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

		/* Do some prep work. */
		i = (ptm->tm_year % 400) + 1900; /* Make sure we don't overflow. */
		isleap = __isleap(i);
		--i;
		day0 = (1
				+ i				/* Normal years increment 1 wday. */
				+ (i/4)
				- (i/100)
				+ (i/400) ) % 7;
		i = 0;
		do {
			day = r->day;		/* Common for 'J' and # case. */
			if (r->rule_type == 'J') {
				if (!isleap || (day < (31+29))) {
					--day;
				}
			} else if (r->rule_type == 'M') {
				/* Find 0-based day number for 1st of the month. */
				day = 31*r->month - day_cor[r->month -1];
				if (isleap && (day >= 59)) {
					++day;
				}
				monlen = 31 + day_cor[r->month -1] - day_cor[r->month];
				if (isleap && (r->month > 1)) {
					++monlen;
				}
				/* Wweekday (0 is Sunday) of 1st of the month
				 * is (day0 + day) % 7. */
				if ((mday = r->day - ((day0 + day) % 7)) >= 0) {
					mday -= 7;	/* Back up into prev month since r->week>0. */
				}
				if ((mday += 7 * r->week) >= monlen) {
					mday -= 7;
				}
				/* So, 0-based day number is... */
				day += mday;
			}

			if (i != 0) {
				/* Adjust sec since dst->std change time is in dst. */
				sec += (r[-1].gmt_offset - r->gmt_offset);
				if (oday > day) {
					++isdst;	/* Year starts in dst. */
				}
			}
			oday = day;

			/* Now convert day to seconds and add offset and compare. */
			if (sec >= (day * 86400L) + r->dst_offset) {
				++isdst;
			}
			++r;
		} while (++i < 2);
	}

	return (isdst & 1);
}

struct tm *localtime_r(register const time_t *__restrict timer,
					   register struct tm *__restrict result)
{
	time_t x[1];
	long offset;
	int days, dst;

	TZLOCK;

	tzset();

	dst = 0;
	do {
		days = -7;
		offset = 604800L - _time_tzinfo[dst].gmt_offset;
		if (*timer > (LONG_MAX - 604800L)) {
			days = -days;
			offset = -offset;
		}
		*x = *timer + offset;

		_time_t2tm(x, days, result);
		
		if (dst) {
			result->tm_isdst = dst;
			break;
		}
		++dst;
	} while ((result->tm_isdst = tm_isdst(result)) != 0);

	TZUNLOCK;

	return result;
}

#endif
/**********************************************************************/
#ifdef L_mktime

time_t mktime(struct tm *timeptr)
{
	return  _time_mktime(timeptr, 1);
}

#endif
/**********************************************************************/
#ifdef L_strftime

#define NO_E_MOD		0x80
#define NO_O_MOD		0x40

#define ILLEGAL_SPEC	0x3f

#define INT_SPEC		0x00	/* must be 0x00!! */
#define STRING_SPEC		0x10	/* must be 0x10!! */
#define CALC_SPEC		0x20
#define STACKED_SPEC	0x30

#define MASK_SPEC		0x30

/* Compatibility:
 *
 * No alternate digit (%O?) handling.  Always uses 0-9.
 * Alternate locale format (%E?) handling is broken for nontrivial ERAs.
 * glibc's %P is currently faked by %p.  This means it doesn't do lower case.
 * glibc's %k, %l, and %s are handled.
 * glibc apparently allows (and ignores) extraneous 'E' and 'O' modifiers,
 *   while they are flagged as illegal conversions here.
 */

/* Warning: Assumes ASCII values! (as do lots of other things in the lib...) */
static const unsigned char spec[] = {
	/* A */		0x03 |  STRING_SPEC | NO_E_MOD | NO_O_MOD,
	/* B */		0x04 |  STRING_SPEC | NO_E_MOD | NO_O_MOD,
	/* C */		0x0a |     INT_SPEC            | NO_O_MOD,
	/* D */		0x02 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* E */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* F */		0x03 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* G */		0x03 |    CALC_SPEC | NO_E_MOD | NO_O_MOD,
	/* H */		0x0b |     INT_SPEC | NO_E_MOD,
	/* I */		0x0c |     INT_SPEC | NO_E_MOD,
	/* J */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* K */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* L */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* M */		0x0d |     INT_SPEC | NO_E_MOD,
	/* N */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* O */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* P */		0x05 |  STRING_SPEC | NO_E_MOD | NO_O_MOD, /* glibc ; use %p */
	/* Q */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* R */		0x04 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* S */		0x0e |     INT_SPEC | NO_E_MOD,
	/* T */		0x05 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* U */		0x04 |    CALC_SPEC | NO_E_MOD,
	/* V */		0x05 |    CALC_SPEC | NO_E_MOD,
	/* W */		0x06 |    CALC_SPEC | NO_E_MOD,
	/* X */		0x0a | STACKED_SPEC            | NO_O_MOD,
	/* Y */		0x0f |     INT_SPEC            | NO_O_MOD,
	/* Z */		0x01 |    CALC_SPEC | NO_E_MOD | NO_O_MOD,
	'?',						/* 26 */
	'?',						/* 27 */
	'?',						/* 28 */
	'?',						/* 29 */
	0,							/* 30 */
	0,							/* 31 */
	/* a */		0x00 |  STRING_SPEC | NO_E_MOD | NO_O_MOD,
	/* b */		0x01 |  STRING_SPEC | NO_E_MOD | NO_O_MOD,
	/* c */		0x08 | STACKED_SPEC            | NO_O_MOD,
	/* d */		0x00 |     INT_SPEC | NO_E_MOD,
	/* e */		0x01 |     INT_SPEC | NO_E_MOD,
	/* f */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* g */		0x02 |    CALC_SPEC | NO_E_MOD | NO_O_MOD,
	/* h */		0x01 |  STRING_SPEC | NO_E_MOD | NO_O_MOD, /* same as b */
	/* i */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* j */		0x08 |     INT_SPEC | NO_E_MOD | NO_O_MOD,
	/* k */		0x03 |     INT_SPEC | NO_E_MOD | NO_O_MOD, /* glibc */
	/* l */		0x04 |     INT_SPEC | NO_E_MOD | NO_O_MOD, /* glibc */
	/* m */		0x05 |     INT_SPEC | NO_E_MOD,
	/* n */		0x00 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* o */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* p */		0x02 |  STRING_SPEC | NO_E_MOD | NO_O_MOD,
	/* q */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* r */		0x0b | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* s */		0x07 |    CALC_SPEC | NO_E_MOD | NO_O_MOD, /* glibc */
	/* t */		0x01 | STACKED_SPEC | NO_E_MOD | NO_O_MOD,
	/* u */		0x07 |     INT_SPEC | NO_E_MOD,
	/* v */		       ILLEGAL_SPEC | NO_E_MOD | NO_O_MOD,
	/* w */		0x02 |     INT_SPEC | NO_E_MOD,
	/* x */		0x09 | STACKED_SPEC            | NO_O_MOD,
	/* y */		0x09 |     INT_SPEC,
	/* z */		0x00 |    CALC_SPEC | NO_E_MOD | NO_O_MOD,


	/* WARNING!!! These are dependent on the layout of struct tm!!! */
#define FIELD_MAX (26+6+26)
	60 /* 61? */, 59, 23, 31, 11, 0 /* 9999 */, 6, 0 /* 365 */,

#define TP_OFFSETS (FIELD_MAX+8)
	3, /* d */
	3, /* e */
	6, /* w */
	2, /* k */
	2, /* l */
	4, /* m */
	0, /* CURRENTLY UNUSED */
	/* NOTE: u,j,y order must be preserved as 6,7,5 seq is used in the code! */
#define CALC_OFFSETS (TP_OFFSETS + 7)
	6, /* u */
	7, /* j */
	5, /* y */
	5, /* C */
	2, /* H */
	2, /* I */
	1, /* M */
	0, /* S */
	5, /* Y */
	6, /* a */
	4, /* b, h */
	2, /* p */
	6, /* A */
	4, /* B */
	2, /* P */

#define TP_CODES (TP_OFFSETS + 16 + 6)
	2 | 16, /* d */
	2, /* e */
	0 | 16, /* w */
	2, /* k */
	2 | 32 | 0, /* l */
	2 | 16 | 1, /* m */
	0, /* CURRENTLY UNUSED */
	0 | 16 | 8 , /* u */
	4 | 16 | 1, /* j */
	2 | 128 | 32 | 16 , /* y */
	2 | 128 | 64 | 32 | 16 , /* C */
	2 | 16, /* H */
	2 | 32 | 16 | 0, /* I */
	2 | 16, /* M */
	2 | 16, /* S */
	6 | 16, /* Y */
	2, /* a */
	2, /* b, h */
	2 | 64, /* p */
	2, /* A */
	2, /* B */
	2 | 64, /* P */

#define STRINGS_NL_ITEM_START (TP_CODES + 16 + 6)
	_NL_ITEM_INDEX(ABDAY_1),	/* a */
	_NL_ITEM_INDEX(ABMON_1),	/* b, h */
	_NL_ITEM_INDEX(AM_STR),		/* p */
	_NL_ITEM_INDEX(DAY_1),		/* A */
	_NL_ITEM_INDEX(MON_1),		/* B */
	_NL_ITEM_INDEX(AM_STR),		/* P -- wrong! need lower case */

#define STACKED_STRINGS_START (STRINGS_NL_ITEM_START+6)
	6, 7, 8, 16, 24, 29,		/* 6 - offsets from offset-count to strings */
	'\n', 0,					/* 2 */
	'\t', 0,					/* 2 */
	'%', 'm', '/', '%', 'd', '/', '%', 'y', 0, /* 9 - %D */
	'%', 'Y', '-', '%', 'm', '-', '%', 'd', 0, /* 9 - %F (glibc extension) */
	'%', 'H', ':', '%', 'M', 0,	/* 6 - %R*/
	'%', 'H', ':', '%', 'M', ':', '%', 'S', 0, /* 9 - %T */

#define STACKED_STRINGS_NL_ITEM_START (STACKED_STRINGS_START + 43)
	_NL_ITEM_INDEX(D_T_FMT),	/* c */
	_NL_ITEM_INDEX(D_FMT),		/* x */
	_NL_ITEM_INDEX(T_FMT),		/* X */
	_NL_ITEM_INDEX(T_FMT_AMPM), /* r */
#ifdef ENABLE_ERA_CODE
	_NL_ITEM_INDEX(ERA_D_T_FMT), /* Ec */
	_NL_ITEM_INDEX(ERA_D_FMT),	/* Ex */
	_NL_ITEM_INDEX(ERA_T_FMT),	/* EX */
#endif
};

static int load_field(int k, const struct tm *__restrict timeptr)
{
	int r;
	int r_max;

	r = ((int *) timeptr)[k];

	r_max = spec[FIELD_MAX + k];

	if (k == 7) {
		r_max = 365;
	} else if (k == 5) {
		r += 1900;
		r_max = 9999;
	}

	if ((((unsigned int) r) > r_max) || ((k == 3) && !r)) {
		r = -1;
	}

	return r;
}

#define MAX_PUSH 4

size_t strftime(char *__restrict s, size_t maxsize,
				const char *__restrict format,
				const struct tm *__restrict timeptr)
{
	long tzo;
	register const char *p;
	register const char *o;
	const rule_struct *rsp;
	const char *stack[MAX_PUSH];
	size_t count;
	size_t o_count;
	int field_val, i, j, lvl;
	int x[3];			/* wday, yday, year */
	int isofm, days;
	char buf[__UIM_BUFLEN_LONG];
	unsigned char mod;
	unsigned char code;

	tzset();					/* We'll, let's get this out of the way. */

	lvl = 0;
	p = format;
	count = maxsize;

 LOOP:
	if (!count) {
		return 0;
	}
	if (!*p) {
		if (lvl == 0) {
			*s = 0;				/* nul-terminate */
			return maxsize - count;
		}
		p = stack[--lvl];
		goto LOOP;
	}

	o_count = 1;
	if ((*(o = p) == '%') && (*++p != '%')) {
		o_count = 2;
		mod = ILLEGAL_SPEC;
		if ((*p == 'O') || (*p == 'E')) { /* modifier */
			mod |= ((*p == 'O') ? NO_O_MOD : NO_E_MOD);
			++o_count;
			++p;
		}
		if ((((unsigned char)(((*p) | 0x20) - 'a')) >= 26)
			|| (((code = spec[(int)(*p - 'A')]) & mod) >= ILLEGAL_SPEC)
			) {
			if (!*p) {
				--p;
				--o_count;
			}
			goto OUTPUT;
		}
		code &= ILLEGAL_SPEC;	/* modifiers are preserved in mod var. */

		if ((code & MASK_SPEC) == STACKED_SPEC) {
			if (lvl == MAX_PUSH) {
				goto OUTPUT;	/* Stack full so treat as illegal spec. */
			}
			stack[lvl++] = ++p;
			if ((code &= 0xf) < 8) {
				p = ((const char *) spec) + STACKED_STRINGS_START + code;
				p += *((unsigned char *)p);
				goto LOOP;
			}
			p = ((const char *) spec) + STACKED_STRINGS_NL_ITEM_START
				+ (code & 7);
#ifdef ENABLE_ERA_CODE
			if ((mod & NO_E_MOD) /* Actually, this means E modifier present. */
				&& (*(o = nl_langinfo(_NL_ITEM(LC_TIME,
											   (int)(((unsigned char *)p)[4]))
									  )))
				) {
				p = o;
				goto LOOP;
			}
#endif
			p = nl_langinfo(_NL_ITEM(LC_TIME,
									 (int)(*((unsigned char *)p))));
			goto LOOP;
		}

		o = spec + 26;		/* set to "????" */
		if ((code & MASK_SPEC) == CALC_SPEC) {

			if (*p == 's') {
				time_t t;

				/* Use a cast to silence the warning since *timeptr won't
				 * be changed. */
				if ((t = _time_mktime((struct tm *) timeptr, 0))
					== ((time_t) -1)
					) {
					o_count = 1;
					goto OUTPUT;
				}
#ifdef TIME_T_IS_UNSIGNED
				o = _uintmaxtostr(buf + sizeof(buf) - 1,
								  (uintmax_t) t,
								  10, __UIM_DECIMAL);
#else
				o = _uintmaxtostr(buf + sizeof(buf) - 1,
								  (uintmax_t) t,
								  -10, __UIM_DECIMAL);
#endif
				o_count = sizeof(buf);
				goto OUTPUT;
			} else if (((*p) | 0x20) == 'z') { /* 'z' or 'Z' */

				if (timeptr->tm_isdst < 0) {
					/* SUSv3 specifies this behavior for 'z', but we'll also
					 * treat it as "no timezone info" for 'Z' too. */
					o_count = 0;
					goto OUTPUT;
				}

				TZLOCK;

				rsp = _time_tzinfo;
				if (timeptr->tm_isdst > 0) {
					++rsp;
				}

				if (*p == 'Z') {
					o = rsp->tzname;
					assert(o != NULL);
#if 0
					if (!o) {	/* PARANOIA */
						o = spec+30; /* empty string */
					}
#endif
					o_count = SIZE_MAX;
					TZUNLOCK;
					goto OUTPUT;
				} else {		/* z */
					*s = '+';
					if ((tzo = -rsp->gmt_offset) < 0) {
						tzo = -tzo;
						*s = '-';
					}
					TZUNLOCK;
					++s;
					--count;

					i = tzo / 60;
					field_val = ((i / 60) * 100) + (i % 60);
			
					i = 16 + 6;	/* 0-fill, width = 4 */
				}
			} else {
				/* TODO: don't need year for U, W */
				for (i=0 ; i < 3 ; i++) {
					if ((x[i] = load_field(spec[CALC_OFFSETS+i],timeptr)) < 0) {
						goto OUTPUT;
					}
				}

				i = 16 + 2;		/* 0-fill, width = 2 */

				if ((*p == 'U') || (*p == 'W')) {
					field_val = ((x[1] - x[0]) + 7);
					if (*p == 'W') {
						++field_val;
					}
					field_val /= 7;
					if ((*p == 'W') && !x[0]) {
						--field_val;
					}
				} else {	/* ((*p == 'g') || (*p == 'G') || (*p == 'V')) */
				ISO_LOOP:
					isofm = (((x[1] - x[0]) + 11) % 7) - 3;	/* [-3,3] */

					if (x[1] < isofm) {	/* belongs to previous year */
						--x[2];
						x[1] += 365 + __isleap(x[2]);
						goto ISO_LOOP;
					}

					field_val = ((x[1] - isofm) / 7) + 1; /* week # */
					days = 365 + __isleap(x[2]);
					isofm = ((isofm + 7*53 + 3 - days)) %7 + days - 3; /* next year */
					if (x[1] >= isofm) { /* next year */
						x[1] -= days;
						++x[2];
						goto ISO_LOOP;
					}

					if (*p != 'V') { /* need year */
						field_val = x[2]; /* TODO: what if x[2] now 10000 ?? */
						if (*p == 'g') {
							field_val %= 100;
						} else {
							i = 16 + 6;	/* 0-fill, width = 4 */
						}
					}
				}
			}
		} else {
			i = TP_OFFSETS + (code & 0x1f);
			if ((field_val = load_field(spec[i],timeptr)) < 0) {
				goto OUTPUT;
			}

			i = spec[i+(TP_CODES - TP_OFFSETS)];

			j = (i & 128) ? 100: 12;
			if (i & 64) {
				field_val /= j;;
			}
			if (i & 32) {
				field_val %= j;