2011-7-29 16:38:16

2011-7-29 16:38:16

 

2011-7-29 16:38:16

 

第一次的设备移除是怎么产生的？

init_udevd_socket

监听了一个unix域的socket

有这样一个主循环

while (!udev_exit) {
  struct udevd_uevent_msg *msg;
  int fdcount;

  FD_ZERO(&readfds);
  FD_SET(signal_pipe[READ_END], &readfds);
  FD_SET(udevd_sock, &readfds);
  FD_SET(uevent_netlink_sock, &readfds);
  if (inotify_fd >= 0)
   FD_SET(inotify_fd, &readfds);

  fdcount = select(maxfd+1, &readfds, NULL, NULL, NULL);
  if (fdcount < 0) {
   if (errno != EINTR)
    err("error in select: %s\n", strerror(errno));
   continue;
  }

  /* get control message */
  if (FD_ISSET(udevd_sock, &readfds))
   get_ctrl_msg();

  /* get netlink message */
  if (FD_ISSET(uevent_netlink_sock, &readfds)) {
   msg = get_netlink_msg();
   if (msg)
    msg_queue_insert(msg);
  }

  /* received a signal, clear our notification pipe */
  if (FD_ISSET(signal_pipe[READ_END], &readfds)) {
   char buf[256];

   read(signal_pipe[READ_END], &buf, sizeof(buf));
  }

  /* rules directory inotify watch */
  if ((inotify_fd >= 0) && FD_ISSET(inotify_fd, &readfds)) {
   int nbytes;

   /* discard all possible events, we can just reload the config */
   if ((ioctl(inotify_fd, FIONREAD, &nbytes) == 0) && nbytes > 0) {
    char *buf;

    reload_config = 1;
    buf = malloc(nbytes);
    if (buf == NULL) {
     err("error getting buffer for inotify, disable watching\n");
     close(inotify_fd);
     inotify_fd = -1;
    }
    read(inotify_fd, buf, nbytes);
    free(buf);
   }
  }

  /* rules changed, set by inotify or a HUP signal */
  if (reload_config) {
   reload_config = 0;
   udev_rules_cleanup(&rules);
   udev_rules_init(&rules, 1);
  }

  /* forked child has returned */
  if (sigchilds_waiting) {
   sigchilds_waiting = 0;
   reap_sigchilds();
  }

  if (run_exec_q) {
   run_exec_q = 0;
   if (!stop_exec_q)
    msg_queue_manager();
  }
 }
 rc = 0;

 

static int init_uevent_netlink_sock(void)
{
 struct sockaddr_nl snl;
 const int buffersize = 16 * 1024 * 1024;
 int retval;

 memset(&snl, 0x00, sizeof(struct sockaddr_nl));
 snl.nl_family = AF_NETLINK;
 snl.nl_pid = getpid();
 snl.nl_groups = 1;

 uevent_netlink_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
 if (uevent_netlink_sock == -1) {
  err("error getting socket: %s\n", strerror(errno));
  return -1;
 }

 /* set receive buffersize */
 setsockopt(uevent_netlink_sock, SOL_SOCKET, SO_RCVBUFFORCE, &buffersize, sizeof(buffersize));

 retval = bind(uevent_netlink_sock, (struct sockaddr *) &snl, sizeof(struct sockaddr_nl));
 if (retval < 0) {
  err("bind failed: %s\n", strerror(errno));
  close(uevent_netlink_sock);
  uevent_netlink_sock = -1;
  return -1;
 }
 return 0;
}
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