udev_dbus.c

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