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.