SD_BUS_MESSAGE_GET_SIGNATURE(3)                   sd_bus_message_get_signature

NAME
       sd_bus_message_get_signature, sd_bus_message_is_empty,
       sd_bus_message_has_signature - Query bus message signature

SYNOPSIS
       #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);

DESCRIPTION
       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().

RETURN VALUE
       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.

   Errors
       Returned errors may indicate the following problems:

       -EINVAL
           The message parameter is NULL.

       NULL
           The message parameter is NULL.

NOTES
       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.

HISTORY
       sd_bus_message_get_signature(), sd_bus_message_is_empty(), and
       sd_bus_message_has_signature() were added in version 240.

SEE ALSO
       systemd(1), sd-bus(3), sd_bus_message_new(3)

systemd 255                                    SD_BUS_MESSAGE_GET_SIGNATURE(3)