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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
/* $OpenBSD: ntpleaps.c,v 1.5 2002/08/03 12:20:34 jakob Exp $ */
/*
* Copyright (c) 2002 by Thorsten "mirabile" Glaser <x86@ePOST.de>
*
* Permission is hereby granted to any person obtaining a copy of this work
* to deal in the work, without restrictions, including unlimited rights to
* use, copy, modify, merge, publish, distribute, sublicense or sell copies
* of the work, and to permit persons to whom the work is furnished to also
* do so, as long as due credit is given to the original author and contri-
* butors, and the following disclaimer is kept in all substantial portions
* of the work or accompanying documentation:
*
* This work is provided "AS IS", without warranty of any kind, neither ex-
* press nor implied, including, but not limited to, the warranties of mer-
* chantability, fitness for particular purposes and noninfringement. In NO
* event shall the author and contributors be liable for any claim, damages
* and such, whether in contract, strict liability or otherwise, arising in
* any way out of this work, even if advised of the possibility of such.
*/
/* Leap second support for NTP clients (generic) */
static const char RCSId[] = "$OpenBSD: ntpleaps.c,v 1.5 2002/08/03 12:20:34 jakob Exp $";
/*
* I could include tzfile.h, but this would make the code unportable
* at no real benefit. Read tzfile.h for why.
*/
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include "ntpleaps.h"
u_int64_t *leapsecs = NULL;
unsigned int leapsecs_num = 0;
static int flaginit = -1;
static int flagwarn = 0;
int
ntpleaps_init(void)
{
if (!flaginit)
return (0);
if (!ntpleaps_read()) {
flaginit = 0;
return (0);
}
/* This does not really hurt, but users will complain about
* off-by-22-seconds (at time of coding) errors if we don't warn.
*/
if (!flagwarn) {
fputs("Warning: error reading tzfile. You will NOT be\n"
"able to get legal time or posix compliance!\n", stderr);
flagwarn = 1; /* put it only once */
}
return (-1);
}
int
ntpleaps_sub(u_int64_t *t)
{
unsigned int i = 0;
u_int64_t u;
int r = 1;
if ((flaginit ? ntpleaps_init() : 0) == -1)
return (-1);
u = *t;
while (i < leapsecs_num) {
if (u < leapsecs[i])
break;
if (u == leapsecs[i++])
goto do_sub;
}
--r;
do_sub:
*t = u - i;
return (r);
}
u_int32_t
read_be_dword(u_int8_t *ptr)
{
u_int32_t res;
memcpy(&res, ptr, 4);
return (ntohl(res));
}
int
ntpleaps_read(void)
{
int fd;
unsigned int r;
u_int8_t buf[32];
u_int32_t m1, m2, m3;
u_int64_t s;
u_int64_t *l;
fd = open("/usr/share/zoneinfo/right/UTC", O_RDONLY | O_NDELAY);
if (fd == -1)
return (-1);
/* Check signature */
read(fd, buf, 4);
buf[4] = 0;
if (strcmp((const char *)buf, "TZif")) {
close(fd);
return (-1);
}
/* Pre-initalize buf[24..27] so we need not check read(2) result */
buf[24] = 0;
buf[25] = 0;
buf[26] = 0;
buf[27] = 0;
/* Skip uninteresting parts of header */
read(fd, buf, 28);
/* Read number of leap second entries */
r = read_be_dword(&buf[24]);
/* Check for plausibility - arbitrary values */
if ((r < 20) || (r > 60000)) {
close(fd);
return (-1);
}
if ((l = (u_int64_t *)malloc(r << 3)) == NULL) {
close(fd);
return (-1);
}
/* Skip further uninteresting stuff */
read(fd, buf, 12);
m1 = read_be_dword(buf);
m2 = read_be_dword(&buf[4]);
m3 = read_be_dword(&buf[8]);
m3 += (m1 << 2)+m1+(m2 << 2)+(m2 << 1);
lseek(fd, (off_t)m3, SEEK_CUR);
/* Now go parse the tzfile leap second info */
for (m1 = 0; m1 < r; m1++) {
if (read(fd, buf, 8) != 8) {
free(l);
close(fd);
return (-1);
}
s = SEC_TO_TAI64(read_be_dword(buf));
/*
* Assume just _one_ leap second on each entry, and compensate
* the lacking error checking by validating the first entry
* against the known value
*/
if (!m1 && s != 0x4000000004B2580AULL)
return (-1);
l[m1] = s;
}
/* Clean up and activate the table */
close(fd);
if (leapsecs != NULL)
free(leapsecs);
leapsecs = l;
leapsecs_num = r;
return (0);
}
|
