contrib/ntp/libntp/prettydate.c

   1 /*
   2  * prettydate - convert a time stamp to something readable
   3  */
   4 #include <stdio.h>
   5
   6 #include "ntp_fp.h"
   7 #include "ntp_unixtime.h"       /* includes <sys/time.h> */
   8 #include "lib_strbuf.h"
   9 #include "ntp_stdlib.h"
  10
  11 static const char *months[] = {
  12   "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  13   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
  14 };
  15
  16 static const char *days[] = {
  17   "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
  18 };
  19
  20 /* Helper function to handle possible wraparound of the ntp epoch.
  21
  22    Works by assuming that the localtime/gmtime library functions
  23    have been updated so that they work
  24 */
  25
  26 #define MAX_EPOCH_NR 1000
  27
  28 struct tm *
  29 ntp2unix_tm(
  30         u_long ntp, int local
  31         )
  32 {
  33         time_t t, curr;
  34         struct tm *tm;
  35         int curr_year, epoch_nr;
  36
  37         /* First get the current year: */
  38         curr = time(NULL);
  39         tm = local ? localtime(&curr) : gmtime(&curr);
  40         if (!tm) return NULL;
  41
  42         curr_year = 1900 + tm->tm_year;
  43
  44         /* Convert the ntp timestamp to a unix utc seconds count: */
  45         t = (time_t) ntp - JAN_1970;
  46
  47         /* Check that the ntp timestamp is not before a 136 year window centered
  48            around the current year:
  49
  50            Failsafe in case of an infinite loop:
  51        Allow up to 1000 epochs of 136 years each!
  52         */
  53     for (epoch_nr = 0; epoch_nr < MAX_EPOCH_NR; epoch_nr++) {
  54                 tm = local ? localtime(&t) : gmtime(&t);
  55
  56 #if SIZEOF_TIME_T < 4
  57 # include "Bletch: sizeof(time_t) < 4!"
  58 #endif
  59
  60 #if SIZEOF_TIME_T == 4
  61                 /* If 32 bits, then year is 1970-2038, so no sense looking */
  62                 epoch_nr = MAX_EPOCH_NR;
  63 #else   /* SIZEOF_TIME_T > 4 */
  64                 /* Check that the resulting year is in the correct epoch: */
  65                 if (1900 + tm->tm_year > curr_year - 68) break;
  66
  67                 /* Epoch wraparound: Add 2^32 seconds! */
  68                 t += (time_t) 65536 << 16;
  69 #endif /* SIZEOF_TIME_T > 4 */
  70         }
  71         return tm;
  72 }
  73
  74 char *
  75 prettydate(
  76         l_fp *ts
  77         )
  78 {
  79         char *bp;
  80         struct tm *tm;
  81         time_t sec;
  82         u_long msec;
  83
  84         LIB_GETBUF(bp);
  85
  86         sec = ts->l_ui;
  87         msec = ts->l_uf / 4294967;      /* fract / (2 ** 32 / 1000) */
  88
  89         tm = ntp2unix_tm(sec, 1);
  90         if (!tm) {
  91                 (void) sprintf(bp, "%08lx.%08lx  --- --- -- ---- --:--:--",
  92                        (u_long)ts->l_ui, (u_long)ts->l_uf);
  93         }
  94         else {
  95                 (void) sprintf(bp, "%08lx.%08lx  %s, %s %2d %4d %2d:%02d:%02d.%03lu",
  96                        (u_long)ts->l_ui, (u_long)ts->l_uf, days[tm->tm_wday],
  97                        months[tm->tm_mon], tm->tm_mday, 1900 + tm->tm_year,
  98                        tm->tm_hour,tm->tm_min, tm->tm_sec, msec);
  99         }
 100
 101         return bp;
 102 }
 103
 104 char *
 105 gmprettydate(
 106         l_fp *ts
 107         )
 108 {
 109         char *bp;
 110         struct tm *tm;
 111         time_t sec;
 112         u_long msec;
 113
 114         LIB_GETBUF(bp);
 115
 116         sec = ts->l_ui;
 117         msec = ts->l_uf / 4294967;      /* fract / (2 ** 32 / 1000) */
 118
 119         tm = ntp2unix_tm(sec, 0);
 120         if (!tm) {
 121                 (void) sprintf(bp, "%08lx.%08lx  --- --- -- ---- --:--:--",
 122                        (u_long)ts->l_ui, (u_long)ts->l_uf);
 123         }
 124         else {
 125                 (void) sprintf(bp, "%08lx.%08lx  %s, %s %2d %4d %2d:%02d:%02d.%03lu",
 126                        (u_long)ts->l_ui, (u_long)ts->l_uf, days[tm->tm_wday],
 127                        months[tm->tm_mon], tm->tm_mday, 1900 + tm->tm_year,
 128                        tm->tm_hour,tm->tm_min, tm->tm_sec, msec);
 129         }
 130
 131         return bp;
 132 }