ctime.c

Algorithms for Image Processing and Computer Vision Source Code

/* This is file CTIME.C */
/* This file may have been modified by DJ Delorie (Jan 1991).  If so,
** these modifications are Coyright (C) 1993 DJ Delorie, 24 Kirsten Ave,
** Rochester NH, 03867-2954, USA.
*/

/*
 * Copyright (c) 1987, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Arthur David Olson of the National Cancer Institute.
 *
 * Redistribution and use in source and binary forms are permitted provided
 * that: (1) source distributions retain this entire copyright notice and
 * comment, and (2) distributions including binaries display the following
 * acknowledgement:  ``This product includes software developed by the
 * University of California, Berkeley and its contributors'' in the
 * documentation or other materials provided with the distribution and in
 * all advertising materials mentioning features or use of this software.
 * 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ctime.c	5.23 (Berkeley) 6/22/90";
#endif /* LIBC_SCCS and not lint */

/*
** Leap second handling from Bradley White ([e-mail]).
** POSIX-style TZ environment variable handling from Guy Harris
** ([e-mail]).
*/

/*LINTLIBRARY*/

#include <sys/param.h>
#include <fcntl.h>
#include <time.h>
#include <tzfile.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>

#ifdef __STDC__
#include <stdlib.h>

#define P(s)		s
#define alloc_size_t	size_t
#define qsort_size_t	size_t
#define fread_size_t	size_t
#define fwrite_size_t	size_t

#else /* !defined __STDC__ */

#define P(s)		()
#define const
#define volatile

typedef char *		genericptr_t;
typedef unsigned	alloc_size_t;
typedef int		qsort_size_t;
typedef int		fread_size_t;
typedef int		fwrite_size_t;

extern char *	calloc();
extern char *	malloc();
extern char *	realloc();
extern char *	getenv();

#endif /* !defined __STDC__ */

extern unsigned long	time();

#define ACCESS_MODE	O_RDONLY|O_BINARY
#define OPEN_MODE	O_RDONLY|O_BINARY

#ifndef WILDABBR
/*
** Someone might make incorrect use of a time zone abbreviation:
**	1.	They might reference tzname[0] before calling tzset (explicitly
**	 	or implicitly).
**	2.	They might reference tzname[1] before calling tzset (explicitly
**	 	or implicitly).
**	3.	They might reference tzname[1] after setting to a time zone
**		in which Daylight Saving Time is never observed.
**	4.	They might reference tzname[0] after setting to a time zone
**		in which Standard Time is never observed.
**	5.	They might reference tm.TM_ZONE after calling offtime.
** What's best to do in the above cases is open to debate;
** for now, we just set things up so that in any of the five cases
** WILDABBR is used.  Another possibility:  initialize tzname[0] to the
** string "tzname[0] used before set", and similarly for the other cases.
** And another:  initialize tzname[0] to "ERA", with an explanation in the
** manual page of what this "time zone abbreviation" means (doing this so
** that tzname[0] has the "normal" length of three characters).
*/
#define WILDABBR	"   "
#endif /* !defined WILDABBR */

#ifndef TRUE
#define TRUE		1
#define FALSE		0
#endif /* !defined TRUE */

static const char GMT[] = "GMT";

struct ttinfo {				/* time type information */
	long		tt_gmtoff;	/* GMT offset in seconds */
	int		tt_isdst;	/* used to set tm_isdst */
	int		tt_abbrind;	/* abbreviation list index */
	int		tt_ttisstd;	/* TRUE if transition is std time */
};

struct lsinfo {				/* leap second information */
	time_t		ls_trans;	/* transition time */
	long		ls_corr;	/* correction to apply */
};

struct state {
	int		leapcnt;
	int		timecnt;
	int		typecnt;
	int		charcnt;
	time_t		ats[TZ_MAX_TIMES];
	unsigned char	types[TZ_MAX_TIMES];
	struct ttinfo	ttis[TZ_MAX_TYPES];
	char		chars[(TZ_MAX_CHARS + 1 > sizeof GMT) ?
				TZ_MAX_CHARS + 1 : sizeof GMT];
	struct lsinfo	lsis[TZ_MAX_LEAPS];
};

struct rule {
	int		r_type;		/* type of rule--see below */
	int		r_day;		/* day number of rule */
	int		r_week;		/* week number of rule */
	int		r_mon;		/* month number of rule */
	long		r_time;		/* transition time of rule */
};

#define	JULIAN_DAY		0	/* Jn - Julian day */
#define	DAY_OF_YEAR		1	/* n - day of year */
#define	MONTH_NTH_DAY_OF_WEEK	2	/* Mm.n.d - month, week, day of week */

/*
** Prototypes for static functions.
*/

static long		detzcode P((const char * codep));
static const char *	getzname P((const char * strp));
static const char *	getnum P((const char * strp, int * nump, int min,
				int max));
static const char *	getsecs P((const char * strp, long * secsp));
static const char *	getoffset P((const char * strp, long * offsetp));
static const char *	getrule P((const char * strp, struct rule * rulep));
static void		gmtload P((struct state * sp));
static void		gmtsub P((const time_t * timep, long offset,
				struct tm * tmp));
static void		localsub P((const time_t * timep, long offset,
				struct tm * tmp));
static void		normalize P((int * tensptr, int * unitsptr, int base));
static void		settzname P((void));
static time_t		time1 P((struct tm * tmp, void (* funcp)(),
				long offset));
static time_t		time2 P((struct tm *tmp, void (* funcp)(),
				long offset, int * okayp));
static void		timesub P((const time_t * timep, long offset,
				const struct state * sp, struct tm * tmp));
static int		tmcomp P((const struct tm * atmp,
				const struct tm * btmp));
static time_t		transtime P((time_t janfirst, int year,
				const struct rule * rulep, long offset));
static int		tzload P((const char * name, struct state * sp));
static int		tzparse P((const char * name, struct state * sp,
				int lastditch));

#ifdef ALL_STATE
static struct state *	lclptr;
static struct state *	gmtptr;
#endif /* defined ALL_STATE */

#ifndef ALL_STATE
static struct state	lclmem;
static struct state	gmtmem;
#define lclptr		(&lclmem)
#define gmtptr		(&gmtmem)
#endif /* State Farm */

static int		lcl_is_set;
static int		gmt_is_set;

char *			tzname[2] = {
	WILDABBR,
	WILDABBR
};

static long
detzcode(codep)
const char * const	codep;
{
	register long	result;
	register int	i;

	result = 0;
	for (i = 0; i < 4; ++i)
		result = (result << 8) | (codep[i] & 0xff);
	return result;
}

static void
settzname()
{
	register const struct state * const	sp = lclptr;
	register int				i;

	tzname[0] = WILDABBR;
	tzname[1] = WILDABBR;
#ifdef ALL_STATE
	if (sp == NULL) {
		tzname[0] = tzname[1] = GMT;
		return;
	}
#endif /* defined ALL_STATE */
	for (i = 0; i < sp->typecnt; ++i) {
		register const struct ttinfo * const	ttisp = &sp->ttis[i];

		tzname[ttisp->tt_isdst] =
			(char *) &sp->chars[ttisp->tt_abbrind];
#if 0
		if (ttisp->tt_isdst)
			_daylight = 1;
		if (i == 0 || !ttisp->tt_isdst)
			_timezone = -(ttisp->tt_gmtoff);
		if (i == 0 || ttisp->tt_isdst)
			_altzone = -(ttisp->tt_gmtoff);
#endif
	}
	/*
	** And to get the latest zone names into tzname. . .
	*/
	for (i = 0; i < sp->timecnt; ++i) {
		register const struct ttinfo * const	ttisp =
							&sp->ttis[sp->types[i]];

		tzname[ttisp->tt_isdst] =
			(char *) &sp->chars[ttisp->tt_abbrind];
	}
}

static char *
tzdir()
{
  static char dir[80]={0}, *cp;
  if (dir[0] == 0)
  {
    if ((cp = getenv("TZDIR")))
    {
      strcpy(dir, cp);
    }
    else if ((cp = getenv("DJDIR")))
    {
      strcpy(dir, cp);
      strcat(dir, "/zoneinfo");
    }
    else
      strcpy(dir, "./");
  }
  return dir;
}

static int
tzload(name, sp)
register const char *		name;
register struct state * const	sp;
{
	register const char *	p;
	register int		i;
	register int		fid;

	if (name == NULL && (name = TZDEFAULT) == NULL)
		return -1;
	{
		char		fullname[FILENAME_MAX + 1];

		if (name[0] == ':')
			++name;
		if (name[0] != '/') {
			if ((p = tzdir()) == NULL)
				return -1;
			if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
				return -1;
			(void) strcpy(fullname, p);
			(void) strcat(fullname, "/");
			(void) strcat(fullname, name);
			name = fullname;
		}
		if ((fid = open(name, OPEN_MODE)) == -1)
			return -1;
	}
	{
		register const struct tzhead *	tzhp;
		char				buf[sizeof *sp + sizeof *tzhp];
		int				ttisstdcnt;

		i = read(fid, buf, sizeof buf);
		if (close(fid) != 0 || i < sizeof *tzhp)
			return -1;
		tzhp = (struct tzhead *) buf;
		ttisstdcnt = (int) detzcode(tzhp->tzh_ttisstdcnt);
		sp->leapcnt = (int) detzcode(tzhp->tzh_leapcnt);
		sp->timecnt = (int) detzcode(tzhp->tzh_timecnt);
		sp->typecnt = (int) detzcode(tzhp->tzh_typecnt);
		sp->charcnt = (int) detzcode(tzhp->tzh_charcnt);
		if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
			sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
			sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
			sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
			(ttisstdcnt != sp->typecnt && ttisstdcnt != 0))
				return -1;
		if (i < sizeof *tzhp +
			sp->timecnt * (4 + sizeof (char)) +
			sp->typecnt * (4 + 2 * sizeof (char)) +
			sp->charcnt * sizeof (char) +
			sp->leapcnt * 2 * 4 +
			ttisstdcnt * sizeof (char))
				return -1;
		p = buf + sizeof *tzhp;
		for (i = 0; i < sp->timecnt; ++i) {
			sp->ats[i] = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->timecnt; ++i) {
			sp->types[i] = (unsigned char) *p++;
			if (sp->types[i] >= sp->typecnt)
				return -1;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			ttisp->tt_gmtoff = detzcode(p);
			p += 4;
			ttisp->tt_isdst = (unsigned char) *p++;
			if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
				return -1;
			ttisp->tt_abbrind = (unsigned char) *p++;
			if (ttisp->tt_abbrind < 0 ||
				ttisp->tt_abbrind > sp->charcnt)
					return -1;
		}
		for (i = 0; i < sp->charcnt; ++i)
			sp->chars[i] = *p++;
		sp->chars[i] = '\0';	/* ensure '\0' at end */
		for (i = 0; i < sp->leapcnt; ++i) {
			register struct lsinfo *	lsisp;

			lsisp = &sp->lsis[i];
			lsisp->ls_trans = detzcode(p);
			p += 4;
			lsisp->ls_corr = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			register struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			if (ttisstdcnt == 0)
				ttisp->tt_ttisstd = FALSE;
			else {
				ttisp->tt_ttisstd = *p++;
				if (ttisp->tt_ttisstd != TRUE &&
					ttisp->tt_ttisstd != FALSE)
						return -1;
			}
		}
	}
	return 0;
}

static const int	mon_lengths[2][MONSPERYEAR] = {
	{ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
	{ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};

static const int	year_lengths[2] = {
	DAYSPERNYEAR, DAYSPERLYEAR
};

/*
** Given a pointer into a time zone string, scan until a character that is not
** a valid character in a zone name is found.  Return a pointer to that
** character.
*/

static const char *
getzname(strp)
register const char *	strp;
{
	register char	c;

	while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' &&
		c != '+')
			++strp;
	return strp;
}

/*
** Given a pointer into a time zone string, extract a number from that string.
** Check that the number is within a specified range; if it is not, return
** NULL.
** Otherwise, return a pointer to the first character not part of the number.
*/

static const char *
getnum(strp, nump, min, max)
register const char *	strp;
int * const		nump;
const int		min;
const int		max;
{
	register char	c;
	register int	num;

	if (strp == NULL || !isdigit(*strp))
		return NULL;
	num = 0;
	while ((c = *strp) != '\0' && isdigit(c)) {
		num = num * 10 + (c - '0');
		if (num > max)
			return NULL;	/* illegal value */
		++strp;
	}
	if (num < min)
		return NULL;		/* illegal value */
	*nump = num;
	return strp;
}

/*
** Given a pointer into a time zone string, extract a number of seconds,
** in hh[:mm[:ss]] form, from the string.
** If any error occurs, return NULL.
** Otherwise, return a pointer to the first character not part of the number
** of seconds.
*/

static const char *
getsecs(strp, secsp)
register const char *	strp;
long * const		secsp;
{
	int	num;

	strp = getnum(strp, &num, 0, HOURSPERDAY);
	if (strp == NULL)