sd_bus_message_get_signature, sd_bus_message_is_empty, sd_bus_message_has_signature — Query bus message signature
#include <systemd/sd-bus.h>
const char* sd_bus_message_get_signature( | sd_bus_message *message, |
int complete) ; |
int sd_bus_message_is_empty( | sd_bus_message *message) ; |
int sd_bus_message_has_signature( | sd_bus_message *message, |
const char *signature) ; |
sd_bus_message_get_signature()
returns the signature of message
message
. If complete
is true, the signature of the
whole message is returned, and just the signature of the currently open container otherwise.
sd_bus_message_is_empty()
returns true if the message is empty,
i.e. when its signature is empty.
sd_bus_message_has_signature()
returns true if the signature of the
message message
matches given signature
. Parameter
signature
may be NULL
, this is treated the same as
an empty string, which is equivalent to calling sd_bus_message_is_empty()
.
On success, sd_bus_message_get_signature()
returns
the signature, and NULL
on error.
The other functions return 0 or a positive integer on success. On failure, they return a negative errno-style error code.
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_signature()
,
sd_bus_message_is_empty()
, and
sd_bus_message_has_signature()
were added in version 240.