summaryrefslogtreecommitdiff
path: root/src/time/strftime.c
blob: a30392044bf8878565715c3618bf2ef88c428cd3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <langinfo.h>
#include <locale.h>
#include <time.h>
#include <limits.h>
#include "locale_impl.h"
#include "libc.h"
#include "time_impl.h"

const char *__nl_langinfo_l(nl_item, locale_t);

static int is_leap(int y)
{
	/* Avoid overflow */
	if (y>INT_MAX-1900) y -= 2000;
	y += 1900;
	return !(y%4) && ((y%100) || !(y%400));
}

static int week_num(const struct tm *tm)
{
	int val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
	/* If 1 Jan is just 1-3 days past Monday,
	 * the previous week is also in this year. */
	if ((tm->tm_wday + 371U - tm->tm_yday - 2) % 7 <= 2)
		val++;
	if (!val) {
		val = 52;
		/* If 31 December of prev year a Thursday,
		 * or Friday of a leap year, then the
		 * prev year has 53 weeks. */
		int dec31 = (tm->tm_wday + 7U - tm->tm_yday - 1) % 7;
		if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1)))
			val++;
	} else if (val == 53) {
		/* If 1 January is not a Thursday, and not
		 * a Wednesday of a leap year, then this
		 * year has only 52 weeks. */
		int jan1 = (tm->tm_wday + 371U - tm->tm_yday) % 7;
		if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year)))
			val = 1;
	}
	return val;
}

const char *__tm_to_tzname(const struct tm *);
size_t __strftime_l(char *restrict, size_t, const char *restrict, const struct tm *restrict, locale_t);

const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc)
{
	nl_item item;
	long long val;
	const char *fmt = "-";
	int width = 2;

	switch (f) {
	case 'a':
		if (tm->tm_wday > 6U) goto string;
		item = ABDAY_1 + tm->tm_wday;
		goto nl_strcat;
	case 'A':
		if (tm->tm_wday > 6U) goto string;
		item = DAY_1 + tm->tm_wday;
		goto nl_strcat;
	case 'h':
	case 'b':
		if (tm->tm_mon > 11U) goto string;
		item = ABMON_1 + tm->tm_mon;
		goto nl_strcat;
	case 'B':
		if (tm->tm_mon > 11U) goto string;
		item = MON_1 + tm->tm_mon;
		goto nl_strcat;
	case 'c':
		item = D_T_FMT;
		goto nl_strftime;
	case 'C':
		val = (1900LL+tm->tm_year) / 100;
		goto number;
	case 'd':
		val = tm->tm_mday;
		goto number;
	case 'D':
		fmt = "%m/%d/%y";
		goto recu_strftime;
	case 'e':
		*l = snprintf(*s, sizeof *s, "%2d", tm->tm_mday);
		return *s;
	case 'F':
		fmt = "%Y-%m-%d";
		goto recu_strftime;
	case 'g':
	case 'G':
		val = tm->tm_year + 1900LL;
		if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
		else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
		if (f=='g') val %= 100;
		else width = 4;
		goto number;
	case 'H':
		val = tm->tm_hour;
		goto number;
	case 'I':
		val = tm->tm_hour;
		if (!val) val = 12;
		else if (val > 12) val -= 12;
		goto number;
	case 'j':
		val = tm->tm_yday+1;
		width = 3;
		goto number;
	case 'm':
		val = tm->tm_mon+1;
		goto number;
	case 'M':
		val = tm->tm_min;
		goto number;
	case 'n':
		*l = 1;
		return "\n";
	case 'p':
		item = tm->tm_hour >= 12 ? PM_STR : AM_STR;
		goto nl_strcat;
	case 'r':
		item = T_FMT_AMPM;
		goto nl_strftime;
	case 'R':
		fmt = "%H:%M";
		goto recu_strftime;
	case 's':
		val = __tm_to_secs(tm) - tm->__tm_gmtoff;
		width = 1;
		goto number;
	case 'S':
		val = tm->tm_sec;
		goto number;
	case 't':
		*l = 1;
		return "\t";
	case 'T':
		fmt = "%H:%M:%S";
		goto recu_strftime;
	case 'u':
		val = tm->tm_wday ? tm->tm_wday : 7;
		width = 1;
		goto number;
	case 'U':
		val = (tm->tm_yday + 7U - tm->tm_wday) / 7;
		goto number;
	case 'W':
		val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
		goto number;
	case 'V':
		val = week_num(tm);
		goto number;
	case 'w':
		val = tm->tm_wday;
		width = 1;
		goto number;
	case 'x':
		item = D_FMT;
		goto nl_strftime;
	case 'X':
		item = T_FMT;
		goto nl_strftime;
	case 'y':
		val = (tm->tm_year + 1900LL) % 100;
		if (val < 0) val = -val;
		goto number;
	case 'Y':
		val = tm->tm_year + 1900LL;
		if (val >= 10000) {
			*l = snprintf(*s, sizeof *s, "+%lld", val);
			return *s;
		}
		width = 4;
		goto number;
	case 'z':
		if (tm->tm_isdst < 0) {
			*l = 0;
			return "";
		}
		*l = snprintf(*s, sizeof *s, "%+.2d%.2d",
			(tm->__tm_gmtoff)/3600,
			abs(tm->__tm_gmtoff%3600)/60);
		return *s;
	case 'Z':
		if (tm->tm_isdst < 0) {
			*l = 0;
			return "";
		}
		fmt = __tm_to_tzname(tm);
		goto string;
	case '%':
		*l = 1;
		return "%";
	default:
		return 0;
	}
number:
	*l = snprintf(*s, sizeof *s, "%0*lld", width, val);
	return *s;
nl_strcat:
	fmt = __nl_langinfo_l(item, loc);
string:
	*l = strlen(fmt);
	return fmt;
nl_strftime:
	fmt = __nl_langinfo_l(item, loc);
recu_strftime:
	*l = __strftime_l(*s, sizeof *s, fmt, tm, loc);
	if (!*l) return 0;
	return *s;
}

size_t __strftime_l(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm, locale_t loc)
{
	size_t l, k;
	char buf[100];
	char *p;
	const char *t;
	int plus;
	unsigned long width;
	for (l=0; l<n; f++) {
		if (!*f) {
			s[l] = 0;
			return l;
		}
		if (*f != '%') {
			s[l++] = *f;
			continue;
		}
		f++;
		if ((plus = (*f == '+'))) f++;
		width = strtoul(f, &p, 10);
		if (*p == 'C' || *p == 'F' || *p == 'G' || *p == 'Y') {
			if (!width && p!=f) width = 1;
		} else {
			width = 0;
		}
		f = p;
		if (*f == 'E' || *f == 'O') f++;
		t = __strftime_fmt_1(&buf, &k, *f, tm, loc);
		if (!t) break;
		if (width) {
			for (; *t=='+' || *t=='-' || (*t=='0'&&t[1]); t++, k--);
			width--;
			if (plus && tm->tm_year >= 10000-1900)
				s[l++] = '+';
			else if (tm->tm_year < -1900)
				s[l++] = '-';
			else
				width++;
			for (; width > k && l < n; width--)
				s[l++] = '0';
		}
		if (k > n-l) k = n-l;
		memcpy(s+l, t, k);
		l += k;
	}
	if (n) {
		if (l==n) l=n-1;
		s[l] = 0;
	}
	return 0;
}

size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm)
{
	return __strftime_l(s, n, f, tm, CURRENT_LOCALE);
}

weak_alias(__strftime_l, strftime_l);