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