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_version.h"
  40 #include "udevd.h"
  41 #include "logging.h"
  42
  43 /* global variables */
  44 static int sock = -1;
  45
  46 #ifdef USE_LOG
  47 void log_message (int priority, const char *format, ...)
  48 {
  49         va_list args;
  50
  51         if (priority > udev_log_priority)
  52                 return;
  53
  54         va_start(args, format);
  55         vsyslog(priority, format, args);
  56         va_end(args);
  57 }
  58 #endif
  59
  60 static int start_daemon(void)
  61 {
  62         pid_t pid;
  63         pid_t child_pid;
  64         char *const argv[] = { "udevd", NULL };
  65         char *const envp[] = { NULL };
  66
  67         pid = fork();
  68         switch (pid) {
  69         case 0:
  70                 /* helper child */
  71                 child_pid = fork();
  72                 switch (child_pid) {
  73                 case 0:
  74                         /* daemon with empty environment */
  75                         close(sock);
  76                         execve(UDEVD_BIN, argv, envp);
  77                         err("exec of daemon failed");
  78                         _exit(1);
  79                 case -1:
  80                         err("fork of daemon failed");
  81                         return -1;
  82                 default:
  83                         exit(0);
  84                 }
  85                 break;
  86         case -1:
  87                 err("fork of helper failed");
  88                 return -1;
  89         default:
  90                 waitpid(pid, NULL, 0);
  91         }
  92         return 0;
  93 }
  94
  95 static void run_udev(const char *subsystem)
  96 {
  97         char *const argv[] = { "udev", (char *)subsystem, NULL };
  98         pid_t pid;
  99
 100         pid = fork();
 101         switch (pid) {
 102         case 0:
 103                 /* child */
 104                 execv(UDEV_BIN, argv);
 105                 err("exec of udev child failed");
 106                 _exit(1);
 107                 break;
 108         case -1:
 109                 err("fork of udev child failed");
 110                 break;
 111         default:
 112                 waitpid(pid, NULL, 0);
 113         }
 114 }
 115
 116 int main(int argc, char *argv[], char *envp[])
 117 {
 118         static struct udevsend_msg usend_msg;
 119         int usend_msg_len;
 120         int i;
 121         int loop;
 122         struct sockaddr_un saddr;
 123         socklen_t addrlen;
 124         int bufpos = 0;
 125         int retval = 1;
 126         int started_daemon = 0;
 127         const char *subsystem = NULL;
 128
 129         logging_init("udevsend");
 130 #ifdef USE_LOG
 131         udev_init_config();
 132 #endif
 133         dbg("version %s", UDEV_VERSION);
 134
 135         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 136         if (sock == -1) {
 137                 err("error getting socket");
 138                 goto fallback;
 139         }
 140
 141         memset(&saddr, 0x00, sizeof(struct sockaddr_un));
 142         saddr.sun_family = AF_LOCAL;
 143         /* use abstract namespace for socket path */
 144         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 145         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 146
 147         memset(&usend_msg, 0x00, sizeof(struct udevsend_msg));
 148         strcpy(usend_msg.magic, UDEV_MAGIC);
 149
 150         /* copy all keys to send buffer */
 151         for (i = 0; envp[i]; i++) {
 152                 const char *key;
 153                 int keylen;
 154
 155                 key = envp[i];
 156                 keylen = strlen(key);
 157
 158                 /* prevent loops in the scripts we execute */
 159                 if (strncmp(key, "UDEVD_EVENT=", 12) == 0) {
 160                         dbg("seems that the event source is not the kernel, just exit");
 161                         goto exit;
 162                 }
 163
 164                 if (bufpos + keylen >= HOTPLUG_BUFFER_SIZE-1) {
 165                         err("environment buffer too small, probably not called by the kernel");
 166                         continue;
 167                 }
 168
 169                 /* remember the SUBSYSTEM */
 170                 if (strncmp(key, "SUBSYSTEM=", 10) == 0)
 171                         subsystem = &key[10];
 172
 173                 dbg("add '%s' to env[%i] buffer", key, i);
 174                 strcpy(&usend_msg.envbuf[bufpos], key);
 175                 bufpos += keylen + 1;
 176         }
 177         /* older kernels passed the SUBSYSTEM only as the first argument */
 178         if (!subsystem && argc == 2) {
 179                 bufpos += sprintf(&usend_msg.envbuf[bufpos], "SUBSYSTEM=%s", argv[1]) + 1;
 180                 dbg("add 'SUBSYSTEM=%s' to env[%i] buffer from argv", argv[1], i);
 181         }
 182
 183         usend_msg_len = offsetof(struct udevsend_msg, envbuf) + bufpos;
 184         dbg("usend_msg_len=%i", usend_msg_len);
 185
 186         /* If we can't send, try to start daemon and resend message */
 187         loop = SEND_WAIT_MAX_SECONDS * SEND_WAIT_LOOP_PER_SECOND;
 188         while (--loop) {
 189                 retval = sendto(sock, &usend_msg, usend_msg_len, 0, (struct sockaddr *)&saddr, addrlen);
 190                 if (retval != -1) {
 191                         retval = 0;
 192                         goto exit;
 193                 }
 194
 195                 if (errno != ECONNREFUSED) {
 196                         err("error sending message (%s)", strerror(errno));
 197                         goto fallback;
 198                 }
 199
 200                 if (!started_daemon) {
 201                         info("try to start udevd daemon");
 202                         retval = start_daemon();
 203                         if (retval) {
 204                                 dbg("error starting daemon");
 205                                 goto fallback;
 206                         }
 207                         dbg("udevd daemon started");
 208                         started_daemon = 1;
 209                 } else {
 210                         dbg("retry to connect %d", SEND_WAIT_MAX_SECONDS * SEND_WAIT_LOOP_PER_SECOND - loop);
 211                         usleep(1000 * 1000 / SEND_WAIT_LOOP_PER_SECOND);
 212                 }
 213         }
 214
 215 fallback:
 216         err("unable to connect to event daemon, try to call udev directly");
 217         run_udev(subsystem);
 218
 219 exit:
 220         if (sock != -1)
 221                 close(sock);
 222
 223         logging_close();
 224
 225         return retval;
 226 }