/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1987-2000 by Sun Microsystems, Inc.
 * All rights reserved.
 */

/*
 * Time management functions for auditreduce.
 */

#include "auditr.h"
#include <locale.h>
#include <libintl.h>

int     derive_date(char *, struct tm *);
void    derive_str(time_t, char *);
int     parse_time(char *, int);
time_t  tm_to_secs(struct tm *);

static int      check_time(struct tm *);
static int      days_in_year(int);
static char *do_invalid(void);
static time_t   local_to_gm(struct tm *);

static char *invalid_inter = NULL;

/*
 * Array of days per month.
 */
static int      days_month[] = {
                31, 28, 31, 30, 31, 30,
                31, 31, 30, 31, 30, 31 };

char *
do_invalid(void)
{
        if (invalid_inter == NULL)
                invalid_inter = gettext("invalid date/time format -");
        return (invalid_inter);
}

/*
 * .func        local_to_gm - local time to gm time.
 * .desc        Convert a local time to Greenwhich Mean Time.
 *      The local time is in the struct tm (time.h) format, which
 *      is easily got from an ASCII input format (10:30:33 Jan 3, 1983).
 *      It works by assuming that the given local time is a GMT time and
 *      then asking the system for the corresponding local time. It then
 *      takes the difference between those two as the correction for
 *      time zones and daylight savings time. This is accurate unless
 *      the time the user asked for is near a DST switch. Then a
 *      correction is applied - it is assumed that if we can produce
 *      a GMT that, when run through localtime(), is equivalent to the
 *      user's original input, we have an accurate GMT. The applied
 *      correction simply adjusts the GMT by the amount that the derived
 *      localtime was off. See?
 *      It should be noted that when there is DST there is one local hour
 *      a year when time occurs twice (in the fall) and one local hour a
 *      year when time never occurs (in the spring).
 *      memcpy() is used because the calls to gmtime() and localtime()
 *      return pointers to static structures that are overwritten at each
 *      call.
 * .call        ret = local_to_gm(tme).
 * .arg tme     - ptr to struct tm (see time.h) containing local time.
 * .ret time_t  - seconds since epoch of equivalent GMT.
 */
time_t
local_to_gm(struct tm *tme)
{
        time_t secs, gsecs, lsecs, save_gsecs;
        time_t r1secs, r2secs;
        struct tm ltime, gtime;

        /*
         * Get the input time in local and gmtime assuming the input
         * was GMT (which it probably wasn't).
         */
        r1secs = secs = tm_to_secs(tme);
        (void) memcpy((void *)&gtime, (void *)gmtime(&secs), sizeof (gtime));
        (void) memcpy((void *)&ltime, (void *)localtime(&secs), sizeof (ltime));

        /*
         * Get the local and gmtime in seconds, from the above tm structures.
         * Calculate difference between local and GMT.
         */
        gsecs = tm_to_secs(&gtime);
        lsecs = tm_to_secs(&ltime);
        secs = lsecs - gsecs;
        gsecs -= secs;
        (void) memcpy((void *)&ltime, (void *)localtime(&gsecs),
            sizeof (ltime));

        /*
         * Now get a computed local time from the computed gmtime.
         */
        save_gsecs = gsecs;
        r2secs = tm_to_secs(&ltime);

        /*
         * If the user given local time is != computed local time then
         * we need to try a correction.
         */
        if (r1secs != r2secs) {
                /*
                 * Use the difference between give localtime and computed
                 * localtime as our correction.
                 */
                if (r2secs > r1secs) {
                        gsecs -= r2secs - r1secs;
                } else {
                        gsecs += r1secs - r2secs;
                }
                /*
                 * And try the comparison again...
                 */
                (void) memcpy((void *)&ltime, (void *)localtime(&gsecs),
                    sizeof (ltime));
                r2secs = tm_to_secs(&ltime);
                /*
                 * If the correction fails then we are on a DST line
                 * and the user-given local time never happened.
                 * Do the best we can.
                 */
                if (r1secs != r2secs) {
                        gsecs = save_gsecs;
                }
        }
        return (gsecs);
}


/*
 * .func        tm_to_secs - convert to seconds.
 * .desc        Convert a tm time structure (time.h) into seconds since
 *      Jan 1, 1970 00:00:00. The time is assumed to be GMT and
 *      so no daylight savings time correction is applied. That
 *      is left up to the system calls (localtime(), gmtime()).
 * .call        ret = tm_to_secs(tme).
 * .arg tme     - ptr to tm structure.
 * .ret time_t  - number of seconds.
 */
time_t
tm_to_secs(struct tm *tme)
{
        int     leap_year = FALSE;
        int     days = 0;
        time_t num_sec = 0;

        int     sec = tme->tm_sec;
        int     min = tme->tm_min;
        int     hour = tme->tm_hour;
        int     day = tme->tm_mday;
        int     month = tme->tm_mon;
        int     year = tme->tm_year + 1900;

        if (days_in_year(year) == 366)
                leap_year = TRUE;

        while (year > 1970) {
                num_sec += days_in_year(--year) * 24 * 60 * 60;
        }
        while (month > 0) {
                days = days_month[--month];
                if (leap_year && month == 1) {  /* 1 is February */
                        days++;
                }
                num_sec += days * 24 * 60 * 60;
        }
        num_sec += --day * 24 * 60 * 60;
        num_sec += hour * 60 * 60;
        num_sec += min * 60;
        num_sec += sec;

        return (num_sec);
}


/*
 * .func        check_time - check tm structure.
 * .desc        Check the time in a tm structure to see if all of the fields
 *      are within range.
 * .call        err = check_time(tme).
 * .arg tme     - ptr to struct tm (see time.h).
 * .ret 0       - time is ok.
 * .ret -1      - time had a problem (description in error_str).
 */
int
check_time(struct tm *tme)
{
        error_str = NULL;

        if (tme->tm_sec < 0 || tme->tm_sec > 59) {
                (void) sprintf(errbuf,
                    gettext("seconds out of range (%d)"), tme->tm_sec + 1);
                error_str = errbuf;
        } else if (tme->tm_min < 0 || tme->tm_min > 59) {
                (void) sprintf(errbuf,
                    gettext("minutes out of range (%d)"), tme->tm_min + 1);
                error_str = errbuf;
        } else if (tme->tm_hour < 0 || tme->tm_hour > 23) {
                (void) sprintf(errbuf,
                    gettext("hours out of range (%d)"), tme->tm_hour + 1);
                error_str = errbuf;
        } else if (tme->tm_mon < 0 || tme->tm_mon > 11) {
                (void) sprintf(errbuf,
                    gettext("months out of range (%d)"), tme->tm_mon + 1);
                error_str = errbuf;
        } else if (tme->tm_year < 0) {
                (void) sprintf(errbuf,
                    gettext("years out of range (%d)"), tme->tm_year);
                error_str = errbuf;
        } else if (tme->tm_mday < 1 || tme->tm_mday > days_month[tme->tm_mon]) {
                if (!(days_in_year(tme->tm_year + 1900) == 366 &&
                        tme->tm_mon == 1 &&
                        tme->tm_mday == 29)) { /* leap year and February */
                        (void) sprintf(errbuf,
                            gettext("days out of range (%d)"), tme->tm_mday);
                        error_str = errbuf;
                }
        } else if (tme->tm_wday < 0 || tme->tm_wday > 6) {
                (void) sprintf(errbuf,
                    gettext("weekday out of range (%d)"), tme->tm_wday);
                error_str = errbuf;
        } else if (tme->tm_yday < 0 || tme->tm_yday > 365) {
                (void) sprintf(errbuf,
                    gettext("day of year out of range (%d)"), tme->tm_yday);
                error_str = errbuf;
        }

        if (error_str == NULL)
                return (0);
        else
                return (-1);
}


/*
 * .func parse_time.
 * .desc Parse a user time from the command line. The user time is assumed
 *      to be local time.
 *      Supported formats currently are:
 *      1.      +xt     - where x is a number and t is a type.
 *              types are - 's' second, 'm' minute, 'h' hour, and 'd' day.
 *      2.      yymmdd - yyyymmdd.
 *              yymmddhh - yyyymmddhh.
 *              yymmddhhmm - yyyymmddhhmm.
 *              yymmddhhmmss - yyyymmddhhmmss.
 * .call        err = parse_time(str, opt).
 * .arg str     - ptr to user input string.
 * .arg opt     - time option being processed.
 * .ret 0       - succesful.
 * .ret -1      - failure (error message in error_str).
 */
int
parse_time(char *str, int opt)
{
        int     ret, len, factor;
        char    *strxx;
        long    lnum;
        struct tm thentime;

        len = strlen(str);
        /*
         * If the strlen < 6 then in the "-b +2d" type of format.
         */
        if (len < 6) {
                if (*str++ != '+') {
                        (void) sprintf(errbuf, gettext("%s needs '+' (%s)"),
                            do_invalid(), str);
                        error_str = errbuf;
                        return (-1);
                }
                if (opt != 'b') {
                        (void) sprintf(errbuf,
                            gettext("%s only allowed with 'b' option (%s)"),
                            do_invalid(), str);
                        error_str = errbuf;
                        return (-1);
                }
                if (m_after == 0) {
                        (void) sprintf(errbuf,
                            gettext("must have -a to use -b +nx form (%s)"),
                            str);
                        error_str = errbuf;
                        return (-1);
                }
                /*
                 * Find out what type of offset it is - 's' 'm' 'h' or 'd'.
                 * Make sure that the offset is all numbers.
                 */
                if ((strxx = strpbrk(str, "dhms")) == NULL) {
                        (void) sprintf(errbuf,
                            gettext("%s needs 'd', 'h', 'm', or 's' (%s)"),
                            do_invalid(), str);
                        error_str = errbuf;
                        return (-1);
                } else {
                        ret = *strxx;
                        *strxx = '\0';
                }
                if (strlen(str) != strspn(str, "0123456789")) {
                        (void) sprintf(errbuf,
                            gettext("%s non-numeric offset (%s)"),
                            do_invalid(), str);
                        error_str = errbuf;
                        return (-1);
                }
                factor = 1;                     /* seconds is default */
                if (ret == 'd')                 /* days */
                        factor = 24 * 60 * 60;
                else if (ret == 'h')            /* hours */
                        factor = 60 * 60;
                else if (ret == 'm')            /* minutes */
                        factor = 60;
                lnum = atol(str);
                m_before = m_after + (lnum * factor);
                return (0);
        }
        /*
         * Must be a specific date/time format.
         */
        if (derive_date(str, &thentime))
                return (-1);
        /*
         * For 'd' option clear out the hh:mm:ss to get to the start of the day.
         * Then add one day's worth of seconds to get the 'b' time.
         */
        if (opt == 'd') {
                thentime.tm_sec = 0;
                thentime.tm_min = 0;
                thentime.tm_hour = 0;
                m_after = local_to_gm(&thentime);
                m_before = m_after + (24 * 60 * 60);
        } else if (opt == 'a') {
                m_after = local_to_gm(&thentime);
        } else if (opt == 'b') {
                m_before = local_to_gm(&thentime);
        }
        return (0);
}


/*
 * .func        derive_date.
 * .desc        Derive a date/time structure (tm) from a string.
 *      String is in one of these formats:
 *      [yy]yymmddhhmmss
 *      [yy]yymmddhhmm
 *      [yy]yymmddhh
 *      [yy]yymmdd
 * .call        ret = derive_date(str, tme).
 * .arg str     - ptr to input string.
 * .arg tme     - ptr to tm structure (time.h).
 * .ret 0       - no errors in string.
 * .ret -1      - errors in string (description in error_str).
 */
int
derive_date(char *str, struct tm *tme)
{
        char    *strs;
        char    *digits = "0123456789";
        size_t  len;
        struct tm nowtime;

        len = strlen(str);

        if (len != strspn(str, digits)) {
                (void) sprintf(errbuf, gettext("%s not all digits (%s)"),
                    do_invalid(), str);
                error_str = errbuf;
                return (-1);
        }
        if (len % 2) {
                (void) sprintf(errbuf, gettext("%s odd number of digits (%s)"),
                    do_invalid(), str);
                error_str = errbuf;
                return (-1);
        }
        /*
         * May need larger string storage to add '19' or '20'.
         */
        strs = (char *)a_calloc(1, len + 4);

        /*
         * Get current time to see what century it is.
         */
        (void) memcpy((char *)&nowtime, (char *)gmtime(&time_now),
            sizeof (nowtime));
        /*
         * If the year does not begin with '19' or '20', then report
         * an error and abort.
         */
        if ((str[0] != '1' || str[1] != '9') &&         /* 19XX */
            (str[0] != '2' || str[1] != '0')) {         /* 20XX */
                (void) sprintf(errbuf, gettext("invalid year (%c%c%c%c)"),
                    str[0], str[1], str[2], str[3]);
                error_str = errbuf;
                free(strs);
                return (-1);
        }

        len = strlen(str);                      /* may have changed */
        if (len < 8 || len > 14) {
                (void) sprintf(errbuf,
                        gettext("invalid date/time length (%s)"), str);
                error_str = errbuf;
                free(strs);
                return (-1);
        }
        /* unspecified values go to 0 */
        (void) memset((void *) tme, 0, (size_t)sizeof (*tme));
        (void) strncpy(strs, str, 4);
        strs[4] = '\0';
        tme->tm_year = atoi(strs) - 1900;       /* get the year */
        (void) strncpy(strs, str + 4, 2);
        strs[2] = '\0';
        tme->tm_mon = atoi(strs) - 1;           /* get months */
        (void) strncpy(strs, str + 6, 2);
        strs[2] = '\0';
        tme->tm_mday = atoi(strs);              /* get days */
        if (len >= 10) {                        /* yyyymmddhh */
                (void) strncpy(strs, str + 8, 2);
                strs[2] = '\0';
                tme->tm_hour = atoi(strs);      /* get hours */
        }
        if (len >= 12) {                        /* yyyymmddhhmm */
                (void) strncpy(strs, str + 10, 2);
                strs[2] = '\0';
                tme->tm_min = atoi(strs);       /* get minutes */
        }
        if (len >= 14) {                        /* yyyymmddhhmmss */
                (void) strncpy(strs, str + 12, 2);
                strs[2] = '\0';
                tme->tm_sec = atoi(strs);       /* get seconds */
        }
        free(strs);
        return (check_time(tme));               /* lastly check the ranges */
}


/*
 * .func        derive_str - derive string.
 * .desc        Derive a string representation of a time for a filename.
 *      The output is in the 14 character format yyyymmddhhmmss.
 * .call        derive_str(clock, buf).
 * .arg clock   - seconds since epoch.
 * .arg buf     - place to put resultant string.
 * .ret void.
 */
void
derive_str(time_t clock, char *buf)
{
        struct tm gtime;

        (void) memcpy((void *) & gtime, (void *)gmtime(&clock), sizeof (gtime));

        (void) sprintf(buf, "%4d", gtime.tm_year + 1900);
        (void) sprintf(buf + 4,  "%.2d", gtime.tm_mon + 1);
        (void) sprintf(buf + 6,  "%.2d", gtime.tm_mday);
        (void) sprintf(buf + 8,  "%.2d", gtime.tm_hour);
        (void) sprintf(buf + 10, "%.2d", gtime.tm_min);
        (void) sprintf(buf + 12, "%.2d", gtime.tm_sec);
        buf[14] = '\0';
}


int
days_in_year(int year)
{
        if (isleap(year))
                return (366);

        return (365);
}