sd_bus_message_new_method_call, sd_bus_message_new_method_return - Create a method call message
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 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:
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.
These APIs are implemented as a shared library, which can be compiled and linked to with the libelogind pkg-config(1) file.
- D-Bus Tutorial