text: /*-
   * SPDX-License-Identifier: BSD-3-Clause
   *
   * 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.
   */
  
  #ifndef lint
  static char const copyright[] =
  "@(#) Copyright (c) 1985, 1987, 1988, 1993\n\
  	The Regents of the University of California.  All rights reserved.\n";
  #endif /* not lint */
  
  #if 0
  #ifndef lint
  static char sccsid[] = "@(#)date.c	8.2 (Berkeley) 4/28/95";
  #endif /* not lint */
  #endif
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  #include <sys/param.h>
  #include <sys/time.h>
  #include <sys/stat.h>
  
  #include <ctype.h>
  #include <err.h>
  #include <locale.h>
  #include <stdbool.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <syslog.h>
  #include <unistd.h>
  #include <utmpx.h>
  
  #include "vary.h"
  
  #ifndef	TM_YEAR_BASE
  #define	TM_YEAR_BASE	1900
  #endif
  
  static time_t tval;
  
  static void badformat(void);
  static void iso8601_usage(const char *);
  static void multipleformats(void);
  static void printdate(const char *);
  static void printisodate(struct tm *);
  static void setthetime(const char *, const char *, int);
  static void usage(void);
  
  static const struct iso8601_fmt {
  	const char *refname;
  	const char *format_string;
  } iso8601_fmts[] = {
  	{ "date", "%Y-%m-%d" },
  	{ "hours", "T%H" },
  	{ "minutes", ":%M" },
  	{ "seconds", ":%S" },
  };
  static const struct iso8601_fmt *iso8601_selected;
  
  static const char *rfc2822_format = "%a, %d %b %Y %T %z";
  
  int
  main(int argc, char *argv[])
  {
  	int ch, rflag;
  	bool Iflag, jflag, Rflag;
  	const char *format;
  	char buf[1024];
  	char *fmt;
  	char *tmp;
  	struct vary *v;
  	const struct vary *badv;
  	struct tm *lt;
  	struct stat sb;
  	size_t i;
  
  	v = NULL;
  	fmt = NULL;
  	(void) setlocale(LC_TIME, "");
  	rflag = 0;
  	Iflag = jflag = Rflag = 0;
  	while ((ch = getopt(argc, argv, "f:I::jnRr:uv:")) != -1)
  		switch((char)ch) {
  		case 'f':
  			fmt = optarg;
  			break;
  		case 'I':
  			if (Rflag)
  				multipleformats();
  			Iflag = 1;
  			if (optarg == NULL) {
  				iso8601_selected = iso8601_fmts;
  				break;
  			}
  			for (i = 0; i < nitems(iso8601_fmts); i++)
  				if (strcmp(optarg, iso8601_fmts[i].refname) == 0)
  					break;
  			if (i == nitems(iso8601_fmts))
  				iso8601_usage(optarg);
  
  			iso8601_selected = &iso8601_fmts[i];
  			break;
  		case 'j':
  			jflag = 1;	/* don't set time */
  			break;
  		case 'n':
  			break;
  		case 'R':		/* RFC 2822 datetime format */
  			if (Iflag)
  				multipleformats();
  			Rflag = 1;
  			break;
  		case 'r':		/* user specified seconds */
  			rflag = 1;
  			tval = strtoq(optarg, &tmp, 0);
  			if (*tmp != 0) {
  				if (stat(optarg, &sb) == 0)
  					tval = sb.st_mtim.tv_sec;
  				else
  					usage();
  			}
  			break;
  		case 'u':		/* do everything in UTC */
  			(void)setenv("TZ", "UTC0", 1);
  			break;
  		case 'v':
  			v = vary_append(v, optarg);
  			break;
  		default:
  			usage();
  		}
  	argc -= optind;
  	argv += optind;
  
  	if (!rflag && time(&tval) == -1)
  		err(1, "time");
  
  	format = "%+";
  
  	if (Rflag)
  		format = rfc2822_format;
  
  	/* allow the operands in any order */
  	if (*argv && **argv == '+') {
  		if (Iflag)
  			multipleformats();
  		format = *argv + 1;
  		++argv;
  	}
  
  	if (*argv) {
  		setthetime(fmt, *argv, jflag);
  		++argv;
  	} else if (fmt != NULL)
  		usage();
  
  	if (*argv && **argv == '+') {
  		if (Iflag)
  			multipleformats();
  		format = *argv + 1;
  	}
  
  	lt = localtime(&tval);
  	if (lt == NULL)
  		errx(1, "invalid time");
  	badv = vary_apply(v, lt);
  	if (badv) {
  		fprintf(stderr, "%s: Cannot apply date adjustment\n",
  			badv->arg);
  		vary_destroy(v);
  		usage();
  	}
  	vary_destroy(v);
  
  	if (Iflag)
  		printisodate(lt);
  
  	if (format == rfc2822_format)
  		/*
  		 * When using RFC 2822 datetime format, don't honor the
  		 * locale.
  		 */
  		setlocale(LC_TIME, "C");
  
  	(void)strftime(buf, sizeof(buf), format, lt);
  	printdate(buf);
  }
  
  static void
  printdate(const char *buf)
  {
  	(void)printf("%s\n", buf);
  	if (fflush(stdout))
  		err(1, "stdout");
  	exit(EXIT_SUCCESS);
  }
  
  static void
  printisodate(struct tm *lt)
  {
  	const struct iso8601_fmt *it;
  	char fmtbuf[32], buf[32], tzbuf[8];
  
  	fmtbuf[0] = 0;
  	for (it = iso8601_fmts; it <= iso8601_selected; it++)
  		strlcat(fmtbuf, it->format_string, sizeof(fmtbuf));
  
  	(void)strftime(buf, sizeof(buf), fmtbuf, lt);
  
  	if (iso8601_selected > iso8601_fmts) {
  		(void)strftime(tzbuf, sizeof(tzbuf), "%z", lt);
  		memmove(&tzbuf[4], &tzbuf[3], 3);
  		tzbuf[3] = ':';
  		strlcat(buf, tzbuf, sizeof(buf));
  	}
  
  	printdate(buf);
  }
  
  #define	ATOI2(s)	((s) += 2, ((s)[-2] - '0') * 10 + ((s)[-1] - '0'))
  
  static void
  setthetime(const char *fmt, const char *p, int jflag)
  {
  	struct utmpx utx;
  	struct tm *lt;
  	struct timeval tv;
  	const char *dot, *t;
  	int century;
  
  	lt = localtime(&tval);
  	if (lt == NULL)
  		errx(1, "invalid time");
  	lt->tm_isdst = -1;		/* divine correct DST */
  
  	if (fmt != NULL) {
  		t = strptime(p, fmt, lt);
  		if (t == NULL) {
  			fprintf(stderr, "Failed conversion of ``%s''"
  				" using format ``%s''\n", p, fmt);
  			badformat();
  		} else if (*t != '\0')
  			fprintf(stderr, "Warning: Ignoring %ld extraneous"
  				" characters in date string (%s)\n",
  				(long) strlen(t), t);
  	} else {
  		for (t = p, dot = NULL; *t; ++t) {
  			if (isdigit(*t))
  				continue;
  			if (*t == '.' && dot == NULL) {
  				dot = t;
  				continue;
  			}
  			badformat();
  		}
  
  		if (dot != NULL) {			/* .ss */
  			dot++; /* *dot++ = '\0'; */
  			if (strlen(dot) != 2)
  				badformat();
  			lt->tm_sec = ATOI2(dot);
  			if (lt->tm_sec > 61)
  				badformat();
  		} else
  			lt->tm_sec = 0;
  
  		century = 0;
  		/* if p has a ".ss" field then let's pretend it's not there */
  		switch (strlen(p) - ((dot != NULL) ? 3 : 0)) {
  		case 12:				/* cc */
  			lt->tm_year = ATOI2(p) * 100 - TM_YEAR_BASE;
  			century = 1;
  			/* FALLTHROUGH */
  		case 10:				/* yy */
  			if (century)
  				lt->tm_year += ATOI2(p);
  			else {
  				lt->tm_year = ATOI2(p);
  				if (lt->tm_year < 69)	/* hack for 2000 ;-} */
  					lt->tm_year += 2000 - TM_YEAR_BASE;
  				else
  					lt->tm_year += 1900 - TM_YEAR_BASE;
  			}
  			/* FALLTHROUGH */
  		case 8:					/* mm */
  			lt->tm_mon = ATOI2(p);
  			if (lt->tm_mon > 12)
  				badformat();
  			--lt->tm_mon;		/* time struct is 0 - 11 */
  			/* FALLTHROUGH */
  		case 6:					/* dd */
  			lt->tm_mday = ATOI2(p);
  			if (lt->tm_mday > 31)
  				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 GMT clock time */
  	if ((tval = mktime(lt)) == -1)
  		errx(1, "nonexistent time");
  
  	if (!jflag) {
  		utx.ut_type = OLD_TIME;
  		memset(utx.ut_id, 0, sizeof(utx.ut_id));
  		(void)gettimeofday(&utx.ut_tv, NULL);
  		pututxline(&utx);
  		tv.tv_sec = tval;
  		tv.tv_usec = 0;
  		if (settimeofday(&tv, NULL) != 0)
  			err(1, "settimeofday (timeval)");
  		utx.ut_type = NEW_TIME;
  		(void)gettimeofday(&utx.ut_tv, NULL);
  		pututxline(&utx);
  
  		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
  iso8601_usage(const char *badarg)
  {
  	errx(1, "invalid argument '%s' for -I", badarg);
  }
  
  static void
  multipleformats(void)
  {
  	errx(1, "multiple output formats specified");
  }
  
  static void
  usage(void)
  {
  	(void)fprintf(stderr, "%s\n%s\n%s\n",
  	    "usage: date [-jnRu] [-r seconds|file] [-v[+|-]val[ymwdHMS]]",
  	    "            "
  	    "[-I[date | hours | minutes | seconds]]",
  	    "            "
  	    "[-f fmt date | [[[[[cc]yy]mm]dd]HH]MM[.ss]] [+format]"
  	    );
  	exit(1);
  }
  