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                 waitpid(pid, NULL, 0);
  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                 waitpid(pid, NULL, 0);
 107         }
 108 }
 109
 110 int main(int argc, char *argv[], char *envp[])
 111 {
 112         static struct udevsend_msg usend_msg;
 113         int usend_msg_len;
 114         int i;
 115         int loop;
 116         struct sockaddr_un saddr;
 117         socklen_t addrlen;
 118         const char *subsystem_argv;
 119         int subsystem_env = 0;
 120         int bufpos = 0;
 121         int retval = 1;
 122         int sock = -1;
 123         int started_daemon = 0;
 124
 125         logging_init("udevsend");
 126         dbg("version %s", UDEV_VERSION);
 127
 128         subsystem_argv = argv[1];
 129         if (subsystem_argv == NULL) {
 130                 dbg("no subsystem");
 131                 goto exit;
 132         }
 133
 134         sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
 135         if (sock == -1) {
 136                 dbg("error getting socket");
 137                 goto fallback;
 138         }
 139
 140         set_cloexec_flag(sock, 1);
 141
 142         memset(&saddr, 0x00, sizeof(struct sockaddr_un));
 143         saddr.sun_family = AF_LOCAL;
 144         /* use abstract namespace for socket path */
 145         strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
 146         addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
 147
 148         memset(&usend_msg, 0x00, sizeof(struct udevsend_msg));
 149
 150         strcpy(usend_msg.magic, UDEV_MAGIC);
 151
 152         /* copy all keys to send buffer */
 153         for (i = 0; envp[i]; i++) {
 154                 const char *key;
 155                 int keylen;
 156
 157                 key = envp[i];
 158                 keylen = strlen(key);
 159                 if (bufpos + keylen >= HOTPLUG_BUFFER_SIZE-1) {
 160                         dbg("environment buffer too small, probably not called by the kernel");
 161                         continue;
 162                 }
 163
 164                 /* older kernels do not have the SUBSYSTEM in the environment */
 165                 if (strncmp(key, "SUBSYSTEM=", 10) == 0)
 166                         subsystem_env = 1;
 167
 168                 dbg("add '%s' to env[%i] buffer", key, i);
 169                 strcpy(&usend_msg.envbuf[bufpos], key);
 170                 bufpos += keylen + 1;
 171         }
 172         if (!subsystem_env) {
 173                 bufpos += sprintf(&usend_msg.envbuf[bufpos], "SUBSYSTEM=%s", subsystem_argv) + 1;
 174                 dbg("add 'SUBSYSTEM=%s' to env[%i] buffer from argv", subsystem_argv, 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                                 info("error starting daemon");
 199                                 goto fallback;
 200                         }
 201                         info("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_argv);
 212
 213 exit:
 214         if (sock != -1)
 215                 close(sock);
 216
 217         logging_close();
 218
 219         return retval;
 220 }