/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2010-2012 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <errno.h> #include <stdio.h> #include <fcntl.h> #include <sys/ioctl.h> #include <sys/time.h> #include <linux/rtc.h> #include "macro.h" #include "util.h" #include "clock-util.h" int clock_get_hwclock(struct tm *tm) { _cleanup_close_ int fd = -1; assert(tm); fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC); if (fd < 0) return -errno; /* This leaves the timezone fields of struct tm * uninitialized! */ if (ioctl(fd, RTC_RD_TIME, tm) < 0) return -errno; /* We don't know daylight saving, so we reset this in order not * to confuse mktime(). */ tm->tm_isdst = -1; return 0; } int clock_set_hwclock(const struct tm *tm) { _cleanup_close_ int fd = -1; assert(tm); fd = open("/dev/rtc", O_RDONLY|O_CLOEXEC); if (fd < 0) return -errno; if (ioctl(fd, RTC_SET_TIME, tm) < 0) return -errno; return 0; } int clock_is_localtime(void) { _cleanup_fclose_ FILE *f; /* * The third line of adjtime is "UTC" or "LOCAL" or nothing. * # /etc/adjtime * 0.0 0 0 * 0 * UTC */ f = fopen("/etc/adjtime", "re"); if (f) { char line[LINE_MAX]; bool b; b = fgets(line, sizeof(line), f) && fgets(line, sizeof(line), f) && fgets(line, sizeof(line), f); if (!b) return -EIO; truncate_nl(line); return streq(line, "LOCAL"); } else if (errno != ENOENT) return -errno; return 0; } int clock_set_timezone(int *min) { const struct timeval *tv_null = NULL; struct timespec ts; struct tm *tm; int minutesdelta; struct timezone tz; assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0); assert_se(tm = localtime(&ts.tv_sec)); minutesdelta = tm->tm_gmtoff / 60; tz.tz_minuteswest = -minutesdelta; tz.tz_dsttime = 0; /* DST_NONE */ /* * If the RTC does not run in UTC but in local time, the very first * call to settimeofday() will set the kernel's timezone and will warp the * system clock, so that it runs in UTC instead of the local time we * have read from the RTC. */ if (settimeofday(tv_null, &tz) < 0) return -errno; if (min) *min = minutesdelta; return 0; } int clock_reset_timewarp(void) { const struct timeval *tv_null = NULL; struct timezone tz; tz.tz_minuteswest = 0; tz.tz_dsttime = 0; /* DST_NONE */ /* * The very first call to settimeofday() does time warp magic. Do a * dummy call here, so the time warping is sealed and all later calls * behave as expected. */ if (settimeofday(tv_null, &tz) < 0) return -errno; return 0; }