blob: 1a6dcf5ec2b61dbfbfe276c6ee8750f4b1f373ab (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
/*
* ntpshmwrite.c - put time information in SHM segment for ntpd
*
* This file is Copyright (c)2010-2018 by the GPSD project
* SPDX-License-Identifier: BSD-2-clause
*/
/* sys/ipc.h needs _XOPEN_SOURCE, 500 means X/Open 1995 */
#define _XOPEN_SOURCE 500
#include <string.h>
#include <libgen.h>
#include <stdbool.h>
#include <math.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <unistd.h>
#include "ntpshm.h"
#include "compiler.h"
#define LEAP_NOWARNING 0x0 /* normal, no leap second warning */
void ntp_write(volatile struct shmTime *shmseg,
struct timedelta_t *td, int precision, int leap_notify)
/* put a received fix time into shared memory for NTP */
{
struct tm tm;
/*
* insist that leap seconds only happen in june and december
* GPS emits leap pending for 3 months prior to insertion
* NTP expects leap pending for only 1 month prior to insertion
* Per http://bugs.ntp.org/1090
*
* ITU-R TF.460-6, Section 2.1, says laep seconds can be primarily
* in Jun/Dec but may be in March or September
*/
(void)gmtime_r( &(td->real.tv_sec), &tm);
if ( 5 != tm.tm_mon && 11 != tm.tm_mon ) {
/* Not june, not December, no way */
leap_notify = LEAP_NOWARNING;
}
/* we use the shmTime mode 1 protocol
*
* ntpd does this:
*
* reads valid.
* IFF valid is 1
* reads count
* reads values
* reads count
* IFF count unchanged
* use values
* clear valid
*
*/
shmseg->valid = 0;
shmseg->count++;
/* We need a memory barrier here to prevent write reordering by
* the compiler or CPU cache */
memory_barrier();
shmseg->clockTimeStampSec = (time_t)td->real.tv_sec;
shmseg->clockTimeStampUSec = (int)(td->real.tv_nsec/1000);
shmseg->clockTimeStampNSec = (unsigned)td->real.tv_nsec;
shmseg->receiveTimeStampSec = (time_t)td->clock.tv_sec;
shmseg->receiveTimeStampUSec = (int)(td->clock.tv_nsec/1000);
shmseg->receiveTimeStampNSec = (unsigned)td->clock.tv_nsec;
shmseg->leap = leap_notify;
shmseg->precision = precision;
memory_barrier();
shmseg->count++;
shmseg->valid = 1;
}
/* end */
|
