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/* $OpenBSD: ntpleaps.c,v 1.6 2002/08/10 21:37:28 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 1.6 2002/08/10 21:37:28 jakob Exp $";
/*
* I could include tzfile.h, but this would make the code unportable
* at no real benefit. Read tzfile.h for why.
*/
#include <sys/types.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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);
}
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