diff options
Diffstat (limited to 'libntp/prettydate.c')
| -rw-r--r-- | libntp/prettydate.c | 82 |
1 files changed, 73 insertions, 9 deletions
diff --git a/libntp/prettydate.c b/libntp/prettydate.c index 9710c84be1734..55adf64aeeb25 100644 --- a/libntp/prettydate.c +++ b/libntp/prettydate.c @@ -17,6 +17,60 @@ static const char *days[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; +/* Helper function to handle possible wraparound of the ntp epoch. + + Works by assuming that the localtime/gmtime library functions + have been updated so that they work +*/ + +#define MAX_EPOCH_NR 1000 + +struct tm * +ntp2unix_tm( + u_long ntp, int local + ) +{ + time_t t, curr; + struct tm *tm; + int curr_year, epoch_nr; + + /* First get the current year: */ + curr = time(NULL); + tm = local ? localtime(&curr) : gmtime(&curr); + if (!tm) return NULL; + + curr_year = 1900 + tm->tm_year; + + /* Convert the ntp timestamp to a unix utc seconds count: */ + t = (time_t) ntp - JAN_1970; + + /* Check that the ntp timestamp is not before a 136 year window centered + around the current year: + + Failsafe in case of an infinite loop: + Allow up to 1000 epochs of 136 years each! + */ + for (epoch_nr = 0; epoch_nr < MAX_EPOCH_NR; epoch_nr++) { + tm = local ? localtime(&t) : gmtime(&t); + +#if SIZEOF_TIME_T < 4 +# include "Bletch: sizeof(time_t) < 4!" +#endif + +#if SIZEOF_TIME_T == 4 + /* If 32 bits, then year is 1970-2038, so no sense looking */ + epoch_nr = MAX_EPOCH_NR; +#else /* SIZEOF_TIME_T > 4 */ + /* Check that the resulting year is in the correct epoch: */ + if (1900 + tm->tm_year > curr_year - 68) break; + + /* Epoch wraparound: Add 2^32 seconds! */ + t += (time_t) 65536 << 16; +#endif /* SIZEOF_TIME_T > 4 */ + } + return tm; +} + char * prettydate( l_fp *ts @@ -29,15 +83,20 @@ prettydate( LIB_GETBUF(bp); - sec = ts->l_ui - JAN_1970; + sec = ts->l_ui; msec = ts->l_uf / 4294967; /* fract / (2 ** 32 / 1000) */ - tm = localtime(&sec); - - (void) sprintf(bp, "%08lx.%08lx %s, %s %2d %4d %2d:%02d:%02d.%03lu", + tm = ntp2unix_tm(sec, 1); + if (!tm) { + (void) sprintf(bp, "%08lx.%08lx --- --- -- ---- --:--:--", + (u_long)ts->l_ui, (u_long)ts->l_uf); + } + else { + (void) sprintf(bp, "%08lx.%08lx %s, %s %2d %4d %2d:%02d:%02d.%03lu", (u_long)ts->l_ui, (u_long)ts->l_uf, days[tm->tm_wday], months[tm->tm_mon], tm->tm_mday, 1900 + tm->tm_year, tm->tm_hour,tm->tm_min, tm->tm_sec, msec); + } return bp; } @@ -54,15 +113,20 @@ gmprettydate( LIB_GETBUF(bp); - sec = ts->l_ui - JAN_1970; + sec = ts->l_ui; msec = ts->l_uf / 4294967; /* fract / (2 ** 32 / 1000) */ - tm = gmtime(&sec); - - (void) sprintf(bp, "%08lx.%08lx %s, %s %2d %4d %2d:%02d:%02d.%03lu UTC", + tm = ntp2unix_tm(sec, 0); + if (!tm) { + (void) sprintf(bp, "%08lx.%08lx --- --- -- ---- --:--:--", + (u_long)ts->l_ui, (u_long)ts->l_uf); + } + else { + (void) sprintf(bp, "%08lx.%08lx %s, %s %2d %4d %2d:%02d:%02d.%03lu", (u_long)ts->l_ui, (u_long)ts->l_uf, days[tm->tm_wday], months[tm->tm_mon], tm->tm_mday, 1900 + tm->tm_year, tm->tm_hour,tm->tm_min, tm->tm_sec, msec); - + } + return bp; } |