1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <string.h>
4 #include <langinfo.h>
5 #include <locale.h>
6 #include <time.h>
7 #include <limits.h>
8 #include "locale_impl.h"
9 #include "time_impl.h"
10
is_leap(int y)11 static int is_leap(int y)
12 {
13 /* Avoid overflow */
14 if (y>INT_MAX-1900) y -= 2000;
15 y += 1900;
16 return !(y%4) && ((y%100) || !(y%400));
17 }
18
week_num(const struct tm * tm)19 static int week_num(const struct tm *tm)
20 {
21 int val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
22 /* If 1 Jan is just 1-3 days past Monday,
23 * the previous week is also in this year. */
24 if ((tm->tm_wday + 371U - tm->tm_yday - 2) % 7 <= 2)
25 val++;
26 if (!val) {
27 val = 52;
28 /* If 31 December of prev year a Thursday,
29 * or Friday of a leap year, then the
30 * prev year has 53 weeks. */
31 {
32 int dec31 = (tm->tm_wday + 7U - tm->tm_yday - 1) % 7;
33 if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1)))
34 val++;
35 }
36 } else if (val == 53) {
37 /* If 1 January is not a Thursday, and not
38 * a Wednesday of a leap year, then this
39 * year has only 52 weeks. */
40 int jan1 = (tm->tm_wday + 371U - tm->tm_yday) % 7;
41 if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year)))
42 val = 1;
43 }
44 return val;
45 }
46
__strftime_fmt_1(char (* s)[100],size_t * l,int f,const struct tm * tm,locale_t loc,int pad)47 const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc, int pad)
48 {
49 nl_item item;
50 long long val;
51 const char *fmt = "-";
52 int width = 2, def_pad = '0';
53
54 switch (f) {
55 case 'a':
56 if (tm->tm_wday > 6U) goto string;
57 item = ABDAY_1 + tm->tm_wday;
58 goto nl_strcat;
59 case 'A':
60 if (tm->tm_wday > 6U) goto string;
61 item = DAY_1 + tm->tm_wday;
62 goto nl_strcat;
63 case 'h':
64 case 'b':
65 if (tm->tm_mon > 11U) goto string;
66 item = ABMON_1 + tm->tm_mon;
67 goto nl_strcat;
68 case 'B':
69 if (tm->tm_mon > 11U) goto string;
70 item = MON_1 + tm->tm_mon;
71 goto nl_strcat;
72 case 'c':
73 item = D_T_FMT;
74 goto nl_strftime;
75 case 'C':
76 val = (1900LL+tm->tm_year) / 100;
77 goto number;
78 case 'e':
79 def_pad = '_';
80 case 'd':
81 val = tm->tm_mday;
82 goto number;
83 case 'D':
84 fmt = "%m/%d/%y";
85 goto recu_strftime;
86 case 'F':
87 fmt = "%Y-%m-%d";
88 goto recu_strftime;
89 case 'g':
90 case 'G':
91 val = tm->tm_year + 1900LL;
92 if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
93 else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
94 if (f=='g') val %= 100;
95 else width = 4;
96 goto number;
97 case 'H':
98 val = tm->tm_hour;
99 goto number;
100 case 'I':
101 val = tm->tm_hour;
102 if (!val) val = 12;
103 else if (val > 12) val -= 12;
104 goto number;
105 case 'j':
106 val = tm->tm_yday+1;
107 width = 3;
108 goto number;
109 case 'm':
110 val = tm->tm_mon+1;
111 goto number;
112 case 'M':
113 val = tm->tm_min;
114 goto number;
115 case 'n':
116 *l = 1;
117 return "\n";
118 case 'p':
119 item = tm->tm_hour >= 12 ? PM_STR : AM_STR;
120 goto nl_strcat;
121 case 'r':
122 item = T_FMT_AMPM;
123 goto nl_strftime;
124 case 'R':
125 fmt = "%H:%M";
126 goto recu_strftime;
127 case 's':
128 val = __tm_to_secs(tm) - tm->__tm_gmtoff;
129 width = 1;
130 goto number;
131 case 'S':
132 val = tm->tm_sec;
133 goto number;
134 case 't':
135 *l = 1;
136 return "\t";
137 case 'T':
138 fmt = "%H:%M:%S";
139 goto recu_strftime;
140 case 'u':
141 val = tm->tm_wday ? tm->tm_wday : 7;
142 width = 1;
143 goto number;
144 case 'U':
145 val = (tm->tm_yday + 7U - tm->tm_wday) / 7;
146 goto number;
147 case 'W':
148 val = (tm->tm_yday + 7U - (tm->tm_wday+6U)%7) / 7;
149 goto number;
150 case 'V':
151 val = week_num(tm);
152 goto number;
153 case 'w':
154 val = tm->tm_wday;
155 width = 1;
156 goto number;
157 case 'x':
158 item = D_FMT;
159 goto nl_strftime;
160 case 'X':
161 item = T_FMT;
162 goto nl_strftime;
163 case 'y':
164 val = (tm->tm_year + 1900LL) % 100;
165 if (val < 0) val = -val;
166 goto number;
167 case 'Y':
168 val = tm->tm_year + 1900LL;
169 if (val >= 10000) {
170 *l = snprintf(*s, sizeof *s, "+%lld", val);
171 return *s;
172 }
173 width = 4;
174 goto number;
175 case 'z':
176 if (tm->tm_isdst < 0) {
177 *l = 0;
178 return "";
179 }
180 *l = snprintf(*s, sizeof *s, "%+.4ld",
181 tm->__tm_gmtoff/3600*100 + tm->__tm_gmtoff%3600/60);
182 return *s;
183 case 'Z':
184 if (tm->tm_isdst < 0) {
185 *l = 0;
186 return "";
187 }
188 fmt = __tm_to_tzname(tm);
189 goto string;
190 case '%':
191 *l = 1;
192 return "%";
193 default:
194 return 0;
195 }
196 number:
197 switch (pad ? pad : def_pad) {
198 case '-': *l = snprintf(*s, sizeof *s, "%lld", val); break;
199 case '_': *l = snprintf(*s, sizeof *s, "%*lld", width, val); break;
200 case '0':
201 default: *l = snprintf(*s, sizeof *s, "%0*lld", width, val); break;
202 }
203 return *s;
204 nl_strcat:
205 fmt = __nl_langinfo_l(item, loc);
206 string:
207 *l = strlen(fmt);
208 return fmt;
209 nl_strftime:
210 fmt = __nl_langinfo_l(item, loc);
211 recu_strftime:
212 *l = __strftime_l(*s, sizeof *s, fmt, tm, loc);
213 if (!*l) return 0;
214 return *s;
215 }
216
__strftime_l(char * restrict s,size_t n,const char * restrict f,const struct tm * restrict tm,locale_t loc)217 size_t __strftime_l(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm, locale_t loc)
218 {
219 size_t l, k;
220 char buf[100];
221 char *p;
222 const char *t;
223 int pad, plus;
224 unsigned long width;
225 for (l=0; l<n; f++) {
226 if (!*f) {
227 s[l] = 0;
228 return l;
229 }
230 if (*f != '%') {
231 s[l++] = *f;
232 continue;
233 }
234 f++;
235 pad = 0;
236 if (*f == '-' || *f == '_' || *f == '0') pad = *f++;
237 if ((plus = (*f == '+'))) f++;
238 width = strtoul(f, &p, 10);
239 if (*p == 'C' || *p == 'F' || *p == 'G' || *p == 'Y') {
240 if (!width && p!=f) width = 1;
241 } else {
242 width = 0;
243 }
244 f = p;
245 if (*f == 'E' || *f == 'O') f++;
246 t = __strftime_fmt_1(&buf, &k, *f, tm, loc, pad);
247 if (!t) break;
248 if (width) {
249 /* Trim off any sign and leading zeros, then
250 * count remaining digits to determine behavior
251 * for the + flag. */
252 if (*t=='+' || *t=='-') t++, k--;
253 for (; *t=='0' && t[1]-'0'<10U; t++, k--);
254 if (width < k) width = k;
255 {
256 size_t d;
257 for (d=0; t[d]-'0'<10U; d++);
258 if (tm->tm_year < -1900) {
259 s[l++] = '-';
260 width--;
261 } else if (plus && d+(width-k) >= (*p=='C'?3:5)) {
262 s[l++] = '+';
263 width--;
264 }
265 for (; width > k && l < n; width--)
266 s[l++] = '0';
267 }
268 }
269 if (k > n-l) k = n-l;
270 memcpy(s+l, t, k);
271 l += k;
272 }
273 if (n) {
274 if (l==n) l=n-1;
275 s[l] = 0;
276 }
277 return 0;
278 }
279
strftime(char * restrict s,size_t n,const char * restrict f,const struct tm * restrict tm)280 size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm)
281 {
282 return __strftime_l(s, n, f, tm, CURRENT_LOCALE);
283 }
284
285 weak_alias(__strftime_l, strftime_l);
286