lib/ansi/strftime.c

   1 /*
   2  * strftime - convert a structure to a string, controlled by an argument
   3  */
   4 /* $Header$ */
   5
   6 #include        <time.h>
   7 #include        "loc_time.h"
   8
   9 /* The width can be -1 in both s_prnt() as in u_prnt(). This
  10  * indicates that as many characters as needed should be printed.
  11  */
  12 static char *
  13 s_prnt(char *s, size_t maxsize, const char *str, int width)
  14 {
  15         while (width > 0 || (width < 0 && *str)) {
  16                 if (!maxsize) break;
  17                 *s++ = *str++;
  18                 maxsize--;
  19                 width--;
  20         }
  21         return s;
  22 }
  23
  24 static char *
  25 u_prnt(char *s, size_t maxsize, unsigned val, int width)
  26 {
  27         int c;
  28
  29         c = val % 10;
  30         val = val / 10;
  31         if (--width > 0 || (width < 0 && val != 0))
  32                 s = u_prnt(s, (maxsize ? maxsize - 1 : 0), val, width);
  33         if (maxsize) *s++ = c + '0';
  34         return s;
  35 }
  36
  37 size_t
  38 strftime(char *s, size_t maxsize,
  39                 const char *format, const struct tm *timeptr)
  40 {
  41         size_t n;
  42         char *firsts, *olds;
  43
  44         if (!format) return 0;
  45
  46         _tzset();       /* for %Z conversion */
  47         firsts = s;
  48         while (maxsize && *format) {
  49                 while (maxsize && *format && *format != '%') {
  50                         *s++ = *format++;
  51                         maxsize--;
  52                 }
  53                 if (!maxsize || !*format) break;
  54                 format++;
  55
  56                 olds = s;
  57                 switch (*format++) {
  58                 case 'a':
  59                         s = s_prnt(s, maxsize,
  60                                         _days[timeptr->tm_wday], ABB_LEN);
  61                         maxsize -= s - olds;
  62                         break;
  63                 case 'A':
  64                         s = s_prnt(s, maxsize, _days[timeptr->tm_wday], -1);
  65                         maxsize -= s - olds;
  66                         break;
  67                 case 'b':
  68                         s = s_prnt(s, maxsize,
  69                                         _months[timeptr->tm_mon], ABB_LEN);
  70                         maxsize -= s - olds;
  71                         break;
  72                 case 'B':
  73                         s = s_prnt(s, maxsize, _months[timeptr->tm_mon], -1);
  74                         maxsize -= s - olds;
  75                         break;
  76                 case 'c':
  77                         n = strftime(s, maxsize,
  78                                         "%a %b %d %H:%M:%S %Y", timeptr);
  79                         if (n) maxsize -= n;
  80                         else maxsize = 0;
  81                         s += n;
  82                         break;
  83                 case 'd':
  84                         s = u_prnt(s, maxsize, timeptr->tm_mday, 2);
  85                         maxsize -= s - olds;
  86                         break;
  87                 case 'H':
  88                         s = u_prnt(s, maxsize, timeptr->tm_hour, 2);
  89                         maxsize -= s - olds;
  90                         break;
  91                 case 'I':
  92                         s = u_prnt(s, maxsize,
  93                                         (timeptr->tm_hour + 11) % 12 + 1, 2);
  94                         maxsize -= s - olds;
  95                         break;
  96                 case 'j':
  97                         s = u_prnt(s, maxsize, timeptr->tm_yday + 1, 3);
  98                         maxsize -= s - olds;
  99                         break;
 100                 case 'm':
 101                         s = u_prnt(s, maxsize, timeptr->tm_mon + 1, 2);
 102                         maxsize -= s - olds;
 103                         break;
 104                 case 'M':
 105                         s = u_prnt(s, maxsize, timeptr->tm_min, 2);
 106                         maxsize -= s - olds;
 107                         break;
 108                 case 'p':
 109                         s = s_prnt(s, maxsize,
 110                                     (timeptr->tm_hour < 12) ? "AM" : "PM", 2);
 111                         maxsize -= s - olds;
 112                         break;
 113                 case 'S':
 114                         s = u_prnt(s, maxsize, timeptr->tm_sec, 2);
 115                         maxsize -= s - olds;
 116                         break;
 117                 case 'U':
 118                         s = u_prnt(s, maxsize,          /* ??? */
 119                             (timeptr->tm_yday + 7 - timeptr->tm_wday) / 7, 2);
 120                         maxsize -= s - olds;
 121                         break;
 122                 case 'w':
 123                         s = u_prnt(s, maxsize, timeptr->tm_wday, 1);
 124                         maxsize -= s - olds;
 125                         break;
 126                 case 'W':
 127                         s = u_prnt(s, maxsize,          /* ??? */
 128                             (timeptr->tm_yday+7-(timeptr->tm_wday+6)%7)/7,2);
 129                         maxsize -= s - olds;
 130                         break;
 131                 case 'x':
 132                         n = strftime(s, maxsize, "%a %b %d %Y", timeptr);
 133                         if (n) maxsize -= n;
 134                         else maxsize = 0;
 135                         s += n;
 136                         break;
 137                 case 'X':
 138                         n = strftime(s, maxsize, "%H:%M:%S", timeptr);
 139                         if (n) maxsize -= n;
 140                         else maxsize = 0;
 141                         s += n;
 142                         break;
 143                 case 'y':
 144                         s = u_prnt(s, maxsize, timeptr->tm_year % 100, 2);
 145                         maxsize -= s - olds;
 146                         break;
 147                 case 'Y':
 148                         s = u_prnt(s, maxsize, timeptr->tm_year + YEAR0, -1);
 149                         maxsize -= s - olds;
 150                         break;
 151                 case 'Z':
 152                         s = s_prnt(s, maxsize,
 153                                         _tzname[(timeptr->tm_isdst > 0)], -1);
 154                         maxsize -= s - olds;
 155                         break;
 156                 case '%':
 157                         *s++ = '%';
 158                         maxsize--;
 159                         break;
 160                 default:
 161                         /* A conversion error. Leave the loop. */
 162                         while (*format) format++;
 163                         break;
 164                 }
 165
 166         }
 167         if (maxsize) {
 168                 *s = '\0';
 169                 return s - firsts;
 170         }
 171         return 0;       /* The buffer is full */
 172 }