libc-top-half/musl/src/time/strftime.c

   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
  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
  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                 int dec31 = (tm->tm_wday + 7U - tm->tm_yday - 1) % 7;
  32                 if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1)))
  33                         val++;
  34         } else if (val == 53) {
  35                 /* If 1 January is not a Thursday, and not
  36                  * a Wednesday of a leap year, then this
  37                  * year has only 52 weeks. */
  38                 int jan1 = (tm->tm_wday + 371U - tm->tm_yday) % 7;
  39                 if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year)))
  40                         val = 1;
  41         }
  42         return val;
  43 }
  44
  45 const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc, int pad)
  46 {
  47         nl_item item;
  48         long long val;
  49         const char *fmt = "-";
  50         int width = 2, def_pad = '0';
  51
  52         switch (f) {
  53         case 'a':
  54                 if (tm->tm_wday > 6U) goto string;
  55                 item = ABDAY_1 + tm->tm_wday;
  56                 goto nl_strcat;
  57         case 'A':
  58                 if (tm->tm_wday > 6U) goto string;
  59                 item = DAY_1 + tm->tm_wday;
  60                 goto nl_strcat;
  61         case 'h':
  62         case 'b':
  63                 if (tm->tm_mon > 11U) goto string;
  64                 item = ABMON_1 + tm->tm_mon;
  65                 goto nl_strcat;
  66         case 'B':
  67                 if (tm->tm_mon > 11U) goto string;
  68                 item = MON_1 + tm->tm_mon;
  69                 goto nl_strcat;
  70         case 'c':
  71                 item = D_T_FMT;
  72                 goto nl_strftime;
  73         case 'C':
  74                 val = (1900LL+tm->tm_year) / 100;
  75                 goto number;
  76         case 'e':
  77                 def_pad = '_';
  78         case 'd':
  79                 val = tm->tm_mday;
  80                 goto number;
  81         case 'D':
  82                 fmt = "%m/%d/%y";
  83                 goto recu_strftime;
  84         case 'F':
  85                 fmt = "%Y-%m-%d";
  86                 goto recu_strftime;
  87         case 'g':
  88         case 'G':
  89                 val = tm->tm_year + 1900LL;
  90                 if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
  91                 else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
  92                 if (f=='g') val %= 100;
  93                 else width = 4;
  94                 goto number;
  95         case 'H':
  96                 val = tm->tm_hour;
  97                 goto number;
  98         case 'I':
  99                 val = tm->tm_hour;
 100                 if (!val) val = 12;
 101                 else if (val > 12) val -= 12;
 102                 goto number;
 103         case 'j':
 104                 val = tm->tm_yday+1;
 105                 width = 3;
 106                 goto number;
 107         case 'm':
 108                 val = tm->tm_mon+1;
 109                 goto number;
 110         case 'M':
 111                 val = tm->tm_min;
 112                 goto number;
 113         case 'n':
 114                 *l = 1;
 115                 return "\n";
 116         case 'p':
 117                 item = tm->tm_hour >= 12 ? PM_STR : AM_STR;
 118                 goto nl_strcat;
 119         case 'r':
 120                 item = T_FMT_AMPM;
 121                 goto nl_strftime;
 122         case 'R':
 123                 fmt = "%H:%M";
 124                 goto recu_strftime;
 125 #ifdef __wasilibc_unmodified_upstream // timezone data
 126         case 's':
 127                 val = __tm_to_secs(tm) - tm->__tm_gmtoff;
 128                 width = 1;
 129                 goto number;
 130 #endif
 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
 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                         size_t d;
 256                         for (d=0; t[d]-'0'<10U; d++);
 257                         if (tm->tm_year < -1900) {
 258                                 s[l++] = '-';
 259                                 width--;
 260                         } else if (plus && d+(width-k) >= (*p=='C'?3:5)) {
 261                                 s[l++] = '+';
 262                                 width--;
 263                         }
 264                         for (; width > k && l < n; width--)
 265                                 s[l++] = '0';
 266                 }
 267                 if (k > n-l) k = n-l;
 268                 memcpy(s+l, t, k);
 269                 l += k;
 270         }
 271         if (n) {
 272                 if (l==n) l=n-1;
 273                 s[l] = 0;
 274         }
 275         return 0;
 276 }
 277
 278 size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm)
 279 {
 280         return __strftime_l(s, n, f, tm, CURRENT_LOCALE);
 281 }
 282
 283 weak_alias(__strftime_l, strftime_l);