time.c

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

static char *read_TZ_file(char *buf)
{
	int fd;
	ssize_t r;
	size_t todo;
	char *p = NULL;

	if ((fd = open(_PATH_TZ, O_RDONLY)) >= 0) {
		todo = TZ_BUFLEN;
		p = buf;
		do {
			if ((r = read(fd, p, todo)) < 0) {
				goto ERROR;
			}
			if (r == 0) {
				break;
			}
			p += r;
			todo -= r;
		} while (todo);

		if ((p > buf) && (p[-1] == '\n')) {	/* Must end with newline. */
			p[-1] = 0;
			p = buf;
#ifdef __TIME_TZ_FILE_ONCE
			++TZ_file_read;
#endif /* __TIME_TZ_FILE_ONCE */
		} else {
		ERROR:
			p = NULL;
		}
		close(fd);
	}
	return p;
}

#endif /* __TIME_TZ_FILE */

void tzset(void)
{
	register const char *e;
	register char *s;
	long off;
	short *p;
	rule_struct new_rules[2];
	int n, count, f;
	char c;
#ifdef __TIME_TZ_FILE
	char buf[TZ_BUFLEN];
#endif /* __TIME_TZ_FILE */
#ifdef __TIME_TZ_OPT_SPEED
	static char oldval[TZ_BUFLEN]; /* BSS-zero'd. */
#endif /* __TIME_TZ_OPT_SPEED */

	TZLOCK;

	e = getenv(TZ);				/* TZ env var always takes precedence. */

#ifdef __TIME_TZ_FILE_ONCE
	/* Put this inside the lock to prevent the possiblity of two different
	 * timezones being used in a threaded app. */

	if (e != NULL) {
		TZ_file_read = 0;		/* Reset if the TZ env var is set. */
	} else if (TZ_file_read > 0) {
		goto FAST_DONE;
	}
#endif /* __TIME_TZ_FILE_ONCE */

	/* Warning!!!  Since uClibc doesn't do lib locking, the following is
	 * potentially unsafe in a multi-threaded program since it is remotely
	 * possible that another thread could call setenv() for TZ and overwrite
	 * the string being parsed.  So, don't do that... */

	if ((!e						/* TZ env var not set... */
#ifdef __TIME_TZ_FILE
		 && !(e = read_TZ_file(buf)) /* and no file or invalid file */
#endif /* __TIME_TZ_FILE */
		 ) || !*e) {			/* or set to empty string. */
	ILLEGAL:					/* TODO: Clean up the following... */
#ifdef __TIME_TZ_OPT_SPEED
		*oldval = 0;			/* Set oldval tonnn empty string. */
#endif /* __TIME_TZ_OPT_SPEED */
		s = _time_tzinfo[0].tzname;
		*s = 'U';
		*++s = 'T';
		*++s = 'C';
		*++s =
		*_time_tzinfo[1].tzname = 0;
		_time_tzinfo[0].gmt_offset = 0;
		goto DONE;
	}

	if (*e == ':') {			/* Ignore leading ':'. */
		++e;
	}

#ifdef __TIME_TZ_OPT_SPEED
	if (strcmp(e, oldval) == 0) { /* Same string as last time... */
		goto FAST_DONE;			/* So nothing to do. */
	}
	/* Make a copy of the TZ env string.  It won't be nul-terminated if
	 * it is too long, but it that case it will be illegal and will be reset
	 * to the empty string anyway. */
	strncpy(oldval, e, TZ_BUFLEN);
#endif /* __TIME_TZ_OPT_SPEED */
	
	count = 0;
	new_rules[1].tzname[0] = 0;
 LOOP:
	/* Get std or dst name. */
	c = 0;
	if (*e == '<') {
		++e;
		c = '>';
	}

	s = new_rules[count].tzname;
	n = 0;
	while (*e
		   && isascii(*e)		/* SUSv3 requires char in portable char set. */
		   && (isalpha(*e)
			   || (c && (isalnum(*e) || (*e == '+') || (*e == '-'))))
		   ) {
		*s++ = *e++;
		if (++n > TZNAME_MAX) {
			goto ILLEGAL;
		}
	}
	*s = 0;

	if ((n < 3)					/* Check for minimum length. */
		|| (c && (*e++ != c))	/* Match any quoting '<'. */
		) {
		goto ILLEGAL;
	}

	/* Get offset */
	s = (char *) e;
	if ((*e != '-') && (*e != '+')) {
		if (count && !isdigit(*e)) {
			off -= 3600;		/* Default to 1 hour ahead of std. */
			goto SKIP_OFFSET;
		}
		--e;
	}

	++e;
	if (!(e = getoffset(e, &off))) {
		goto ILLEGAL;
	}

	if (*s == '-') {
		off = -off;				/* Save off in case needed for dst default. */
	}
 SKIP_OFFSET:
	new_rules[count].gmt_offset = off;

	if (!count) {
		if (*e) {
			++count;
			goto LOOP;
		}
	} else {					/* OK, we have dst, so get some rules. */
		count = 0;
		if (!*e) {				/* No rules so default to US rules. */
			e = DEFAULT_RULES;
		}

		do {
			if (*e++ != ',') {
				goto ILLEGAL;
			}

			n = 365;
			s = (char *) RULE;
			if ((c = *e++) == 'M') {
				n = 12;
			} else if (c == 'J') {
				s += 8;
			} else {
				--e;
				c = 0;
				s += 6;
			}

			*(p = &new_rules[count].rule_type) = c;
			if (c != 'M') {
				p -= 2;
			}

			do {
				++s;
				if (!(e = getnumber(e, &f))
					|| (((unsigned int)(f - s[1])) > n)
					|| (*s && (*e++ != *s))
					) {
					goto ILLEGAL;
				}
				*--p = f;
			} while ((n = *(s += 2)) > 0);

			off = 2 * 60 * 60;	/* Default to 2:00:00 */
			if (*e == '/') {
				++e;
				if (!(e = getoffset(e, &off))) {
					goto ILLEGAL;
				}
			}
			new_rules[count].dst_offset = off;
		} while (++count < 2);

		if (*e) {
			goto ILLEGAL;
		}
	}

	memcpy(_time_tzinfo, new_rules, sizeof(new_rules));
 DONE:
	tzname[0] = _time_tzinfo[0].tzname;
	tzname[1] = _time_tzinfo[1].tzname;
	daylight = !!_time_tzinfo[1].tzname[0];
	timezone = _time_tzinfo[0].gmt_offset;

 FAST_DONE:
	TZUNLOCK;
}

#endif
/**********************************************************************/
/*  #ifdef L_utime */

/* utime is a syscall in both linux and elks. */
/*  int utime(const char *path, const struct utimbuf *times) */

/*  #endif */
/**********************************************************************/
/* Non-SUSv3 */
/**********************************************************************/
#ifdef L_utimes

#ifndef __BCC__
#error The uClibc version of utimes is in sysdeps/linux/common.
#endif

#include <utime.h>
#include <sys/time.h>

int utimes(const char *filename, register const struct timeval *tvp)
{
	register struct utimbuf *p = NULL;
	struct utimbuf utb;

	if (tvp) {
		p = &utb;
		p->actime = tvp[0].tv_sec;
		p->modtime = tvp[1].tv_sec;
	}
	return utime(filename, p);
}

#endif
/**********************************************************************/
#ifdef L__time_t2tm

static const uint16_t vals[] = {
	60, 60, 24, 7 /* special */, 36524, 1461, 365, 0
};

static const unsigned char days[] = {
	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, /* non-leap */
	    29,
};

/* Notes:
 * If time_t is 32 bits, then no overflow is possible.
 * It time_t is > 32 bits, this needs to be adjusted to deal with overflow.
 */

/* Note: offset is the correction in _days_ to *timer! */

struct tm *_time_t2tm(const time_t *__restrict timer,
					  int offset, struct tm *__restrict result)
{
	register int *p;
	time_t t1, t, v;
	int wday=0;					/* Note: wday can be uninitialized. */

	{
		register const uint16_t *vp;
		t = *timer;
		p = (int *) result;
		p[7] = 0;
		vp = vals;
		do {
			if ((v = *vp) == 7) {
				/* Overflow checking, assuming time_t is long int... */
#if (LONG_MAX > INT_MAX) && (LONG_MAX > 2147483647L)
#if (INT_MAX == 2147483647L) && (LONG_MAX == 9223372036854775807L)
				/* Valid range for t is [-784223472856L, 784223421720L].
				 * Outside of this range, the tm_year field will overflow. */
				if (((unsigned long)(t + offset- -784223472856L))
					> (784223421720L - -784223472856L)
					) {
					return NULL;
				}
#else
#error overflow conditions unknown
#endif
#endif

				/* We have days since the epoch, so caluclate the weekday. */
#if defined(__BCC__) && TIME_T_IS_UNSIGNED
				wday = (t + 4) % (*vp);	/* t is unsigned */
#else
				wday = ((int)((t % (*vp)) + 11)) % ((int)(*vp)); /* help bcc */
#endif
				/* Set divisor to days in 400 years.  Be kind to bcc... */
				v = ((time_t)(vp[1])) << 2;
				++v;
				/* Change to days since 1/1/1601 so that for 32 bit time_t
				 * values, we'll have t >= 0.  This should be changed for
				 * archs with larger time_t types. 
				 * Also, correct for offset since a multiple of 7. */

				/* TODO: Does this still work on archs with time_t > 32 bits? */
				t += (135140L - 366) + offset; /* 146097 - (365*30 + 7) -366 */
			}
#if defined(__BCC__) && TIME_T_IS_UNSIGNED
			t -= ((t1 = t / v) * v);
#else
			if ((t -= ((t1 = t / v) * v)) < 0) {
				t += v;
				--t1;
			}
#endif

			if ((*vp == 7) && (t == v-1)) {
				--t;			/* Correct for 400th year leap case */
				++p[4];			/* Stash the extra day... */
			}

#if defined(__BCC__) && 0
			*p = t1;
			if (v <= 60) {
				*p = t;
				t = t1;
			}
			++p;
#else
			if (v <= 60) {
				*p++ = t;
				t = t1;
			} else {
				*p++ = t1;
			}
#endif
		} while (*++vp);
	}

	if (p[-1] == 4) {
		--p[-1];
		t = 365;
	}


	*p += ((int) t);			/* result[7] .. tm_yday */

	p -= 2;						/* at result[5] */

#if (LONG_MAX > INT_MAX) && (LONG_MAX > 2147483647L)
	/* Protect against overflow.  TODO: Unecessary if int arith wraps? */
	*p = ((((p[-2]<<2) + p[-1])*25 + p[0])<< 2) + (p[1] - 299); /* tm_year */
#else
	*p = ((((p[-2]<<2) + p[-1])*25 + p[0])<< 2) + p[1] - 299; /* tm_year */
#endif

	p[1] = wday;				/* result[6] .. tm_wday */

	{
		register const unsigned char *d = days;

		wday = 1900 + *p;
		if (__isleap(wday)) {
			d += 11;
		}

		wday = p[2] + 1;		/* result[7] .. tm_yday */
		*--p = 0;				/* at result[4] .. tm_mon */
		while (wday > *d) {
			wday -= *d;
			if (*d == 29) {
				d -= 11;		/* Backup to non-leap Feb. */
			}
			++d;
			++*p;				/* Increment tm_mon. */
		}
		p[-1] = wday;			/* result[3] .. tm_mday */
	}
	/* TODO -- should this be 0? */
	p[4] = 0;					/* result[8] .. tm_isdst */

	return result;
}

#endif
/**********************************************************************/
#ifdef L___time_tm

struct tm __time_tm;	/* Global shared by gmtime() and localtime(). */

#endif
/**********************************************************************/
#ifdef L__time_mktime

static const unsigned char vals[] = {
	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, /* non-leap */
	    29,
};

time_t _time_mktime(struct tm *timeptr, int store_on_success)
{
#ifdef __BCC__
	long days, secs;
#else
	long long secs;
#endif
	time_t t;
	struct tm x;
	/* 0:sec  1:min  2:hour  3:mday  4:mon  5:year  6:wday  7:yday  8:isdst */
	register int *p = (int *) &x;
	register const unsigned char *s;
	int d;

	tzset();

	memcpy(p, timeptr, sizeof(struct tm));

	d = 400;
	p[5] = (p[5] - ((p[6] = p[5]/d) * d)) + (p[7] = p[4]/12);
	if ((p[4] -= 12 * p[7]) < 0) {
		p[4] += 12;
		--p[5];
	}

	s = vals;
	d = (p[5] += 1900);			/* Correct year.  Now between 1900 and 2300. */
	if (__isleap(d)) {
		s += 11;
	}
	
	p[7] = 0;
	d = p[4];
	while (d) {
		p[7] += *s;
		if (*s == 29) {
			s -= 11;			/* Backup to non-leap Feb. */
		}
		++s;
		--d;
	}

#ifdef __BCC__
	d = p[5] - 1;
	days = -719163L + ((long)d)*365 + ((d/4) - (d/100) + (d/400) + p[3] + p[7]);
	secs = p[0] + 60*( p[1] + 60*((long)(p[2])) )
		+ _time_tzinfo[timeptr->tm_isdst > 0].gmt_offset;
	if (secs < 0) {
		secs += 120009600L;
		days -= 1389;
	}
	if ( ((unsigned long)(days + secs/86400L)) > 49710L) {
		return -1;
	}
	secs += (days * 86400L);
#else
	TZLOCK;
	d = p[5] - 1;
	d = -719163L + d*365 + (d/4) - (d/100) + (d/400);
	secs = p[0]
		+ _time_tzinfo[timeptr->tm_isdst > 0].gmt_offset
		+ 60*( p[1]
			   + 60*(p[2]
					 + 24*(((146073L * ((long long)(p[6])) + d)
							+ p[3]) + p[7])));
	TZUNLOCK;
	if (((unsigned long long)(secs - LONG_MIN))
		> (((unsigned long long)LONG_MAX) - LONG_MIN)
		) {
		return -1;
	}
#endif

	t = secs;

	localtime_r(&t, (struct tm *)p);

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

	if (store_on_success) {
		memcpy(timeptr, p, sizeof(struct tm));
	}

	return t;
}

#endif
/**********************************************************************/