Movatterモバイル変換

sd_bus_slot_set_userdata(3) — Linux manual page

SD_BUS_SL..._USERDATA(3) sd_bus_slot_set_userdataSD_BUS_SL..._USERDATA(3)

NAME        top

       sd_bus_slot_set_userdata, sd_bus_slot_get_userdata - Set and query       the value in the "userdata" field

SYNOPSIS        top

#include <systemd/sd-bus.h>void* sd_bus_slot_set_userdata(sd_bus_slot*slot, void*userdata);void* sd_bus_slot_get_userdata(sd_bus_slot*slot);

DESCRIPTION        top

       The userdata pointer allows data to be passed between the point       where a callback is registered, for example when a filter is added       usingsd_bus_add_filter(3) or an asynchronous function call is       made usingsd_bus_call_async(3), and the point where the callback       is called, without having any global state. The pointer has typevoid*and is not used by the sd-bus functions in any way, except       to pass to the callback function.       Usually, the userdata field is set when the slot object is       initially registered.sd_bus_slot_set_userdata()may be used to       change it later for the bus slot objectslot. Previous value of       the field is returned. The argument and returned value may beNULL. It will be passed as theuserdata argument to the callback       function attached to the slot.sd_bus_slot_set_userdata()gets the value of the userdata field in       the bus slot objectslot.

RETURN VALUE        top

       On success, these functions return the value of the userdata field       before the function call. If theslot object isNULL,NULLwill be       returned to signify an error, but this is not distinguishable from       the userdata field value beingNULL.

NOTES        top

       Functions described here are available as a shared library, which       can be compiled against and linked to with thelibsystemd pkg-config(1) file.       The code described here usesgetenv(3), which is declared to be       not multi-thread-safe. This means that the code calling the       functions described here must not callsetenv(3) from a parallel       thread. It is recommended to only do calls tosetenv()from an       early phase of the program when no other threads have been       started.

HISTORY        top

sd_bus_slot_set_userdata()andsd_bus_slot_get_userdata()were       added in version 240.

SEE ALSO        top

systemd(1),sd-bus(3),sd_bus_slot_set_destroy_callback(3),sd_bus_add_match(3),sd_bus_slot_get_current_userdata(3)

COLOPHON        top

       This page is part of thesystemd (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 2025-08-11.  (At that       time, the date of the most recent commit that was found in the       repository was 2025-08-11.)  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 isnot part of the original manual page), send a mail to       man-pages@man7.orgsystemd 258~rc2SD_BUS_SL..._USERDATA(3)

Pages that refer to this page:sd-bus(3), sd_bus_slot_set_description(3), sd_bus_slot_set_destroy_callback(3), systemd.directives(7), systemd.index(7)

HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH.