libc/tzcode/strptime.c - platform/bionic - Git at Google

 /*	$OpenBSD: strptime.c,v 1.31 2023/03/02 16:21:51 millert Exp $ */
 /*	$NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $	*/
 /*-
  * Copyright (c) 1997, 1998, 2005, 2008 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code was contributed to The NetBSD Foundation by Klaus Klein.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */

 #include "private.h"

 #include <ctype.h>
 #include <errno.h>
 #include <limits.h>
 #include <locale.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>

 #include "localedef.h"
 #include "tzfile.h"

 // Android: ignore OpenBSD's DEF_WEAK() stuff.
 #define DEF_WEAK(sym) /* */
 // Android: this code is not pointer-sign clean.
 #pragma clang diagnostic ignored "-Wpointer-sign"
 #pragma clang diagnostic ignored "-Wunused-function"
 // Android: clang thinks people don't know && has higher precedence than ||.
 #pragma clang diagnostic ignored "-Wlogical-op-parentheses"

 #define	_ctloc(x)		(_CurrentTimeLocale->x)

 /*
  * We do not implement alternate representations. However, we always
  * check whether a given modifier is allowed for a certain conversion.
  */
 #define _ALT_E			0x01
 #define _ALT_O			0x02
 #define	_LEGAL_ALT(x)		{ if (alt_format & ~(x)) return (0); }

 /*
  * We keep track of some of the fields we set in order to compute missing ones.
  */
 #define FIELD_TM_MON	(1 << 0)
 #define FIELD_TM_MDAY	(1 << 1)
 #define FIELD_TM_WDAY	(1 << 2)
 #define FIELD_TM_YDAY	(1 << 3)
 #define FIELD_TM_YEAR	(1 << 4)

 static char gmt[] = { "GMT" };
 static char utc[] = { "UTC" };
 /* RFC-822/RFC-2822 */
 static const char * const nast[5] = {
        "EST",    "CST",    "MST",    "PST",    "\0\0\0"
 };
 static const char * const nadt[5] = {
        "EDT",    "CDT",    "MDT",    "PDT",    "\0\0\0"
 };

 static const int mon_lengths[2][MONSPERYEAR] = {
         { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
         { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
 };

 static	int _conv_num(const unsigned char **, int *, int, int);
 static	int epoch_to_tm(const unsigned char **, struct tm *);
 static	int leaps_thru_end_of(const int y);
 static	char *_strptime(const char *, const char *, struct tm *, int);
 static	const u_char *_find_string(const u_char *, int *, const char * const *,
 	    const char * const *, int);


 char *
 strptime(const char *buf, const char *fmt, struct tm *tm)
 {
 	return(_strptime(buf, fmt, tm, 1));
 }
 DEF_WEAK(strptime);

 static char *
 _strptime(const char *buf, const char *fmt, struct tm *tm, int initialize)
 {
 	unsigned char c;
 	const unsigned char *bp, *ep;
 	size_t len;
 	int alt_format, i, offs;
 	int neg = 0;
 	static int century, relyear, fields;

 	if (initialize) {
 		century = TM_YEAR_BASE;
 		relyear = -1;
 		fields = 0;
 	}

 	bp = (const unsigned char *)buf;
 	while ((c = *fmt) != '\0') {
 		/* Clear `alternate' modifier prior to new conversion. */
 		alt_format = 0;

 		/* Eat up white-space. */
 		if (isspace(c)) {
 			while (isspace(*bp))
 				bp++;

 			fmt++;
 			continue;
 		}

 		if ((c = *fmt++) != '%')
 			goto literal;


 again:		switch (c = *fmt++) {
 		case '%':	/* "%%" is converted to "%". */
 literal:
 		if (c != *bp++)
 			return (NULL);

 		break;

 		/*
 		 * "Alternative" modifiers. Just set the appropriate flag
 		 * and start over again.
 		 */
 		case 'E':	/* "%E?" alternative conversion modifier. */
 			_LEGAL_ALT(0);
 			alt_format |= _ALT_E;
 			goto again;

 		case 'O':	/* "%O?" alternative conversion modifier. */
 			_LEGAL_ALT(0);
 			alt_format |= _ALT_O;
 			goto again;

 		/*
 		 * "Complex" conversion rules, implemented through recursion.
 		 */
 		case 'c':	/* Date and time, using the locale's format. */
 			_LEGAL_ALT(_ALT_E);
 			if (!(bp = _strptime(bp, _ctloc(d_t_fmt), tm, 0)))
 				return (NULL);
 			break;

 		case 'D':	/* The date as "%m/%d/%y". */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%m/%d/%y", tm, 0)))
 				return (NULL);
 			break;

 		case 'F':	/* The date as "%Y-%m-%d". */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%Y-%m-%d", tm, 0)))
 				return (NULL);
 			continue;

 		case 'R':	/* The time as "%H:%M". */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%H:%M", tm, 0)))
 				return (NULL);
 			break;

 		case 'r':	/* The time as "%I:%M:%S %p". */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%I:%M:%S %p", tm, 0)))
 				return (NULL);
 			break;

 		case 'T':	/* The time as "%H:%M:%S". */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%H:%M:%S", tm, 0)))
 				return (NULL);
 			break;

 		case 'v':	/* Android: the date as "%e-%b-%Y" for strftime() compat; glibc does this too. */
 			_LEGAL_ALT(0);
 			if (!(bp = _strptime(bp, "%e-%b-%Y", tm, 0)))
 				return (NULL);
 			break;

 		case 'X':	/* The time, using the locale's format. */
 			_LEGAL_ALT(_ALT_E);
 			if (!(bp = _strptime(bp, _ctloc(t_fmt), tm, 0)))
 				return (NULL);
 			break;

 		case 'x':	/* The date, using the locale's format. */
 			_LEGAL_ALT(_ALT_E);
 			if (!(bp = _strptime(bp, _ctloc(d_fmt), tm, 0)))
 				return (NULL);
 			break;

 		/*
 		 * "Elementary" conversion rules.
 		 */
 		case 'A':	/* The day of week, using the locale's form. */
 		case 'a':
 			_LEGAL_ALT(0);
 			for (i = 0; i < 7; i++) {
 				/* Full name. */
 				len = strlen(_ctloc(day[i]));
 				if (strncasecmp(_ctloc(day[i]), bp, len) == 0)
 					break;

 				/* Abbreviated name. */
 				len = strlen(_ctloc(abday[i]));
 				if (strncasecmp(_ctloc(abday[i]), bp, len) == 0)
 					break;
 			}

 			/* Nothing matched. */
 			if (i == 7)
 				return (NULL);

 			tm->tm_wday = i;
 			bp += len;
 			fields |= FIELD_TM_WDAY;
 			break;

 		case 'B':	/* The month, using the locale's form. */
 		case 'b':
 		case 'h':
 			_LEGAL_ALT(0);
 			for (i = 0; i < 12; i++) {
 				/* Full name. */
 				len = strlen(_ctloc(mon[i]));
 				if (strncasecmp(_ctloc(mon[i]), bp, len) == 0)
 					break;

 				/* Abbreviated name. */
 				len = strlen(_ctloc(abmon[i]));
 				if (strncasecmp(_ctloc(abmon[i]), bp, len) == 0)
 					break;
 			}

 			/* Nothing matched. */
 			if (i == 12)
 				return (NULL);

 			tm->tm_mon = i;
 			bp += len;
 			fields |= FIELD_TM_MON;
 			break;

 		case 'C':	/* The century number. */
 			_LEGAL_ALT(_ALT_E);
 			if (!(_conv_num(&bp, &i, 0, 99)))
 				return (NULL);

 			century = i * 100;
 			break;

 		case 'e':	/* The day of month. */
 			if (isspace(*bp))
 				bp++;
 			/* FALLTHROUGH */
 		case 'd':
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_mday, 1, 31)))
 				return (NULL);
 			fields |= FIELD_TM_MDAY;
 			break;

 		case 'k':	/* The hour (24-hour clock representation). */
 			_LEGAL_ALT(0);
 			/* FALLTHROUGH */
 		case 'H':
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_hour, 0, 23)))
 				return (NULL);
 			break;

 		case 'l':	/* The hour (12-hour clock representation). */
 			_LEGAL_ALT(0);
 			/* FALLTHROUGH */
 		case 'I':
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_hour, 1, 12)))
 				return (NULL);
 			break;

 		case 'j':	/* The day of year. */
 			_LEGAL_ALT(0);
 			if (!(_conv_num(&bp, &tm->tm_yday, 1, 366)))
 				return (NULL);
 			tm->tm_yday--;
 			fields |= FIELD_TM_YDAY;
 			break;

 		case 'M':	/* The minute. */
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_min, 0, 59)))
 				return (NULL);
 			break;

 		case 'm':	/* The month. */
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_mon, 1, 12)))
 				return (NULL);
 			tm->tm_mon--;
 			fields |= FIELD_TM_MON;
 			break;

 		case 'P':	/* Android addition for strftime() compat; glibc does this too. */
 		case 'p':	/* The locale's equivalent of AM/PM. */
 			_LEGAL_ALT(0);
 			/* AM? */
 			len = strlen(_ctloc(am_pm[0]));
 			if (strncasecmp(_ctloc(am_pm[0]), bp, len) == 0) {
 				if (tm->tm_hour > 12)	/* i.e., 13:00 AM ?! */
 					return (NULL);
 				else if (tm->tm_hour == 12)
 					tm->tm_hour = 0;

 				bp += len;
 				break;
 			}
 			/* PM? */
 			len = strlen(_ctloc(am_pm[1]));
 			if (strncasecmp(_ctloc(am_pm[1]), bp, len) == 0) {
 				if (tm->tm_hour > 12)	/* i.e., 13:00 PM ?! */
 					return (NULL);
 				else if (tm->tm_hour < 12)
 					tm->tm_hour += 12;

 				bp += len;
 				break;
 			}

 			/* Nothing matched. */
 			return (NULL);

 		case 'S':	/* The seconds. */
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_sec, 0, 60)))
 				return (NULL);
 			break;
 		case 's':	/* Seconds since epoch. */
 			if (!(epoch_to_tm(&bp, tm)))
 				return (NULL);
 			fields = 0xffff;	 /* everything */
 			break;
 		case 'U':	/* The week of year, beginning on sunday. */
 		case 'W':	/* The week of year, beginning on monday. */
 			_LEGAL_ALT(_ALT_O);
 			/*
 			 * XXX This is bogus, as we can not assume any valid
 			 * information present in the tm structure at this
 			 * point to calculate a real value, so just check the
 			 * range for now.
 			 */
 			 if (!(_conv_num(&bp, &i, 0, 53)))
 				return (NULL);
 			 break;

 		case 'w':	/* The day of week, beginning on sunday. */
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &tm->tm_wday, 0, 6)))
 				return (NULL);
 			fields |= FIELD_TM_WDAY;
 			break;

 		case 'u':	/* The day of week, monday = 1. */
 			_LEGAL_ALT(_ALT_O);
 			if (!(_conv_num(&bp, &i, 1, 7)))
 				return (NULL);
 			tm->tm_wday = i % 7;
 			fields |= FIELD_TM_WDAY;
 			continue;

 		case 'g':	/* The year corresponding to the ISO week
 				 * number but without the century.
 				 */
 			if (!(_conv_num(&bp, &i, 0, 99)))
 				return (NULL);
 			continue;

 		case 'G':	/* The year corresponding to the ISO week
 				 * number with century.
 				 */
 			do
 				bp++;
 			while (isdigit(*bp));
 			continue;

 		case 'V':	/* The ISO 8601:1988 week number as decimal */
 			if (!(_conv_num(&bp, &i, 0, 53)))
 				return (NULL);
 			continue;

 		case 'Y':	/* The year. */
 			_LEGAL_ALT(_ALT_E);
 			if (!(_conv_num(&bp, &i, 0, 9999)))
 				return (NULL);

 			relyear = -1;
 			tm->tm_year = i - TM_YEAR_BASE;
 			fields |= FIELD_TM_YEAR;
 			break;

 		case 'y':	/* The year within the century (2 digits). */
 			_LEGAL_ALT(_ALT_E | _ALT_O);
 			if (!(_conv_num(&bp, &relyear, 0, 99)))
 				return (NULL);
 			break;

 		case 'Z':
 			tzset();
 			if (strncmp((const char *)bp, gmt, 3) == 0) {
 				tm->tm_isdst = 0;
 				tm->tm_gmtoff = 0;
 				tm->tm_zone = gmt;
 				bp += 3;
 			} else if (strncmp((const char *)bp, utc, 3) == 0) {
 				tm->tm_isdst = 0;
 				tm->tm_gmtoff = 0;
 				tm->tm_zone = utc;
 				bp += 3;
 			} else {
 				ep = _find_string(bp, &i,
 						 (const char * const *)tzname,
 						  NULL, 2);
 				if (ep == NULL)
 					return (NULL);

 				tm->tm_isdst = i;
 				tm->tm_gmtoff = -(timezone);
 				tm->tm_zone = tzname[i];
 				bp = ep;
 			}
 			continue;

 		case 'z':
 			/*
 			 * We recognize all ISO 8601 formats:
 			 * Z	= Zulu time/UTC
 			 * [+-]hhmm
 			 * [+-]hh:mm
 			 * [+-]hh
 			 * We recognize all RFC-822/RFC-2822 formats:
 			 * UT|GMT
 			 *          North American : UTC offsets
 			 * E[DS]T = Eastern : -4 | -5
 			 * C[DS]T = Central : -5 | -6
 			 * M[DS]T = Mountain: -6 | -7
 			 * P[DS]T = Pacific : -7 | -8
 			 */
 			while (isspace(*bp))
 				bp++;

 			switch (*bp++) {
 			case 'G':
 				if (*bp++ != 'M')
 					return NULL;
 				/*FALLTHROUGH*/
 			case 'U':
 				if (*bp++ != 'T')
 					return NULL;
 				/*FALLTHROUGH*/
 			case 'Z':
 				tm->tm_isdst = 0;
 				tm->tm_gmtoff = 0;
 				tm->tm_zone = utc;
 				continue;
 			case '+':
 				neg = 0;
 				break;
 			case '-':
 				neg = 1;
 				break;
 			default:
 				--bp;
 				ep = _find_string(bp, &i, nast, NULL, 4);
 				if (ep != NULL) {
 					tm->tm_gmtoff = (-5 - i) * SECSPERHOUR;
 					tm->tm_zone = (char *)nast[i];
 					bp = ep;
 					continue;
 				}
 				ep = _find_string(bp, &i, nadt, NULL, 4);
 				if (ep != NULL) {
 					tm->tm_isdst = 1;
 					tm->tm_gmtoff = (-4 - i) * SECSPERHOUR;
 					tm->tm_zone = (char *)nadt[i];
 					bp = ep;
 					continue;
 				}
 				return NULL;
 			}
 			if (!isdigit(bp[0]) || !isdigit(bp[1]))
 				return NULL;
 			offs = ((bp[0]-'0') * 10 + (bp[1]-'0')) * SECSPERHOUR;
 			bp += 2;
 			if (*bp == ':')
 				bp++;
 			if (isdigit(*bp)) {
 				offs += (*bp++ - '0') * 10 * SECSPERMIN;
 				if (!isdigit(*bp))
 					return NULL;
 				offs += (*bp++ - '0') * SECSPERMIN;
 			}
 			if (neg)
 				offs = -offs;
 			tm->tm_isdst = 0;	/* XXX */
 			tm->tm_gmtoff = offs;
 			tm->tm_zone = NULL;	/* XXX */
 			continue;

 		/*
 		 * Miscellaneous conversions.
 		 */
 		case 'n':	/* Any kind of white-space. */
 		case 't':
 			_LEGAL_ALT(0);
 			while (isspace(*bp))
 				bp++;
 			break;


 		default:	/* Unknown/unsupported conversion. */
 			return (NULL);
 		}


 	}

 	/*
 	 * We need to evaluate the two digit year spec (%y)
 	 * last as we can get a century spec (%C) at any time.
 	 */
 	if (relyear != -1) {
 		if (century == TM_YEAR_BASE) {
 			if (relyear <= 68)
 				tm->tm_year = relyear + 2000 - TM_YEAR_BASE;
 			else
 				tm->tm_year = relyear + 1900 - TM_YEAR_BASE;
 		} else {
 			tm->tm_year = relyear + century - TM_YEAR_BASE;
 		}
 		fields |= FIELD_TM_YEAR;
 	}

 	/* Compute some missing values when possible. */
 	if (fields & FIELD_TM_YEAR) {
 		const int year = tm->tm_year + TM_YEAR_BASE;
 		const int *mon_lens = mon_lengths[isleap(year)];
 		if (!(fields & FIELD_TM_YDAY) &&
 		    (fields & FIELD_TM_MON) && (fields & FIELD_TM_MDAY)) {
 			tm->tm_yday = tm->tm_mday - 1;
 			for (i = 0; i < tm->tm_mon; i++)
 				tm->tm_yday += mon_lens[i];
 			fields |= FIELD_TM_YDAY;
 		}
 		if (fields & FIELD_TM_YDAY) {
 			int days = tm->tm_yday;
 			if (!(fields & FIELD_TM_WDAY)) {
 				tm->tm_wday = EPOCH_WDAY +
 				    ((year - EPOCH_YEAR) % DAYSPERWEEK) *
 				    (DAYSPERNYEAR % DAYSPERWEEK) +
 				    leaps_thru_end_of(year - 1) -
 				    leaps_thru_end_of(EPOCH_YEAR - 1) +
 				    tm->tm_yday;
 				tm->tm_wday %= DAYSPERWEEK;
 				if (tm->tm_wday < 0)
 					tm->tm_wday += DAYSPERWEEK;
 			}
 			if (!(fields & FIELD_TM_MON)) {
 				tm->tm_mon = 0;
 				while (tm->tm_mon < MONSPERYEAR && days >= mon_lens[tm->tm_mon])
 					days -= mon_lens[tm->tm_mon++];
 			}
 			if (!(fields & FIELD_TM_MDAY))
 				tm->tm_mday = days + 1;
 		}
 	}

 	return ((char *)bp);
 }


 static int
 _conv_num(const unsigned char **buf, int *dest, int llim, int ulim)
 {
 	int result = 0;
 	int rulim = ulim;

 	if (**buf < '0' || **buf > '9')
 		return (0);

 	/* we use rulim to break out of the loop when we run out of digits */
 	do {
 		result *= 10;
 		result += *(*buf)++ - '0';
 		rulim /= 10;
 	} while ((result * 10 <= ulim) && rulim && **buf >= '0' && **buf <= '9');

 	if (result < llim || result > ulim)
 		return (0);

 	*dest = result;
 	return (1);
 }

 static int
 epoch_to_tm(const unsigned char **buf, struct tm *tm)
 {
 	int saved_errno = errno;
 	int ret = 0;
 	time_t secs;
 	char *ep;

 	errno = 0;
 	secs = strtoll(*buf, &ep, 10);
 	if (*buf == (unsigned char *)ep)
 		goto done;
 	if (secs < 0 ||
 	    secs == LLONG_MAX && errno == ERANGE)
 		goto done;
 	if (localtime_r(&secs, tm) == NULL)
 		goto done;
 	ret = 1;
 done:
 	*buf = ep;
 	errno = saved_errno;
 	return (ret);
 }

 static const u_char *
 _find_string(const u_char *bp, int *tgt, const char * const *n1,
 		const char * const *n2, int c)
 {
 	int i;
 	unsigned int len;

 	/* check full name - then abbreviated ones */
 	for (; n1 != NULL; n1 = n2, n2 = NULL) {
 		for (i = 0; i < c; i++, n1++) {
 			len = strlen(*n1);
 			if (strncasecmp(*n1, (const char *)bp, len) == 0) {
 				*tgt = i;
 				return bp + len;
 			}
 		}
 	}

 	/* Nothing matched */
 	return NULL;
 }

 static int
 leaps_thru_end_of(const int y)
 {
 	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
 		-(leaps_thru_end_of(-(y + 1)) + 1);
 }
	/* $OpenBSD: strptime.c,v 1.31 2023/03/02 16:21:51 millert Exp $ */
	/* $NetBSD: strptime.c,v 1.12 1998/01/20 21:39:40 mycroft Exp $ */
	/*-
	* Copyright (c) 1997, 1998, 2005, 2008 The NetBSD Foundation, Inc.
	* All rights reserved.
	*
	* This code was contributed to The NetBSD Foundation by Klaus Klein.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
	* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
	* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
	* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	* POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "private.h"

	#include <ctype.h>
	#include <errno.h>
	#include <limits.h>
	#include <locale.h>
	#include <stdlib.h>
	#include <string.h>
	#include <time.h>

	#include "localedef.h"
	#include "tzfile.h"

	// Android: ignore OpenBSD's DEF_WEAK() stuff.
	#define DEF_WEAK(sym) /* */
	// Android: this code is not pointer-sign clean.
	#pragma clang diagnostic ignored "-Wpointer-sign"
	#pragma clang diagnostic ignored "-Wunused-function"
	// Android: clang thinks people don't know && has higher precedence than \|\|.
	#pragma clang diagnostic ignored "-Wlogical-op-parentheses"

	#define _ctloc(x) (_CurrentTimeLocale->x)

	/*
	* We do not implement alternate representations. However, we always
	* check whether a given modifier is allowed for a certain conversion.
	*/
	#define _ALT_E 0x01
	#define _ALT_O 0x02
	#define _LEGAL_ALT(x) { if (alt_format & ~(x)) return (0); }

	/*
	* We keep track of some of the fields we set in order to compute missing ones.
	*/
	#define FIELD_TM_MON (1 << 0)
	#define FIELD_TM_MDAY (1 << 1)
	#define FIELD_TM_WDAY (1 << 2)
	#define FIELD_TM_YDAY (1 << 3)
	#define FIELD_TM_YEAR (1 << 4)

	static char gmt[] = { "GMT" };
	static char utc[] = { "UTC" };
	/* RFC-822/RFC-2822 */
	static const char * const nast[5] = {
	"EST", "CST", "MST", "PST", "\0\0\0"
	};
	static const char * const nadt[5] = {
	"EDT", "CDT", "MDT", "PDT", "\0\0\0"
	};

	static const int mon_lengths[2][MONSPERYEAR] = {
	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
	};

	static int _conv_num(const unsigned char *, int , int, int);
	static int epoch_to_tm(const unsigned char *, struct tm );
	static int leaps_thru_end_of(const int y);
	static char _strptime(const char , const char , struct tm , int);
	static const u_char _find_string(const u_char , int , const char const *,
	const char * const *, int);


	char *
	strptime(const char buf, const char fmt, struct tm *tm)
	{
	return(_strptime(buf, fmt, tm, 1));
	}
	DEF_WEAK(strptime);

	static char *
	_strptime(const char buf, const char fmt, struct tm *tm, int initialize)
	{
	unsigned char c;
	const unsigned char bp, ep;
	size_t len;
	int alt_format, i, offs;
	int neg = 0;
	static int century, relyear, fields;

	if (initialize) {
	century = TM_YEAR_BASE;
	relyear = -1;
	fields = 0;
	}

	bp = (const unsigned char *)buf;
	while ((c = *fmt) != '\0') {
	/* Clear `alternate' modifier prior to new conversion. */
	alt_format = 0;

	/* Eat up white-space. */
	if (isspace(c)) {
	while (isspace(*bp))
	bp++;

	fmt++;
	continue;
	}

	if ((c = *fmt++) != '%')
	goto literal;


	again: switch (c = *fmt++) {
	case '%': /* "%%" is converted to "%". */
	literal:
	if (c != *bp++)
	return (NULL);

	break;

	/*
	* "Alternative" modifiers. Just set the appropriate flag
	* and start over again.
	*/
	case 'E': /* "%E?" alternative conversion modifier. */
	_LEGAL_ALT(0);
	alt_format \|= _ALT_E;
	goto again;

	case 'O': /* "%O?" alternative conversion modifier. */
	_LEGAL_ALT(0);
	alt_format \|= _ALT_O;
	goto again;

	/*
	* "Complex" conversion rules, implemented through recursion.
	*/
	case 'c': /* Date and time, using the locale's format. */
	_LEGAL_ALT(_ALT_E);
	if (!(bp = _strptime(bp, _ctloc(d_t_fmt), tm, 0)))
	return (NULL);
	break;

	case 'D': /* The date as "%m/%d/%y". */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%m/%d/%y", tm, 0)))
	return (NULL);
	break;

	case 'F': /* The date as "%Y-%m-%d". */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%Y-%m-%d", tm, 0)))
	return (NULL);
	continue;

	case 'R': /* The time as "%H:%M". */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%H:%M", tm, 0)))
	return (NULL);
	break;

	case 'r': /* The time as "%I:%M:%S %p". */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%I:%M:%S %p", tm, 0)))
	return (NULL);
	break;

	case 'T': /* The time as "%H:%M:%S". */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%H:%M:%S", tm, 0)))
	return (NULL);
	break;

	case 'v': /* Android: the date as "%e-%b-%Y" for strftime() compat; glibc does this too. */
	_LEGAL_ALT(0);
	if (!(bp = _strptime(bp, "%e-%b-%Y", tm, 0)))
	return (NULL);
	break;

	case 'X': /* The time, using the locale's format. */
	_LEGAL_ALT(_ALT_E);
	if (!(bp = _strptime(bp, _ctloc(t_fmt), tm, 0)))
	return (NULL);
	break;

	case 'x': /* The date, using the locale's format. */
	_LEGAL_ALT(_ALT_E);
	if (!(bp = _strptime(bp, _ctloc(d_fmt), tm, 0)))
	return (NULL);
	break;

	/*
	* "Elementary" conversion rules.
	*/
	case 'A': /* The day of week, using the locale's form. */
	case 'a':
	_LEGAL_ALT(0);
	for (i = 0; i < 7; i++) {
	/* Full name. */
	len = strlen(_ctloc(day[i]));
	if (strncasecmp(_ctloc(day[i]), bp, len) == 0)
	break;

	/* Abbreviated name. */
	len = strlen(_ctloc(abday[i]));
	if (strncasecmp(_ctloc(abday[i]), bp, len) == 0)
	break;
	}

	/* Nothing matched. */
	if (i == 7)
	return (NULL);

	tm->tm_wday = i;
	bp += len;
	fields \|= FIELD_TM_WDAY;
	break;

	case 'B': /* The month, using the locale's form. */
	case 'b':
	case 'h':
	_LEGAL_ALT(0);
	for (i = 0; i < 12; i++) {
	/* Full name. */
	len = strlen(_ctloc(mon[i]));
	if (strncasecmp(_ctloc(mon[i]), bp, len) == 0)
	break;

	/* Abbreviated name. */
	len = strlen(_ctloc(abmon[i]));
	if (strncasecmp(_ctloc(abmon[i]), bp, len) == 0)
	break;
	}

	/* Nothing matched. */
	if (i == 12)
	return (NULL);

	tm->tm_mon = i;
	bp += len;
	fields \|= FIELD_TM_MON;
	break;

	case 'C': /* The century number. */
	_LEGAL_ALT(_ALT_E);
	if (!(_conv_num(&bp, &i, 0, 99)))
	return (NULL);

	century = i * 100;
	break;

	case 'e': /* The day of month. */
	if (isspace(*bp))
	bp++;
	/* FALLTHROUGH */
	case 'd':
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_mday, 1, 31)))
	return (NULL);
	fields \|= FIELD_TM_MDAY;
	break;

	case 'k': /* The hour (24-hour clock representation). */
	_LEGAL_ALT(0);
	/* FALLTHROUGH */
	case 'H':
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_hour, 0, 23)))
	return (NULL);
	break;

	case 'l': /* The hour (12-hour clock representation). */
	_LEGAL_ALT(0);
	/* FALLTHROUGH */
	case 'I':
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_hour, 1, 12)))
	return (NULL);
	break;

	case 'j': /* The day of year. */
	_LEGAL_ALT(0);
	if (!(_conv_num(&bp, &tm->tm_yday, 1, 366)))
	return (NULL);
	tm->tm_yday--;
	fields \|= FIELD_TM_YDAY;
	break;

	case 'M': /* The minute. */
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_min, 0, 59)))
	return (NULL);
	break;

	case 'm': /* The month. */
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_mon, 1, 12)))
	return (NULL);
	tm->tm_mon--;
	fields \|= FIELD_TM_MON;
	break;

	case 'P': /* Android addition for strftime() compat; glibc does this too. */
	case 'p': /* The locale's equivalent of AM/PM. */
	_LEGAL_ALT(0);
	/* AM? */
	len = strlen(_ctloc(am_pm[0]));
	if (strncasecmp(_ctloc(am_pm[0]), bp, len) == 0) {
	if (tm->tm_hour > 12) /* i.e., 13:00 AM ?! */
	return (NULL);
	else if (tm->tm_hour == 12)
	tm->tm_hour = 0;

	bp += len;
	break;
	}
	/* PM? */
	len = strlen(_ctloc(am_pm[1]));
	if (strncasecmp(_ctloc(am_pm[1]), bp, len) == 0) {
	if (tm->tm_hour > 12) /* i.e., 13:00 PM ?! */
	return (NULL);
	else if (tm->tm_hour < 12)
	tm->tm_hour += 12;

	bp += len;
	break;
	}

	/* Nothing matched. */
	return (NULL);

	case 'S': /* The seconds. */
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_sec, 0, 60)))
	return (NULL);
	break;
	case 's': /* Seconds since epoch. */
	if (!(epoch_to_tm(&bp, tm)))
	return (NULL);
	fields = 0xffff; /* everything */
	break;
	case 'U': /* The week of year, beginning on sunday. */
	case 'W': /* The week of year, beginning on monday. */
	_LEGAL_ALT(_ALT_O);
	/*
	* XXX This is bogus, as we can not assume any valid
	* information present in the tm structure at this
	* point to calculate a real value, so just check the
	* range for now.
	*/
	if (!(_conv_num(&bp, &i, 0, 53)))
	return (NULL);
	break;

	case 'w': /* The day of week, beginning on sunday. */
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &tm->tm_wday, 0, 6)))
	return (NULL);
	fields \|= FIELD_TM_WDAY;
	break;

	case 'u': /* The day of week, monday = 1. */
	_LEGAL_ALT(_ALT_O);
	if (!(_conv_num(&bp, &i, 1, 7)))
	return (NULL);
	tm->tm_wday = i % 7;
	fields \|= FIELD_TM_WDAY;
	continue;

	case 'g': /* The year corresponding to the ISO week
	* number but without the century.
	*/
	if (!(_conv_num(&bp, &i, 0, 99)))
	return (NULL);
	continue;

	case 'G': /* The year corresponding to the ISO week
	* number with century.
	*/
	do
	bp++;
	while (isdigit(*bp));
	continue;

	case 'V': /* The ISO 8601:1988 week number as decimal */
	if (!(_conv_num(&bp, &i, 0, 53)))
	return (NULL);
	continue;

	case 'Y': /* The year. */
	_LEGAL_ALT(_ALT_E);
	if (!(_conv_num(&bp, &i, 0, 9999)))
	return (NULL);

	relyear = -1;
	tm->tm_year = i - TM_YEAR_BASE;
	fields \|= FIELD_TM_YEAR;
	break;

	case 'y': /* The year within the century (2 digits). */
	_LEGAL_ALT(_ALT_E \| _ALT_O);
	if (!(_conv_num(&bp, &relyear, 0, 99)))
	return (NULL);
	break;

	case 'Z':
	tzset();
	if (strncmp((const char *)bp, gmt, 3) == 0) {
	tm->tm_isdst = 0;
	tm->tm_gmtoff = 0;
	tm->tm_zone = gmt;
	bp += 3;
	} else if (strncmp((const char *)bp, utc, 3) == 0) {
	tm->tm_isdst = 0;
	tm->tm_gmtoff = 0;
	tm->tm_zone = utc;
	bp += 3;
	} else {
	ep = _find_string(bp, &i,
	(const char * const *)tzname,
	NULL, 2);
	if (ep == NULL)
	return (NULL);

	tm->tm_isdst = i;
	tm->tm_gmtoff = -(timezone);
	tm->tm_zone = tzname[i];
	bp = ep;
	}
	continue;

	case 'z':
	/*
	* We recognize all ISO 8601 formats:
	* Z = Zulu time/UTC
	* [+-]hhmm
	* [+-]hh:mm
	* [+-]hh
	* We recognize all RFC-822/RFC-2822 formats:
	* UT\|GMT
	* North American : UTC offsets
	* E[DS]T = Eastern : -4 \| -5
	* C[DS]T = Central : -5 \| -6
	* M[DS]T = Mountain: -6 \| -7
	* P[DS]T = Pacific : -7 \| -8
	*/
	while (isspace(*bp))
	bp++;

	switch (*bp++) {
	case 'G':
	if (*bp++ != 'M')
	return NULL;
	/FALLTHROUGH/
	case 'U':
	if (*bp++ != 'T')
	return NULL;
	/FALLTHROUGH/
	case 'Z':
	tm->tm_isdst = 0;
	tm->tm_gmtoff = 0;
	tm->tm_zone = utc;
	continue;
	case '+':
	neg = 0;
	break;
	case '-':
	neg = 1;
	break;
	default:
	--bp;
	ep = _find_string(bp, &i, nast, NULL, 4);
	if (ep != NULL) {
	tm->tm_gmtoff = (-5 - i) * SECSPERHOUR;
	tm->tm_zone = (char *)nast[i];
	bp = ep;
	continue;
	}
	ep = _find_string(bp, &i, nadt, NULL, 4);
	if (ep != NULL) {
	tm->tm_isdst = 1;
	tm->tm_gmtoff = (-4 - i) * SECSPERHOUR;
	tm->tm_zone = (char *)nadt[i];
	bp = ep;
	continue;
	}
	return NULL;
	}
	if (!isdigit(bp[0]) \|\| !isdigit(bp[1]))
	return NULL;
	offs = ((bp[0]-'0') * 10 + (bp[1]-'0')) * SECSPERHOUR;
	bp += 2;
	if (*bp == ':')
	bp++;
	if (isdigit(*bp)) {
	offs += (bp++ - '0') 10 * SECSPERMIN;
	if (!isdigit(*bp))
	return NULL;
	offs += (bp++ - '0') SECSPERMIN;
	}
	if (neg)
	offs = -offs;
	tm->tm_isdst = 0; /* XXX */
	tm->tm_gmtoff = offs;
	tm->tm_zone = NULL; /* XXX */
	continue;

	/*
	* Miscellaneous conversions.
	*/
	case 'n': /* Any kind of white-space. */
	case 't':
	_LEGAL_ALT(0);
	while (isspace(*bp))
	bp++;
	break;


	default: /* Unknown/unsupported conversion. */
	return (NULL);
	}


	}

	/*
	* We need to evaluate the two digit year spec (%y)
	* last as we can get a century spec (%C) at any time.
	*/
	if (relyear != -1) {
	if (century == TM_YEAR_BASE) {
	if (relyear <= 68)
	tm->tm_year = relyear + 2000 - TM_YEAR_BASE;
	else
	tm->tm_year = relyear + 1900 - TM_YEAR_BASE;
	} else {
	tm->tm_year = relyear + century - TM_YEAR_BASE;
	}
	fields \|= FIELD_TM_YEAR;
	}

	/* Compute some missing values when possible. */
	if (fields & FIELD_TM_YEAR) {
	const int year = tm->tm_year + TM_YEAR_BASE;
	const int *mon_lens = mon_lengths[isleap(year)];
	if (!(fields & FIELD_TM_YDAY) &&
	(fields & FIELD_TM_MON) && (fields & FIELD_TM_MDAY)) {
	tm->tm_yday = tm->tm_mday - 1;
	for (i = 0; i < tm->tm_mon; i++)
	tm->tm_yday += mon_lens[i];
	fields \|= FIELD_TM_YDAY;
	}
	if (fields & FIELD_TM_YDAY) {
	int days = tm->tm_yday;
	if (!(fields & FIELD_TM_WDAY)) {
	tm->tm_wday = EPOCH_WDAY +
	((year - EPOCH_YEAR) % DAYSPERWEEK) *
	(DAYSPERNYEAR % DAYSPERWEEK) +
	leaps_thru_end_of(year - 1) -
	leaps_thru_end_of(EPOCH_YEAR - 1) +
	tm->tm_yday;
	tm->tm_wday %= DAYSPERWEEK;
	if (tm->tm_wday < 0)
	tm->tm_wday += DAYSPERWEEK;
	}
	if (!(fields & FIELD_TM_MON)) {
	tm->tm_mon = 0;
	while (tm->tm_mon < MONSPERYEAR && days >= mon_lens[tm->tm_mon])
	days -= mon_lens[tm->tm_mon++];
	}
	if (!(fields & FIELD_TM_MDAY))
	tm->tm_mday = days + 1;
	}
	}

	return ((char *)bp);
	}


	static int
	_conv_num(const unsigned char *buf, int dest, int llim, int ulim)
	{
	int result = 0;
	int rulim = ulim;

	if (buf < '0' \|\| buf > '9')
	return (0);

	/* we use rulim to break out of the loop when we run out of digits */
	do {
	result *= 10;
	result += (buf)++ - '0';
	rulim /= 10;
	} while ((result * 10 <= ulim) && rulim && buf >= '0' && buf <= '9');

	if (result < llim \|\| result > ulim)
	return (0);

	*dest = result;
	return (1);
	}

	static int
	epoch_to_tm(const unsigned char *buf, struct tm tm)
	{
	int saved_errno = errno;
	int ret = 0;
	time_t secs;
	char *ep;

	errno = 0;
	secs = strtoll(*buf, &ep, 10);
	if (buf == (unsigned char )ep)
	goto done;
	if (secs < 0 \|\|
	secs == LLONG_MAX && errno == ERANGE)
	goto done;
	if (localtime_r(&secs, tm) == NULL)
	goto done;
	ret = 1;
	done:
	*buf = ep;
	errno = saved_errno;
	return (ret);
	}

	static const u_char *
	_find_string(const u_char bp, int tgt, const char * const *n1,
	const char * const *n2, int c)
	{
	int i;
	unsigned int len;

	/* check full name - then abbreviated ones */
	for (; n1 != NULL; n1 = n2, n2 = NULL) {
	for (i = 0; i < c; i++, n1++) {
	len = strlen(*n1);
	if (strncasecmp(n1, (const char )bp, len) == 0) {
	*tgt = i;
	return bp + len;
	}
	}
	}

	/* Nothing matched */
	return NULL;
	}

	static int
	leaps_thru_end_of(const int y)
	{
	return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
	-(leaps_thru_end_of(-(y + 1)) + 1);
	}