util: split-out hwclock.[ch]

1 files changed, 228 insertions, 0 deletions

diff --git a/src/shared/hwclock.c b/src/shared/hwclock.c
new file mode 100644
index 0000000000..d40bb2653f
--- /dev/null
+++ b/src/shared/hwclock.c
@@ -0,0 +1,228 @@
+/*-*- 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 <assert.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <stdarg.h>
+#include <ctype.h>
+#include <sys/prctl.h>
+#include <sys/time.h>
+#include <linux/rtc.h>
+
+#include "macro.h"
+#include "util.h"
+#include "log.h"
+#include "strv.h"
+#include "hwclock.h"
+
+static int rtc_open(int flags) {
+        int fd;
+        DIR *d;
+
+        /* First, we try to make use of the /dev/rtc symlink. If that
+         * doesn't exist, we open the first RTC which has hctosys=1
+         * set. If we don't find any we just take the first RTC that
+         * exists at all. */
+
+        fd = open("/dev/rtc", flags);
+        if (fd >= 0)
+                return fd;
+
+        d = opendir("/sys/class/rtc");
+        if (!d)
+                goto fallback;
+
+        for (;;) {
+                char *p, *v;
+                struct dirent buf, *de;
+                int r;
+
+                r = readdir_r(d, &buf, &de);
+                if (r != 0)
+                        goto fallback;
+
+                if (!de)
+                        goto fallback;
+
+                if (ignore_file(de->d_name))
+                        continue;
+
+                p = join("/sys/class/rtc/", de->d_name, "/hctosys", NULL);
+                if (!p) {
+                        closedir(d);
+                        return -ENOMEM;
+                }
+
+                r = read_one_line_file(p, &v);
+                free(p);
+
+                if (r < 0)
+                        continue;
+
+                r = parse_boolean(v);
+                free(v);
+
+                if (r <= 0)
+                        continue;
+
+                p = strappend("/dev/", de->d_name);
+                fd = open(p, flags);
+                free(p);
+
+                if (fd >= 0) {
+                        closedir(d);
+                        return fd;
+                }
+        }
+
+fallback:
+        if (d)
+                closedir(d);
+
+        fd = open("/dev/rtc0", flags);
+        if (fd < 0)
+                return -errno;
+
+        return fd;
+}
+
+int hwclock_get_time(struct tm *tm) {
+        int fd;
+        int err = 0;
+
+        assert(tm);
+
+        fd = rtc_open(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)
+                err = -errno;
+
+        /* We don't know daylight saving, so we reset this in order not
+         * to confused mktime(). */
+        tm->tm_isdst = -1;
+
+        close_nointr_nofail(fd);
+
+        return err;
+}
+
+int hwclock_set_time(const struct tm *tm) {
+        int fd;
+        int err = 0;
+
+        assert(tm);
+
+        fd = rtc_open(O_RDONLY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        if (ioctl(fd, RTC_SET_TIME, tm) < 0)
+                err = -errno;
+
+        close_nointr_nofail(fd);
+
+        return err;
+}
+int hwclock_is_localtime(void) {
+        FILE *f;
+        bool local = false;
+
+        /*
+         * 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);
+
+                fclose(f);
+
+                if (!b)
+                        return -EIO;
+
+                truncate_nl(line);
+                local = streq(line, "LOCAL");
+
+        } else if (errno != -ENOENT)
+                return -errno;
+
+        return local;
+}
+
+int hwclock_apply_localtime_delta(int *min) {
+        const struct timeval *tv_null = NULL;
+        struct timespec ts;
+        struct tm *tm;
+        int minuteswest;
+        struct timezone tz;
+
+        assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
+        assert_se(tm = localtime(&ts.tv_sec));
+        minuteswest = tm->tm_gmtoff / 60;
+
+        tz.tz_minuteswest = -minuteswest;
+        tz.tz_dsttime = 0; /* DST_NONE*/
+
+        /*
+         * If the hardware clock does not run in UTC, but in local time:
+         * The very first time we set the kernel's timezone, it will warp
+         * the clock so that it runs in UTC instead of local time.
+         */
+        if (settimeofday(tv_null, &tz) < 0)
+                return -errno;
+        if (min)
+                *min = minuteswest;
+        return 0;
+}
+
+int hwclock_reset_localtime_delta(void) {
+        const struct timeval *tv_null = NULL;
+        struct timezone tz;
+
+        tz.tz_minuteswest = 0;
+        tz.tz_dsttime = 0; /* DST_NONE*/
+
+        if (settimeofday(tv_null, &tz) < 0)
+                return -errno;
+
+        return 0;
+}