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udev.c

/*
 * udev.c
 *
 * Userspace devfs
 *
 * Copyright (C) 2003,2004 Greg Kroah-Hartman <greg@kroah.com>
 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
 *
 *    This program is free software; you can redistribute it and/or modify it
 *    under the terms of the GNU General Public License as published by the
 *    Free Software Foundation version 2 of the License.
 * 
 *    This program is distributed in the hope that it will be useful, but
 *    WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    General Public License for more details.
 * 
 *    You should have received a copy of the GNU General Public License along
 *    with this program; if not, write to the Free Software Foundation, Inc.,
 *    675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>

#include "libsysfs/sysfs/libsysfs.h"
#include "udev_libc_wrapper.h"
#include "udev.h"
#include "udev_utils.h"
#include "udev_sysfs.h"
#include "udev_version.h"
#include "udev_rules.h"
#include "logging.h"


#ifdef USE_LOG
void log_message(int level, const char *format, ...)
{
      va_list args;

      if (!udev_log)
            return;

      va_start(args, format);
      vsyslog(level, format, args);
      va_end(args);
}
#endif

/* decide if we should manage the whole hotplug event
 * for now look if the kernel calls udevsend instead of /sbin/hotplug
 */
static int manage_hotplug_event(void) {
      char helper[256];
      int fd;
      int len;

      /* don't handle hotplug.d if we are called directly */
      if (!getenv("UDEVD_EVENT"))
            return 0;

      fd = open("/proc/sys/kernel/hotplug", O_RDONLY);
      if (fd < 0)
            return 0;

      len = read(fd, helper, 256);
      close(fd);

      if (len < 0)
            return 0;
      helper[len] = '\0';

      if (strstr(helper, "udevsend"))
            return 1;

      return 0;
}

static void asmlinkage sig_handler(int signum)
{
      switch (signum) {
            case SIGALRM:
                  exit(1);
            case SIGINT:
            case SIGTERM:
                  exit(20 + signum);
      }
}

int main(int argc, char *argv[], char *envp[])
{
      struct sysfs_class_device *class_dev;
      struct sysfs_device *devices_dev;
      struct udevice udev;
      char path[PATH_SIZE];
      const char *error;
      const char *action;
      const char *devpath;
      const char *subsystem;
      int managed_event;
      struct sigaction act;
      int retval = -EINVAL;

      if (argc == 2 && strcmp(argv[1], "-V") == 0) {
            printf("%s\n", UDEV_VERSION);
            exit(0);
      }

      logging_init("udev");
      dbg("version %s", UDEV_VERSION);

      udev_init_config();

      /* set signal handlers */
      memset(&act, 0x00, sizeof(act));
      act.sa_handler = (void (*) (int))sig_handler;
      sigemptyset (&act.sa_mask);
      act.sa_flags = 0;
      sigaction(SIGALRM, &act, NULL);
      sigaction(SIGINT, &act, NULL);
      sigaction(SIGTERM, &act, NULL);

      /* trigger timeout to prevent hanging processes */
      alarm(ALARM_TIMEOUT);

      /* let the executed programs know if we handle the whole hotplug event */
      managed_event = manage_hotplug_event();
      if (managed_event)
            setenv("MANAGED_EVENT", "1", 1);

      action = getenv("ACTION");
      devpath = getenv("DEVPATH");
      subsystem = getenv("SUBSYSTEM");
      /* older kernels passed the SUBSYSTEM only as argument */
      if (!subsystem && argc == 2)
            subsystem = argv[1];

      udev_init_device(&udev, devpath, subsystem);

      if (!action || !subsystem || !devpath) {
            dbg("action, subsystem or devpath missing");
            goto hotplug;
      }

      /* export logging flag, as called scripts may want to do the same as udev */
      if (udev_log)
            setenv("UDEV_LOG", "1", 1);

      if (udev.type == DEV_BLOCK || udev.type == DEV_CLASS || udev.type == DEV_NET) {
            if (strcmp(action, "add") == 0) {
                  /* wait for sysfs and possibly add node */
                  dbg("udev add");

                  /* skip subsystems without "dev", but handle net devices */
                  if (udev.type != DEV_NET && subsystem_expect_no_dev(udev.subsystem)) {
                        dbg("don't care about '%s' devices", udev.subsystem);
                        goto hotplug;
                  }

                  snprintf(path, sizeof(path), "%s%s", sysfs_path, udev.devpath);
                  path[sizeof(path)-1] = '\0';
                  class_dev = wait_class_device_open(path);
                  if (class_dev == NULL) {
                        dbg ("open class device failed");
                        goto hotplug;
                  }
                  dbg("opened class_dev->name='%s'", class_dev->name);

                  wait_for_class_device(class_dev, &error);

                  /* init rules */
                  udev_rules_init();

                  /* name, create node, store in db */
                  retval = udev_add_device(&udev, class_dev);

                  sysfs_close_class_device(class_dev);
            } else if (strcmp(action, "remove") == 0) {
                  /* possibly remove a node */
                  dbg("udev remove");

                  /* skip subsystems without "dev" */
                  if (subsystem_expect_no_dev(udev.subsystem)) {
                        dbg("don't care about '%s' devices", udev.subsystem);
                        goto hotplug;
                  }

                  /* get node from db, remove db-entry, delete created node */
                  retval = udev_remove_device(&udev);
            }

            /* run dev.d/ scripts if we created/deleted a node or changed a netif name */
            if (udev.devname[0] != '\0') {
                  setenv("DEVNAME", udev.devname, 1);
                  if (udev_dev_d)
                        udev_multiplex_directory(&udev, DEVD_DIR, DEVD_SUFFIX);
            }
      } else if (udev.type == DEV_DEVICE) {
            if (strcmp(action, "add") == 0) {
                  /* wait for sysfs */
                  dbg("devices add");

                  snprintf(path, sizeof(path), "%s%s", sysfs_path, devpath);
                  path[sizeof(path)-1] = '\0';
                  devices_dev = wait_devices_device_open(path);
                  if (!devices_dev) {
                        dbg("devices device unavailable (probably remove has beaten us)");
                        goto hotplug;
                  }
                  dbg("devices device opened '%s'", path);

                  wait_for_devices_device(devices_dev, &error);

                  sysfs_close_device(devices_dev);
            } else if (strcmp(action, "remove") == 0) {
                  dbg("devices remove");
            }
      } else {
            dbg("unhandled");
      }

hotplug:
      udev_cleanup_device(&udev);
      if (udev_hotplug_d && managed_event)
            udev_multiplex_directory(&udev, HOTPLUGD_DIR, HOTPLUG_SUFFIX);

      logging_close();
      return retval;
}

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