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 #include "logging.h"
  16
  17
  18 /** variable for the connection the to system message bus or #NULL
  19  *  if we cannot connect or acquire the org.kernel.udev service
  20  */
  21 static DBusConnection* sysbus_connection;
  22
  23 /** Disconnect from the system message bus */
  24 void sysbus_disconnect(void)
  25 {
  26         if (sysbus_connection == NULL)
  27                 return;
  28
  29         dbus_connection_disconnect(sysbus_connection);
  30         sysbus_connection = NULL;
  31 }
  32
  33 /** Connect to the system message bus */
  34 void sysbus_connect(void)
  35 {
  36         DBusError error;
  37
  38         /* Connect to a well-known bus instance, the system bus */
  39         dbus_error_init(&error);
  40         sysbus_connection = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
  41         if (sysbus_connection == NULL) {
  42                 dbg("cannot connect to system message bus, error %s: %s",
  43                     error.name, error.message);
  44                 dbus_error_free(&error);
  45                 return;
  46         }
  47
  48         /*  Acquire the org.kernel.udev service such that listeners
  49          *  know that the message is really from us and not from a
  50          *  random attacker. See the file udev_sysbus_policy.conf for
  51          *  details.
  52          *
  53          *  Note that a service can have multiple owners (though there
  54          *  is a concept of a primary owner for reception of messages)
  55          *  so no race is introduced if two copies of udev is running
  56          *  at the same time.
  57          */
  58         dbus_bus_acquire_service(sysbus_connection, "org.kernel.udev", 0,
  59                                  &error);
  60         if (dbus_error_is_set(&error)) {
  61                 printf("cannot acquire org.kernel.udev service, error %s: %s'",
  62                        error.name, error.message);
  63                 sysbus_disconnect();
  64                 return;
  65         }
  66 }
  67
  68
  69 /** Send out a signal that a device node is created
  70  *
  71  *  @param  dev                 udevice object
  72  *  @param  path                Sysfs path of device
  73  */
  74 void sysbus_send_create(struct udevice *dev, const char *path)
  75 {
  76         char filename[255];
  77         DBusMessage* message;
  78         DBusMessageIter iter;
  79
  80         if (sysbus_connection == NULL)
  81                 return;
  82
  83         strncpy(filename, udev_root, sizeof(filename));
  84         strncat(filename, dev->name, sizeof(filename));
  85
  86         /* object, interface, member */
  87         message = dbus_message_new_signal("/org/kernel/udev/NodeMonitor",
  88                                           "org.kernel.udev.NodeMonitor",
  89                                           "NodeCreated");
  90
  91         dbus_message_iter_init(message, &iter);
  92         dbus_message_iter_append_string(&iter, filename);
  93         dbus_message_iter_append_string(&iter, path);
  94
  95         if ( !dbus_connection_send(sysbus_connection, message, NULL) )
  96                 dbg("error sending d-bus signal");
  97
  98         dbus_message_unref(message);
  99
 100         dbus_connection_flush(sysbus_connection);
 101 }
 102
 103 /** Send out a signal that a device node is deleted
 104  *
 105  *  @param  name                Name of the device node, e.g. /udev/sda1
 106  *  @param  path                Sysfs path of device
 107  */
 108 void sysbus_send_remove(const char* name, const char *path)
 109 {
 110         char filename[255];
 111         DBusMessage* message;
 112         DBusMessageIter iter;
 113
 114         if (sysbus_connection == NULL)
 115                 return;
 116
 117         strncpy(filename, udev_root, sizeof(filename));
 118         strncat(filename, name, sizeof(filename));
 119
 120         /* object, interface, member */
 121         message = dbus_message_new_signal("/org/kernel/udev/NodeMonitor",
 122                                           "org.kernel.udev.NodeMonitor",
 123                                           "NodeDeleted");
 124
 125         dbus_message_iter_init(message, &iter);
 126         dbus_message_iter_append_string(&iter, filename);
 127         dbus_message_iter_append_string(&iter, path);
 128
 129         if ( !dbus_connection_send(sysbus_connection, message, NULL) )
 130                 dbg("error sending d-bus signal");
 131
 132         dbus_message_unref(message);
 133
 134         dbus_connection_flush(sysbus_connection);
 135 }