int)mkt);
					} else {
						sprintf(buf, "%lu", (unsigned long int)mkt);
					}
					pt = _add(buf, pt, ptlim);
					continue;
				}
				case 'T':
					pt = _fmt("%H:%M:%S", t, pt, ptlim, warnp);
					continue;
				case 't':
					pt = _add("\t", pt, ptlim);
					continue;
				case 'U':
					pt = _conv((t->tm_yday + DAYSPERWEEK - t->tm_wday) / DAYSPERWEEK,
						"%02d", pt, ptlim);
					continue;
				case 'u':
					/*
					** From Arnold Robbins' strftime version 3.0:
					** "ISO 8601: Weekday as a decimal number
					** [1 (Monday) - 7]"
					** (ado, 1993-05-24)
					*/
					pt = _conv((t->tm_wday == 0) ? DAYSPERWEEK : t->tm_wday, "%d", pt, ptlim);
					continue;
				case 'V':          /* ISO 8601 week number */
				case 'G':          /* ISO 8601 year (four digits) */
				case 'g': {
					/* ISO 8601 year (two digits) */
					int year;
					int yday;
					int wday;
					int w;

					year = t->tm_year + TM_YEAR_BASE;
					yday = t->tm_yday;
					wday = t->tm_wday;
					while(1) {
						int len;
						int bot;
						int top;

						len = __isleap(year) ? DAYSPERLYEAR : DAYSPERNYEAR;
						/*
						** What yday (-3 ... 3) does
						** the ISO year begin on?
						*/
						bot = ((yday + 11 - wday) % DAYSPERWEEK) - 3;
						/*
						** What yday does the NEXT
						** ISO year begin on?
						*/
						top = bot - (len % DAYSPERWEEK);
						if(top < -3) top += DAYSPERWEEK;
						top += len;
						if(yday >= top) {
							++year;
							w = 1;
							break;
						}
						if(yday >= bot) {
							w = 1 + ((yday - bot) / DAYSPERWEEK);
							break;
						}
						year--;
						yday += __isleap(year) ? DAYSPERLYEAR : DAYSPERNYEAR;
					}
					if(*format == 'V') {
						pt = _conv(w, "%02d", pt, ptlim);
					} else if(*format == 'g') {
						*warnp = IN_ALL;
						pt = _conv(year % 100, "%02d", pt, ptlim);
					} else {
						pt = _conv(year, "%04d", pt, ptlim);
					}
					continue;
				}
				case 'v':
					pt = _fmt("%e-%b-%Y", t, pt, ptlim, warnp);
					continue;
				case 'W':
					pt = _conv((t->tm_yday + DAYSPERWEEK -
						(t->tm_wday ? (t->tm_wday - 1) : (DAYSPERWEEK - 1))) / DAYSPERWEEK,
						"%02d", pt, ptlim);
					continue;
				case 'w':
					pt = _conv(t->tm_wday, "%d", pt, ptlim);
					continue;
				case 'X':
					pt = _fmt(Locale->X_fmt, t, pt, ptlim, warnp);
					continue;
				case 'x': {
					int warn2 = IN_SOME;
					pt = _fmt(Locale->x_fmt, t, pt, ptlim, &warn2);
					if(warn2 == IN_ALL) warn2 = IN_THIS;
					if(warn2 > *warnp) *warnp = warn2;
					continue;
				}
				case 'y':
					*warnp = IN_ALL;
					pt = _conv((t->tm_year + TM_YEAR_BASE) % 100, "%02d", pt, ptlim);
					continue;
				case 'Y':
					pt = _conv(t->tm_year + TM_YEAR_BASE, "%04d", pt, ptlim);
					continue;
				case 'Z':
					if(t->tm_isdst >= 0) {
						//pt = _add(tzname[t->tm_isdst != 0], pt, ptlim);
						pt = _add("CST", pt, ptlim);		// TODO: implement the tzset
					}
					/*
					** C99 says that %Z must be replaced by the
					** empty string if the time zone is not
					** determinable.
					*/
					continue;
				case 'z': {
					//int diff;
					//char const *sign;

					//if(t->tm_isdst < 0) continue;
					continue;
				}
				case '+':
					pt = _fmt(Locale->date_fmt, t, pt, ptlim, warnp);
					continue;
				case '%':
				default:
					break;
			}
		}
		if(pt == ptlim) break;
		*pt++ = *format;
	}
	return pt;
}

size_t strftime (char *s, const size_t maxsize, const char *format, const struct tm *t) {
	char *p;
	int warn;

	warn = IN_NONE;
	p = _fmt(format ? : "%c", t, s, s + maxsize, &warn);

	if(p == s + maxsize) {
		if (maxsize > 0) s[maxsize - 1] = 0;
		return 0;
	}
	*p = 0;
	return p - s;
}