/*
 * Copyright (c) 2014 Gary Mills
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 * Copyright 2011, Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 1994 Powerdog Industries.  All rights reserved.
 *
 * 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 POWERDOG INDUSTRIES ``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 POWERDOG INDUSTRIES 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.
 *
 * The views and conclusions contained in the software and documentation
 * are those of the authors and should not be interpreted as representing
 * official policies, either expressed or implied, of Powerdog Industries.
 */

#include "lint.h"
#include <time.h>
#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <alloca.h>
#include <locale.h>
#include "timelocal.h"
#include "localeimpl.h"

#define asizeof(a)      (sizeof (a) / sizeof ((a)[0]))

#define F_GMT           (1 << 0)
#define F_RECURSE       (1 << 2)

static char *
__strptime(const char *_RESTRICT_KYWD buf, const char *_RESTRICT_KYWD fmt,
    struct tm *_RESTRICT_KYWD tm, int *_RESTRICT_KYWD flagsp,
    locale_t _RESTRICT_KYWD loc)
{
        char    c;
        const char *ptr;
        int     i, len, recurse = 0;
        int Ealternative, Oalternative;
        const struct lc_time *tptr = loc->time;

        if (*flagsp & F_RECURSE)
                recurse = 1;
        *flagsp |= F_RECURSE;

        ptr = fmt;
        while (*ptr != 0) {
                if (*buf == 0)
                        break;

                c = *ptr++;

                if (c != '%') {
                        if (isspace(c))
                                while (isspace(*buf))
                                        buf++;
                        else if (c != *buf++)
                                return (NULL);
                        continue;
                }

                Ealternative = 0;
                Oalternative = 0;
label:
                c = *ptr++;
                switch (c) {
                case 0:
                case '%':
                        if (*buf++ != '%')
                                return (NULL);
                        break;

                case '+':
                        buf = __strptime(buf, tptr->date_fmt, tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'C':
                        if (!isdigit(*buf))
                                return (NULL);

                        /* XXX This will break for 3-digit centuries. */
                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (i < 19)
                                return (NULL);

                        tm->tm_year = i * 100 - 1900;
                        break;

                case 'c':
                        buf = __strptime(buf, tptr->c_fmt, tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'D':
                        buf = __strptime(buf, "%m/%d/%y", tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'E':
                        if (Ealternative || Oalternative)
                                break;
                        Ealternative++;
                        goto label;

                case 'O':
                        if (Ealternative || Oalternative)
                                break;
                        Oalternative++;
                        goto label;

                case 'F':
                        buf = __strptime(buf, "%Y-%m-%d", tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'R':
                        buf = __strptime(buf, "%H:%M", tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'r':
                        buf = __strptime(buf, tptr->ampm_fmt, tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'T':
                        buf = __strptime(buf, "%H:%M:%S", tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'X':
                        buf = __strptime(buf, tptr->X_fmt, tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'x':
                        buf = __strptime(buf, tptr->x_fmt, tm, flagsp, loc);
                        if (buf == NULL)
                                return (NULL);
                        break;

                case 'j':
                        if (!isdigit(*buf))
                                return (NULL);

                        len = 3;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (i < 1 || i > 366)
                                return (NULL);

                        tm->tm_yday = i - 1;
                        break;

                case 'M':
                case 'S':
                        if (*buf == 0 || isspace(*buf))
                                break;

                        if (!isdigit(*buf))
                                return (NULL);

                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }

                        if (c == 'M') {
                                if (i > 59)
                                        return (NULL);
                                tm->tm_min = i;
                        } else {
                                if (i > 60)
                                        return (NULL);
                                tm->tm_sec = i;
                        }

                        break;

                case 'H':
                case 'I':
                case 'k':
                case 'l':
                        /*
                         * Of these, %l is the only specifier explicitly
                         * documented as not being zero-padded.  However,
                         * there is no harm in allowing zero-padding.
                         *
                         * XXX The %l specifier may gobble one too many
                         * digits if used incorrectly.
                         */
                        if (!isdigit(*buf))
                                return (NULL);

                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (c == 'H' || c == 'k') {
                                if (i > 23)
                                        return (NULL);
                        } else if (i > 12)
                                return (NULL);

                        tm->tm_hour = i;

                        break;

                case 'p':
                        /*
                         * XXX This is bogus if parsed before hour-related
                         * specifiers.
                         */
                        len = strlen(tptr->am);
                        if (strncasecmp(buf, tptr->am, len) == 0) {
                                if (tm->tm_hour > 12)
                                        return (NULL);
                                if (tm->tm_hour == 12)
                                        tm->tm_hour = 0;
                                buf += len;
                                break;
                        }

                        len = strlen(tptr->pm);
                        if (strncasecmp(buf, tptr->pm, len) == 0) {
                                if (tm->tm_hour > 12)
                                        return (NULL);
                                if (tm->tm_hour != 12)
                                        tm->tm_hour += 12;
                                buf += len;
                                break;
                        }

                        return (NULL);

                case 'A':
                case 'a':
                        for (i = 0; i < asizeof(tptr->weekday); i++) {
                                len = strlen(tptr->weekday[i]);
                                if (strncasecmp(buf, tptr->weekday[i], len) ==
                                    0)
                                        break;
                                len = strlen(tptr->wday[i]);
                                if (strncasecmp(buf, tptr->wday[i], len) == 0)
                                        break;
                        }
                        if (i == asizeof(tptr->weekday))
                                return (NULL);

                        tm->tm_wday = i;
                        buf += len;
                        break;

                case 'U':
                case 'W':
                        /*
                         * 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 (!isdigit(*buf))
                                return (NULL);

                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (i > 53)
                                return (NULL);

                        break;

                case 'w':
                        if (!isdigit(*buf))
                                return (NULL);

                        i = *buf - '0';
                        if (i > 6)
                                return (NULL);

                        tm->tm_wday = i;

                        break;

                case 'd':
                case 'e':
                        /*
                         * The %e format has a space before single digits
                         * which we need to skip.
                         */
                        if (isspace(*buf))
                                buf++;
                        /*
                         * The %e specifier is explicitly documented as not
                         * being zero-padded but there is no harm in allowing
                         * such padding.
                         *
                         * XXX The %e specifier may gobble one too many
                         * digits if used incorrectly.
                         */
                        if (!isdigit(*buf))
                                return (NULL);

                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (i > 31)
                                return (NULL);

                        tm->tm_mday = i;

                        break;

                case 'B':
                case 'b':
                case 'h':
                        for (i = 0; i < asizeof(tptr->month); i++) {
                                len = strlen(tptr->month[i]);
                                if (strncasecmp(buf, tptr->month[i], len) == 0)
                                        break;
                        }
                        /*
                         * Try the abbreviated month name if the full name
                         * wasn't found.
                         */
                        if (i == asizeof(tptr->month)) {
                                for (i = 0; i < asizeof(tptr->month); i++) {
                                        len = strlen(tptr->mon[i]);
                                        if (strncasecmp(buf, tptr->mon[i],
                                            len) == 0)
                                                break;
                                }
                        }
                        if (i == asizeof(tptr->month))
                                return (NULL);

                        tm->tm_mon = i;
                        buf += len;
                        break;

                case 'm':
                        if (!isdigit(*buf))
                                return (NULL);

                        len = 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (i < 1 || i > 12)
                                return (NULL);

                        tm->tm_mon = i - 1;

                        break;

                case 's':
                        {
                        char *cp;
                        int sverrno;
                        time_t t;

                        sverrno = errno;
                        errno = 0;
                        t = strtol(buf, &cp, 10);
                        if (errno == ERANGE) {
                                errno = sverrno;
                                return (NULL);
                        }
                        errno = sverrno;
                        buf = cp;
                        (void) gmtime_r(&t, tm);
                        *flagsp |= F_GMT;
                        }
                        break;

                case 'Y':
                case 'y':
                        if (*buf == '\0' || isspace(*buf))
                                break;

                        if (!isdigit(*buf))
                                return (NULL);

                        len = (c == 'Y') ? 4 : 2;
                        for (i = 0; len && isdigit(*buf); buf++) {
                                i *= 10;
                                i += *buf - '0';
                                len--;
                        }
                        if (c == 'Y')
                                i -= 1900;
                        if (c == 'y' && i < 69)
                                i += 100;
                        if (i < 0)
                                return (NULL);

                        tm->tm_year = i;

                        break;

                case 'Z':
                        {
                        const char *cp = buf;
                        char *zonestr;

                        while (isupper(*cp))
                                ++cp;
                        if (cp - buf) {
                                zonestr = alloca(cp - buf + 1);
                                (void) strncpy(zonestr, buf, cp - buf);
                                zonestr[cp - buf] = '\0';
                                tzset();
                                if (strcmp(zonestr, "GMT") == 0) {
                                        *flagsp |= F_GMT;
                                } else if (0 == strcmp(zonestr, tzname[0])) {
                                        tm->tm_isdst = 0;
                                } else if (0 == strcmp(zonestr, tzname[1])) {
                                        tm->tm_isdst = 1;
                                } else {
                                        return (NULL);
                                }
                                buf += cp - buf;
                        }
                        }
                        break;

                case 'z':
                        {
                        int sign = 1;

                        if (*buf != '+') {
                                if (*buf == '-')
                                        sign = -1;
                                else
                                        return (NULL);
                        }
                        buf++;
                        i = 0;
                        for (len = 4; len > 0; len--) {
                                if (!isdigit(*buf))
                                        return (NULL);
                                i *= 10;
                                i += *buf - '0';
                                buf++;
                        }

                        tm->tm_hour -= sign * (i / 100);
                        tm->tm_min -= sign * (i % 100);
                        *flagsp |= F_GMT;
                        }
                        break;
                case 'n':
                case 't':
                        while (isspace(*buf))
                                buf++;
                        break;
                }
        }

        if (!recurse) {
                if (buf && (*flagsp & F_GMT)) {
                        time_t t = timegm(tm);
                        (void) localtime_r(&t, tm);
                }
        }

        return ((char *)buf);
}

char *
strptime(const char *_RESTRICT_KYWD buf, const char *_RESTRICT_KYWD fmt,
    struct tm *_RESTRICT_KYWD tm)
{
        int     flags = 0;

        (void) memset(tm, 0, sizeof (*tm));

        return (__strptime(buf, fmt, tm, &flags, uselocale(NULL)));
}

/*
 * This is used by Solaris, and is a variant that does not clear the
 * incoming tm.  It is triggered by -D_STRPTIME_DONTZERO.
 */
char *
__strptime_dontzero(const char *_RESTRICT_KYWD buf,
    const char *_RESTRICT_KYWD fmt, struct tm *_RESTRICT_KYWD tm)
{
        int     flags = 0;

        return (__strptime(buf, fmt, tm, &flags, uselocale(NULL)));
}

/*
 * strptime_l is an extension that seems natural, and indeed, MacOS X
 * includes it within their <xlocale.h> and it is part of GNU libc as well.
 * For now we restrict it to the cases where strict namespaces are not
 * included.  We expect to see it in a future version of POSIX.  locale_t is
 * not a restrict, since the spec for it doesn't assume its a pointer.  We
 * therefore pass it analagously to the way strftime_l is specified.
 *
 * We are not providing a non-zeroing version at this time.
 */
char *
strptime_l(const char *_RESTRICT_KYWD buf, const char *_RESTRICT_KYWD fmt,
    struct tm *_RESTRICT_KYWD tm, locale_t loc)
{
        int     flags =  0;

        (void) memset(tm, 0, sizeof (*tm));

        return (__strptime(buf, fmt, tm, &flags, loc));
}