/*      $OpenBSD: date.c,v 1.60 2024/04/28 16:43:15 florian Exp $       */
/*      $NetBSD: date.c,v 1.11 1995/09/07 06:21:05 jtc Exp $    */

/*
 * Copyright (c) 1985, 1987, 1988, 1993
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/types.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>
#include <util.h>

extern  char *__progname;

time_t tval;
int jflag;
int slidetime;

static void setthetime(char *, const char *);
static void badformat(void);
static void __dead usage(void);

int
main(int argc, char *argv[])
{
        const char *errstr;
        struct tm *tp;
        int ch, rflag;
        char *format, buf[1024], *outzone = NULL;
        const char *pformat = NULL;

        rflag = 0;
        while ((ch = getopt(argc, argv, "af:jr:uz:")) != -1)
                switch(ch) {
                case 'a':
                        slidetime = 1;
                        break;
                case 'f':               /* parse with strptime */
                        pformat = optarg;
                        break;
                case 'j':               /* don't set */
                        jflag = 1;
                        break;
                case 'r':               /* user specified seconds */
                        rflag = 1;
                        tval = strtonum(optarg, LLONG_MIN, LLONG_MAX, &errstr);
                        if (errstr)
                                errx(1, "seconds is %s: %s", errstr, optarg);
                        break;
                case 'u':               /* do everything in UTC */
                        if (setenv("TZ", "UTC", 1) == -1)
                                err(1, "cannot unsetenv TZ");
                        break;
                case 'z':
                        outzone = optarg;
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (!rflag && time(&tval) == -1)
                err(1, "time");

        format = "%a %b %e %H:%M:%S %Z %Y";

        /* allow the operands in any order */
        if (*argv && **argv == '+') {
                format = *argv + 1;
                argv++;
                argc--;
        }

        if (*argv) {
                setthetime(*argv, pformat);
                argv++;
                argc--;
        }

        if (pledge("stdio", NULL) == -1)
                err(1, "pledge");

        if (*argv && **argv == '+') {
                format = *argv + 1;
                argc--;
        }

        if (argc > 0)
                errx(1, "too many arguments");

        if (outzone)
                setenv("TZ", outzone, 1);

        tp = localtime(&tval);
        if (tp == NULL)
                errx(1, "conversion error");
        (void)strftime(buf, sizeof(buf), format, tp);
        (void)printf("%s\n", buf);
        return 0;
}

#define ATOI2(ar)       ((ar) += 2, ((ar)[-2] - '0') * 10 + ((ar)[-1] - '0'))
void
setthetime(char *p, const char *pformat)
{
        struct tm *lt, tm;
        struct timeval tv;
        char *dot, *t;
        time_t now;
        int yearset = 0;

        /* Let us set the time even if logwtmp would fail. */
        unveil("/var/log/wtmp", "w");
        if (pledge("stdio settime wpath", NULL) == -1)
                err(1, "pledge");

        lt = localtime(&tval);
        if (lt == NULL)
                errx(1, "conversion error");

        lt->tm_isdst = -1;                      /* correct for DST */

        if (pformat) {
                tm = *lt;
                if (strptime(p, pformat, &tm) == NULL) {
                        fprintf(stderr, "trouble %s %s\n", p, pformat);
                        badformat();
                }
                lt = &tm;
        } else {
                for (t = p, dot = NULL; *t; ++t) {
                        if (isdigit((unsigned char)*t))
                                continue;
                        if (*t == '.' && dot == NULL) {
                                dot = t;
                                continue;
                        }
                        badformat();
                }

                if (dot != NULL) {                      /* .SS */
                        *dot++ = '\0';
                        if (strlen(dot) != 2)
                                badformat();
                        lt->tm_sec = ATOI2(dot);
                        if (lt->tm_sec > 61)
                                badformat();
                } else
                        lt->tm_sec = 0;

                switch (strlen(p)) {
                case 12:                                /* cc */
                        lt->tm_year = (ATOI2(p) * 100) - 1900;
                        yearset = 1;
                        /* FALLTHROUGH */
                case 10:                                /* yy */
                        if (!yearset) {
                                /* mask out current year, leaving only century */
                                lt->tm_year = ((lt->tm_year / 100) * 100);
                        }
                        lt->tm_year += ATOI2(p);
                        /* FALLTHROUGH */
                case 8:                                 /* mm */
                        lt->tm_mon = ATOI2(p);
                        if ((lt->tm_mon > 12) || !lt->tm_mon)
                                badformat();
                        --lt->tm_mon;                   /* time struct is 0 - 11 */
                        /* FALLTHROUGH */
                case 6:                                 /* dd */
                        lt->tm_mday = ATOI2(p);
                        if ((lt->tm_mday > 31) || !lt->tm_mday)
                                badformat();
                        /* FALLTHROUGH */
                case 4:                                 /* HH */
                        lt->tm_hour = ATOI2(p);
                        if (lt->tm_hour > 23)
                                badformat();
                        /* FALLTHROUGH */
                case 2:                                 /* MM */
                        lt->tm_min = ATOI2(p);
                        if (lt->tm_min > 59)
                                badformat();
                        break;
                default:
                        badformat();
                }
        }

        /* convert broken-down time to UTC clock time */
        if (pformat != NULL && strstr(pformat, "%s") != NULL)
                tval = timegm(lt);
        else
                tval = mktime(lt);
        if (tval == -1)
                errx(1, "specified date is outside allowed range");

        if (jflag)
                return;

        /* set the time */
        if (slidetime) {
                if ((now = time(NULL)) == -1)
                        err(1, "time");
                tv.tv_sec = tval - now;
                tv.tv_usec = 0;
                if (adjtime(&tv, NULL) == -1)
                        err(1, "adjtime");
        } else {
#ifndef SMALL
                logwtmp("|", "date", "");
#endif
                tv.tv_sec = tval;
                tv.tv_usec = 0;
                if (settimeofday(&tv, NULL))
                        err(1, "settimeofday");
#ifndef SMALL
                logwtmp("{", "date", "");
#endif
        }

        if ((p = getlogin()) == NULL)
                p = "???";
        syslog(LOG_AUTH | LOG_NOTICE, "date set by %s", p);
}

static void
badformat(void)
{
        warnx("illegal time format");
        usage();
}

static void __dead
usage(void)
{
        fprintf(stderr,
            "usage: %s [-aju] [-f pformat] [-r seconds]\n"
            "\t[-z output_zone] [+format] [[[[[[cc]yy]mm]dd]HH]MM[.SS]]\n",
            __progname);
        exit(1);
}