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.
Functions described here are available as a shared
library, which can be compiled against and linked to with the
libsystemd
pkg-config(1)
file.
The code described here uses
getenv(3),
which is declared to be not multi-thread-safe. This means that the code calling the functions described
here must not call
setenv(3)
from a parallel thread. It is recommended to only do calls to setenv()
from an early phase of the program when no other threads have been started.
sd_bus_message_get_type()
,
sd_bus_message_is_signal()
,
sd_bus_message_is_method_call()
, and
sd_bus_message_is_method_error()
were added in version 240.
sd_bus_message_get_error()
,
sd_bus_message_get_errno()
, and
sd_bus_message_get_creds()
were added in version 246.