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| author | Miroslav Lichvar <mlichvar@redhat.com> | 2022-09-16 15:06:36 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2023-01-17 16:48:54 +0100 |
| commit | 85acf71d2579ebe4eec05c6f31901adffa700adc (patch) | |
| tree | 1f350548b148e952971a547667a8b2ec80029feb /networking | |
| parent | ca96022d6edaaf619324db5a481698231d74d1df (diff) | |
| download | busybox-85acf71d2579ebe4eec05c6f31901adffa700adc.tar.gz | |
ntpd: make NTP client and server Y2036/2038-ready
The 32-bit integer part of the NTP timestamp overflows in year 2036,
which starts the second NTP era.
Modify the timestamp conversion to shift values between 1900-1970 (in
the first era) to the second era to enable the client to measure its
offset correctly until year 2106 (assuming 64-bit time_t).
Also update the conversion from double used when stepping the clock to
work with 64-bit time_t after reaching the maximum 32-bit value in 2038
and the server conversion to work correctly in the next NTP era.
function old new delta
lfp_to_d 51 64 +13
step_time 326 332 +6
.rodata 105260 105264 +4
d_to_lfp 100 86 -14
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/1 up/down: 23/-14) Total: 9 bytes
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/ntpd.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index 204e1d7c2..4365166ff 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -554,7 +554,7 @@ gettime1900d(void) static void d_to_tv(struct timeval *tv, double d) { - tv->tv_sec = (long)d; + tv->tv_sec = (time_t)d; tv->tv_usec = (d - tv->tv_sec) * 1000000; } @@ -565,6 +565,14 @@ lfp_to_d(l_fixedpt_t lfp) lfp.int_partl = ntohl(lfp.int_partl); lfp.fractionl = ntohl(lfp.fractionl); ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX); + /* + * Shift timestamps before 1970 to the second NTP era (2036-2106): + * int_partl value of OFFSET_1900_1970 (2208988800) is interpreted as + * the start of year 1970 and it is the minimal representable time, + * all values form the sequence 2208988800..0xffffffff,0..2208988799. + */ + if (lfp.int_partl < OFFSET_1900_1970) + ret += (double)(1ULL << 32); /* because int_partl is 32-bit wide */ return ret; } static NOINLINE double @@ -582,8 +590,8 @@ d_to_lfp(l_fixedpt_t *lfp, double d) { uint32_t intl; uint32_t frac; - intl = (uint32_t)d; - frac = (uint32_t)((d - intl) * UINT_MAX); + intl = (uint32_t)(time_t)d; + frac = (uint32_t)((d - (time_t)d) * UINT_MAX); lfp->int_partl = htonl(intl); lfp->fractionl = htonl(frac); } |