nsz Git - musl/blob - src/time/strftime.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <langinfo.h>
   4 #include <locale.h>
   5 #include <time.h>
   6 #include <limits.h>
   7 #include "libc.h"
   8
   9 // FIXME: integer overflows
  10
  11 const char *__nl_langinfo_l(nl_item, locale_t);
  12
  13 static int is_leap(int y)
  14 {
  15         /* Avoid overflow */
  16         if (y>INT_MAX-1900) y -= 2000;
  17         y += 1900;
  18         return !(y%4) && ((y%100) || !(y%400));
  19 }
  20
  21 static int week_num(const struct tm *tm)
  22 {
  23         int val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7;
  24         /* If 1 Jan is just 1-3 days past Monday,
  25          * the previous week is also in this year. */
  26         if ((tm->tm_wday - tm->tm_yday - 2 + 371) % 7 <= 2)
  27                 val++;
  28         if (!val) {
  29                 val = 52;
  30                 /* If 31 December of prev year a Thursday,
  31                  * or Friday of a leap year, then the
  32                  * prev year has 53 weeks. */
  33                 int dec31 = (tm->tm_wday - tm->tm_yday - 1 + 7) % 7;
  34                 if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1)))
  35                         val++;
  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 - tm->tm_yday + 371) % 7;
  41                 if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year)))
  42                         val = 1;
  43         }
  44         return val;
  45 }
  46
  47 size_t __strftime_l(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm, locale_t loc)
  48 {
  49         nl_item item;
  50         int val;
  51         const char *fmt;
  52         size_t l;
  53         for (l=0; *f && l<n; f++) {
  54                 if (*f == '%') {
  55 do_fmt:
  56                 switch (*++f) {
  57                 case '%':
  58                         goto literal;
  59                 case 'E':
  60                 case 'O':
  61                         goto do_fmt;
  62                 case 'a':
  63                         item = ABDAY_1 + tm->tm_wday;
  64                         goto nl_strcat;
  65                 case 'A':
  66                         item = DAY_1 + tm->tm_wday;
  67                         goto nl_strcat;
  68                 case 'h':
  69                 case 'b':
  70                         item = ABMON_1 + tm->tm_mon;
  71                         goto nl_strcat;
  72                 case 'B':
  73                         item = MON_1 + tm->tm_mon;
  74                         goto nl_strcat;
  75                 case 'c':
  76                         item = D_T_FMT;
  77                         goto nl_strftime;
  78                 case 'C':
  79                         val = (1900+tm->tm_year) / 100;
  80                         fmt = "%02d";
  81                         goto number;
  82                 case 'd':
  83                         val = tm->tm_mday;
  84                         fmt = "%02d";
  85                         goto number;
  86                 case 'D':
  87                         fmt = "%m/%d/%y";
  88                         goto recu_strftime;
  89                 case 'e':
  90                         val = tm->tm_mday;
  91                         fmt = "%2d";
  92                         goto number;
  93                 case 'F':
  94                         fmt = "%Y-%m-%d";
  95                         goto recu_strftime;
  96                 case 'g':
  97                 case 'G':
  98                         fmt = "%04d";
  99                         val = tm->tm_year + 1900;
 100                         if (tm->tm_yday < 3 && week_num(tm) != 1) val--;
 101                         else if (tm->tm_yday > 360 && week_num(tm) == 1) val++;
 102                         if (*f=='g') {
 103                                 fmt = "%02d";
 104                                 val %= 100;
 105                         }
 106                         goto number;
 107                 case 'H':
 108                         val = tm->tm_hour;
 109                         fmt = "%02d";
 110                         goto number;
 111                 case 'I':
 112                         val = tm->tm_hour;
 113                         if (!val) val = 12;
 114                         else if (val > 12) val -= 12;
 115                         fmt = "%02d";
 116                         goto number;
 117                 case 'j':
 118                         val = tm->tm_yday+1;
 119                         fmt = "%03d";
 120                         goto number;
 121                 case 'm':
 122                         val = tm->tm_mon+1;
 123                         fmt = "%02d";
 124                         goto number;
 125                 case 'M':
 126                         val = tm->tm_min;
 127                         fmt = "%02d";
 128                         goto number;
 129                 case 'n':
 130                         s[l++] = '\n';
 131                         continue;
 132                 case 'p':
 133                         item = tm->tm_hour >= 12 ? PM_STR : AM_STR;
 134                         goto nl_strcat;
 135                 case 'r':
 136                         item = T_FMT_AMPM;
 137                         goto nl_strftime;
 138                 case 'R':
 139                         fmt = "%H:%M";
 140                         goto recu_strftime;
 141                 case 'S':
 142                         val = tm->tm_sec;
 143                         fmt = "%02d";
 144                         goto number;
 145                 case 't':
 146                         s[l++] = '\t';
 147                         continue;
 148                 case 'T':
 149                         fmt = "%H:%M:%S";
 150                         goto recu_strftime;
 151                 case 'u':
 152                         val = tm->tm_wday ? tm->tm_wday : 7;
 153                         fmt = "%d";
 154                         goto number;
 155                 case 'U':
 156                         val = (tm->tm_yday + 7 - tm->tm_wday) / 7;
 157                         fmt = "%02d";
 158                         goto number;
 159                 case 'W':
 160                         val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7;
 161                         fmt = "%02d";
 162                         goto number;
 163                 case 'V':
 164                         val = week_num(tm);
 165                         fmt = "%02d";
 166                         goto number;
 167                 case 'w':
 168                         val = tm->tm_wday;
 169                         fmt = "%d";
 170                         goto number;
 171                 case 'x':
 172                         item = D_FMT;
 173                         goto nl_strftime;
 174                 case 'X':
 175                         item = T_FMT;
 176                         goto nl_strftime;
 177                 case 'y':
 178                         val = tm->tm_year % 100;
 179                         fmt = "%02d";
 180                         goto number;
 181                 case 'Y':
 182                         val = tm->tm_year + 1900;
 183                         fmt = "%04d";
 184                         goto number;
 185                 case 'z':
 186                         val = -tm->__tm_gmtoff;
 187                         l += snprintf(s+l, n-l, "%+.2d%.2d", val/3600, abs(val%3600)/60);
 188                         continue;
 189                 case 'Z':
 190                         l += snprintf(s+l, n-l, "%s", tm->__tm_zone);
 191                         continue;
 192                 default:
 193                         return 0;
 194                 }
 195                 }
 196 literal:
 197                 s[l++] = *f;
 198                 continue;
 199 number:
 200                 l += snprintf(s+l, n-l, fmt, val);
 201                 continue;
 202 nl_strcat:
 203                 l += snprintf(s+l, n-l, "%s", __nl_langinfo_l(item, loc));
 204                 continue;
 205 nl_strftime:
 206                 fmt = __nl_langinfo_l(item, loc);
 207 recu_strftime:
 208                 l += __strftime_l(s+l, n-l, fmt, tm, loc);
 209         }
 210         if (l >= n) return 0;
 211         s[l] = 0;
 212         return l;
 213 }
 214
 215 size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm)
 216 {
 217         return __strftime_l(s, n, f, tm, LC_GLOBAL_LOCALE);
 218 }
 219
 220 weak_alias(__strftime_l, strftime_l);