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 <time.h>
  30 #include <errno.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <stddef.h>
  34 #include <string.h>
  35 #include <unistd.h>
  36 #include <linux/stddef.h>
  37
  38 #include "udev.h"
  39 #include "udev_lib.h"
  40 #include "udev_version.h"
  41 #include "udevd.h"
  42 #include "logging.h"
  43
  44 #ifdef LOG
  45 unsigned char logname[LOGNAME_SIZE];
  46 void log_message (int level, const char *format, ...)
  47 {
  48         va_list args;
  49
  50         va_start(args, format);
  51         vsyslog(level, format, args);
  52         va_end(args);
  53 }
  54 #endif
  55
  56 static void build_hotplugmsg(struct hotplug_msg *msg, char *action,
  57                              char *devpath, char *subsystem, int seqnum)
  58 {
  59         memset(msg, 0x00, sizeof(struct hotplug_msg));
  60         strfieldcpy(msg->magic, UDEV_MAGIC);
  61         msg->seqnum = seqnum;
  62         strfieldcpy(msg->action, action);
  63         strfieldcpy(msg->devpath, devpath);
  64         strfieldcpy(msg->subsystem, subsystem);
  65 }
  66
  67 static int start_daemon(void)
  68 {
  69         pid_t pid;
  70         pid_t child_pid;
  71
  72         pid = fork();
  73         switch (pid) {
  74         case 0:
  75                 /* helper child */
  76                 child_pid = fork();
  77                 switch (child_pid) {
  78                 case 0:
  79                         /* daemon */
  80                         setsid();
  81                         chdir("/");
  82                         execl(UDEVD_BIN, "udevd", NULL);
  83                         dbg("exec of daemon failed");
  84                         exit(1);
  85                 case -1:
  86                         dbg("fork of daemon failed");
  87                         return -1;
  88                 default:
  89                         exit(0);
  90                 }
  91                 break;
  92         case -1:
  93                 dbg("fork of helper failed");
  94                 return -1;
  95         default:
  96                 wait(NULL);
  97         }
  98         return 0;
  99 }
 100
 101 static void run_udev(const char *subsystem)
 102 {
 103         pid_t pid;
 104
 105         pid = fork();
 106         switch (pid) {
 107         case 0:
 108                 /* child */
 109                 execl(UDEV_BIN, "udev", subsystem, NULL);
 110                 dbg("exec of child failed");
 111                 exit(1);
 112                 break;
 113         case -1:
 114                 dbg("fork of child failed");
 115                 break;
 116         default:
 117                 wait(NULL);
 118         }
 119 }
 120
 121 int main(int argc, char* argv[])
 122 {
 123         struct hotplug_msg msg;
 124         char *action;
 125         char *devpath;
 126         char *subsystem;
 127         char *seqnum;
 128         int seq;
 129         int retval = 1;
 130         int loop;
 131         struct timespec tspec;
 132         int sock = -1;
 133         struct sockaddr_un saddr;
 134         socklen_t addrlen;
 135         int started_daemon = 0;
 136
 137         init_logging("udevsend");
 138         dbg("version %s", UDEV_VERSION);
 139
 140         subsystem = get_subsystem(argv[1]);
 141         if (subsystem == NULL) {
 142                 dbg("no subsystem");
 143                 goto exit;
 144         }
 145         dbg("subsystem = '%s'", subsystem);
 146
 147         devpath = get_devpath();
 148         if (devpath == NULL) {
 149                 dbg("no devpath");
 150                 goto exit;
 151         }
 152         dbg("DEVPATH = '%s'", devpath);
 153
 154         action = get_action();
 155         if (action == NULL) {
 156                 dbg("no action");
 157                 goto exit;
 158         }
 159         dbg("ACTION = '%s'", action);
 160
 161         seqnum = get_seqnum();
 162         if (seqnum == NULL)
 163                 seq = -1;
 164         else
 165                 seq = atoi(seqnum);
 166         dbg("SEQNUM = '%d'", seq);
 167
 168         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 169         if (sock == -1) {
 170                 dbg("error getting socket");
 171                 goto fallback;
 172         }
 173
 174         memset(&saddr, 0x00, sizeof(struct sockaddr_un));
 175         saddr.sun_family = AF_LOCAL;
 176         /* use abstract namespace for socket path */
 177         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 178         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 179
 180         build_hotplugmsg(&msg, action, devpath, subsystem, seq);
 181
 182         /* If we can't send, try to start daemon and resend message */
 183         loop = UDEVSEND_CONNECT_RETRY;
 184         while (loop--) {
 185                 retval = sendto(sock, &msg, sizeof(struct hotplug_msg), 0,
 186                                 (struct sockaddr *)&saddr, addrlen);
 187                 if (retval != -1) {
 188                         retval = 0;
 189                         goto exit;
 190                 }
 191
 192                 if (errno != ECONNREFUSED) {
 193                         dbg("error sending message");
 194                         goto fallback;
 195                 }
 196
 197                 if (!started_daemon) {
 198                         info("starting udevd daemon");
 199                         retval = start_daemon();
 200                         if (retval) {
 201                                 info("error starting daemon");
 202                                 goto fallback;
 203                         }
 204                         dbg("daemon started");
 205                         started_daemon = 1;
 206                 } else {
 207                         dbg("retry to connect %d", UDEVSEND_CONNECT_RETRY - loop);
 208                         tspec.tv_sec = 0;
 209                         tspec.tv_nsec = 100000000;  /* 100 millisec */
 210                         nanosleep(&tspec, NULL);
 211                 }
 212         }
 213
 214 fallback:
 215         info("unable to connect to event daemon, try to call udev directly");
 216         run_udev(subsystem);
 217
 218 exit:
 219         if (sock != -1)
 220                 close(sock);
 221
 222         return retval;
 223 }