|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | NOTES | COLOPHON |
SD_BUS_MESSAGE_NEW(3) sd_bus_message_new SD_BUS_MESSAGE_NEW(3)
sd_bus_message_new, sd_bus_message_ref, sd_bus_message_unref,
sd_bus_message_unrefp, SD_BUS_MESSAGE_METHOD_CALL,
SD_BUS_MESSAGE_METHOD_RETURN, SD_BUS_MESSAGE_METHOD_ERROR,
SD_BUS_MESSAGE_SIGNAL, sd_bus_message_get_bus - Create a new bus
message object and create or destroy references to it
#include <systemd/sd-bus.h>
enum {
SD_BUS_MESSAGE_METHOD_CALL,
SD_BUS_MESSAGE_METHOD_RETURN,
SD_BUS_MESSAGE_METHOD_ERROR,
SD_BUS_MESSAGE_SIGNAL,
};
int sd_bus_message_new(sd_bus *bus, sd_bus_message **m,
uint8_t type);
sd_bus_message *sd_bus_message_ref(sd_bus_message *m);
sd_bus_message *sd_bus_message_unref(sd_bus_message *m);
void sd_bus_message_unrefp(sd_bus_message **mp);
sd_bus *sd_bus_message_get_bus(sd_bus_message *m);
sd_bus_message_new() creates a new bus message object attached to the
bus bus and returns it in the output parameter m. This object is
reference-counted, and will be destroyed when all references are
gone. Initially, the caller of this function owns the sole reference
to the message object. Note that the message object holds a reference
to the bus object, so the bus object will not be destroyed as long as
the message exists.
Note: this is a low-level call. In most cases functions like
sd_bus_message_new_method_call(3),
sd_bus_message_new_method_error(3),
sd_bus_message_new_method_return(3), and sd_bus_message_new_signal(3)
that create a message of a certain type and initialize various fields
are easier to use.
The type parameter specifies the type of the message. It must be one
of SD_BUS_MESSAGE_METHOD_CALL — a method call,
SD_BUS_MESSAGE_METHOD_RETURN — a method call reply,
SD_BUS_MESSAGE_METHOD_ERROR — an error reply to a method call,
SD_BUS_MESSAGE_SIGNAL — a broadcast message with no reply.
The flag to allow interactive authorization is initialized based on
the current value set in the bus object, see
sd_bus_set_allow_interactive_authorization(3). This may be changed
using sd_bus_message_set_allow_interactive_authorization(3).
sd_bus_message_ref() increases the reference counter of m by one.
sd_bus_message_unref() decreases the reference counter of m by one.
Once the reference count has dropped to zero, message object is
destroyed and cannot be used anymore, so further calls to
sd_bus_message_ref() or sd_bus_message_unref() are illegal.
sd_bus_message_unrefp() is similar to sd_bus_message_unref() but
takes a pointer to a pointer to an sd_bus_message object. This call
is useful in conjunction with GCC's and LLVM's Clean-up Variable
Attribute[1]. See sd_bus_new(3) for an example how to use the cleanup
attribute.
sd_bus_message_ref() and sd_bus_message_unref() execute no operation
if the passed in bus object address is NULL. sd_bus_message_unrefp()
will first dereference its argument, which must not be NULL, and will
execute no operation if that is NULL.
sd_bus_message_get_bus() returns the bus object that message m is
attached to.
On success, sd_bus_message_new() returns 0 or a positive integer. On
failure, it returns a negative errno-style error code.
sd_bus_message_ref() always returns the argument.
sd_bus_message_unref() always returns NULL.
sd_bus_message_get_bus() always returns the bus object.
Errors
Returned errors may indicate the following problems:
-EINVAL
Specified type is invalid.
-ENOTCONN
The bus parameter bus is NULL or the bus is not connected.
-ENOMEM
Memory allocation failed.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-bus(3), sd_bus_new(3),
sd_bus_message_new_method_call(3),
sd_bus_message_new_method_error(3),
sd_bus_message_new_method_return(3), sd_bus_message_new_signal(3)
1. Clean-up Variable Attribute
https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
systemd 246 SD_BUS_MESSAGE_NEW(3)
Pages that refer to this page: sd-bus(3) , sd_bus_message_get_creds(3) , sd_bus_message_get_errno(3) , sd_bus_message_get_error(3) , sd_bus_message_get_signature(3) , sd_bus_message_get_type(3) , sd_bus_message_has_signature(3) , sd_bus_message_is_empty(3) , sd_bus_message_is_method_call(3) , sd_bus_message_is_method_error(3) , sd_bus_message_is_signal(3) , sd_bus_slot_ref(3) , sd_bus_slot_unref(3) , sd_bus_slot_unrefp(3) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7)