sd_bus_message_get_signature

systemd
sd_bus_message_get_signature 3
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

## 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`.

## See Also

systemd 1, sd-bus 3, sd_bus_message_new 3