+int rtc_open(int flags) {
+ int fd;
+ DIR *d;
+
+ /* We open the first RTC which has hctosys=1 set. If we don't
+ * find any we just take the first one */
+
+ 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;
+}
+