1SD_BUS_MESSAGE_NEW(3)         sd_bus_message_new         SD_BUS_MESSAGE_NEW(3)
2
3
4

NAME

6       sd_bus_message_new, sd_bus_message_ref, sd_bus_message_unref,
7       sd_bus_message_unrefp, SD_BUS_MESSAGE_METHOD_CALL,
8       SD_BUS_MESSAGE_METHOD_RETURN, SD_BUS_MESSAGE_METHOD_ERROR,
9       SD_BUS_MESSAGE_SIGNAL, sd_bus_message_get_bus - Create a new bus
10       message object and create or destroy references to it
11

SYNOPSIS

13       #include <systemd/sd-bus.h>
14
15       enum {
16             SD_BUS_MESSAGE_METHOD_CALL,
17             SD_BUS_MESSAGE_METHOD_RETURN,
18             SD_BUS_MESSAGE_METHOD_ERROR,
19             SD_BUS_MESSAGE_SIGNAL,
20       };
21
22       int sd_bus_message_new(sd_bus *bus, sd_bus_message **m, uint8_t type);
23
24       sd_bus_message *sd_bus_message_ref(sd_bus_message *m);
25
26       sd_bus_message *sd_bus_message_unref(sd_bus_message *m);
27
28       void sd_bus_message_unrefp(sd_bus_message **mp);
29
30       sd_bus *sd_bus_message_get_bus(sd_bus_message *m);
31

DESCRIPTION

33       sd_bus_message_new() creates a new bus message object attached to the
34       bus bus and returns it in the output parameter m. This object is
35       reference-counted, and will be destroyed when all references are gone.
36       Initially, the caller of this function owns the sole reference to the
37       message object. Note that the message object holds a reference to the
38       bus object, so the bus object will not be destroyed as long as the
39       message exists.
40
41       Note: this is a low-level call. In most cases functions like
42       sd_bus_message_new_method_call(3), sd_bus_message_new_method_error(3),
43       sd_bus_message_new_method_return(3), and sd_bus_message_new_signal(3)
44       that create a message of a certain type and initialize various fields
45       are easier to use.
46
47       The type parameter specifies the type of the message. It must be one of
48       SD_BUS_MESSAGE_METHOD_CALL — a method call,
49       SD_BUS_MESSAGE_METHOD_RETURN — a method call reply,
50       SD_BUS_MESSAGE_METHOD_ERROR — an error reply to a method call,
51       SD_BUS_MESSAGE_SIGNAL — a broadcast message with no reply.
52
53       The flag to allow interactive authorization is initialized based on the
54       current value set in the bus object, see
55       sd_bus_set_allow_interactive_authorization(3). This may be changed
56       using sd_bus_message_set_allow_interactive_authorization(3).
57
58       sd_bus_message_ref() increases the reference counter of m by one.
59
60       sd_bus_message_unref() decreases the reference counter of m by one.
61       Once the reference count has dropped to zero, message object is
62       destroyed and cannot be used anymore, so further calls to
63       sd_bus_message_ref() or sd_bus_message_unref() are illegal.
64
65       sd_bus_message_unrefp() is similar to sd_bus_message_unref() but takes
66       a pointer to a pointer to an sd_bus_message object. This call is useful
67       in conjunction with GCC's and LLVM's Clean-up Variable Attribute[1].
68       See sd_bus_new(3) for an example how to use the cleanup attribute.
69
70       sd_bus_message_ref() and sd_bus_message_unref() execute no operation if
71       the passed in bus message object address is NULL.
72       sd_bus_message_unrefp() will first dereference its argument, which must
73       not be NULL, and will execute no operation if that is NULL.
74
75       sd_bus_message_get_bus() returns the bus object that message m is
76       attached to.
77

RETURN VALUE

79       On success, sd_bus_message_new() returns 0 or a positive integer. On
80       failure, it returns a negative errno-style error code.
81
82       sd_bus_message_ref() always returns the argument.
83
84       sd_bus_message_unref() always returns NULL.
85
86       sd_bus_message_get_bus() always returns the bus object.
87
88   Errors
89       Returned errors may indicate the following problems:
90
91       -EINVAL
92           Specified type is invalid.
93
94       -ENOTCONN
95           The bus parameter bus is NULL or the bus is not connected.
96
97       -ENOMEM
98           Memory allocation failed.
99

NOTES

101       These APIs are implemented as a shared library, which can be compiled
102       and linked to with the libsystemd pkg-config(1) file.
103

SEE ALSO

105       systemd(1), sd-bus(3), sd_bus_new(3),
106       sd_bus_message_new_method_call(3), sd_bus_message_new_method_error(3),
107       sd_bus_message_new_method_return(3), sd_bus_message_new_signal(3)
108

NOTES

110        1. Clean-up Variable Attribute
111           https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
112
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114
115systemd 250                                              SD_BUS_MESSAGE_NEW(3)