localtime.c

asterisk 是一个很有知名度开源软件

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[e-mail]>
 *
 * Most of this code is in the public domain, so clarified as of
 * June 5, 1996 by Arthur David Olson ([e-mail]).
 *
 * All modifications to this code to abstract timezones away from
 * the environment are by Tilghman Lesher, <[e-mail]>, with
 * the copyright assigned to Digium.
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * Multi-timezone Localtime code
 *
 * The original source from this file may be obtained from ftp://elsie.nci.nih.gov/pub/
 */

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

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

/* #define DEBUG */

/*LINTLIBRARY*/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 144991 $")

#include <sys/stat.h>
#include <fcntl.h>
#include <float.h>

#include "private.h"
#include "tzfile.h"

#include "asterisk/lock.h"
#include "asterisk/localtime.h"
#include "asterisk/strings.h"
#include "asterisk/linkedlists.h"
#include "asterisk/utils.h"

#ifndef lint
#ifndef NOID
static char	__attribute__((unused)) elsieid[] = "@(#)localtime.c	8.5";
#endif /* !defined NOID */
#endif /* !defined lint */

#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 */

/*
** 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 */

static const char	gmt[] = "GMT";
static const struct timeval WRONG = { 0, 0 };

/*! \note
 * 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 */

/*!< \brief time type information */
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 */
};

/*! \brief leap second information */
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 */
#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX	255
#endif /* !defined TZ_STRLEN_MAX */

struct state {
	/*! Name of the file that this references */
	char    name[TZ_STRLEN_MAX + 1];
	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];
	AST_LIST_ENTRY(state) list;
};

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 int		gmtload P((struct state * sp));
static struct ast_tm *	gmtsub P((const struct timeval * timep, long offset,
				struct ast_tm * tmp));
static struct ast_tm *	localsub P((const struct timeval * timep, long offset,
				struct ast_tm * tmp, const 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, const int base));
static int		normalize_overflow P((int * tensptr, int * unitsptr,
				const int base));
static struct timeval	time1 P((struct ast_tm * tmp,
				struct ast_tm * (*funcp) P((const struct timeval *,
				long, struct ast_tm *, const struct state *sp)),
				long offset, const struct state *sp));
static struct timeval	time2 P((struct ast_tm *tmp,
				struct ast_tm * (*funcp) P((const struct timeval *,
				long, struct ast_tm*, const struct state *sp)),
				long offset, int * okayp, const struct state *sp));
static struct timeval	time2sub P((struct ast_tm *tmp,
				struct ast_tm * (*funcp) (const struct timeval *,
				long, struct ast_tm*, const struct state *sp),
				long offset, int * okayp, int do_norm_secs, const struct state *sp));
static struct ast_tm *	timesub P((const struct timeval * timep, long offset,
				const struct state * sp, struct ast_tm * tmp));
static int		tmcomp P((const struct ast_tm * atmp,
				const struct ast_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		tzparse P((const char * name, struct state * sp,
				int lastditch));

static AST_LIST_HEAD_STATIC(zonelist, state);

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

/*! \note
** 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 long detzcode(const char * const codep)
{
	long	result;
	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(const char * const codep)
{
	time_t	result;
	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(const time_t t1, const time_t t0)
{
	const long long at1 = t1, at0 = t0;
	if (TYPE_INTEGRAL(time_t) &&
		TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
			return 0;
	return at1 - at0 == SECSPERREPEAT;
}

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

	if (name == NULL && (name = TZDEFAULT) == NULL)
		return -1;
	{
		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];

		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)
			return -1;
	}
	nread = read(fid, u.buf, sizeof u.buf);
	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) {
			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) {
			struct lsinfo *	lsisp;

			lsisp = &sp->lsis[i];
			lsisp->ls_trans = (stored == 4) ?
				detzcode(p) : detzcode64(p);
			p += stored;
			lsisp->ls_corr = detzcode(p);
			p += 4;
		}
		for (i = 0; i < sp->typecnt; ++i) {
			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;
			}
		}
		for (i = 0; i < sp->typecnt; ++i) {
			struct ttinfo *	ttisp;

			ttisp = &sp->ttis[i];
			if (ttisgmtcnt == 0)
				ttisp->tt_ttisgmt = FALSE;
			else {
				ttisp->tt_ttisgmt = *p++;
				if (ttisp->tt_ttisgmt != TRUE &&
					ttisp->tt_ttisgmt != FALSE)
						return -1;
			}
		}
		/*
		** Out-of-sort ats should mean we're running on a
		** signed time_t system but using a data file with
		** unsigned values (or vice versa).
		*/
		for (i = 0; i < sp->timecnt - 2; ++i)
			if (sp->ats[i] > sp->ats[i + 1]) {
				++i;
				if (TYPE_SIGNED(time_t)) {
					/*
					** Ignore the end (easy).
					*/
					sp->timecnt = i;
				} else {
					/*
					** Ignore the beginning (harder).
					*/
					int	j;

					for (j = 0; j + i < sp->timecnt; ++j) {
						sp->ats[j] = sp->ats[j + i];
						sp->types[j] = sp->types[j + i];
					}
					sp->timecnt = j;
				}
				break;
			}
		/*
		** If this is an old file, we're done.
		*/
		if (u.tzhead.tzh_version[0] == '\0')
			break;
		nread -= p - u.buf;
		for (i = 0; i < nread; ++i)
			u.buf[i] = p[i];
		/*
		** If this is a narrow integer time_t system, we're done.
		*/
		if (stored >= (int) sizeof(time_t) && TYPE_INTEGRAL(time_t))
			break;
	}
	if (doextend && nread > 2 &&
		u.buf[0] == '\n' && u.buf[nread - 1] == '\n' &&
		sp->typecnt + 2 <= TZ_MAX_TYPES) {
			struct state	ts;
			int	result;

			u.buf[nread - 1] = '\0';
			result = tzparse(&u.buf[1], &ts, FALSE);
			if (result == 0 && ts.typecnt == 2 &&
				sp->charcnt + ts.charcnt <= TZ_MAX_CHARS) {
					for (i = 0; i < 2; ++i)
						ts.ttis[i].tt_abbrind +=
							sp->charcnt;
					for (i = 0; i < ts.charcnt; ++i)