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/* ripped from uclibc
*
* Copyright (C) 2010 Denys Vlasenko <vda.linux@googlemail.com>
* Copyright (C) 2011 Natanael Copa <ncopa@alpinelinux.org>
*
* GNU Library General Public License (LGPL) version 2 or later.
*
*/
#include <sys/stat.h>
#include <sys/types.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "posixtz.h"
#ifndef TZNAME_MAX
#define TZNAME_MAX _POSIX_TZNAME_MAX
#endif
#define TZ_BUFLEN (2*TZNAME_MAX + 56)
char *posix_tz(const char *filename)
{
int fd, r;
static char buf[TZ_BUFLEN];
char *p = NULL;
fd = open(filename, O_RDONLY);
if (fd < 0)
return NULL;
r = read(fd, buf, TZ_BUFLEN);
if (r != TZ_BUFLEN
|| strncmp(buf, "TZif", 4) != 0
|| (unsigned char)buf[4] < 2
|| lseek(fd, (off_t) -TZ_BUFLEN, SEEK_END) < 0
)
goto ERROR;
/* tzfile.h from tzcode database says about TZif2+ files:
**
** If tzh_version is '2' or greater, the above is followed by a second instance
** of tzhead and a second instance of the data in which each coded transition
** time uses 8 rather than 4 chars,
** then a POSIX-TZ-environment-variable-style string for use in handling
** instants after the last transition time stored in the file
** (with nothing between the newlines if there is no POSIX representation for
** such instants).
*/
r = read(fd, buf, TZ_BUFLEN);
if (r <= 0 || buf[--r] != '\n')
goto ERROR;
buf[r] = 0;
while (r != 0) {
if (buf[--r] == '\n') {
p = buf + r + 1;
break;
}
} /* else ('\n' not found): p remains NULL */
ERROR:
close(fd);
return p;
}
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