udev_dbus.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <stdio.h>
   4 #include <fcntl.h>
   5 #include <unistd.h>
   6 #include <errno.h>
   7 #include <ctype.h>
   8
   9 #define DBUS_API_SUBJECT_TO_CHANGE
  10 #include <dbus/dbus.h>
  11
  12 #include "udev.h"
  13 #include "udev_version.h"
  14 #include "udev_dbus.h"
  15
  16
  17 /** variable for the connection the to system message bus or #NULL
  18  *  if we cannot connect or acquire the org.kernel.udev service
  19  */
  20 static DBusConnection* sysbus_connection;
  21
  22 /** Disconnect from the system message bus */
  23 void sysbus_disconnect(void)
  24 {
  25         if (sysbus_connection == NULL)
  26                 return;
  27
  28         dbus_connection_disconnect(sysbus_connection);
  29         sysbus_connection = NULL;
  30 }
  31
  32 /** Connect to the system message bus */
  33 void sysbus_connect(void)
  34 {
  35         DBusError error;
  36
  37         /* Connect to a well-known bus instance, the system bus */
  38         dbus_error_init(&error);
  39         sysbus_connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
  40         if (sysbus_connection == NULL) {
  41                 dbg("cannot connect to system message bus, error %s: %s",
  42                     error.name, error.message);
  43                 dbus_error_free(&error);
  44                 return;
  45         }
  46
  47         /*  Acquire the org.kernel.udev service such that listeners
  48          *  know that the message is really from us and not from a
  49          *  random attacker. See the file udev_sysbus_policy.conf for
  50          *  details.
  51          *
  52          *  Note that a service can have multiple owners (though there
  53          *  is a concept of a primary owner for reception of messages)
  54          *  so no race is introduced if two copies of udev is running
  55          *  at the same time.
  56          */
  57         dbus_bus_acquire_service(sysbus_connection, "org.kernel.udev", 0,
  58                                  &error);
  59         if (dbus_error_is_set(&error)) {
  60                 printf("cannot acquire org.kernel.udev service, error %s: %s'",
  61                        error.name, error.message);
  62                 sysbus_disconnect();
  63                 return;
  64         }
  65 }
  66
  67
  68 /** Send out a signal that a device node is created
  69  *
  70  *  @param  dev                 udevice object
  71  *  @param  path                Sysfs path of device
  72  */
  73 void sysbus_send_create(struct udevice *dev, const char *path)
  74 {
  75         char filename[255];
  76         DBusMessage* message;
  77         DBusMessageIter iter;
  78
  79         if (sysbus_connection == NULL)
  80                 return;
  81
  82         strncpy(filename, udev_root, sizeof(filename));
  83         strncat(filename, dev->name, sizeof(filename));
  84
  85         /* object, interface, member */
  86         message = dbus_message_new_signal("/org/kernel/udev/NodeMonitor",
  87                                           "org.kernel.udev.NodeMonitor",
  88                                           "NodeCreated");
  89
  90         dbus_message_iter_init(message, &iter);
  91         dbus_message_iter_append_string(&iter, filename);
  92         dbus_message_iter_append_string(&iter, path);
  93
  94         if ( !dbus_connection_send(sysbus_connection, message, NULL) )
  95                 dbg("error sending d-bus signal");
  96
  97         dbus_message_unref(message);
  98
  99         dbus_connection_flush(sysbus_connection);
 100 }
 101
 102 /** Send out a signal that a device node is deleted
 103  *
 104  *  @param  name                Name of the device node, e.g. /udev/sda1
 105  *  @param  path                Sysfs path of device
 106  */
 107 void sysbus_send_remove(const char* name, const char *path)
 108 {
 109         char filename[255];
 110         DBusMessage* message;
 111         DBusMessageIter iter;
 112
 113         if (sysbus_connection == NULL)
 114                 return;
 115
 116         strncpy(filename, udev_root, sizeof(filename));
 117         strncat(filename, name, sizeof(filename));
 118
 119         /* object, interface, member */
 120         message = dbus_message_new_signal("/org/kernel/udev/NodeMonitor",
 121                                           "org.kernel.udev.NodeMonitor",
 122                                           "NodeDeleted");
 123
 124         dbus_message_iter_init(message, &iter);
 125         dbus_message_iter_append_string(&iter, filename);
 126         dbus_message_iter_append_string(&iter, path);
 127
 128         if ( !dbus_connection_send(sysbus_connection, message, NULL) )
 129                 dbg("error sending d-bus signal");
 130
 131         dbus_message_unref(message);
 132
 133         dbus_connection_flush(sysbus_connection);
 134 }