Comment 1 for bug 1215911

I confirmed that below patch fixes my problem.

---------- patch start ----------
--- a/src/wait-for-root.c
+++ b/src/wait-for-root.c
@@ -88,7 +88,9 @@ main (int argc,
  /* When the device doesn't exist yet, or is still being processed
   * by udev, use the monitor socket to wait it to be done.
   */
- while ((udev_device = udev_monitor_receive_device (udev_monitor)) != NULL) {
+ while (1) {
+ while ((udev_device = udev_monitor_receive_device (udev_monitor)) == NULL)
+ sleep (1);
   if (matching_device (udev_device, devpath)) {
    type = udev_device_get_property_value (udev_device, "ID_FS_TYPE");
    if (type) {
---------- patch end ----------

But why need to handle udev_monitor_receive_device() errors?
I think that wait-for-root.c could be written as short as below code.

---------- simplified wait-for-root.c start ----------
#include <libudev.h>

#include <sys/types.h>
#include <sys/stat.h>

#include <stdio.h>
#include <limits.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void alarm_handler(int signum)
{
 exit(1);
}

int main(int argc, char *argv[])
{
 const char *devpath;
 char path[PATH_MAX];
 struct udev *udev;

 if (argc != 3) {
  fprintf(stderr, "Usage: %s DEVICE TIMEOUT\n", argv[0]);
  exit(2);
 }

 devpath = argv[1];
 if (!strncmp(devpath, "UUID=", 5))
  snprintf(path, sizeof(path), "/dev/disk/by-uuid/%s", devpath + 5);
 else if (!strncmp(devpath, "LABEL=", 6))
  snprintf(path, sizeof(path), "/dev/disk/by-label/%s", devpath + 6);
 else
  snprintf(path, sizeof(path), "%s", devpath);

 signal(SIGALRM, alarm_handler);
 alarm(atoi(argv[2]));

 udev = udev_new();
 while (1) {
  struct stat devstat;
  const char *type;
  struct udev_device *udev_device;
  if (stat(path, &devstat) || !S_ISBLK(devstat.st_mode)) {
   sleep(1);
   continue;
  }
  udev_device = udev_device_new_from_devnum(udev, 'b', devstat.st_rdev);
  if (!udev_device) {
   sleep(1);
   continue;
  }
  type = udev_device_get_property_value(udev_device, "ID_FS_TYPE");
  if (type)
   printf("%s\n", type);
  udev_device_unref(udev_device);
  if (type)
   break;
 }
 udev_unref(udev);
 exit(0);
}
---------- simplified wait-for-root.c end ----------