systemd sd_bus_message_get_type 3 sd_bus_message_get_type sd_bus_message_is_signal sd_bus_message_is_method_call sd_bus_message_is_method_error Query bus message addressing metadata #include <systemd/sd-bus.h> int sd_bus_message_get_type sd_bus_message *message uint8_t *type int sd_bus_message_is_signal sd_bus_message *message const char *interface const char *member int sd_bus_message_is_method_call sd_bus_message *message const char *interface const char *member int sd_bus_message_is_method_error sd_bus_message *message const char *name sd_bus_message_get_type() returns the type of a message in the output parameter type, one of SD_BUS_MESSAGE_METHOD_CALL, SD_BUS_MESSAGE_METHOD_RETURN, SD_BUS_MESSAGE_METHOD_ERROR, SD_BUS_MESSAGE_SIGNAL. This type is either specified as a parameter when the message is created using sd_bus_set_message_new3, or is set automatically when the message is created using sd_bus_set_message_new_signal3, sd_bus_set_message_new_method_call3, sd_bus_set_message_new_method_error3 and similar functions. sd_bus_message_is_signal() checks if message m is a signal message. If interface is non-null, it also checks if the message has the same interface set. If member is non-null, it also checks if the message has the same member set. Also see sd_bus_set_message_new_signal3. It returns true when all checks pass. sd_bus_message_is_method_call() checks if message m is a method call message. If interface is non-null, it also checks if the message has the same interface set. If member is non-null, it also checks if the message has the same member set. Also see sd_bus_set_message_new_method_call3. It returns true when all checks pass. sd_bus_message_is_method_error() checks if message m is an error reply message. If name is non-null, it also checks if the message has the same error identifier set. Also see sd_bus_set_message_new_method_error3. It returns true when all checks pass. On success, those functions return 0 or a positive integer. On failure, it returns a negative errno-style error code. Returned errors may indicate the following problems: -EINVAL The message parameter or the output parameter are NULL. systemd1, sd-bus3, sd_bus_message_new3, sd_bus_message_set_destination3