udevsend.c

   1 /*
   2  * udevsend.c
   3  *
   4  * Userspace devfs
   5  *
   6  * Copyright (C) 2004 Ling, Xiaofeng <xiaofeng.ling@intel.com>
   7  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   8  *
   9  *
  10  *      This program is free software; you can redistribute it and/or modify it
  11  *      under the terms of the GNU General Public License as published by the
  12  *      Free Software Foundation version 2 of the License.
  13  *
  14  *      This program is distributed in the hope that it will be useful, but
  15  *      WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *      General Public License for more details.
  18  *
  19  *      You should have received a copy of the GNU General Public License along
  20  *      with this program; if not, write to the Free Software Foundation, Inc.,
  21  *      675 Mass Ave, Cambridge, MA 02139, USA.
  22  *
  23  */
  24
  25 #include <sys/types.h>
  26 #include <sys/ipc.h>
  27 #include <sys/msg.h>
  28 #include <errno.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <unistd.h>
  33 #include <time.h>
  34 #include <wait.h>
  35
  36 #include "udev.h"
  37 #include "udevd.h"
  38 #include "logging.h"
  39
  40 static inline char *get_action(void)
  41 {
  42         char *action;
  43
  44         action = getenv("ACTION");
  45         return action;
  46 }
  47
  48 static inline char *get_devpath(void)
  49 {
  50         char *devpath;
  51
  52         devpath = getenv("DEVPATH");
  53         return devpath;
  54 }
  55
  56 static inline char *get_seqnum(void)
  57 {
  58         char *seqnum;
  59
  60         seqnum = getenv("SEQNUM");
  61         return seqnum;
  62 }
  63
  64 static int build_hotplugmsg(struct hotplug_msg *msg, char *action,
  65                             char *devpath, char *subsystem, int seqnum)
  66 {
  67         msg->mtype = HOTPLUGMSGTYPE;
  68         msg->seqnum = seqnum;
  69         strncpy(msg->action, action, 8);
  70         strncpy(msg->devpath, devpath, 128);
  71         strncpy(msg->subsystem, subsystem, 16);
  72         return sizeof(struct hotplug_msg);
  73 }
  74
  75 static int start_daemon(void)
  76 {
  77         pid_t pid;
  78         pid_t child_pid;
  79
  80         pid = fork();
  81         switch (pid) {
  82         case 0:
  83                 /* helper child */
  84                 child_pid = fork();
  85                 switch (child_pid) {
  86                 case 0:
  87                         /* daemon */
  88                         execl(DEFAULT_UDEVD_EXEC, NULL);
  89                         dbg("exec of daemon failed");
  90                         exit(1);
  91                 case -1:
  92                         dbg("fork of daemon failed");
  93                         return -1;
  94                 default:
  95                         exit(0);
  96                 }
  97                 break;
  98         case -1:
  99                 dbg("fork of helper failed");
 100                 return -1;
 101         default:
 102                 wait(0);
 103         }
 104         return 0;
 105 }
 106
 107
 108 int main(int argc, char* argv[])
 109 {
 110         int msgid;
 111         key_t key;
 112         struct msqid_ds msg_queue;
 113         struct hotplug_msg message;
 114         char *action;
 115         char *devpath;
 116         char *subsystem;
 117         char *seqnum;
 118         int seq;
 119         int retval = -EINVAL;
 120         int size;
 121         int loop;
 122         struct timespec tspec;
 123
 124         subsystem = argv[1];
 125         if (subsystem == NULL) {
 126                 dbg("no subsystem");
 127                 goto exit;
 128         }
 129
 130         devpath = get_devpath();
 131         if (devpath == NULL) {
 132                 dbg("no devpath");
 133                 goto exit;
 134         }
 135
 136         action = get_action();
 137         if (action == NULL) {
 138                 dbg("no action");
 139                 goto exit;
 140         }
 141
 142         seqnum = get_seqnum();
 143         if (seqnum == NULL) {
 144                 dbg("no seqnum");
 145                 goto exit;
 146         }
 147         seq = atoi(seqnum);
 148
 149         /* create ipc message queue or get id of our existing one */
 150         key = ftok(DEFAULT_UDEVD_EXEC, IPC_KEY_ID);
 151         size =  build_hotplugmsg(&message, action, devpath, subsystem, seq);
 152         msgid = msgget(key, IPC_CREAT);
 153         if (msgid == -1) {
 154                 dbg("error open ipc queue");
 155                 goto exit;
 156         }
 157
 158         /* send ipc message to the daemon */
 159         retval = msgsnd(msgid, &message, size, 0);
 160         if (retval == -1) {
 161                 dbg("error sending ipc message");
 162                 goto exit;
 163         }
 164
 165         /* get state of ipc queue */
 166         tspec.tv_sec = 0;
 167         tspec.tv_nsec = 10000000;  /* 10 millisec */
 168         loop = 20;
 169         while (loop--) {
 170                 retval = msgctl(msgid, IPC_STAT, &msg_queue);
 171                 if (retval == -1) {
 172                         dbg("error getting info on ipc queue");
 173                         goto exit;
 174                 }
 175                 if (msg_queue.msg_qnum == 0)
 176                         goto exit;
 177                 nanosleep(&tspec, NULL);
 178         }
 179
 180         info("message is still in the ipc queue, starting daemon...");
 181         retval = start_daemon();
 182
 183 exit:
 184         return retval;
 185 }