sd_bus_message_set_expect_reply - Man Page

Set and query bus message metadata


#include <systemd/sd-bus.h>

int sd_bus_message_set_expect_reply(sd_bus_message *message, int b);

int sd_bus_message_get_expect_reply(sd_bus_message *message);

int sd_bus_message_set_auto_start(sd_bus_message *message, int b);

int sd_bus_message_get_auto_start(sd_bus_message *message);

int sd_bus_message_set_allow_interactive_authorization(sd_bus_message *message, int b);

int sd_bus_message_get_allow_interactive_authorization(sd_bus_message *message);


sd_bus_message_set_expect_reply() sets or clears the NO_REPLY_EXPECTED flag on the message m. This flag matters only for method call messages and is used to specify that no method return or error reply is expected. It is ignored for other types. Thus, for a method call message, calling

sd_bus_message_set_expect_reply(..., 0)

sets the flag and suppresses the reply.

sd_bus_message_get_expect_reply() checks if the NO_REPLY_EXPECTED flag is set on the message m. It will return positive if it is not set, and zero if it is.

sd_bus_message_set_auto_start() sets or clears the NO_AUTO_START flag on the message m. When the flag is set, the bus must not launch an owner for the destination name in response to this message. Calling

sd_bus_message_set_auto_start(..., 0)

sets the flag.

sd_bus_message_get_auto_start() checks if the NO_AUTO_START flag is set on the message m. It will return positive if it is not set, and zero if it is.

sd_bus_message_set_allow_interactive_authorization() sets or clears the ALLOW_INTERACTIVE_AUTHORIZATION flag on the message m. Setting this flag informs the receiver that the caller is prepared to wait for interactive authorization via polkit or a similar framework. Note that setting this flag does not guarantee that the receiver will actually perform interactive authorization. Also, make sure to set a suitable message timeout when using this flag since interactive authorization could potentially take a long time as it depends on user input. If b is non-zero, the flag is set.

sd_bus_message_get_allow_interactive_authorization() checks if the ALLOW_INTERACTIVE_AUTHORIZATION flag is set on the message m. It will return a positive integer if the flag is set. Otherwise, it returns zero.

Return Value

On success, these functions return a non-negative integer. On failure, they return a negative errno-style error code.


Returned errors may indicate the following problems:


The message parameter is NULL.


The message message is sealed when trying to set a flag.

The message message has wrong type.


These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.

See Also

systemd(1), sd-bus(3), sd_bus_set_description(3)

Referenced By

sd-bus(3), sd-bus-errors(3), sd_bus_message_new(3), systemd.directives(7), systemd.index(7).

The man pages sd_bus_message_get_allow_interactive_authorization(3), sd_bus_message_get_auto_start(3), sd_bus_message_get_expect_reply(3), sd_bus_message_set_allow_interactive_authorization(3) and sd_bus_message_set_auto_start(3) are aliases of sd_bus_message_set_expect_reply(3).

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