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