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/socket.h>
  27 #include <sys/wait.h>
  28 #include <sys/un.h>
  29 #include <errno.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <stddef.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35 #include <time.h>
  36 #include <linux/stddef.h>
  37
  38 #include "udev.h"
  39 #include "udev_version.h"
  40 #include "udevd.h"
  41 #include "logging.h"
  42
  43 unsigned char logname[42];
  44
  45 static inline char *get_action(void)
  46 {
  47         char *action;
  48
  49         action = getenv("ACTION");
  50         return action;
  51 }
  52
  53 static inline char *get_devpath(void)
  54 {
  55         char *devpath;
  56
  57         devpath = getenv("DEVPATH");
  58         return devpath;
  59 }
  60
  61 static inline char *get_seqnum(void)
  62 {
  63         char *seqnum;
  64
  65         seqnum = getenv("SEQNUM");
  66         return seqnum;
  67 }
  68
  69 static int build_hotplugmsg(struct hotplug_msg *msg, char *action,
  70                             char *devpath, char *subsystem, int seqnum)
  71 {
  72         memset(msg, 0x00, sizeof(*msg));
  73         strfieldcpy(msg->magic, UDEV_MAGIC);
  74         msg->seqnum = seqnum;
  75         strncpy(msg->action, action, 8);
  76         strncpy(msg->devpath, devpath, 128);
  77         strncpy(msg->subsystem, subsystem, 16);
  78         return sizeof(struct hotplug_msg);
  79 }
  80
  81 static int start_daemon(void)
  82 {
  83         pid_t pid;
  84         pid_t child_pid;
  85
  86         pid = fork();
  87         switch (pid) {
  88         case 0:
  89                 /* helper child */
  90                 child_pid = fork();
  91                 switch (child_pid) {
  92                 case 0:
  93                         /* daemon */
  94                         setsid();
  95                         chdir("/");
  96                         execl(UDEVD_BIN, "udevd", NULL);
  97                         dbg("exec of daemon failed");
  98                         exit(1);
  99                 case -1:
 100                         dbg("fork of daemon failed");
 101                         return -1;
 102                 default:
 103                         exit(0);
 104                 }
 105                 break;
 106         case -1:
 107                 dbg("fork of helper failed");
 108                 return -1;
 109         default:
 110                 wait(NULL);
 111         }
 112         return 0;
 113 }
 114
 115 int main(int argc, char* argv[])
 116 {
 117         struct hotplug_msg message;
 118         char *action;
 119         char *devpath;
 120         char *subsystem;
 121         char *seqnum;
 122         int seq;
 123         int retval = 1;
 124         int size;
 125         int loop;
 126         struct timespec tspec;
 127         int sock;
 128         struct sockaddr_un saddr;
 129         socklen_t addrlen;
 130         int started_daemon = 0;
 131
 132 #ifdef DEBUG
 133         init_logging("udevsend");
 134 #endif
 135
 136         subsystem = argv[1];
 137         if (subsystem == NULL) {
 138                 dbg("no subsystem");
 139                 goto exit;
 140         }
 141
 142         devpath = get_devpath();
 143         if (devpath == NULL) {
 144                 dbg("no devpath");
 145                 goto exit;
 146         }
 147
 148         action = get_action();
 149         if (action == NULL) {
 150                 dbg("no action");
 151                 goto exit;
 152         }
 153
 154         seqnum = get_seqnum();
 155         if (seqnum == NULL)
 156                 seq = -1;
 157         else
 158                 seq = atoi(seqnum);
 159
 160         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 161         if (sock == -1) {
 162                 dbg("error getting socket");
 163                 goto exit;
 164         }
 165
 166         memset(&saddr, 0x00, sizeof(saddr));
 167         saddr.sun_family = AF_LOCAL;
 168         /* use abstract namespace for socket path */
 169         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 170         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 171
 172         size = build_hotplugmsg(&message, action, devpath, subsystem, seq);
 173
 174         /* If we can't send, try to start daemon and resend message */
 175         loop = UDEVSEND_CONNECT_RETRY;
 176         while (loop--) {
 177                 retval = sendto(sock, &message, size, 0, (struct sockaddr*)&saddr, addrlen);
 178                 if (retval != -1) {
 179                         retval = 0;
 180                         goto close_and_exit;
 181                 }
 182
 183                 if (errno != ECONNREFUSED) {
 184                         dbg("error sending message");
 185                         goto close_and_exit;
 186                 }
 187
 188                 if (!started_daemon) {
 189                         dbg("connect failed, try starting daemon...");
 190                         retval = start_daemon();
 191                         if (retval) {
 192                                 dbg("error starting daemon");
 193                                 goto exit;
 194                         }
 195
 196                         dbg("daemon started");
 197                         started_daemon = 1;
 198                 } else {
 199                         dbg("retry to connect %d", UDEVSEND_CONNECT_RETRY - loop);
 200                         tspec.tv_sec = 0;
 201                         tspec.tv_nsec = 100000000;  /* 100 millisec */
 202                         nanosleep(&tspec, NULL);
 203                 }
 204         }
 205
 206 close_and_exit:
 207         close(sock);
 208 exit:
 209         return retval;
 210 }