| SD_BUS_MESSAGE_GET_SIGNATURE(3) | sd_bus_message_get_signature | SD_BUS_MESSAGE_GET_SIGNATURE(3) |
.SH "NAME" sd_bus_message_get_signature, sd_bus_message_is_empty,
sd_bus_message_has_signature - Query bus message signature
.SH "SYNOPSIS"
#include <systemd/sd-bus.h>
.HP 984u const char*
sd_bus_message_get_signature(sd_bus_message *message,
int complete);
.HP 672u int
sd_bus_message_is_empty(sd_bus_message *message);
.HP 792u int
sd_bus_message_has_signature(sd_bus_message *message,
const char *signature);
.SH "DESCRIPTION"
.PP 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.
.PP sd_bus_message_is_empty() returns true if the message is empty,
i.e. when its signature is empty.
.PP 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().
.SH "RETURN VALUE"
.PP On success, sd_bus_message_get_signature() returns the signature,
and NULL on error.
.PP The other functions return 0 or a positive integer on success. On
failure, they return a negative errno-style error code.
.SS "Errors"
.PP Returned errors may indicate the following problems:
.PP -EINVAL
The message parameter is NULL.
.RE
.PP NULL
The message parameter is NULL.
.RE
.SH "NOTES"
.PP Functions described here are available as a shared library, which can be
compiled against and linked to with the
libsystemd pkg-config(1) file.
.PP All functions listed here are thread-agnostic and only a single thread
may operate on a given object at any given time. Different threads may
access the same object at different times. Multiple independent objects may
be used from different threads in parallel.
.PP 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.
.SH "HISTORY"
.PP sd_bus_message_get_signature(), sd_bus_message_is_empty(),
and sd_bus_message_has_signature() were added in version 240.
.SH "SEE ALSO"
| systemd 262.2 |