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         memset(msg, 0x00, sizeof(msg));
  68         msg->mtype = HOTPLUGMSGTYPE;
  69         msg->seqnum = seqnum;
  70         strncpy(msg->action, action, 8);
  71         strncpy(msg->devpath, devpath, 128);
  72         strncpy(msg->subsystem, subsystem, 16);
  73         return sizeof(struct hotplug_msg);
  74 }
  75
  76 static int start_daemon(void)
  77 {
  78         pid_t pid;
  79         pid_t child_pid;
  80
  81         pid = fork();
  82         switch (pid) {
  83         case 0:
  84                 /* helper child */
  85                 child_pid = fork();
  86                 switch (child_pid) {
  87                 case 0:
  88                         /* daemon */
  89                         setsid();
  90                         chdir("/");
  91                         execl(UDEVD_EXEC, "udevd", NULL);
  92                         dbg("exec of daemon failed");
  93                         exit(1);
  94                 case -1:
  95                         dbg("fork of daemon failed");
  96                         return -1;
  97                 default:
  98                         exit(0);
  99                 }
 100                 break;
 101         case -1:
 102                 dbg("fork of helper failed");
 103                 return -1;
 104         default:
 105                 wait(NULL);
 106         }
 107         return 0;
 108 }
 109
 110
 111 int main(int argc, char* argv[])
 112 {
 113         int msgid;
 114         key_t key;
 115         struct msqid_ds msg_queue;
 116         struct hotplug_msg message;
 117         char *action;
 118         char *devpath;
 119         char *subsystem;
 120         char *seqnum;
 121         int seq;
 122         int retval = -EINVAL;
 123         int size;
 124         int loop;
 125         struct timespec tspec;
 126
 127         subsystem = argv[1];
 128         if (subsystem == NULL) {
 129                 dbg("no subsystem");
 130                 goto exit;
 131         }
 132
 133         devpath = get_devpath();
 134         if (devpath == NULL) {
 135                 dbg("no devpath");
 136                 goto exit;
 137         }
 138
 139         action = get_action();
 140         if (action == NULL) {
 141                 dbg("no action");
 142                 goto exit;
 143         }
 144
 145         seqnum = get_seqnum();
 146         if (seqnum == NULL) {
 147                 dbg("no seqnum");
 148                 goto exit;
 149         }
 150         seq = atoi(seqnum);
 151
 152         /* create ipc message queue or get id of our existing one */
 153         key = ftok(UDEVD_EXEC, IPC_KEY_ID);
 154         size =  build_hotplugmsg(&message, action, devpath, subsystem, seq);
 155         msgid = msgget(key, IPC_CREAT);
 156         if (msgid == -1) {
 157                 dbg("error open ipc queue");
 158                 goto exit;
 159         }
 160
 161         /* send ipc message to the daemon */
 162         retval = msgsnd(msgid, &message, size, 0);
 163         if (retval == -1) {
 164                 dbg("error sending ipc message");
 165                 goto exit;
 166         }
 167
 168         /* get state of ipc queue */
 169         tspec.tv_sec = 0;
 170         tspec.tv_nsec = 10000000;  /* 10 millisec */
 171         loop = 30;
 172         while (loop--) {
 173                 retval = msgctl(msgid, IPC_STAT, &msg_queue);
 174                 if (retval == -1) {
 175                         dbg("error getting info on ipc queue");
 176                         goto exit;
 177                 }
 178                 if (msg_queue.msg_qnum == 0)
 179                         goto exit;
 180                 nanosleep(&tspec, NULL);
 181         }
 182
 183         info("message is still in the ipc queue, starting daemon...");
 184         retval = start_daemon();
 185
 186 exit:
 187         return retval;
 188 }