tztime.c

Android 一些工具

/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/

#include <stdio.h>

#ifndef lint
#ifndef NOID
static char	elsieid[] = "@(#)localtime.c	8.3";
#endif /* !defined NOID */
#endif /* !defined lint */

/*
** Leap second handling from Bradley White.
** POSIX-style TZ environment variable handling from Guy Harris.
*/

/*LINTLIBRARY*/

#include "private.h"
#include "tzfile.h"
#include "fcntl.h"
#include "float.h"	/* for FLT_MAX and DBL_MAX */

#ifndef TZ_ABBR_MAX_LEN
#define TZ_ABBR_MAX_LEN	16
#endif /* !defined TZ_ABBR_MAX_LEN */

#ifndef TZ_ABBR_CHAR_SET
#define TZ_ABBR_CHAR_SET \
	"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
#endif /* !defined TZ_ABBR_CHAR_SET */

#ifndef TZ_ABBR_ERR_CHAR
#define TZ_ABBR_ERR_CHAR	'_'
#endif /* !defined TZ_ABBR_ERR_CHAR */

#define INDEXFILE "/system/usr/share/zoneinfo/zoneinfo.idx"
#define DATAFILE "/system/usr/share/zoneinfo/zoneinfo.dat"
#define NAMELEN 40
#define INTLEN 4
#define READLEN (NAMELEN + 3 * INTLEN)

/*
** SunOS 4.1.1 headers lack O_BINARY.
*/

#ifdef O_BINARY
#define OPEN_MODE	(O_RDONLY | O_BINARY)
#endif /* defined O_BINARY */
#ifndef O_BINARY
#define OPEN_MODE	O_RDONLY
#endif /* !defined 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 */

static char		wildabbr[] = WILDABBR;

static const char	gmt[] = "GMT";

/*
** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
** We default to US rules as of 1999-08-17.
** POSIX 1003.1 section 8.1.1 says that the default DST rules are
** implementation dependent; for historical reasons, US rules are a
** common default.
*/
#ifndef TZDEFRULESTRING
#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
#endif /* !defined TZDEFDST */

struct ttinfo {				/* time type information */
	long		tt_gmtoff;	/* UTC 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 */
	int		tt_ttisgmt;	/* TRUE if transition is UTC */
};

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

#define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))

#ifdef TZNAME_MAX
#define MY_TZNAME_MAX	TZNAME_MAX
#endif /* defined TZNAME_MAX */
#ifndef TZNAME_MAX
#define MY_TZNAME_MAX	255
#endif /* !defined TZNAME_MAX */

struct state {
	int		leapcnt;
	int		timecnt;
	int		typecnt;
	int		charcnt;
	int		goback;
	int		goahead;
	time_t		ats[TZ_MAX_TIMES];
	unsigned char	types[TZ_MAX_TIMES];
	struct ttinfo	ttis[TZ_MAX_TYPES];
	char		chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof gmt),
				(2 * (MY_TZNAME_MAX + 1)))];
	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 time_t		detzcode64 P((const char * codep));
static int		differ_by_repeat P((time_t t1, time_t t0));
static const char *	getzname P((const char * strp));
static const char *	getqzname P((const char * strp, const int delim));
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 struct tm *	gmtsub P((const time_t * timep, long offset,
				struct tm * tmp));
static struct tm *	localsub P((const time_t * timep, long offset,
				struct tm * tmp, struct state *sp));
static int		increment_overflow P((int * number, int delta));
static int		leaps_thru_end_of P((int y));
static int		long_increment_overflow P((long * number, int delta));
static int		long_normalize_overflow P((long * tensptr,
				int * unitsptr, int base));
static int		normalize_overflow P((int * tensptr, int * unitsptr,
				int base));
static void		settzname P((void));
static time_t		time1 P((struct tm * tmp,
				struct tm * (*funcp) P((const time_t *,
				long, struct tm *, const struct state* sp)),
				long offset, const struct state *	sp));
static time_t		time2 P((struct tm *tmp,
				struct tm * (*funcp) P((const time_t *,
				long, struct tm*, const struct state* sp)),
				long offset, int * okayp, const struct state *	sp));
static time_t		time2sub P((struct tm *tmp,
				struct tm * (*funcp) P((const time_t*, long, struct tm*,const struct state *sp)),
				long offset, int * okayp, int do_norm_secs,
                const struct state *sp));
static struct tm *	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,
				int doextend));
static int		tzload_uncached P((const char * name, struct state * sp,
				int doextend));
static int		tzparse P((const char * name, struct state * sp,
				int lastditch));

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

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

#define CACHE_COUNT 4
static char * g_cacheNames[CACHE_COUNT] = {0,0};
static struct state	g_cacheStates[CACHE_COUNT];
static int g_lastCache = 0;
static struct state g_utc;
unsigned char g_utcSet = 0;


#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX 255
#endif /* !defined TZ_STRLEN_MAX */

static char		lcl_TZname[TZ_STRLEN_MAX + 1];
static int		lcl_is_set;
static int		gmt_is_set;

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

/*
** Section 4.12.3 of X3.159-1989 requires that
**	Except for the strftime function, these functions [asctime,
**	ctime, gmtime, localtime] return values in one of two static
**	objects: a broken-down time structure and an array of char.
** Thanks to Paul Eggert for noting this.
*/

static struct tm	tm;

#ifdef USG_COMPAT
time_t			timezone = 0;
int			daylight = 0;
#endif /* defined USG_COMPAT */

#ifdef ALTZONE
time_t			altzone = 0;
#endif /* defined ALTZONE */

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

	result = (codep[0] & 0x80) ? ~0L : 0;
	for (i = 0; i < 4; ++i)
		result = (result << 8) | (codep[i] & 0xff);
	return result;
}

static time_t
detzcode64(codep)
const char * const	codep;
{
	register time_t	result;
	register int	i;

	result = (codep[0] & 0x80) ?  (~(int_fast64_t) 0) : 0;
	for (i = 0; i < 8; ++i)
		result = result * 256 + (codep[i] & 0xff);
	return result;
}

static int
differ_by_repeat(t1, t0)
const time_t	t1;
const time_t	t0;
{
	if (TYPE_INTEGRAL(time_t) &&
		TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
			return 0;
	return t1 - t0 == SECSPERREPEAT;
}

static int toint(unsigned char *s) {
    return (s[0] << 24) | (s[1] << 16) | (s[2] << 8) | s[3];
}

static int
tzload(const char *name, struct state * const sp, const int doextend)
{
    if (name) {
        int i, err;
        if (0 == strcmp(name, "UTC")) {
            if (!g_utcSet) {
                tzload_uncached(name, &g_utc, 1);
                g_utcSet = 1;
            }
            //printf("tzload: utc\n");
            *sp = g_utc;
            return 0;
        }
        for (i=0; i<CACHE_COUNT; i++) {
            if (g_cacheNames[i] && 0 == strcmp(name, g_cacheNames[i])) {
                *sp = g_cacheStates[i];
                //printf("tzload: hit: %s\n", name);
                return 0;
            }
        }
        //printf("tzload: miss: %s\n", name);
        g_lastCache++;
        if (g_lastCache >= CACHE_COUNT) {
            g_lastCache = 0;
        }
        i = g_lastCache;
        if (g_cacheNames[i]) {
            free(g_cacheNames[i]);
        }
        err = tzload_uncached(name, &(g_cacheStates[i]), 1);
        if (err == 0) {
            g_cacheNames[i] = strdup(name);
            *sp = g_cacheStates[i];
            return 0;
        } else {
            g_cacheNames[i] = NULL;
            return err;
        }
    }
    return tzload_uncached(name, sp, doextend);
}

static int
tzload_uncached(name, sp, doextend)
register const char *		name;
register struct state * const	sp;
register const int		doextend;
{
	register const char *		p;
	register int			i;
	register int			fid;
	register int			stored;
	register int			nread;
	union {
		struct tzhead	tzhead;
		char		buf[2 * sizeof(struct tzhead) +
					2 * sizeof *sp +
					4 * TZ_MAX_TIMES];
	} u;
    int                     toread = sizeof u.buf;

	if (name == NULL && (name = TZDEFAULT) == NULL)
		return -1;
	{
		register int	doaccess;
		/*
		** Section 4.9.1 of the C standard says that
		** "FILENAME_MAX expands to an integral constant expression
		** that is the size needed for an array of char large enough
		** to hold the longest file name string that the implementation
		** guarantees can be opened."
		*/
		char		fullname[FILENAME_MAX + 1];
		const char	*origname = name;

		if (name[0] == ':')
			++name;
		doaccess = name[0] == '/';
		if (!doaccess) {
			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);
			/*
			** Set doaccess if '.' (as in "../") shows up in name.
			*/
			if (strchr(name, '.') != NULL)
				doaccess = TRUE;
			name = fullname;
		}
		if (doaccess && access(name, R_OK) != 0)
			return -1;
		if ((fid = open(name, OPEN_MODE)) == -1) {
            char buf[READLEN];
            char name[NAMELEN + 1];
            int fidix = open(INDEXFILE, OPEN_MODE);
            int off = -1;

            if (fidix < 0) {
                return -1;
            }

            while (read(fidix, buf, sizeof(buf)) == sizeof(buf)) {
                memcpy(name, buf, NAMELEN);
                name[NAMELEN] = '\0';

                if (strcmp(name, origname) == 0) {
                    off = toint((unsigned char *) buf + NAMELEN);
                    toread = toint((unsigned char *) buf + NAMELEN + INTLEN);
                    break;
                }
            }

            close(fidix);

            if (off < 0)
                return -1;

            fid = open(DATAFILE, OPEN_MODE);

            if (fid < 0) {
                return -1;
            }

            if (lseek(fid, off, SEEK_SET) < 0) {
                return -1;
            }
        }
	}
	nread = read(fid, u.buf, toread);
	if (close(fid) < 0 || nread <= 0)
		return -1;
	for (stored = 4; stored <= 8; stored *= 2) {
		int		ttisstdcnt;
		int		ttisgmtcnt;

		ttisstdcnt = (int) detzcode(u.tzhead.tzh_ttisstdcnt);
		ttisgmtcnt = (int) detzcode(u.tzhead.tzh_ttisgmtcnt);
		sp->leapcnt = (int) detzcode(u.tzhead.tzh_leapcnt);
		sp->timecnt = (int) detzcode(u.tzhead.tzh_timecnt);
		sp->typecnt = (int) detzcode(u.tzhead.tzh_typecnt);
		sp->charcnt = (int) detzcode(u.tzhead.tzh_charcnt);
		p = u.tzhead.tzh_charcnt + sizeof u.tzhead.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) ||
			(ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
				return -1;
		if (nread - (p - u.buf) <
			sp->timecnt * stored +		/* ats */
			sp->timecnt +			/* types */
			sp->typecnt * 6 +		/* ttinfos */
			sp->charcnt +			/* chars */
			sp->leapcnt * (stored + 4) +	/* lsinfos */
			ttisstdcnt +			/* ttisstds */
			ttisgmtcnt)			/* ttisgmts */
				return -1;
		for (i = 0; i < sp->timecnt; ++i) {
			sp->ats[i] = (stored == 4) ?
				detzcode(p) : detzcode64(p);
			p += stored;
		}
		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 = (stored == 4) ?