1SD_BUS_SLOT_SET_FLOATING(3)sd_bus_slot_set_floatingSD_BUS_SLOT_SET_FLOATING(3)
2
3
4

NAME

6       sd_bus_slot_set_floating, sd_bus_slot_get_floating - Control whether a
7       bus slot object is "floating".
8

SYNOPSIS

10       #include <systemd/sd-bus.h>
11
12       int sd_bus_slot_set_floating(sd_bus_slot *slot, int b);
13
14       int sd_bus_slot_get_floating(sd_bus_slot *slot);
15

DESCRIPTION

17       sd_bus_slot_set_floating() controls whether the specified bus slot
18       object slot shall be "floating" or not. A floating bus slot object's
19       lifetime is bound to the lifetime of the bus object it is associated
20       with, meaning that it remains allocated as long as the bus object
21       itself and is freed automatically when the bus object is freed. Regular
22       (i.e. non-floating) bus slot objects keep the bus referenced, hence the
23       bus object remains allocated at least as long as there remains at least
24       one referenced bus slot object around. The floating state hence
25       controls the direction of referencing between the bus object and the
26       bus slot objects: if floating the bus pins the bus slot, and otherwise
27       the bus slot pins the bus objects. Use sd_bus_slot_set_floating() to
28       switch between both modes: if the b parameter is zero, the slot object
29       is considered floating, otherwise it is made a regular (non-floating)
30       slot object.
31
32       Bus slot objects may be allocated with calls such as
33       sd_bus_add_match(3). If the slot of these functions is non-NULL the
34       slot object will be of the regular kind (i.e. non-floating), otherwise
35       it will be created floating. With sd_bus_slot_set_floating() a bus slot
36       object allocated as regular can be converted into a floating object and
37       back. This is particularly useful for creating a bus slot object, then
38       changing parameters of it, and then turning it into a floating object,
39       whose lifecycle is managed by the bus object.
40
41       sd_bus_slot_get_floating() returns the current floating state of the
42       specified bus slot object. It returns negative on error, zero if the
43       bus slot object is a regular (non-floating) object and positive
44       otherwise.
45

RETURN VALUE

47       On success, these functions return 0 or a positive integer. On failure,
48       they return a negative errno-style error code.
49
50   Errors
51       Returned errors may indicate the following problems:
52
53       -EINVAL
54           The slot parameter is NULL.
55
56       -ECHILD
57           The bus connection has been created in a different process.
58
59       -ESTALE
60           The bus object the specified bus slot object is associated with has
61           already been freed, and hence no change in the floating state can
62           be made anymore.
63

NOTES

65       These APIs are implemented as a shared library, which can be compiled
66       and linked to with the libsystemd pkg-config(1) file.
67

SEE ALSO

69       systemd(1), sd-bus(3), sd_bus_slot_set_destroy_callback(3),
70       sd_bus_add_match(3)
71
72
73
74systemd 243                                        SD_BUS_SLOT_SET_FLOATING(3)
Impressum