sd_bus_message_new_method_call, sd_bus_message_new_method_return − Create a method call message
#include <elogind/sd−bus.h>
|
int sd_bus_message_new_method_call(sd_bus *bus, sd_bus_message **m, const char *destination, const char *path, const char *interface, const char *member); |
||
|
int sd_bus_message_new_method_return(sd_bus_message *call, sd_bus_message **m); |
The sd_bus_message_new_method_call() function creates a new bus message object that encapsulates a D−Bus method call, and returns it in the m output parameter. The call will be made on the destination destination, path path, on the interface interface, member member.
Briefly, the destination is a dot−separated name that identifies a service connected to the bus. The path is a slash−separated identifier of an object within the destination that resembles a file system path. The meaning of this path is defined by the destination. The interface is a dot−separated name that resembles a Java interface name that identifies a group of methods and signals supported by the object identified by path. Methods and signals are collectively called members and are identified by a simple name composed of ASCII letters, numbers, and underscores. See the D−Bus Tutorial [1] for an in−depth explanation.
The destination parameter may be NULL. The interface parameter may be NULL, if the destination has only a single member with the given name and there is no ambiguity if the interface name is omitted.
Note that this is a low level interface. See sd_bus_call_method(3) for a more convenient way of calling D−Bus methods.
The sd_bus_message_new_method_return() function creates a new bus message object that is a reply to the method call call and returns it in the m output parameter. The call parameter must be a method call message. The sender of call is used as the destination.
On success, these functions return a non−negative integer. On failure, they return a negative errno−style error code.
Returned errors may indicate the following problems:
−EINVAL
The output parameter m is NULL.
The destination parameter is non−null and is not a valid D−Bus service name (org.somewhere.Something), the path parameter is not a valid D−Bus path (/an/object/path), the interface parameter is non−null and is not a valid D−Bus interface name (an.interface.name), or the member parameter is not a valid D−Bus member (Name).
The call parameter is not a method call object.
−ENOTCONN
The bus parameter bus is NULL or the bus is not connected.
−ENOMEM
Memory allocation failed.
−EPERM
The call parameter is not sealed.
−EOPNOTSUPP
The call message does not have a cookie.
These APIs are implemented as a shared library, which can be compiled and linked to with the libelogind pkg-config(1) file.
elogind(8), sd-bus(3), sd_bus_call(3), sd_bus_call_method(3), sd_bus_path_encode(3)
|
1. |
D-Bus Tutorial |
https://dbus.freedesktop.org/doc/dbus-tutorial.html#concepts