src/libsystemd/sd-bus/bus-track.c - systemd-stable - Rivoreo Source Code Repositories

 /***
   This file is part of systemd.

   Copyright 2013 Lennart Poettering

   systemd is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.

   systemd 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/

 #include "sd-bus.h"

 #include "alloc-util.h"
 #include "bus-internal.h"
 #include "bus-track.h"
 #include "bus-util.h"

 struct track_item {
         unsigned n_ref;
         char *name;
         sd_bus_slot *slot;
 };

 struct sd_bus_track {
         unsigned n_ref;
         unsigned n_adding; /* are we in the process of adding a new name? */
         sd_bus *bus;
         sd_bus_track_handler_t handler;
         void *userdata;
         Hashmap *names;
         LIST_FIELDS(sd_bus_track, queue);
         Iterator iterator;
         bool in_list:1;    /* In bus->tracks? */
         bool in_queue:1;   /* In bus->track_queue? */
         bool modified:1;
         bool recursive:1;

         LIST_FIELDS(sd_bus_track, tracks);
 };

 #define MATCH_PREFIX                                        \
         "type='signal',"                                    \
         "sender='org.freedesktop.DBus',"                    \
         "path='/org/freedesktop/DBus',"                     \
         "interface='org.freedesktop.DBus',"                 \
         "member='NameOwnerChanged',"                        \
         "arg0='"

 #define MATCH_SUFFIX \
         "'"

 #define MATCH_FOR_NAME(name)                                            \
         ({                                                              \
                 char *_x;                                               \
                 size_t _l = strlen(name);                               \
                 _x = alloca(strlen(MATCH_PREFIX)+_l+strlen(MATCH_SUFFIX)+1); \
                 strcpy(stpcpy(stpcpy(_x, MATCH_PREFIX), name), MATCH_SUFFIX); \
                 _x;                                                     \
         })

 static struct track_item* track_item_free(struct track_item *i) {

         if (!i)
                 return NULL;

         sd_bus_slot_unref(i->slot);
         free(i->name);
         return mfree(i);
 }

 DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_free);

 static void bus_track_add_to_queue(sd_bus_track *track) {
         assert(track);

         /* Adds the bus track object to the queue of objects we should dispatch next, subject to a number of
          * conditions. */

         /* Already in the queue? */
         if (track->in_queue)
                 return;

         /* if we are currently in the process of adding a new name, then let's not enqueue this just yet, let's wait
          * until the addition is complete. */
         if (track->n_adding > 0)
                 return;

         /* still referenced? */
         if (hashmap_size(track->names) > 0)
                 return;

         /* Nothing to call? */
         if (!track->handler)
                 return;

         /* Already closed? */
         if (!track->in_list)
                 return;

         LIST_PREPEND(queue, track->bus->track_queue, track);
         track->in_queue = true;
 }

 static void bus_track_remove_from_queue(sd_bus_track *track) {
         assert(track);

         if (!track->in_queue)
                 return;

         LIST_REMOVE(queue, track->bus->track_queue, track);
         track->in_queue = false;
 }

 static int bus_track_remove_name_fully(sd_bus_track *track, const char *name) {
         struct track_item *i;

         assert(track);
         assert(name);

         i = hashmap_remove(track->names, name);
         if (!i)
                 return 0;

         track_item_free(i);

         bus_track_add_to_queue(track);

         track->modified = true;
         return 1;
 }

 _public_ int sd_bus_track_new(
                 sd_bus *bus,
                 sd_bus_track **track,
                 sd_bus_track_handler_t handler,
                 void *userdata) {

         sd_bus_track *t;

         assert_return(bus, -EINVAL);
         assert_return(track, -EINVAL);

         if (!bus->bus_client)
                 return -EINVAL;

         t = new0(sd_bus_track, 1);
         if (!t)
                 return -ENOMEM;

         t->n_ref = 1;
         t->handler = handler;
         t->userdata = userdata;
         t->bus = sd_bus_ref(bus);

         LIST_PREPEND(tracks, bus->tracks, t);
         t->in_list = true;

         bus_track_add_to_queue(t);

         *track = t;
         return 0;
 }

 _public_ sd_bus_track* sd_bus_track_ref(sd_bus_track *track) {

         if (!track)
                 return NULL;

         assert(track->n_ref > 0);

         track->n_ref++;

         return track;
 }

 _public_ sd_bus_track* sd_bus_track_unref(sd_bus_track *track) {
         struct track_item *i;

         if (!track)
                 return NULL;

         assert(track->n_ref > 0);

         if (track->n_ref > 1) {
                 track->n_ref--;
                 return NULL;
         }

         while ((i = hashmap_steal_first(track->names)))
                 track_item_free(i);

         if (track->in_list)
                 LIST_REMOVE(tracks, track->bus->tracks, track);

         bus_track_remove_from_queue(track);
         hashmap_free(track->names);
         sd_bus_unref(track->bus);
         return mfree(track);
 }

 static int on_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {
         sd_bus_track *track = userdata;
         const char *name, *old, *new;
         int r;

         assert(message);
         assert(track);

         r = sd_bus_message_read(message, "sss", &name, &old, &new);
         if (r < 0)
                 return 0;

         bus_track_remove_name_fully(track, name);
         return 0;
 }

 _public_ int sd_bus_track_add_name(sd_bus_track *track, const char *name) {
         _cleanup_(track_item_freep) struct track_item *n = NULL;
         struct track_item *i;
         const char *match;
         int r;

         assert_return(track, -EINVAL);
         assert_return(service_name_is_valid(name), -EINVAL);

         i = hashmap_get(track->names, name);
         if (i) {
                 if (track->recursive) {
                         unsigned k = track->n_ref + 1;

                         if (k < track->n_ref) /* Check for overflow */
                                 return -EOVERFLOW;

                         track->n_ref = k;
                 }

                 bus_track_remove_from_queue(track);
                 return 0;
         }

         r = hashmap_ensure_allocated(&track->names, &string_hash_ops);
         if (r < 0)
                 return r;

         n = new0(struct track_item, 1);
         if (!n)
                 return -ENOMEM;
         n->name = strdup(name);
         if (!n->name)
                 return -ENOMEM;

         /* First, subscribe to this name */
         match = MATCH_FOR_NAME(name);

         bus_track_remove_from_queue(track); /* don't dispatch this while we work in it */

         track->n_adding++; /* make sure we aren't dispatched while we synchronously add this match */
         r = sd_bus_add_match(track->bus, &n->slot, match, on_name_owner_changed, track);
         track->n_adding--;
         if (r < 0) {
                 bus_track_add_to_queue(track);
                 return r;
         }

         r = hashmap_put(track->names, n->name, n);
         if (r < 0) {
                 bus_track_add_to_queue(track);
                 return r;
         }

         /* Second, check if it is currently existing, or maybe doesn't, or maybe disappeared already. */
         track->n_adding++; /* again, make sure this isn't dispatch while we are working in it */
         r = sd_bus_get_name_creds(track->bus, name, 0, NULL);
         track->n_adding--;
         if (r < 0) {
                 hashmap_remove(track->names, name);
                 bus_track_add_to_queue(track);
                 return r;
         }

         n->n_ref = 1;
         n = NULL;

         bus_track_remove_from_queue(track);
         track->modified = true;

         return 1;
 }

 _public_ int sd_bus_track_remove_name(sd_bus_track *track, const char *name) {
         struct track_item *i;

         assert_return(name, -EINVAL);

         if (!track) /* Treat a NULL track object as an empty track object */
                 return 0;

         if (!track->recursive)
                 return bus_track_remove_name_fully(track, name);

         i = hashmap_get(track->names, name);
         if (!i)
                 return -EUNATCH;
         if (i->n_ref <= 0)
                 return -EUNATCH;

         i->n_ref--;

         if (i->n_ref <= 0)
                 return bus_track_remove_name_fully(track, name);

         return 1;
 }

 _public_ unsigned sd_bus_track_count(sd_bus_track *track) {

         if (!track) /* Let's consider a NULL object equivalent to an empty object */
                 return 0;

         /* This signature really should have returned an int, so that we can propagate errors. But well, ... Also, note
          * that this returns the number of names being watched, and multiple references to the same name are not
          * counted. */

         return hashmap_size(track->names);
 }

 _public_ const char* sd_bus_track_contains(sd_bus_track *track, const char *name) {
         assert_return(name, NULL);

         if (!track) /* Let's consider a NULL object equivalent to an empty object */
                 return NULL;

         return hashmap_get(track->names, (void*) name) ? name : NULL;
 }

 _public_ const char* sd_bus_track_first(sd_bus_track *track) {
         const char *n = NULL;

         if (!track)
                 return NULL;

         track->modified = false;
         track->iterator = ITERATOR_FIRST;

         hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
         return n;
 }

 _public_ const char* sd_bus_track_next(sd_bus_track *track) {
         const char *n = NULL;

         if (!track)
                 return NULL;

         if (track->modified)
                 return NULL;

         hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
         return n;
 }

 _public_ int sd_bus_track_add_sender(sd_bus_track *track, sd_bus_message *m) {
         const char *sender;

         assert_return(track, -EINVAL);
         assert_return(m, -EINVAL);

         if (sd_bus_message_get_bus(m) != track->bus)
                 return -EINVAL;

         sender = sd_bus_message_get_sender(m);
         if (!sender)
                 return -EINVAL;

         return sd_bus_track_add_name(track, sender);
 }

 _public_ int sd_bus_track_remove_sender(sd_bus_track *track, sd_bus_message *m) {
         const char *sender;

         assert_return(m, -EINVAL);

         if (!track) /* Treat a NULL track object as an empty track object */
                 return 0;

         if (sd_bus_message_get_bus(m) != track->bus)
                 return -EINVAL;

         sender = sd_bus_message_get_sender(m);
         if (!sender)
                 return -EINVAL;

         return sd_bus_track_remove_name(track, sender);
 }

 _public_ sd_bus* sd_bus_track_get_bus(sd_bus_track *track) {
         assert_return(track, NULL);

         return track->bus;
 }

 void bus_track_dispatch(sd_bus_track *track) {
         int r;

         assert(track);
         assert(track->handler);

         bus_track_remove_from_queue(track);

         sd_bus_track_ref(track);

         r = track->handler(track, track->userdata);
         if (r < 0)
                 log_debug_errno(r, "Failed to process track handler: %m");
         else if (r == 0)
                 bus_track_add_to_queue(track);

         sd_bus_track_unref(track);
 }

 void bus_track_close(sd_bus_track *track) {
         struct track_item *i;

         assert(track);

         /* Called whenever our bus connected is closed. If so, and our track object is non-empty, dispatch it
          * immediately, as we are closing now, but first flush out all names. */

         if (!track->in_list)
                 return; /* We already closed this one, don't close it again. */

         /* Remember that this one is closed now */
         LIST_REMOVE(tracks, track->bus->tracks, track);
         track->in_list = false;

         /* If there's no name in this one anyway, we don't have to dispatch */
         if (hashmap_isempty(track->names))
                 return;

         /* Let's flush out all names */
         while ((i = hashmap_steal_first(track->names)))
                 track_item_free(i);

         /* Invoke handler */
         if (track->handler)
                 bus_track_dispatch(track);
 }

 _public_ void *sd_bus_track_get_userdata(sd_bus_track *track) {
         assert_return(track, NULL);

         return track->userdata;
 }

 _public_ void *sd_bus_track_set_userdata(sd_bus_track *track, void *userdata) {
         void *ret;

         assert_return(track, NULL);

         ret = track->userdata;
         track->userdata = userdata;

         return ret;
 }

 _public_ int sd_bus_track_set_recursive(sd_bus_track *track, int b) {
         assert_return(track, -EINVAL);

         if (track->recursive == !!b)
                 return 0;

         if (!hashmap_isempty(track->names))
                 return -EBUSY;

         track->recursive = b;
         return 0;
 }

 _public_ int sd_bus_track_get_recursive(sd_bus_track *track) {
         assert_return(track, -EINVAL);

         return track->recursive;
 }

 _public_ int sd_bus_track_count_sender(sd_bus_track *track, sd_bus_message *m) {
         const char *sender;

         assert_return(m, -EINVAL);

         if (!track) /* Let's consider a NULL object equivalent to an empty object */
                 return 0;

         if (sd_bus_message_get_bus(m) != track->bus)
                 return -EINVAL;

         sender = sd_bus_message_get_sender(m);
         if (!sender)
                 return -EINVAL;

         return sd_bus_track_count_name(track, sender);
 }

 _public_ int sd_bus_track_count_name(sd_bus_track *track, const char *name) {
         struct track_item *i;

         assert_return(service_name_is_valid(name), -EINVAL);

         if (!track) /* Let's consider a NULL object equivalent to an empty object */
                 return 0;

         i = hashmap_get(track->names, name);
         if (!i)
                 return 0;

         return i->n_ref;
 }
	/***
	This file is part of systemd.

	Copyright 2013 Lennart Poettering

	systemd is free software; you can redistribute it and/or modify it
	under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2.1 of the License, or
	(at your option) any later version.

	systemd 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
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	***/

	#include "sd-bus.h"

	#include "alloc-util.h"
	#include "bus-internal.h"
	#include "bus-track.h"
	#include "bus-util.h"

	struct track_item {
	unsigned n_ref;
	char *name;
	sd_bus_slot *slot;
	};

	struct sd_bus_track {
	unsigned n_ref;
	unsigned n_adding; /* are we in the process of adding a new name? */
	sd_bus *bus;
	sd_bus_track_handler_t handler;
	void *userdata;
	Hashmap *names;
	LIST_FIELDS(sd_bus_track, queue);
	Iterator iterator;
	bool in_list:1; /* In bus->tracks? */
	bool in_queue:1; /* In bus->track_queue? */
	bool modified:1;
	bool recursive:1;

	LIST_FIELDS(sd_bus_track, tracks);
	};

	#define MATCH_PREFIX \
	"type='signal'," \
	"sender='org.freedesktop.DBus'," \
	"path='/org/freedesktop/DBus'," \
	"interface='org.freedesktop.DBus'," \
	"member='NameOwnerChanged'," \
	"arg0='"

	#define MATCH_SUFFIX \
	"'"

	#define MATCH_FOR_NAME(name) \
	({ \
	char *_x; \
	size_t _l = strlen(name); \
	_x = alloca(strlen(MATCH_PREFIX)+_l+strlen(MATCH_SUFFIX)+1); \
	strcpy(stpcpy(stpcpy(_x, MATCH_PREFIX), name), MATCH_SUFFIX); \
	_x; \
	})

	static struct track_item* track_item_free(struct track_item *i) {

	if (!i)
	return NULL;

	sd_bus_slot_unref(i->slot);
	free(i->name);
	return mfree(i);
	}

	DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_free);

	static void bus_track_add_to_queue(sd_bus_track *track) {
	assert(track);

	/* Adds the bus track object to the queue of objects we should dispatch next, subject to a number of
	* conditions. */

	/* Already in the queue? */
	if (track->in_queue)
	return;

	/* if we are currently in the process of adding a new name, then let's not enqueue this just yet, let's wait
	* until the addition is complete. */
	if (track->n_adding > 0)
	return;

	/* still referenced? */
	if (hashmap_size(track->names) > 0)
	return;

	/* Nothing to call? */
	if (!track->handler)
	return;

	/* Already closed? */
	if (!track->in_list)
	return;

	LIST_PREPEND(queue, track->bus->track_queue, track);
	track->in_queue = true;
	}

	static void bus_track_remove_from_queue(sd_bus_track *track) {
	assert(track);

	if (!track->in_queue)
	return;

	LIST_REMOVE(queue, track->bus->track_queue, track);
	track->in_queue = false;
	}

	static int bus_track_remove_name_fully(sd_bus_track track, const char name) {
	struct track_item *i;

	assert(track);
	assert(name);

	i = hashmap_remove(track->names, name);
	if (!i)
	return 0;

	track_item_free(i);

	bus_track_add_to_queue(track);

	track->modified = true;
	return 1;
	}

	_public_ int sd_bus_track_new(
	sd_bus *bus,
	sd_bus_track **track,
	sd_bus_track_handler_t handler,
	void *userdata) {

	sd_bus_track *t;

	assert_return(bus, -EINVAL);
	assert_return(track, -EINVAL);

	if (!bus->bus_client)
	return -EINVAL;

	t = new0(sd_bus_track, 1);
	if (!t)
	return -ENOMEM;

	t->n_ref = 1;
	t->handler = handler;
	t->userdata = userdata;
	t->bus = sd_bus_ref(bus);

	LIST_PREPEND(tracks, bus->tracks, t);
	t->in_list = true;

	bus_track_add_to_queue(t);

	*track = t;
	return 0;
	}

	_public_ sd_bus_track* sd_bus_track_ref(sd_bus_track *track) {

	if (!track)
	return NULL;

	assert(track->n_ref > 0);

	track->n_ref++;

	return track;
	}

	_public_ sd_bus_track* sd_bus_track_unref(sd_bus_track *track) {
	struct track_item *i;

	if (!track)
	return NULL;

	assert(track->n_ref > 0);

	if (track->n_ref > 1) {
	track->n_ref--;
	return NULL;
	}

	while ((i = hashmap_steal_first(track->names)))
	track_item_free(i);

	if (track->in_list)
	LIST_REMOVE(tracks, track->bus->tracks, track);

	bus_track_remove_from_queue(track);
	hashmap_free(track->names);
	sd_bus_unref(track->bus);
	return mfree(track);
	}

	static int on_name_owner_changed(sd_bus_message message, void userdata, sd_bus_error *error) {
	sd_bus_track *track = userdata;
	const char name, old, *new;
	int r;

	assert(message);
	assert(track);

	r = sd_bus_message_read(message, "sss", &name, &old, &new);
	if (r < 0)
	return 0;

	bus_track_remove_name_fully(track, name);
	return 0;
	}

	_public_ int sd_bus_track_add_name(sd_bus_track track, const char name) {
	_cleanup_(track_item_freep) struct track_item *n = NULL;
	struct track_item *i;
	const char *match;
	int r;

	assert_return(track, -EINVAL);
	assert_return(service_name_is_valid(name), -EINVAL);

	i = hashmap_get(track->names, name);
	if (i) {
	if (track->recursive) {
	unsigned k = track->n_ref + 1;

	if (k < track->n_ref) /* Check for overflow */
	return -EOVERFLOW;

	track->n_ref = k;
	}

	bus_track_remove_from_queue(track);
	return 0;
	}

	r = hashmap_ensure_allocated(&track->names, &string_hash_ops);
	if (r < 0)
	return r;

	n = new0(struct track_item, 1);
	if (!n)
	return -ENOMEM;
	n->name = strdup(name);
	if (!n->name)
	return -ENOMEM;

	/* First, subscribe to this name */
	match = MATCH_FOR_NAME(name);

	bus_track_remove_from_queue(track); /* don't dispatch this while we work in it */

	track->n_adding++; /* make sure we aren't dispatched while we synchronously add this match */
	r = sd_bus_add_match(track->bus, &n->slot, match, on_name_owner_changed, track);
	track->n_adding--;
	if (r < 0) {
	bus_track_add_to_queue(track);
	return r;
	}

	r = hashmap_put(track->names, n->name, n);
	if (r < 0) {
	bus_track_add_to_queue(track);
	return r;
	}

	/* Second, check if it is currently existing, or maybe doesn't, or maybe disappeared already. */
	track->n_adding++; /* again, make sure this isn't dispatch while we are working in it */
	r = sd_bus_get_name_creds(track->bus, name, 0, NULL);
	track->n_adding--;
	if (r < 0) {
	hashmap_remove(track->names, name);
	bus_track_add_to_queue(track);
	return r;
	}

	n->n_ref = 1;
	n = NULL;

	bus_track_remove_from_queue(track);
	track->modified = true;

	return 1;
	}

	_public_ int sd_bus_track_remove_name(sd_bus_track track, const char name) {
	struct track_item *i;

	assert_return(name, -EINVAL);

	if (!track) /* Treat a NULL track object as an empty track object */
	return 0;

	if (!track->recursive)
	return bus_track_remove_name_fully(track, name);

	i = hashmap_get(track->names, name);
	if (!i)
	return -EUNATCH;
	if (i->n_ref <= 0)
	return -EUNATCH;

	i->n_ref--;

	if (i->n_ref <= 0)
	return bus_track_remove_name_fully(track, name);

	return 1;
	}

	_public_ unsigned sd_bus_track_count(sd_bus_track *track) {

	if (!track) /* Let's consider a NULL object equivalent to an empty object */
	return 0;

	/* This signature really should have returned an int, so that we can propagate errors. But well, ... Also, note
	* that this returns the number of names being watched, and multiple references to the same name are not
	* counted. */

	return hashmap_size(track->names);
	}

	_public_ const char* sd_bus_track_contains(sd_bus_track track, const char name) {
	assert_return(name, NULL);

	if (!track) /* Let's consider a NULL object equivalent to an empty object */
	return NULL;

	return hashmap_get(track->names, (void*) name) ? name : NULL;
	}

	_public_ const char* sd_bus_track_first(sd_bus_track *track) {
	const char *n = NULL;

	if (!track)
	return NULL;

	track->modified = false;
	track->iterator = ITERATOR_FIRST;

	hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
	return n;
	}

	_public_ const char* sd_bus_track_next(sd_bus_track *track) {
	const char *n = NULL;

	if (!track)
	return NULL;

	if (track->modified)
	return NULL;

	hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
	return n;
	}

	_public_ int sd_bus_track_add_sender(sd_bus_track track, sd_bus_message m) {
	const char *sender;

	assert_return(track, -EINVAL);
	assert_return(m, -EINVAL);

	if (sd_bus_message_get_bus(m) != track->bus)
	return -EINVAL;

	sender = sd_bus_message_get_sender(m);
	if (!sender)
	return -EINVAL;

	return sd_bus_track_add_name(track, sender);
	}

	_public_ int sd_bus_track_remove_sender(sd_bus_track track, sd_bus_message m) {
	const char *sender;

	assert_return(m, -EINVAL);

	if (!track) /* Treat a NULL track object as an empty track object */
	return 0;

	if (sd_bus_message_get_bus(m) != track->bus)
	return -EINVAL;

	sender = sd_bus_message_get_sender(m);
	if (!sender)
	return -EINVAL;

	return sd_bus_track_remove_name(track, sender);
	}

	_public_ sd_bus* sd_bus_track_get_bus(sd_bus_track *track) {
	assert_return(track, NULL);

	return track->bus;
	}

	void bus_track_dispatch(sd_bus_track *track) {
	int r;

	assert(track);
	assert(track->handler);

	bus_track_remove_from_queue(track);

	sd_bus_track_ref(track);

	r = track->handler(track, track->userdata);
	if (r < 0)
	log_debug_errno(r, "Failed to process track handler: %m");
	else if (r == 0)
	bus_track_add_to_queue(track);

	sd_bus_track_unref(track);
	}

	void bus_track_close(sd_bus_track *track) {
	struct track_item *i;

	assert(track);

	/* Called whenever our bus connected is closed. If so, and our track object is non-empty, dispatch it
	* immediately, as we are closing now, but first flush out all names. */

	if (!track->in_list)
	return; /* We already closed this one, don't close it again. */

	/* Remember that this one is closed now */
	LIST_REMOVE(tracks, track->bus->tracks, track);
	track->in_list = false;

	/* If there's no name in this one anyway, we don't have to dispatch */
	if (hashmap_isempty(track->names))
	return;

	/* Let's flush out all names */
	while ((i = hashmap_steal_first(track->names)))
	track_item_free(i);

	/* Invoke handler */
	if (track->handler)
	bus_track_dispatch(track);
	}

	_public_ void sd_bus_track_get_userdata(sd_bus_track track) {
	assert_return(track, NULL);

	return track->userdata;
	}

	_public_ void sd_bus_track_set_userdata(sd_bus_track track, void *userdata) {
	void *ret;

	assert_return(track, NULL);

	ret = track->userdata;
	track->userdata = userdata;

	return ret;
	}

	_public_ int sd_bus_track_set_recursive(sd_bus_track *track, int b) {
	assert_return(track, -EINVAL);

	if (track->recursive == !!b)
	return 0;

	if (!hashmap_isempty(track->names))
	return -EBUSY;

	track->recursive = b;
	return 0;
	}

	_public_ int sd_bus_track_get_recursive(sd_bus_track *track) {
	assert_return(track, -EINVAL);

	return track->recursive;
	}

	_public_ int sd_bus_track_count_sender(sd_bus_track track, sd_bus_message m) {
	const char *sender;

	assert_return(m, -EINVAL);

	if (!track) /* Let's consider a NULL object equivalent to an empty object */
	return 0;

	if (sd_bus_message_get_bus(m) != track->bus)
	return -EINVAL;

	sender = sd_bus_message_get_sender(m);
	if (!sender)
	return -EINVAL;

	return sd_bus_track_count_name(track, sender);
	}

	_public_ int sd_bus_track_count_name(sd_bus_track track, const char name) {
	struct track_item *i;

	assert_return(service_name_is_valid(name), -EINVAL);

	if (!track) /* Let's consider a NULL object equivalent to an empty object */
	return 0;

	i = hashmap_get(track->names, name);
	if (!i)
	return 0;

	return i->n_ref;
	}