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 int log_ok(void)
  46 {
  47         return 1;
  48 }
  49
  50 static inline char *get_action(void)
  51 {
  52         char *action;
  53
  54         action = getenv("ACTION");
  55         return action;
  56 }
  57
  58 static inline char *get_devpath(void)
  59 {
  60         char *devpath;
  61
  62         devpath = getenv("DEVPATH");
  63         return devpath;
  64 }
  65
  66 static inline char *get_seqnum(void)
  67 {
  68         char *seqnum;
  69
  70         seqnum = getenv("SEQNUM");
  71         return seqnum;
  72 }
  73
  74 static int build_hotplugmsg(struct hotplug_msg *msg, char *action,
  75                             char *devpath, char *subsystem, int seqnum)
  76 {
  77         memset(msg, 0x00, sizeof(*msg));
  78         strfieldcpy(msg->magic, UDEV_MAGIC);
  79         msg->seqnum = seqnum;
  80         strncpy(msg->action, action, 8);
  81         strncpy(msg->devpath, devpath, 128);
  82         strncpy(msg->subsystem, subsystem, 16);
  83         return sizeof(struct hotplug_msg);
  84 }
  85
  86 static int start_daemon(void)
  87 {
  88         pid_t pid;
  89         pid_t child_pid;
  90
  91         pid = fork();
  92         switch (pid) {
  93         case 0:
  94                 /* helper child */
  95                 child_pid = fork();
  96                 switch (child_pid) {
  97                 case 0:
  98                         /* daemon */
  99                         setsid();
 100                         chdir("/");
 101                         execl(UDEVD_BIN, "udevd", NULL);
 102                         dbg("exec of daemon failed");
 103                         exit(1);
 104                 case -1:
 105                         dbg("fork of daemon failed");
 106                         return -1;
 107                 default:
 108                         exit(0);
 109                 }
 110                 break;
 111         case -1:
 112                 dbg("fork of helper failed");
 113                 return -1;
 114         default:
 115                 wait(NULL);
 116         }
 117         return 0;
 118 }
 119
 120 int main(int argc, char* argv[])
 121 {
 122         struct hotplug_msg msg;
 123         char *action;
 124         char *devpath;
 125         char *subsystem;
 126         char *seqnum;
 127         int seq;
 128         int retval = 1;
 129         int size;
 130         int loop;
 131         struct timespec tspec;
 132         int sock;
 133         struct sockaddr_un saddr;
 134         socklen_t addrlen;
 135         int started_daemon = 0;
 136         struct iovec iov;
 137         struct msghdr smsg;
 138         char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
 139         struct cmsghdr *cmsg;
 140         struct ucred *cred;
 141
 142
 143
 144 #ifdef DEBUG
 145         init_logging("udevsend");
 146 #endif
 147
 148         subsystem = argv[1];
 149         if (subsystem == NULL) {
 150                 dbg("no subsystem");
 151                 goto exit;
 152         }
 153
 154         devpath = get_devpath();
 155         if (devpath == NULL) {
 156                 dbg("no devpath");
 157                 goto exit;
 158         }
 159
 160         action = get_action();
 161         if (action == NULL) {
 162                 dbg("no action");
 163                 goto exit;
 164         }
 165
 166         seqnum = get_seqnum();
 167         if (seqnum == NULL)
 168                 seq = -1;
 169         else
 170                 seq = atoi(seqnum);
 171
 172         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 173         if (sock == -1) {
 174                 dbg("error getting socket");
 175                 goto exit;
 176         }
 177
 178         memset(&saddr, 0x00, sizeof(saddr));
 179         saddr.sun_family = AF_LOCAL;
 180         /* use abstract namespace for socket path */
 181         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 182         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 183
 184         size = build_hotplugmsg(&msg, action, devpath, subsystem, seq);
 185
 186         /* prepare message with credentials to authenticate ourself */
 187         iov.iov_base = &msg;
 188         iov.iov_len = size;
 189
 190         smsg.msg_name = &saddr;
 191         smsg.msg_namelen = addrlen;
 192         smsg.msg_iov = &iov;
 193         smsg.msg_iovlen = 1;
 194         smsg.msg_control = cred_msg;
 195         smsg.msg_controllen = CMSG_LEN(sizeof(struct ucred));;
 196         smsg.msg_flags = 0;
 197
 198         cmsg = CMSG_FIRSTHDR(&smsg);
 199         cmsg->cmsg_level = SOL_SOCKET;
 200         cmsg->cmsg_type = SCM_CREDENTIALS;
 201         cmsg->cmsg_len = sizeof(cred_msg);
 202         cred = (struct ucred *) CMSG_DATA(cmsg);
 203         cred->uid = getuid();
 204         cred->gid = getgid();
 205         cred->pid = getpid();
 206         cred->pid = getpid();
 207
 208         /* If we can't send, try to start daemon and resend message */
 209         loop = UDEVSEND_CONNECT_RETRY;
 210         while (loop--) {
 211                 retval = sendmsg(sock, &smsg, 0);
 212                 if (retval != -1) {
 213                         retval = 0;
 214                         goto close_and_exit;
 215                 }
 216
 217                 if (errno != ECONNREFUSED) {
 218                         dbg("error sending message");
 219                         goto close_and_exit;
 220                 }
 221
 222                 if (!started_daemon) {
 223                         dbg("connect failed, try starting daemon...");
 224                         retval = start_daemon();
 225                         if (retval) {
 226                                 dbg("error starting daemon");
 227                                 goto exit;
 228                         }
 229
 230                         dbg("daemon started");
 231                         started_daemon = 1;
 232                 } else {
 233                         dbg("retry to connect %d", UDEVSEND_CONNECT_RETRY - loop);
 234                         tspec.tv_sec = 0;
 235                         tspec.tv_nsec = 100000000;  /* 100 millisec */
 236                         nanosleep(&tspec, NULL);
 237                 }
 238         }
 239
 240 close_and_exit:
 241         close(sock);
 242 exit:
 243         return retval;
 244 }