sd_bus_slot_ref(3) — Linux manual page


SD_BUS_SLOT_REF(3)           sd_bus_slot_ref          SD_BUS_SLOT_REF(3)

NAME         top

       sd_bus_slot_ref, sd_bus_slot_unref, sd_bus_slot_unrefp - Create
       and destroy references to a bus slot object

SYNOPSIS         top

       #include <systemd/sd-bus.h>

       sd_bus_slot *sd_bus_slot_ref(sd_bus_slot *slot);

       sd_bus_slot *sd_bus_slot_unref(sd_bus_slot *slot);

       void sd_bus_slot_unrefp(sd_bus_slot **slotp);

DESCRIPTION         top

       sd_bus_slot_ref() increases the internal reference counter of
       slot by one.

       sd_bus_slot_unref() decreases the internal reference counter of
       slot by one. Once the reference count has dropped to zero, slot
       object is destroyed and cannot be used anymore, so further calls
       to sd_bus_slot_ref() or sd_bus_slot_unref() are illegal.

       sd_bus_slot_unrefp() is similar to sd_bus_slot_unref() but takes
       a pointer to a pointer to an sd_bus_slot 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_slot_ref() and sd_bus_slot_unref() execute no operation if
       the passed in bus object address is NULL.  sd_bus_slot_unrefp()
       will first dereference its argument, which must not be NULL, and
       will execute no operation if that is NULL.

RETURN VALUE         top

       sd_bus_slot_ref() always returns the argument.

       sd_bus_slot_unref() always returns NULL.

NOTES         top

       Functions described here are available as a shared library, which
       can be compiled against and linked to with the
       libsystemd pkg-config(1) file.

       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

HISTORY         top

       sd_bus_slot_ref(), sd_bus_slot_unref(), and sd_bus_slot_unrefp()
       were added in version 240.

SEE ALSO         top

       systemd(1), sd-bus(3), sd_bus_new(3), sd_bus_message_new(3),

NOTES         top

        1. Clean-up Variable Attribute

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
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       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

systemd 255                                           SD_BUS_SLOT_REF(3)

Pages that refer to this page: sd_bus_add_match(3)sd_bus_add_node_enumerator(3)sd_bus_add_object(3)sd_bus_add_object_manager(3)sd_bus_call(3)sd_bus_request_name(3)sd_bus_slot_set_description(3)systemd.directives(7)systemd.index(7)