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 #include <sys/socket.h>
  36 #include <sys/un.h>
  37
  38 #include "udev.h"
  39 #include "udev_version.h"
  40 #include "udevd.h"
  41 #include "logging.h"
  42
  43
  44 static inline char *get_action(void)
  45 {
  46         char *action;
  47
  48         action = getenv("ACTION");
  49         return action;
  50 }
  51
  52 static inline char *get_devpath(void)
  53 {
  54         char *devpath;
  55
  56         devpath = getenv("DEVPATH");
  57         return devpath;
  58 }
  59
  60 static inline char *get_seqnum(void)
  61 {
  62         char *seqnum;
  63
  64         seqnum = getenv("SEQNUM");
  65         return seqnum;
  66 }
  67
  68 static int build_hotplugmsg(struct hotplug_msg *msg, char *action,
  69                             char *devpath, char *subsystem, int seqnum)
  70 {
  71         memset(msg, 0x00, sizeof(*msg));
  72         strfieldcpy(msg->magic, UDEV_MAGIC);
  73         msg->seqnum = seqnum;
  74         strncpy(msg->action, action, 8);
  75         strncpy(msg->devpath, devpath, 128);
  76         strncpy(msg->subsystem, subsystem, 16);
  77         return sizeof(struct hotplug_msg);
  78 }
  79
  80 static int start_daemon(void)
  81 {
  82         pid_t pid;
  83         pid_t child_pid;
  84
  85         pid = fork();
  86         switch (pid) {
  87         case 0:
  88                 /* helper child */
  89                 child_pid = fork();
  90                 switch (child_pid) {
  91                 case 0:
  92                         /* daemon */
  93                         setsid();
  94                         chdir("/");
  95                         execl(UDEVD_BIN, "udevd", NULL);
  96                         dbg("exec of daemon failed");
  97                         exit(1);
  98                 case -1:
  99                         dbg("fork of daemon failed");
 100                         return -1;
 101                 default:
 102                         exit(0);
 103                 }
 104                 break;
 105         case -1:
 106                 dbg("fork of helper failed");
 107                 return -1;
 108         default:
 109                 wait(NULL);
 110         }
 111         return 0;
 112 }
 113
 114 int main(int argc, char* argv[])
 115 {
 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         int sock;
 127         struct sockaddr_un saddr;
 128
 129         subsystem = argv[1];
 130         if (subsystem == NULL) {
 131                 dbg("no subsystem");
 132                 goto exit;
 133         }
 134
 135         devpath = get_devpath();
 136         if (devpath == NULL) {
 137                 dbg("no devpath");
 138                 goto exit;
 139         }
 140
 141         action = get_action();
 142         if (action == NULL) {
 143                 dbg("no action");
 144                 goto exit;
 145         }
 146
 147         seqnum = get_seqnum();
 148         if (seqnum == NULL) {
 149                 dbg("no seqnum");
 150                 goto exit;
 151         }
 152         seq = atoi(seqnum);
 153
 154         sock = socket(AF_LOCAL, SOCK_STREAM, 0);
 155         if (sock == -1) {
 156                 dbg("error getting socket");
 157                 goto exit;
 158         }
 159
 160         memset(&saddr, 0x00, sizeof(saddr));
 161         saddr.sun_family = AF_LOCAL;
 162         strcpy(saddr.sun_path, UDEVD_SOCKET);
 163
 164         /* try to connect, if it fails start daemon */
 165         retval = connect(sock, &saddr, sizeof(saddr));
 166         if (retval != -1) {
 167                 goto send;
 168         } else {
 169                 dbg("connect failed, try starting daemon...");
 170                 retval = start_daemon();
 171                 if (retval == 0) {
 172                         dbg("daemon started");
 173                 } else {
 174                         dbg("error starting daemon");
 175                         goto exit;
 176                 }
 177         }
 178
 179         /* try to connect while daemon to starts */
 180         tspec.tv_sec = 0;
 181         tspec.tv_nsec = 100000000;  /* 100 millisec */
 182         loop = UDEVSEND_CONNECT_RETRY;
 183         while (loop--) {
 184                 retval = connect(sock, &saddr, sizeof(saddr));
 185                 if (retval != -1)
 186                         goto send;
 187                 else
 188                         dbg("retry to connect %d",
 189                             UDEVSEND_CONNECT_RETRY - loop);
 190                 nanosleep(&tspec, NULL);
 191         }
 192         dbg("error connecting to daemon, start daemon failed");
 193         goto exit;
 194
 195 send:
 196         size = build_hotplugmsg(&message, action, devpath, subsystem, seq);
 197         retval = send(sock, &message, size, 0);
 198         if (retval == -1) {
 199                 dbg("error sending message");
 200                 close (sock);
 201                 goto exit;
 202         }
 203         close (sock);
 204         return 0;
 205
 206 exit:
 207         return 1;
 208 }