|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | SEE ALSO | COLOPHON |
SD_BUS_CALL(3) sd_bus_call SD_BUS_CALL(3)
sd_bus_call, sd_bus_call_async - Invoke a D-Bus method call
#include <systemd/sd-bus.h>
typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,
void *userdata,
sd_bus_error *ret_error);
int sd_bus_call(sd_bus *bus, sd_bus_message *m, uint64_t usec,
sd_bus_error *ret_error, sd_bus_message **reply);
int sd_bus_call_async(sd_bus *bus, sd_bus_slot **slot,
sd_bus_message *m,
sd_bus_message_handler_t callback,
void *userdata, uint64_t usec);
sd_bus_call() takes a complete bus message object and calls the
corresponding D-Bus method. On success, the response is stored in
reply. usec indicates the timeout in microseconds. If ret_error is
not NULL and sd_bus_call() fails (either because of an internal error
or because it received a D-Bus error reply), ret_error is initialized
to an instance of sd_bus_error describing the error.
sd_bus_call_async() is like sd_bus_call() but works asynchronously.
The callback indicates the function to call when the response
arrives. The userdata pointer will be passed to the callback
function, and may be chosen freely by the caller. If slot is not NULL
and sd_bus_call_async() succeeds, slot is set to a slot object which
can be used to cancel the method call at a later time using
sd_bus_slot_unref(3). If slot is NULL, the lifetime of the method
call is bound to the lifetime of the bus object itself, and it cannot
be cancelled independently. See sd_bus_slot_set_floating(3) for
details. callback is called when a reply arrives with the reply,
userdata and an sd_bus_error output parameter as its arguments.
Unlike sd_bus_call(), the sd_bus_error output parameter passed to the
callback will be empty. To determine whether the method call
succeeded, use sd_bus_message_is_method_error(3) on the reply message
passed to the callback instead. If the callback returns zero and the
sd_bus_error output parameter is still empty when the callback
finishes, other handlers registered with functions such as
sd_bus_add_filter(3) or sd_bus_add_match(3) are given a chance to
process the message. If the callback returns a non-zero value or the
sd_bus_error output parameter is not empty when the callback
finishes, no further processing of the message is done. Generally,
you want to return zero from the callback to give other registered
handlers a chance to process the reply as well. (Note that the
sd_bus_error parameter is an output parameter of the callback
function, not an input parameter; it can be used to propagate errors
from the callback handler, it will not receive any error that was
received as method reply.)
If usec is zero, the default D-Bus method call timeout is used. See
sd_bus_get_method_call_timeout(3).
On success, these functions return a non-negative integer. On
failure, they return a negative errno-style error code.
Errors
Returned errors may indicate the following problems:
-EINVAL
The input parameter m is NULL. The input parameter m is not a
D-Bus method call. To create a new D-Bus method call, use
sd_bus_message_new_method_call(3). The input parameter m has the
BUS_MESSAGE_NO_REPLY_EXPECTED flag set. The input parameter
error is non-NULL but was not set to SD_BUS_ERROR_NULL.
-ECHILD
The bus connection was allocated in a parent process and is being
reused in a child process after fork().
-ENOTCONN
The input parameter bus is NULL or the bus is not connected.
-ECONNRESET
The bus connection was closed while waiting for the response.
-ETIMEDOUT
A response was not received within the given timeout.
-ELOOP
The message m is addressed to its own client.
-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_call_method(3),
sd_bus_call_method_async(3), sd_bus_message_new_method_call(3),
sd_bus_message_append(3)
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_CALL(3)
Pages that refer to this page: sd-bus(3) , sd_bus_call_method(3) , sd_bus_call_method_async(3) , sd_bus_call_method_asyncv(3) , sd_bus_call_methodv(3) , sd_bus_get_method_call_timeout(3) , sd_bus_get_watch_bind(3) , sd_bus_message_new_method_call(3) , sd_bus_message_new_method_return(3) , sd_bus_message_seal(3) , sd_bus_set_method_call_timeout(3) , sd_bus_set_watch_bind(3) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7)