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 int start_daemon(void)
  57 {
  58         pid_t pid;
  59         pid_t child_pid;
  60
  61         pid = fork();
  62         switch (pid) {
  63         case 0:
  64                 /* helper child */
  65                 child_pid = fork();
  66                 switch (child_pid) {
  67                 case 0:
  68                         /* daemon */
  69                         setsid();
  70                         chdir("/");
  71                         execl(UDEVD_BIN, "udevd", NULL);
  72                         dbg("exec of daemon failed");
  73                         exit(1);
  74                 case -1:
  75                         dbg("fork of daemon failed");
  76                         return -1;
  77                 default:
  78                         exit(0);
  79                 }
  80                 break;
  81         case -1:
  82                 dbg("fork of helper failed");
  83                 return -1;
  84         default:
  85                 wait(NULL);
  86         }
  87         return 0;
  88 }
  89
  90 static void run_udev(const char *subsystem)
  91 {
  92         pid_t pid;
  93
  94         pid = fork();
  95         switch (pid) {
  96         case 0:
  97                 /* child */
  98                 execl(UDEV_BIN, "udev", subsystem, NULL);
  99                 dbg("exec of child failed");
 100                 exit(1);
 101                 break;
 102         case -1:
 103                 dbg("fork of child failed");
 104                 break;
 105         default:
 106                 wait(NULL);
 107         }
 108 }
 109
 110 int main(int argc, char* argv[])
 111 {
 112         struct hotplug_msg msg;
 113         char *action;
 114         char *devpath;
 115         char *subsystem;
 116         char *seqnum;
 117         unsigned long long seq;
 118         int retval = 1;
 119         int loop;
 120         struct timespec tspec;
 121         int sock = -1;
 122         struct sockaddr_un saddr;
 123         socklen_t addrlen;
 124         int started_daemon = 0;
 125
 126         init_logging("udevsend");
 127         dbg("version %s", UDEV_VERSION);
 128
 129         subsystem = get_subsystem(argv[1]);
 130         if (subsystem == NULL) {
 131                 dbg("no subsystem");
 132                 goto exit;
 133         }
 134         dbg("subsystem = '%s'", subsystem);
 135
 136         devpath = get_devpath();
 137         if (devpath == NULL) {
 138                 dbg("no devpath");
 139                 goto exit;
 140         }
 141         dbg("DEVPATH = '%s'", devpath);
 142
 143         action = get_action();
 144         if (action == NULL) {
 145                 dbg("no action");
 146                 goto exit;
 147         }
 148         dbg("ACTION = '%s'", action);
 149
 150         seqnum = get_seqnum();
 151         if (seqnum == NULL)
 152                 seq = 0;
 153         else
 154                 seq = strtoull(seqnum, NULL, 10);
 155         dbg("SEQNUM = '%llu'", seq);
 156
 157         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 158         if (sock == -1) {
 159                 dbg("error getting socket");
 160                 goto fallback;
 161         }
 162
 163         set_cloexec_flag(sock, 1);
 164
 165         memset(&saddr, 0x00, sizeof(struct sockaddr_un));
 166         saddr.sun_family = AF_LOCAL;
 167         /* use abstract namespace for socket path */
 168         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 169         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 170
 171         memset(&msg, 0x00, sizeof(struct hotplug_msg));
 172         strcpy(msg.magic, UDEV_MAGIC);
 173         msg.seqnum = seq;
 174         strfieldcpy(msg.action, action);
 175         strfieldcpy(msg.devpath, devpath);
 176         strfieldcpy(msg.subsystem, subsystem);
 177
 178         /* If we can't send, try to start daemon and resend message */
 179         loop = UDEVSEND_CONNECT_RETRY;
 180         while (loop--) {
 181                 retval = sendto(sock, &msg, sizeof(struct hotplug_msg), 0,
 182                                 (struct sockaddr *)&saddr, addrlen);
 183                 if (retval != -1) {
 184                         retval = 0;
 185                         goto exit;
 186                 }
 187
 188                 if (errno != ECONNREFUSED) {
 189                         dbg("error sending message");
 190                         goto fallback;
 191                 }
 192
 193                 if (!started_daemon) {
 194                         info("starting udevd daemon");
 195                         retval = start_daemon();
 196                         if (retval) {
 197                                 info("error starting daemon");
 198                                 goto fallback;
 199                         }
 200                         dbg("daemon started");
 201                         started_daemon = 1;
 202                 } else {
 203                         dbg("retry to connect %d", UDEVSEND_CONNECT_RETRY - loop);
 204                         tspec.tv_sec = 0;
 205                         tspec.tv_nsec = 100000000;  /* 100 millisec */
 206                         nanosleep(&tspec, NULL);
 207                 }
 208         }
 209
 210 fallback:
 211         info("unable to connect to event daemon, try to call udev directly");
 212         run_udev(subsystem);
 213
 214 exit:
 215         if (sock != -1)
 216                 close(sock);
 217
 218         return retval;
 219 }