/*	$NetBSD: strptime.c,v 1.35 2009/12/14 20:45:02 matt 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.
 * Heavily optimised by David Laight
 *
 * 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.
 */
#ifndef _WIN32
#include <sys/cdefs.h>
#endif
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: strptime.c,v 1.35 2009/12/14 20:45:02 matt Exp $");
#endif

#ifndef _WIN32
#include "namespace.h"
#include <sys/localedef.h>
#endif
#include <ctype.h>
#include <locale.h>
#include <string.h>
#include <time.h>
#ifndef _WIN32
#include <tzfile.h>
#include "private.h"
#endif

#ifdef _WIN32
#define u_char unsigned char
#define uint unsigned int
#define TM_YEAR_BASE 1900
#define __UNCONST(X) X
#include <stdint.h>

#ifdef __BORLANDC__
#define strncasecmp strncmpi
#define tzname _tzname
#endif

#ifdef _MSC_VER
#define strncasecmp _strnicmp
#endif

#endif

#ifdef __weak_alias
__weak_alias(strptime,_strptime)
#endif

#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 STRPTIME_ALT_E			0x01
#define STRPTIME_ALT_O			0x02
#define	LEGAL_ALT(x)		{ if (alt_format & ~(x)) return NULL; }

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 u_char *conv_num(const unsigned char *, int *, uint, uint);
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)
{
        unsigned char c;
        const unsigned char *bp, *ep;
        int alt_format, i, split_year = 0, neg = 0, offs;
        const char *new_fmt;

        // bp = (const u_char *)buf;
        bp = (u_char *)buf;

        while (bp != NULL && (c = *fmt++) != '\0') {
                /* Clear `alternate' modifier prior to new conversion. */
                alt_format = 0;
                i = 0;

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

                if (c != '%')
                        goto literal;


again:		switch (c = *fmt++) {
                case '%':	/* "%%" is converted to "%". */
literal:
                        if (c != *bp++)
                                return NULL;
                        LEGAL_ALT(0);
                        continue;

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

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

#ifndef _WIN32
                /*
                 * "Complex" conversion rules, implemented through recursion.
                 */
                case 'c':	/* Date and time, using the locale's format. */
                        new_fmt = _ctloc(d_t_fmt);
                        goto recurse;
#endif
                case 'D':	/* The date as "%m/%d/%y". */
                        new_fmt = "%m/%d/%y";
                        LEGAL_ALT(0);
                        goto recurse;

                case 'F':	/* The date as "%Y-%m-%d". */
                        new_fmt = "%Y-%m-%d";
                        LEGAL_ALT(0);
                        goto recurse;

                case 'R':	/* The time as "%H:%M". */
                        new_fmt = "%H:%M";
                        LEGAL_ALT(0);
                        goto recurse;

#ifndef _WIN32
                case 'r':	/* The time in 12-hour clock representation. */
                        new_fmt =_ctloc(t_fmt_ampm);
                        LEGAL_ALT(0);
                        goto recurse;
#endif
                case 'T':	/* The time as "%H:%M:%S". */
                        new_fmt = "%H:%M:%S";
                        LEGAL_ALT(0);
                        goto recurse;

#ifndef _WIN32
                case 'X':	/* The time, using the locale's format. */
                        new_fmt =_ctloc(t_fmt);
                        goto recurse;

                case 'x':	/* The date, using the locale's format. */
                        new_fmt =_ctloc(d_fmt);
#endif
                recurse:
                        bp = (const u_char *)strptime((const char *)bp,
                                                            new_fmt, tm);
                        LEGAL_ALT(STRPTIME_ALT_E);
                        continue;

#ifndef _WIN32
                /*
                 * "Elementary" conversion rules.
                 */
                case 'A':	/* The day of week, using the locale's form. */
                case 'a':
                        bp = find_string(bp, &tm->tm_wday, _ctloc(day),
                                        _ctloc(abday), 7);
                        LEGAL_ALT(0);
                        continue;

                case 'B':	/* The month, using the locale's form. */
                case 'b':
                case 'h':
                        bp = find_string(bp, &tm->tm_mon, _ctloc(mon),
                                        _ctloc(abmon), 12);
                        LEGAL_ALT(0);
                        continue;
#endif
                case 'C':	/* The century number. */
                        i = 20;
                        bp = conv_num(bp, &i, 0, 99);

                        i = i * 100 - TM_YEAR_BASE;
                        if (split_year)
                                i += tm->tm_year % 100;
                        split_year = 1;
                        tm->tm_year = i;
                        LEGAL_ALT(STRPTIME_ALT_E);
                        continue;

                case 'd':	/* The day of month. */
                case 'e':
                        bp = conv_num(bp, &tm->tm_mday, 1, 31);
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'k':	/* The hour (24-hour clock representation). */
                        LEGAL_ALT(0);
                        /* FALLTHROUGH */
                case 'H':
                        bp = conv_num(bp, &tm->tm_hour, 0, 23);
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'l':	/* The hour (12-hour clock representation). */
                        LEGAL_ALT(0);
                        /* FALLTHROUGH */
                case 'I':
                        bp = conv_num(bp, &tm->tm_hour, 1, 12);
                        if (tm->tm_hour == 12)
                                tm->tm_hour = 0;
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'j':	/* The day of year. */
                        i = 1;
                        bp = conv_num(bp, &i, 1, 366);
                        tm->tm_yday = i - 1;
                        LEGAL_ALT(0);
                        continue;

                case 'M':	/* The minute. */
                        bp = conv_num(bp, &tm->tm_min, 0, 59);
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'm':	/* The month. */
                        i = 1;
                        bp = conv_num(bp, &i, 1, 12);
                        tm->tm_mon = i - 1;
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;
#ifndef _WIN32

                case 'p':	/* The locale's equivalent of AM/PM. */
                        bp = find_string(bp, &i, _ctloc(am_pm), NULL, 2);
                        if (tm->tm_hour > 11)
                                return NULL;
                        tm->tm_hour += i * 12;
                        LEGAL_ALT(0);
                        continue;
#endif
                case 'S':	/* The seconds. */
                        bp = conv_num(bp, &tm->tm_sec, 0, 61);
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

#ifndef TIME_MAX
#define TIME_MAX	INT64_MAX
#endif
                case 's':	/* seconds since the epoch */
                        {
                                time_t sse = 0;
                                uint64_t rulim = TIME_MAX;

                                if (*bp < '0' || *bp > '9') {
                                        bp = NULL;
                                        continue;
                                }

                                do {
                                        sse *= 10;
                                        sse += *bp++ - '0';
                                        rulim /= 10;
                                } while ((sse * 10 <= TIME_MAX) &&
                                         rulim && *bp >= '0' && *bp <= '9');

                                if (sse < 0 || (uint64_t)sse > TIME_MAX) {
                                        bp = NULL;
                                        continue;
                                }

#ifdef _WIN32
                                if ((tm = localtime(&sse)) == NULL)
#else
                                if (localtime_r(&sse, tm) == NULL)
#endif
                                        bp = NULL;
                        }
                        continue;

                case 'U':	/* The week of year, beginning on sunday. */
                case 'W':	/* The week of year, beginning on monday. */
                        /*
                         * 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.
                         */
                         bp = conv_num(bp, &i, 0, 53);
                         LEGAL_ALT(STRPTIME_ALT_O);
                         continue;

                case 'w':	/* The day of week, beginning on sunday. */
                        bp = conv_num(bp, &tm->tm_wday, 0, 6);
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'u':	/* The day of week, monday = 1. */
                        bp = conv_num(bp, &i, 1, 7);
                        tm->tm_wday = i % 7;
                        LEGAL_ALT(STRPTIME_ALT_O);
                        continue;

                case 'g':	/* The year corresponding to the ISO week
                                 * number but without the century.
                                 */
                        bp = conv_num(bp, &i, 0, 99);
                        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 */
                        bp = conv_num(bp, &i, 0, 53);
                        continue;

                case 'Y':	/* The year. */
                        i = TM_YEAR_BASE;	/* just for data sanity... */
                        bp = conv_num(bp, &i, 0, 9999);
                        tm->tm_year = i - TM_YEAR_BASE;
                        LEGAL_ALT(STRPTIME_ALT_E);
                        continue;

                case 'y':	/* The year within 100 years of the epoch. */
                        /* LEGAL_ALT(STRPTIME_ALT_E | STRPTIME_ALT_O); */
                        bp = conv_num(bp, &i, 0, 99);

                        if (split_year)
                                /* preserve century */
                                i += (tm->tm_year / 100) * 100;
                        else {
                                split_year = 1;
                                if (i <= 68)
                                        i = i + 2000 - TM_YEAR_BASE;
                                else
                                        i = i + 1900 - TM_YEAR_BASE;
                        }
                        tm->tm_year = i;
                        continue;

                case 'Z':
                        tzset();
                        if (strncmp((const char *)bp, gmt, 3) == 0) {
                                tm->tm_isdst = 0;
#ifdef TM_GMTOFF
                                tm->TM_GMTOFF = 0;
#endif
#ifdef TM_ZONE
                                tm->TM_ZONE = gmt;
#endif
                                bp += 3;
                        } else {
                                ep = find_string(bp, &i,
                                                 (const char * const *)tzname,
                                                  NULL, 2);
                                if (ep != NULL) {
                                        tm->tm_isdst = i;
#ifdef TM_GMTOFF
                                        tm->TM_GMTOFF = -(timezone);
#endif
#ifdef TM_ZONE
                                        tm->TM_ZONE = tzname[i];
#endif
                                }
                                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
                         *          Military
                         * [A-IL-M] = -1 ... -9 (J not used)
                         * [N-Y]  = +1 ... +12
                         */
                        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;
#ifdef TM_GMTOFF
                                tm->TM_GMTOFF = 0;
#endif
#ifdef TM_ZONE
                                tm->TM_ZONE = utc;
#endif
                                continue;
                        case '+':
                                neg = 0;
                                break;
                        case '-':
                                neg = 1;
                                break;
                        default:
                                --bp;
                                ep = find_string(bp, &i, nast, NULL, 4);
                                if (ep != NULL) {
#ifdef TM_GMTOFF
                                        tm->TM_GMTOFF = -5 - i;
#endif
#ifdef TM_ZONE
                                        tm->TM_ZONE = __UNCONST(nast[i]);
#endif
                                        bp = ep;
                                        continue;
                                }
                                ep = find_string(bp, &i, nadt, NULL, 4);
                                if (ep != NULL) {
                                        tm->tm_isdst = 1;
#ifdef TM_GMTOFF
                                        tm->TM_GMTOFF = -4 - i;
#endif
#ifdef TM_ZONE
                                        tm->TM_ZONE = __UNCONST(nadt[i]);
#endif
                                        bp = ep;
                                        continue;
                                }

                                if ((*bp >= 'A' && *bp <= 'I') ||
                                    (*bp >= 'L' && *bp <= 'Y')) {
#ifdef TM_GMTOFF
                                        /* Argh! No 'J'! */
                                        if (*bp >= 'A' && *bp <= 'I')
                                                tm->TM_GMTOFF =
                                                    ('A' - 1) - (int)*bp;
                                        else if (*bp >= 'L' && *bp <= 'M')
                                                tm->TM_GMTOFF = 'A' - (int)*bp;
                                        else if (*bp >= 'N' && *bp <= 'Y')
                                                tm->TM_GMTOFF = (int)*bp - 'M';
#endif
#ifdef TM_ZONE
                                        tm->TM_ZONE = NULL; /* XXX */
#endif
                                        bp++;
                                        continue;
                                }
                                return NULL;
                        }
                        offs = 0;
                        for (i = 0; i < 4; ) {
                                if (isdigit(*bp)) {
                                        offs = offs * 10 + (*bp++ - '0');
                                        i++;
                                        continue;
                                }
                                if (i == 2 && *bp == ':') {
                                        bp++;
                                        continue;
                                }
                                break;
                        }
                        switch (i) {
                        case 2:
                                offs *= 100;
                                break;
                        case 4:
                                i = offs % 100;
                                if (i >= 60)
                                        return NULL;
                                /* Convert minutes into decimal */
                                offs = (offs / 100) * 100 + (i * 50) / 30;
                                break;
                        default:
                                return NULL;
                        }
                        if (neg)
                                offs = -offs;
                        tm->tm_isdst = 0;	/* XXX */
#ifdef TM_GMTOFF
                        tm->TM_GMTOFF = offs;
#endif
#ifdef TM_ZONE
                        tm->TM_ZONE = NULL;	/* XXX */
#endif
                        continue;

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


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

        return (char *)bp;
}


static const u_char *
conv_num(const unsigned char *buf, int *dest, uint llim, uint ulim)
{
        uint result = 0;
        unsigned char ch;

        /* The limit also determines the number of valid digits. */
        uint rulim = ulim;

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

        do {
                result *= 10;
                result += ch - '0';
                rulim /= 10;
                ch = *++buf;
        } while ((result * 10 <= ulim) && rulim && ch >= '0' && ch <= '9');

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

        *dest = result;
        return buf;
}

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;
}
