1SD_BUS_ADD_OBJECT(3)           sd_bus_add_object          SD_BUS_ADD_OBJECT(3)
2
3
4

NAME

6       sd_bus_add_object, sd_bus_add_fallback, sd_bus_add_object_vtable,
7       sd_bus_add_fallback_vtable, sd_bus_add_filter,
8       SD_BUS_VTABLE_CAPABILITY, SD_BUS_VTABLE_START, SD_BUS_VTABLE_END,
9       SD_BUS_METHOD_WITH_NAMES_OFFSET, SD_BUS_METHOD_WITH_NAMES,
10       SD_BUS_METHOD_WITH_OFFSET, SD_BUS_METHOD, SD_BUS_SIGNAL_WITH_NAMES,
11       SD_BUS_SIGNAL, SD_BUS_WRITABLE_PROPERTY, SD_BUS_PROPERTY, SD_BUS_PARAM
12       - Declare properties and methods for a D-Bus path
13

SYNOPSIS

15       #include <systemd/sd-bus-vtable.h>
16
17
18       typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,
19                                               void *userdata,
20                                               sd_bus_error *ret_error);
21
22       typedef int (*sd_bus_property_get_t)(sd_bus *bus, const char *path,
23                                            const char *interface,
24                                            const char *property,
25                                            sd_bus_message *reply,
26                                            void *userdata,
27                                            sd_bus_error *ret_error);
28
29       typedef int (*sd_bus_property_set_t)(sd_bus *bus, const char *path,
30                                            const char *interface,
31                                            const char *property,
32                                            sd_bus_message *value,
33                                            void *userdata,
34                                            sd_bus_error *ret_error);
35
36       typedef int (*sd_bus_object_find_t)(const char *path,
37                                           const char *interface,
38                                           void *userdata, void **ret_found,
39                                           sd_bus_error *ret_error);
40
41       int sd_bus_add_object(sd_bus *bus, sd_bus_slot **slot,
42                             const char *path,
43                             sd_bus_message_handler_t callback,
44                             void *userdata);
45
46       int sd_bus_add_fallback(sd_bus *bus, sd_bus_slot **slot,
47                               const char *path,
48                               sd_bus_message_handler_t callback,
49                               void *userdata);
50
51       int sd_bus_add_object_vtable(sd_bus *bus, sd_bus_slot **slot,
52                                    const char *path, const char *interface,
53                                    const sd_bus_vtable *vtable,
54                                    void *userdata);
55
56       int sd_bus_add_fallback_vtable(sd_bus *bus, sd_bus_slot **slot,
57                                      const char *prefix,
58                                      const char *interface,
59                                      const sd_bus_vtable *vtable,
60                                      sd_bus_object_find_t find,
61                                      void *userdata);
62
63       int sd_bus_add_filter(sd_bus *bus, sd_bus_slot **slot,
64                             sd_bus_message_handler_t callback,
65                             void *userdata);
66
67       SD_BUS_VTABLE_CAPABILITY(capability)
68
69       SD_BUS_VTABLE_START(flags)
70
71       SD_BUS_VTABLE_END
72
73       SD_BUS_METHOD_WITH_ARGS_OFFSET(member, args, result, handler, offset,
74       flags)
75
76       SD_BUS_METHOD_WITH_ARGS(member, args, result, handler, flags)
77
78       SD_BUS_METHOD_WITH_NAMES_OFFSET(member, signature, in_names, result,
79       out_names, handler, offset, flags)
80
81       SD_BUS_METHOD_WITH_NAMES(member, signature, in_names, result,
82       out_names, handler, flags)
83
84       SD_BUS_METHOD_WITH_OFFSET(member, signature, result, handler, offset,
85       flags)
86
87       SD_BUS_METHOD(member, signature, result, handler, flags)
88
89       SD_BUS_SIGNAL_WITH_ARGS(member, args, flags)
90
91       SD_BUS_SIGNAL_WITH_NAMES(member, signature, names, flags)
92
93       SD_BUS_SIGNAL(member, signature, flags)
94
95       SD_BUS_WRITABLE_PROPERTY(member, signature, get, set, offset, flags)
96
97       SD_BUS_PROPERTY(member, signature, get, offset, flags)
98
99       SD_BUS_PARAM(name)
100
101       SD_BUS_ARGS(...)
102
103       SD_BUS_RESULT(...)
104
105       SD_BUS_NO_ARGS
106
107       SD_BUS_NO_RESULT
108

DESCRIPTION

110       sd_bus_add_object_vtable() is used to declare attributes for the object
111       path path connected to the bus connection bus under the interface
112       interface. The table vtable may contain property declarations using
113       SD_BUS_PROPERTY() or SD_BUS_WRITABLE_PROPERTY(), method declarations
114       using SD_BUS_METHOD(), SD_BUS_METHOD_WITH_NAMES(),
115       SD_BUS_METHOD_WITH_OFFSET(), or SD_BUS_METHOD_WITH_NAMES_OFFSET(), and
116       signal declarations using SD_BUS_SIGNAL_WITH_NAMES() or
117       SD_BUS_SIGNAL(), see below. The userdata parameter contains a pointer
118       that will be passed to various callback functions. It may be specified
119       as NULL if no value is necessary. An interface can have any number of
120       vtables attached to it.
121
122       sd_bus_add_fallback_vtable() is similar to sd_bus_add_object_vtable(),
123       but is used to register "fallback" attributes. When looking for an
124       attribute declaration, bus object paths registered with
125       sd_bus_add_object_vtable() are checked first. If no match is found, the
126       fallback vtables are checked for each prefix of the bus object path,
127       i.e. with the last slash-separated components successively removed.
128       This allows the vtable to be used for an arbitrary number of
129       dynamically created objects.
130
131       Parameter find is a function which is used to locate the target object
132       based on the bus object path path. It must return 1 and set the
133       ret_found output parameter if the object is found, return 0 if the
134       object was not found, and return a negative errno-style error code or
135       initialize the error structure ret_error on error. The pointer passed
136       in ret_found will be used as the userdata parameter for the callback
137       functions (offset by the offset offsets as specified in the vtable
138       entries).
139
140       sd_bus_add_object() attaches a callback directly to the object path
141       path. An object path can have any number of callbacks attached to it.
142       Each callback is prepended to the list of callbacks which are always
143       called in order.  sd_bus_add_fallback() is similar to
144       sd_bus_add_object() but applies to fallback paths instead.
145
146       sd_bus_add_filter() installs a callback that is invoked for each
147       incoming D-Bus message. Filters can be used to handle logic common to
148       all messages received by a service (e.g. authentication or
149       authorization).
150
151       When a request is received, any associated callbacks are called
152       sequentially until a callback returns a non-zero integer. Return zero
153       from a callback to give other callbacks the chance to process the
154       request. Callbacks are called in the following order: first, global
155       callbacks installed with sd_bus_add_filter() are called. Second,
156       callbacks attached directly to the request object path are called,
157       followed by any D-Bus method callbacks attached to the request object
158       path, interface and member. Finally, the property callbacks attached to
159       the request object path, interface and member are called. If the final
160       callback returns zero, an error reply is sent back to the caller
161       indicating no matching object for the request was found.
162
163       Note that you can return a positive integer from a method callback
164       without immediately sending a reply. This informs sd-bus this callback
165       will take responsibility for replying to the request without forcing
166       the callback to produce a reply immediately. This allows a callback to
167       perform any number of asynchronous operations required to construct a
168       reply. However, if producing a reply takes too long, the method call
169       will time out at the caller. This is only available to methods and not
170       properties.
171
172       If a callback was invoked to handle a request that expects a reply and
173       the callback returns a negative value, the value is interpreted as a
174       negative errno-style error code and sent back to the caller as a D-Bus
175       error as if sd_bus_reply_method_errno(3) was called. Additionally, all
176       callbacks take a sd_bus_error output parameter that can be used to
177       provide more detailed error information. If ret_error is set when the
178       callback finishes, the corresponding D-Bus error is sent back to the
179       caller as if sd_bus_reply_method_error(3) was called. Any error stored
180       in ret_error takes priority over any negative values returned by the
181       same callback when determining which error to send back to the caller.
182       Use sd_bus_error_set(3) or one of its variants to set ret_error and
183       return a negative integer from a callback with a single function call.
184       To send an error reply after a callback has already finished, use
185       sd_bus_reply_method_errno(3) or one of its variants.
186
187       For all functions, a match slot is created internally. If the output
188       parameter slot is NULL, a "floating" slot object is created, see
189       sd_bus_slot_set_floating(3). Otherwise, a pointer to the slot object is
190       returned. In that case, the reference to the slot object should be
191       dropped when the vtable is not needed anymore, see
192       sd_bus_slot_unref(3).
193
194   The sd_bus_vtable array
195       The array consists of the structures of type sd_bus_vtable, but it
196       should never be filled in manually, but through one of the following
197       macros:
198
199       SD_BUS_VTABLE_START(flags), SD_BUS_VTABLE_END
200           Those must always be the first and last element. The flags
201           parameter can be used to set attributes that apply to the whole
202           array; see the "Flags" section below.
203
204       SD_BUS_METHOD_WITH_ARGS_OFFSET(), SD_BUS_METHOD_WITH_ARGS()
205           Declare a D-Bus method with the name member, arguments args and
206           result result.  args expects a sequence of argument type/name pairs
207           wrapped in the SD_BUS_ARGS() macro. The elements at even indices in
208           this list describe the types of the method's arguments. The
209           method's parameter signature is the concatenation of all the string
210           literals at even indices in args. If a method has no parameters,
211           pass SD_BUS_NO_ARGS to args. The elements at uneven indices
212           describe the names of the method's arguments.  result expects a
213           sequence of type/name pairs wrapped in the SD_BUS_RESULT() macro in
214           the same format as SD_BUS_ARGS(). The method's result signature is
215           the concatenation of all the string literals at even indices in
216           result. If a method has no result, pass SD_BUS_NO_RESULT to result.
217           Note that argument types are expected to be quoted string literals
218           and argument names are expected to be unquoted string literals. See
219           below for a complete example.
220
221           The handler function handler must be of type
222           sd_bus_message_handler_t. It will be called to handle the incoming
223           messages that call this method. It receives a pointer that is the
224           userdata parameter passed to the registration function offset by
225           offset bytes. This may be used to pass pointers to different fields
226           in the same data structure to different methods in the same vtable.
227           To send a reply from handler, call sd_bus_reply_method_return(3)
228           with the message the callback was invoked with. Parameter flags is
229           a combination of flags, see below.
230
231           SD_BUS_METHOD_WITH_ARGS() is a shorthand for calling
232           SD_BUS_METHOD_WITH_ARGS_OFFSET() with an offset of zero.
233
234       SD_BUS_METHOD_WITH_NAMES_OFFSET(), SD_BUS_METHOD_WITH_NAMES(),
235       SD_BUS_METHOD_WITH_OFFSET(), SD_BUS_METHOD()
236           Declare a D-Bus method with the name member, parameter signature
237           signature, result signature result. Parameters in_names and
238           out_names specify the argument names of the input and output
239           arguments in the function signature.  in_names and out_names should
240           be created using the SD_BUS_PARAM() macro, see below. In all other
241           regards, this macro behaves exactly the same as
242           SD_BUS_METHOD_WITH_ARGS_OFFSET().
243
244           SD_BUS_METHOD_WITH_NAMES(), SD_BUS_METHOD_WITH_OFFSET(), and
245           SD_BUS_METHOD() are variants which specify zero offset (userdata
246           parameter is passed with no change), leave the names unset (i.e. no
247           parameter names), or both.
248
249           Prefer using SD_BUS_METHOD_WITH_ARGS_OFFSET() and
250           SD_BUS_METHOD_WITH_ARGS() over these macros as they allow
251           specifying argument types and names next to each other which is
252           less error-prone than first specifying all argument types followed
253           by specifying all argument names.
254
255       SD_BUS_SIGNAL_WITH_ARGS()
256           Declare a D-Bus signal with the name member and arguments args.
257           args expects a sequence of argument type/name pairs wrapped in the
258           SD_BUS_ARGS() macro. The elements at even indices in this list
259           describe the types of the signal's arguments. The signal's
260           parameter signature is the concatenation of all the string literals
261           at even indices in args. If a signal has no parameters, pass
262           SD_BUS_NO_ARGS to args. The elements at uneven indices describe the
263           names of the signal's arguments. Parameter flags is a combination
264           of flags. See below for a complete example.
265
266       SD_BUS_SIGNAL_WITH_NAMES(), SD_BUS_SIGNAL()
267           Declare a D-Bus signal with the name member, parameter signature
268           signature, and argument names names.  names should be created using
269           the SD_BUS_PARAM() macro, see below. Parameter flags is a
270           combination of flags, see below.
271
272           SD_BUS_SIGNAL() is equivalent to SD_BUS_SIGNAL_WITH_NAMES() with
273           the names parameter unset (i.e. no parameter names).
274
275           Prefer using SD_BUS_SIGNAL_WITH_ARGS() over these macros as it
276           allows specifying argument types and names next to each other which
277           is less error-prone than first specifying all argument types
278           followed by specifying all argument names.
279
280       SD_BUS_WRITABLE_PROPERTY(), SD_BUS_PROPERTY()
281           Declare a D-Bus property with the name member and value signature
282           signature. Parameters get and set are the getter and setter
283           methods. They are called with a pointer that is the userdata
284           parameter passed to the registration function offset by offset
285           bytes. This may be used pass pointers to different fields in the
286           same data structure to different setters and getters in the same
287           vtable. Parameter flags is a combination of flags, see below.
288
289           The setter and getter methods may be omitted (specified as NULL),
290           if the property is one of the basic types or "as" in case of
291           read-only properties. In those cases, the userdata and offset
292           parameters must together point to a valid variable of the
293           corresponding type. A default setter and getter will be provided,
294           which simply copy the argument between this variable and the
295           message.
296
297           SD_BUS_PROPERTY() is used to define a read-only property.
298
299       SD_BUS_PARAM()
300           Parameter names should be wrapped in this macro, see the example
301           below.
302
303   Flags
304       The flags parameter is used to specify a combination of D-Bus
305       annotations[1].
306
307       SD_BUS_VTABLE_DEPRECATED
308           Mark this vtable entry as deprecated using the
309           org.freedesktop.DBus.Deprecated annotation in introspection data.
310           If specified for SD_BUS_VTABLE_START(), the annotation is applied
311           to the enclosing interface.
312
313       SD_BUS_VTABLE_HIDDEN
314           Make this vtable entry hidden. It will not be shown in
315           introspection data. If specified for SD_BUS_VTABLE_START(), all
316           entries in the array are hidden.
317
318       SD_BUS_VTABLE_METHOD_NO_REPLY
319           Mark this vtable entry as a method that will not return a reply
320           using the org.freedesktop.DBus.Method.NoReply annotation in
321           introspection data.
322
323       SD_BUS_VTABLE_PROPERTY_CONST, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE,
324       SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION
325           Those three flags correspond to different values of the
326           org.freedesktop.DBus.Property.EmitsChangedSignal annotation, which
327           specifies whether the
328           org.freedesktop.DBus.Properties.PropertiesChanged signal is emitted
329           whenever the property changes.  SD_BUS_VTABLE_PROPERTY_CONST
330           corresponds to const and means that the property never changes
331           during the lifetime of the object it belongs to, so no signal needs
332           to be emitted.  SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE corresponds to
333           true and means that the signal is emitted.
334           SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION corresponds to
335           invalidates and means that the signal is emitted, but the value is
336           not included in the signal.
337
338       SD_BUS_VTABLE_PROPERTY_EXPLICIT
339           Mark this vtable property entry as requiring explicit request to
340           for the value to be shown (generally because the value is large or
341           slow to calculate). This entry cannot be combined with
342           SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE, and will not be shown in
343           property listings by default (e.g.  busctl introspect). This
344           corresponds to the org.freedesktop.systemd1.Explicit annotation in
345           introspection data.
346
347       SD_BUS_VTABLE_SENSITIVE
348           Mark this vtable method entry as processing sensitive data. When
349           set, incoming method call messages and their outgoing reply
350           messages are marked as sensitive using sd_bus_message_sensitive(3),
351           so that they are erased from memory when freed.
352
353       SD_BUS_VTABLE_ABSOLUTE_OFFSET
354           Mark this vtable method or property entry so that the user data
355           pointer passed to its associated handler functions is determined
356           slightly differently: instead of adding the offset parameter of the
357           entry to the user data pointer specified during vtable
358           registration, the offset is passed directly, converted to a
359           pointer, without taking the user data pointer specified during
360           vtable registration into account.
361
362       SD_BUS_VTABLE_CAPABILITY(capability)
363           Access to this vtable entry will be allowed if the calling process
364           has the capability capability, as described in
365           sd_bus_query_sender_privilege(3). If used for
366           SD_BUS_VTABLE_START(), provides a default for all entries in the
367           array. If not specified, either for an individual entry or the
368           whole array, CAP_SYS_ADMIN is checked by default. See
369           capabilities(7) for information about capabilities.
370
371           Note that vtable entries may be marked as unprivileged and the
372           whole bus may be marked as trusted, see the discussion of
373           SD_BUS_VTABLE_UNPRIVILEGED below.
374
375       SD_BUS_VTABLE_UNPRIVILEGED
376           Mark this vtable entry as unprivileged. Access to privileged
377           entries is limited to users with appropriate capabilities as
378           described above. In practice many vtable entries are marked as
379           unprivileged, and either are open to everyone, or the decision
380           whether to allow access is taken later, e.g. by delegating to
381           polkit[2].
382
383           The whole bus may be marked as trusted, in which case annotations
384           at the entry level are ignored, see sd_bus_set_trusted(3).
385
386           When not specified, the org.freedesktop.systemd1.Privileged
387           annotation with value "true" will be shown in introspection data.
388
389           Note that this page describes checks implemented in the D-Bus
390           client. The D-Bus server has an additional policy that may permit
391           or deny connections, see "CONFIGURATION FILE" in dbus-daemon(1).
392

EXAMPLES

394       Example 1. Create a simple listener on the bus
395
396           /* SPDX-License-Identifier: MIT-0 */
397
398           #include <errno.h>
399           #include <stdbool.h>
400           #include <stddef.h>
401           #include <stdlib.h>
402           #include <stdio.h>
403           #include <systemd/sd-bus.h>
404
405           #define _cleanup_(f) __attribute__((cleanup(f)))
406
407           #define check(x) ({                             \
408             int r = (x);                                  \
409             errno = r < 0 ? -r : 0;                       \
410             printf(#x ": %m\n");                          \
411             if (r < 0)                                    \
412               return EXIT_FAILURE;                        \
413             })
414
415           typedef struct object {
416             char *name;
417             uint32_t number;
418           } object;
419
420           static int method(sd_bus_message *m, void *userdata, sd_bus_error *error) {
421             printf("Got called with userdata=%p\n", userdata);
422
423             if (sd_bus_message_is_method_call(m,
424                                               "org.freedesktop.systemd.VtableExample",
425                                               "Method4"))
426               return 1;
427
428             const char *string;
429             check(sd_bus_message_read(m, "s", &string));
430             check(sd_bus_reply_method_return(m, "s", string));
431
432             return 1;
433           }
434
435           static const sd_bus_vtable vtable[] = {
436                   SD_BUS_VTABLE_START(0),
437                   SD_BUS_METHOD(
438                       "Method1", "s", "s", method, 0),
439                   SD_BUS_METHOD_WITH_NAMES_OFFSET(
440                       "Method2",
441                       "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
442                       "s", SD_BUS_PARAM(returnstring),
443                       method, offsetof(object, number),
444                       SD_BUS_VTABLE_DEPRECATED),
445                   SD_BUS_METHOD_WITH_ARGS_OFFSET(
446                       "Method3",
447                       SD_BUS_ARGS("s", string, "o", path),
448                       SD_BUS_RESULT("s", returnstring),
449                       method, offsetof(object, number),
450                       SD_BUS_VTABLE_UNPRIVILEGED),
451                   SD_BUS_METHOD_WITH_ARGS(
452                       "Method4",
453                       SD_BUS_NO_ARGS,
454                       SD_BUS_NO_RESULT,
455                       method,
456                       SD_BUS_VTABLE_UNPRIVILEGED),
457                   SD_BUS_SIGNAL(
458                       "Signal1",
459                       "so",
460                       0),
461                   SD_BUS_SIGNAL_WITH_NAMES(
462                       "Signal2",
463                       "so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
464                       0),
465                   SD_BUS_SIGNAL_WITH_ARGS(
466                       "Signal3",
467                       SD_BUS_ARGS("s", string, "o", path),
468                       0),
469                   SD_BUS_WRITABLE_PROPERTY(
470                       "AutomaticStringProperty", "s", NULL, NULL,
471                       offsetof(object, name),
472                       SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
473                   SD_BUS_WRITABLE_PROPERTY(
474                       "AutomaticIntegerProperty", "u", NULL, NULL,
475                       offsetof(object, number),
476                       SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
477                   SD_BUS_VTABLE_END
478           };
479
480           int main(int argc, char **argv) {
481             _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
482
483             sd_bus_default(&bus);
484
485             object object = { .number = 666 };
486             check((object.name = strdup("name")) != NULL);
487
488             check(sd_bus_add_object_vtable(bus, NULL,
489                                            "/org/freedesktop/systemd/VtableExample",
490                                            "org.freedesktop.systemd.VtableExample",
491                                            vtable,
492                                            &object));
493
494             check(sd_bus_request_name(bus,
495                                       "org.freedesktop.systemd.VtableExample",
496                                       0));
497
498             for (;;) {
499               check(sd_bus_wait(bus, UINT64_MAX));
500               check(sd_bus_process(bus, NULL));
501             }
502
503             check(sd_bus_release_name(bus, "org.freedesktop.systemd.VtableExample"));
504             free(object.name);
505
506             return 0;
507           }
508
509       This creates a simple client on the bus (the user bus, when run as
510       normal user). We may use the D-Bus
511       org.freedesktop.DBus.Introspectable.Introspect call to acquire the XML
512       description of the interface:
513
514           <!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN"
515           "https://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
516           <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
517           <node>
518            <interface name="org.freedesktop.DBus.Peer">
519             <method name="Ping"/>
520             <method name="GetMachineId">
521              <arg type="s" name="machine_uuid" direction="out"/>
522             </method>
523            </interface>
524            <interface name="org.freedesktop.DBus.Introspectable">
525             <method name="Introspect">
526              <arg name="xml_data" type="s" direction="out"/>
527             </method>
528            </interface>
529            <interface name="org.freedesktop.DBus.Properties">
530             <method name="Get">
531              <arg name="interface_name" direction="in" type="s"/>
532              <arg name="property_name" direction="in" type="s"/>
533              <arg name="value" direction="out" type="v"/>
534             </method>
535             <method name="GetAll">
536              <arg name="interface_name" direction="in" type="s"/>
537              <arg name="props" direction="out" type="a{sv}"/>
538             </method>
539             <method name="Set">
540              <arg name="interface_name" direction="in" type="s"/>
541              <arg name="property_name" direction="in" type="s"/>
542              <arg name="value" direction="in" type="v"/>
543             </method>
544             <signal name="PropertiesChanged">
545              <arg type="s" name="interface_name"/>
546              <arg type="a{sv}" name="changed_properties"/>
547              <arg type="as" name="invalidated_properties"/>
548             </signal>
549            </interface>
550            <interface name="org.freedesktop.systemd.VtableExample">
551             <method name="Method1">
552              <arg type="s" direction="in"/>
553              <arg type="s" direction="out"/>
554             </method>
555             <method name="Method2">
556              <arg type="s" name="string" direction="in"/>
557              <arg type="o" name="path" direction="in"/>
558              <arg type="s" name="returnstring" direction="out"/>
559              <annotation name="org.freedesktop.DBus.Deprecated" value="true"/>
560             </method>
561             <property name="AutomaticStringProperty" type="s" access="readwrite">
562             </property>
563             <property name="AutomaticIntegerProperty" type="u" access="readwrite">
564              <annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="invalidates"/>
565             </property>
566            </interface>
567           </node>
568
569

RETURN VALUE

571       On success, sd_bus_add_object_vtable() and sd_bus_add_fallback_vtable()
572       return a non-negative integer. On failure, they return a negative
573       errno-style error code.
574
575   Errors
576       Returned errors may indicate the following problems:
577
578       -EINVAL
579           One of the required parameters is NULL or invalid. A reserved D-Bus
580           interface was passed as the interface parameter.
581
582       -ENOPKG
583           The bus cannot be resolved.
584
585       -ECHILD
586           The bus was created in a different process, library or module
587           instance.
588
589       -ENOMEM
590           Memory allocation failed.
591
592       -EPROTOTYPE
593           sd_bus_add_object_vtable() and sd_bus_add_fallback_vtable() have
594           been both called for the same bus object path, which is not
595           allowed.
596
597       -EEXIST
598           This vtable has already been registered for this interface and
599           path.
600

NOTES

602       Functions described here are available as a shared library, which can
603       be compiled against and linked to with the libsystemd pkg-config(1)
604       file.
605
606       The code described here uses getenv(3), which is declared to be not
607       multi-thread-safe. This means that the code calling the functions
608       described here must not call setenv(3) from a parallel thread. It is
609       recommended to only do calls to setenv() from an early phase of the
610       program when no other threads have been started.
611

SEE ALSO

613       sd-bus(3), busctl(1), sd_bus_emit_properties_changed(3),
614       sd_bus_emit_object_added(3)
615

NOTES

617        1. D-Bus annotations
618           https://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format
619
620        2. polkit
621           https://www.freedesktop.org/software/polkit/docs/latest/
622
623
624
625systemd 254                                               SD_BUS_ADD_OBJECT(3)
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