адресация сообщений шины запросов / метаданные учетных данных (query bus message addressing/credentials metadata)
Имя (Name)
sd_bus_message_get_type, sd_bus_message_get_error,
sd_bus_message_get_errno, sd_bus_message_get_creds,
sd_bus_message_is_signal, sd_bus_message_is_method_call,
sd_bus_message_is_method_error - Query bus message
addressing/credentials metadata
Синопсис (Synopsis)
#include <systemd/sd-bus.h>
int sd_bus_message_get_type(sd_bus_message *m, uint8_t *type);
sd_bus_error* sd_bus_message_get_error(sd_bus_message *m);
int sd_bus_message_get_errno(sd_bus_message *m);
sd_bus_creds* sd_bus_message_get_creds(sd_bus_message *m);
int sd_bus_message_is_signal(sd_bus_message *m,
const char *interface,
const char *member);
int sd_bus_message_is_method_call(sd_bus_message *m,
const char *interface,
const char *member);
int sd_bus_message_is_method_error(sd_bus_message *m,
const char *name);
Описание (Description)
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_message_new(3), or is set automatically when the message
is created using sd_bus_message_new_signal(3),
sd_bus_message_new_method_call(3),
sd_bus_message_new_method_error(3) and similar functions.
sd_bus_message_get_error() returns the error stored in the
message m, if there is any. Otherwise, it returns NULL.
sd_bus_message_get_errno() returns the error stored in the
message m as a positive errno-style value, if there is any.
Otherwise, it returns zero. Errors are mapped to errno values
according to the default and any additional registered error
mappings. See sd-bus-errors(3) and sd_bus_error_add_map(3).
sd_bus_message_get_creds() returns the message credentials
attached to the message m. If no credentials are attached to the
message, it returns NULL. Ownership of the credentials instance
is not transferred to the caller and hence should not be freed.
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_message_new_signal(3). 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_message_new_method_call(3). 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_message_new_method_error(3). It returns true when all
checks pass.
Возвращаемое значение (Return value)
On success, these functions (except sd_bus_message_get_error()
and sd_bus_message_get_creds()) return a non-negative integer. On
failure, they return a negative errno-style error code.
sd_bus_message_get_errno() always returns a non-negative integer,
even on failure.
Errors
Returned errors may indicate the following problems:
-EINVAL
The message parameter m or an output parameter is NULL.
Примечание (Note)
These APIs are implemented as a shared library, which can be
compiled and linked to with the libsystemd pkg-config(1) file.
Смотри также (See also)
systemd(1), sd-bus(3), sd_bus_message_new(3),
sd_bus_message_set_destination(3), sd-bus-errors(3),
sd_bus_error_add_map(3)
