| SD_BUS_ADD_OBJECT(3) | sd_bus_add_object | SD_BUS_ADD_OBJECT(3) |
.SH "NAME" sd_bus_add_object, sd_bus_add_fallback,
sd_bus_add_object_vtable, sd_bus_add_fallback_vtable, sd_bus_add_filter,
SD_BUS_VTABLE_CAPABILITY, SD_BUS_VTABLE_START, SD_BUS_VTABLE_END,
SD_BUS_METHOD_WITH_NAMES_OFFSET, SD_BUS_METHOD_WITH_NAMES,
SD_BUS_METHOD_WITH_OFFSET, SD_BUS_METHOD, SD_BUS_SIGNAL_WITH_NAMES,
SD_BUS_SIGNAL, SD_BUS_WRITABLE_PROPERTY, SD_BUS_PROPERTY, SD_BUS_PARAM -
Declare properties and methods for a D-Bus path
.SH "SYNOPSIS"
#include <systemd/sd-bus-vtable.h>
.HP 960u typedef int
(*sd_bus_message_handler_t)(sd_bus_message *m,
void *userdata,
sd_bus_error *ret_error);
.HP 888u typedef int
(*sd_bus_property_get_t)(sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *reply,
void *userdata,
sd_bus_error *ret_error);
.HP 888u typedef int
(*sd_bus_property_set_t)(sd_bus *bus,
const char *path,
const char *interface,
const char *property,
sd_bus_message *value,
void *userdata,
sd_bus_error *ret_error);
.HP 864u typedef int
(*sd_bus_object_find_t)(const char *path,
const char *interface,
void *userdata, void **ret_found,
sd_bus_error *ret_error);
.HP 528u int sd_bus_add_object(sd_bus *bus,
sd_bus_slot **slot,
const char *path,
sd_bus_message_handler_t callback,
void *userdata);
.HP 576u int sd_bus_add_fallback(sd_bus *bus,
sd_bus_slot **slot,
const char *path,
sd_bus_message_handler_t callback,
void *userdata);
.HP 696u int sd_bus_add_object_vtable(sd_bus *bus,
sd_bus_slot **slot,
const char *path,
const char *interface,
const sd_bus_vtable *vtable,
void *userdata);
.HP 744u int sd_bus_add_fallback_vtable(sd_bus *bus,
sd_bus_slot **slot,
const char *prefix,
const char *interface,
const sd_bus_vtable *vtable,
sd_bus_object_find_t find,
void *userdata);
.HP 528u int sd_bus_add_filter(sd_bus *bus,
sd_bus_slot **slot,
sd_bus_message_handler_t callback,
void *userdata);
.PP SD_BUS_VTABLE_CAPABILITY(capability)
.PP SD_BUS_VTABLE_START(flags)
.PP SD_BUS_VTABLE_END
.PP SD_BUS_METHOD_WITH_ARGS_OFFSET(member,
args, result,
handler, offset,
flags)
.PP SD_BUS_METHOD_WITH_ARGS(member,
args, result,
handler, flags)
.PP SD_BUS_METHOD_WITH_NAMES_OFFSET(member,
signature, in_names,
result, out_names,
handler, offset,
flags)
.PP SD_BUS_METHOD_WITH_NAMES(member,
signature, in_names,
result, out_names,
handler, flags)
.PP SD_BUS_METHOD_WITH_OFFSET(member,
signature, result,
handler, offset,
flags)
.PP SD_BUS_METHOD(member,
signature, result,
handler, flags)
.PP SD_BUS_SIGNAL_WITH_ARGS(member,
args, flags)
.PP SD_BUS_SIGNAL_WITH_NAMES(member,
signature, names,
flags)
.PP SD_BUS_SIGNAL(member,
signature, flags)
.PP SD_BUS_WRITABLE_PROPERTY(member,
signature, get,
set, offset,
flags)
.PP SD_BUS_PROPERTY(member,
signature, get,
offset, flags)
.PP SD_BUS_PARAM(name)
.PP SD_BUS_ARGS(...)
.PP SD_BUS_RESULT(...)
.PP SD_BUS_NO_ARGS
.PP SD_BUS_NO_RESULT
.SH "DESCRIPTION"
.PP sd_bus_add_object_vtable() is used to declare attributes for the
object path path connected to the bus connection bus under the
interface interface. The table vtable may contain property
declarations using SD_BUS_PROPERTY() or
SD_BUS_WRITABLE_PROPERTY(), method declarations using
SD_BUS_METHOD(), SD_BUS_METHOD_WITH_NAMES(),
SD_BUS_METHOD_WITH_OFFSET(), or
SD_BUS_METHOD_WITH_NAMES_OFFSET(), and signal declarations using
SD_BUS_SIGNAL_WITH_NAMES() or SD_BUS_SIGNAL(), see below. The
userdata parameter contains a pointer that will be passed to various
callback functions. It may be specified as NULL if no value is
necessary. An interface can have any number of vtables attached to it.
.PP sd_bus_add_fallback_vtable() is similar to
sd_bus_add_object_vtable(), but is used to register
"fallback" attributes. When looking for an attribute declaration,
bus object paths registered with sd_bus_add_object_vtable() are
checked first. If no match is found, the fallback vtables are checked for
each prefix of the bus object path, i.e. with the last slash-separated
components successively removed. This allows the vtable to be used for an
arbitrary number of dynamically created objects.
.PP Parameter find is a function which is used to locate the target
object based on the bus object path path. It must return 1 and
set the ret_found output parameter if the object is found, return
0 if the object was not found, and return a negative errno-style
error code or initialize the error structure ret_error on error. The
pointer passed in ret_found will be used as the userdata
parameter for the callback functions (offset by the offset offsets as
specified in the vtable entries).
.PP sd_bus_add_object() attaches a callback directly to the object
path path. An object path can have any number of callbacks attached
to it. Each callback is prepended to the list of callbacks which are always
called in order. sd_bus_add_fallback() is similar to
sd_bus_add_object() but applies to fallback paths instead.
.PP sd_bus_add_filter() installs a callback that is invoked for each
incoming D-Bus message. Filters can be used to handle logic common to all
messages received by a service (e.g. authentication or authorization).
.PP When a request is received, any associated callbacks are called
sequentially until a callback returns a non-zero integer. Return zero from a
callback to give other callbacks the chance to process the request.
Callbacks are called in the following order: first, global callbacks
installed with sd_bus_add_filter() are called. Second, callbacks
attached directly to the request object path are called, followed by any
D-Bus method callbacks attached to the request object path, interface and
member. Finally, the property callbacks attached to the request object path,
interface and member are called. If the final callback returns zero, an
error reply is sent back to the caller indicating no matching object for the
request was found.
.PP Note that you can return a positive integer from a method callback
without immediately sending a reply. This informs sd-bus this callback will
take responsibility for replying to the request without forcing the callback
to produce a reply immediately. This allows a callback to perform any number
of asynchronous operations required to construct a reply. However, if
producing a reply takes too long, the method call will time out at the
caller. This is only available to methods and not properties.
.PP If a callback was invoked to handle a request that expects a reply and
the callback returns a negative value, the value is interpreted as a
negative errno-style error code and sent back to the caller as a D-Bus error
as if sd_bus_reply_method_errno(3) was called. Additionally, all
callbacks take a sd_bus_error output parameter that can be used to provide
more detailed error information. If ret_error is set when the
callback finishes, the corresponding D-Bus error is sent back to the caller
as if sd_bus_reply_method_error(3) was called. Any error stored in
ret_error takes priority over any negative values returned by the
same callback when determining which error to send back to the caller. Use
sd_bus_error_set(3) or one of its variants to set ret_error
and return a negative integer from a callback with a single function call.
To send an error reply after a callback has already finished, use
sd_bus_reply_method_errno(3) or one of its variants.
.PP For all functions, a match slot is created internally. If the output
parameter slot is NULL, a "floating" slot object is
created, see sd_bus_slot_set_floating(3). Otherwise, a pointer to the
slot object is returned. In that case, the reference to the slot object
should be dropped when the vtable is not needed anymore, see
sd_bus_slot_unref(3).
.SS "The sd_bus_vtable array"
.PP The array consists of the structures of type sd_bus_vtable, but it should
never be filled in manually, but through one of the following macros:
.PP SD_BUS_VTABLE_START(flags),
SD_BUS_VTABLE_END
Those must always be the first and last element. The flags parameter
can be used to set attributes that apply to the whole array; see the
"Flags" section below.
.RE
.PP SD_BUS_METHOD_WITH_ARGS_OFFSET(),
SD_BUS_METHOD_WITH_ARGS()
Declare a D-Bus method with the name member, arguments args and
result result. args expects a sequence of argument type/name
pairs wrapped in the SD_BUS_ARGS() macro. The elements at even
indices in this list describe the types of the method's arguments. The
method's parameter signature is the concatenation of all the string literals
at even indices in args. If a method has no parameters, pass
SD_BUS_NO_ARGS to args. The elements at uneven indices
describe the names of the method's arguments. result expects a
sequence of type/name pairs wrapped in the SD_BUS_RESULT() macro in
the same format as SD_BUS_ARGS(). The method's result signature is
the concatenation of all the string literals at even indices in
result. If a method has no result, pass SD_BUS_NO_RESULT to
result. Note that argument types are expected to be quoted string
literals and argument names are expected to be unquoted string literals. See
below for a complete example.
The handler function handler must be of type
sd_bus_message_handler_t. It will be called to handle the incoming
messages that call this method. It receives a pointer that is the
userdata parameter passed to the registration function offset by
offset bytes. This may be used to pass pointers to different fields
in the same data structure to different methods in the same vtable. To send
a reply from handler, call sd_bus_reply_method_return(3) with
the message the callback was invoked with. Parameter flags is a
combination of flags, see below.
SD_BUS_METHOD_WITH_ARGS() is a shorthand for calling
SD_BUS_METHOD_WITH_ARGS_OFFSET() with an offset of zero.
.RE
.PP SD_BUS_METHOD_WITH_NAMES_OFFSET(),
SD_BUS_METHOD_WITH_NAMES(), SD_BUS_METHOD_WITH_OFFSET(),
SD_BUS_METHOD()
Declare a D-Bus method with the name member, parameter signature
signature, result signature result. Parameters in_names
and out_names specify the argument names of the input and output
arguments in the function signature. in_names and out_names
should be created using the SD_BUS_PARAM() macro, see below. In all
other regards, this macro behaves exactly the same as
SD_BUS_METHOD_WITH_ARGS_OFFSET().
SD_BUS_METHOD_WITH_NAMES(), SD_BUS_METHOD_WITH_OFFSET(), and
SD_BUS_METHOD() are variants which specify zero offset
(userdata parameter is passed with no change), leave the names unset
(i.e. no parameter names), or both.
Prefer using SD_BUS_METHOD_WITH_ARGS_OFFSET() and
SD_BUS_METHOD_WITH_ARGS() over these macros as they allow specifying
argument types and names next to each other which is less error-prone than
first specifying all argument types followed by specifying all argument
names.
.RE
.PP SD_BUS_SIGNAL_WITH_ARGS()
Declare a D-Bus signal with the name member and arguments args.
args expects a sequence of argument type/name pairs wrapped in the
SD_BUS_ARGS() macro. The elements at even indices in this list
describe the types of the signal's arguments. The signal's parameter
signature is the concatenation of all the string literals at even indices in
args. If a signal has no parameters, pass SD_BUS_NO_ARGS to
args. The elements at uneven indices describe the names of the
signal's arguments. Parameter flags is a combination of flags. See
below for a complete example.
.RE
.PP SD_BUS_SIGNAL_WITH_NAMES(), SD_BUS_SIGNAL()
Declare a D-Bus signal with the name member, parameter signature
signature, and argument names names. names should be
created using the SD_BUS_PARAM() macro, see below. Parameter
flags is a combination of flags, see below.
SD_BUS_SIGNAL() is equivalent to SD_BUS_SIGNAL_WITH_NAMES()
with the names parameter unset (i.e. no parameter names).
Prefer using SD_BUS_SIGNAL_WITH_ARGS() over these macros as it allows
specifying argument types and names next to each other which is less
error-prone than first specifying all argument types followed by specifying
all argument names.
.RE
.PP SD_BUS_WRITABLE_PROPERTY(), SD_BUS_PROPERTY()
Declare a D-Bus property with the name member and value signature
signature. Parameters get and set are the getter and
setter methods. They are called with a pointer that is the userdata
parameter passed to the registration function offset by offset bytes.
This may be used pass pointers to different fields in the same data
structure to different setters and getters in the same vtable. Parameter
flags is a combination of flags, see below.
The setter and getter methods may be omitted (specified as NULL), if
the property is one of the basic types or as in case of read-only
properties. In those cases, the userdata and offset parameters
must together point to a valid variable of the corresponding type. A default
setter and getter will be provided, which simply copy the argument between
this variable and the message.
SD_BUS_PROPERTY() is used to define a read-only property.
.RE
.PP SD_BUS_PARAM()
Parameter names should be wrapped in this macro, see the example below.
.RE
.SS "Flags"
.PP The flags parameter is used to specify a combination of D-Bus
annotations[1].
.PP SD_BUS_VTABLE_DEPRECATED
Mark this vtable entry as deprecated using the
org.freedesktop.DBus.Deprecated annotation in introspection data. If
specified for SD_BUS_VTABLE_START(), the annotation is applied to the
enclosing interface.
.RE
.PP SD_BUS_VTABLE_HIDDEN
Make this vtable entry hidden. It will not be shown in introspection data. If
specified for SD_BUS_VTABLE_START(), all entries in the array are
hidden.
.RE
.PP SD_BUS_VTABLE_METHOD_NO_REPLY
Mark this vtable entry as a method that will not return a reply using the
org.freedesktop.DBus.Method.NoReply annotation in introspection
data.
.RE
.PP SD_BUS_VTABLE_PROPERTY_CONST,
SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE,
SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION
Those three flags correspond to different values of the
org.freedesktop.DBus.Property.EmitsChangedSignal annotation, which
specifies whether the
org.freedesktop.DBus.Properties.PropertiesChanged signal is emitted
whenever the property changes. SD_BUS_VTABLE_PROPERTY_CONST
corresponds to const and means that the property never changes during
the lifetime of the object it belongs to, so no signal needs to be emitted.
SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE corresponds to true and
means that the signal is emitted.
SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION corresponds to
invalidates and means that the signal is emitted, but the value is
not included in the signal.
.RE
.PP SD_BUS_VTABLE_PROPERTY_EXPLICIT
Mark this vtable property entry as requiring explicit request to for the
value to be shown (generally because the value is large or slow to
calculate). This entry cannot be combined with
SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE, and will not be shown in
property listings by default (e.g. busctl introspect). This
corresponds to the org.freedesktop.systemd1.Explicit annotation in
introspection data.
.RE
.PP SD_BUS_VTABLE_SENSITIVE
Mark this vtable method entry as processing sensitive data. When set,
incoming method call messages and their outgoing reply messages are marked
as sensitive using sd_bus_message_sensitive(3), so that they are
erased from memory when freed.
.RE
.PP SD_BUS_VTABLE_ABSOLUTE_OFFSET
Mark this vtable method or property entry so that the user data pointer
passed to its associated handler functions is determined slightly
differently: instead of adding the offset parameter of the entry to the user
data pointer specified during vtable registration, the offset is passed
directly, converted to a pointer, without taking the user data pointer
specified during vtable registration into account.
.RE
.PP SD_BUS_VTABLE_CAPABILITY(capability)
Access to this vtable entry will be allowed if the calling process has the
capability capability, as described in
sd_bus_query_sender_privilege(3). If used for
SD_BUS_VTABLE_START(), provides a default for all entries in the
array. If not specified, either for an individual entry or the whole array,
CAP_SYS_ADMIN is checked by default. See capabilities(7) for
information about capabilities.
Note that vtable entries may be marked as unprivileged and the whole bus may
be marked as trusted, see the discussion of
SD_BUS_VTABLE_UNPRIVILEGED below.
.RE
.PP SD_BUS_VTABLE_UNPRIVILEGED
Mark this vtable entry as unprivileged. Access to privileged entries is
limited to users with appropriate capabilities as described above. In
practice many vtable entries are marked as unprivileged, and either are open
to everyone, or the decision whether to allow access is taken later, e.g. by
delegating to polkit[2].
The whole bus may be marked as trusted, in which case annotations at the
entry level are ignored, see sd_bus_set_trusted(3).
When not specified, the org.freedesktop.systemd1.Privileged
annotation with value true will be shown in introspection data.
SD_BUS_VTABLE_UNPRIVILEGED may not be applied to read-only properties,
but read access (to both read-only and writable properties) is always
unrestricted.
Note that this page describes checks implemented in the D-Bus client. The
D-Bus server has an additional policy that may permit or deny connections,
see "CONFIGURATION FILE" in dbus-daemon(1).
.RE
.SH "EXAMPLES"
.PP Example 1. Create a simple listener on the bus
/* SPDX-License-Identifier: MIT-0 */
#define _GNU_SOURCE 1
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <systemd/sd-bus.h>
#define _cleanup_(f) __attribute__((cleanup(f)))
typedef struct object {
char *name;
uint32_t number;
} object;
static int method(sd_bus_message *m, void *userdata, sd_bus_error *error) {
int r;
printf("Got called with userdata=%p\n", userdata);
if (sd_bus_message_is_method_call(m,
"org.freedesktop.systemd.VtableExample",
"Method4"))
return 1;
const char *string;
r = sd_bus_message_read(m, "s", &string);
if (r < 0) {
fprintf(stderr, "sd_bus_message_read() failed: %s\n", strerror(-r));
return 0;
}
r = sd_bus_reply_method_return(m, "s", string);
if (r < 0) {
fprintf(stderr, "sd_bus_reply_method_return() failed: %s\n", strerror(-r));
return 0;
}
return 1;
}
static const sd_bus_vtable vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_METHOD(
"Method1", "s", "s", method, 0),
SD_BUS_METHOD_WITH_NAMES_OFFSET(
"Method2",
"so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
"s", SD_BUS_PARAM(returnstring),
method, offsetof(object, number),
SD_BUS_VTABLE_DEPRECATED),
SD_BUS_METHOD_WITH_ARGS_OFFSET(
"Method3",
SD_BUS_ARGS("s", string, "o", path),
SD_BUS_RESULT("s", returnstring),
method, offsetof(object, number),
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_METHOD_WITH_ARGS(
"Method4",
SD_BUS_NO_ARGS,
SD_BUS_NO_RESULT,
method,
SD_BUS_VTABLE_UNPRIVILEGED),
SD_BUS_SIGNAL(
"Signal1",
"so",
0),
SD_BUS_SIGNAL_WITH_NAMES(
"Signal2",
"so", SD_BUS_PARAM(string) SD_BUS_PARAM(path),
0),
SD_BUS_SIGNAL_WITH_ARGS(
"Signal3",
SD_BUS_ARGS("s", string, "o", path),
0),
SD_BUS_WRITABLE_PROPERTY(
"AutomaticStringProperty", "s", NULL, NULL,
offsetof(object, name),
SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
SD_BUS_WRITABLE_PROPERTY(
"AutomaticIntegerProperty", "u", NULL, NULL,
offsetof(object, number),
SD_BUS_VTABLE_PROPERTY_EMITS_INVALIDATION),
SD_BUS_VTABLE_END
};
int main(int argc, char **argv) {
_cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
int r;
sd_bus_default(&bus);
object object = { .number = 666 };
object.name = strdup("name");
if (!object.name) {
fprintf(stderr, "OOM\n");
return EXIT_FAILURE;
}
r = sd_bus_add_object_vtable(bus, NULL,
"/org/freedesktop/systemd/VtableExample",
"org.freedesktop.systemd.VtableExample",
vtable,
&object);
if (r < 0) {
fprintf(stderr, "sd_bus_add_object_vtable() failed: %s\n", strerror(-r));
return EXIT_FAILURE;
}
r = sd_bus_request_name(bus,
"org.freedesktop.systemd.VtableExample",
0);
if (r < 0) {
fprintf(stderr, "sd_bus_request_name() failed: %s\n", strerror(-r));
return EXIT_FAILURE;
}
for (;;) {
r = sd_bus_wait(bus, UINT64_MAX);
if (r < 0) {
fprintf(stderr, "sd_bus_wait() failed: %s\n", strerror(-r));
return EXIT_FAILURE;
}
r = sd_bus_process(bus, NULL);
if (r < 0) {
fprintf(stderr, "sd_bus_process() failed: %s\n", strerror(-r));
return EXIT_FAILURE;
}
}
r = sd_bus_release_name(bus, "org.freedesktop.systemd.VtableExample");
if (r < 0) {
fprintf(stderr, "sd_bus_release_name() failed: %s\n", strerror(-r));
return EXIT_FAILURE;
}
free(object.name);
return 0;
}
.PP This creates a simple client on the bus (the user bus, when run as normal
user). We may use the D-Bus
org.freedesktop.DBus.Introspectable.Introspect call to acquire the
XML description of the interface:
<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "https://www.freedesktop.org/standards/dbus/1.0/introspect.dtd"> <!-- SPDX-License-Identifier: LGPL-2.1-or-later --> <node>
<interface name="org.freedesktop.DBus.Peer">
<method name="Ping"/>
<method name="GetMachineId">
<arg type="s" name="machine_uuid" direction="out"/>
</method>
</interface>
<interface name="org.freedesktop.DBus.Introspectable">
<method name="Introspect">
<arg name="xml_data" type="s" direction="out"/>
</method>
</interface>
<interface name="org.freedesktop.DBus.Properties">
<method name="Get">
<arg name="interface_name" direction="in" type="s"/>
<arg name="property_name" direction="in" type="s"/>
<arg name="value" direction="out" type="v"/>
</method>
<method name="GetAll">
<arg name="interface_name" direction="in" type="s"/>
<arg name="props" direction="out" type="a{sv}"/>
</method>
<method name="Set">
<arg name="interface_name" direction="in" type="s"/>
<arg name="property_name" direction="in" type="s"/>
<arg name="value" direction="in" type="v"/>
</method>
<signal name="PropertiesChanged">
<arg type="s" name="interface_name"/>
<arg type="a{sv}" name="changed_properties"/>
<arg type="as" name="invalidated_properties"/>
</signal>
</interface>
<interface name="org.freedesktop.systemd.VtableExample">
<method name="Method1">
<arg type="s" direction="in"/>
<arg type="s" direction="out"/>
</method>
<method name="Method2">
<arg type="s" name="string" direction="in"/>
<arg type="o" name="path" direction="in"/>
<arg type="s" name="returnstring" direction="out"/>
<annotation name="org.freedesktop.DBus.Deprecated" value="true"/>
</method>
<property name="AutomaticStringProperty" type="s" access="readwrite">
</property>
<property name="AutomaticIntegerProperty" type="u" access="readwrite">
<annotation name="org.freedesktop.DBus.Property.EmitsChangedSignal" value="invalidates"/>
</property>
</interface> </node>
.SH "RETURN VALUE"
.PP On success, sd_bus_add_object_vtable() and
sd_bus_add_fallback_vtable() return a non-negative integer. On
failure, they return a negative errno-style error code.
.SS "Errors"
.PP Returned errors may indicate the following problems:
.PP -EINVAL
One of the required parameters is NULL or invalid. A reserved D-Bus
interface was passed as the interface parameter.
.RE
.PP -ENOPKG
The bus cannot be resolved.
.RE
.PP -ECHILD
The bus was created in a different process, library or module instance.
.RE
.PP -ENOMEM
Memory allocation failed.
.RE
.PP -EPROTOTYPE
sd_bus_add_object_vtable() and sd_bus_add_fallback_vtable()
have been both called for the same bus object path, which is not
allowed.
.RE
.PP -EEXIST
This vtable has already been registered for this interface and
path.
.RE
.SH "NOTES"
.PP Functions described here are available as a shared library, which can be
compiled against and linked to with the
libsystemd pkg-config(1) file.
.PP All functions listed here are thread-agnostic and only a single thread
may operate on a given object at any given time. Different threads may
access the same object at different times. Multiple independent objects may
be used from different threads in parallel.
.PP The code described here uses getenv(3), which is declared to be
not multi-thread-safe. This means that the code calling the functions
described here must not call setenv(3) from a parallel thread. It is
recommended to only do calls to setenv() from an early phase of the
program when no other threads have been started.
.SH "HISTORY"
.PP sd_bus_property_get_t(), sd_bus_property_set_t(),
sd_bus_object_find_t(), sd_bus_add_object(),
sd_bus_add_fallback(), sd_bus_add_object_vtable(),
sd_bus_add_fallback_vtable(), and sd_bus_add_filter() were
added in version 221.
.SH "SEE ALSO"
.PP sd-bus(3), busctl(1),
sd_bus_emit_properties_changed(3),
sd_bus_emit_object_added(3)
NOTES
- 1.
- D-Bus annotations
- 2.
- polkit
| systemd 262.2 |