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   sd_bus_close_unref    ( 3 )

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Имя (Name)

sd_bus_new, sd_bus_ref, sd_bus_unref, sd_bus_unrefp,
       sd_bus_close_unref, sd_bus_close_unrefp,
       sd_bus_flush_close_unref, sd_bus_flush_close_unrefp - Create a
       new bus object and create or destroy references to it

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Синопсис (Synopsis)

#include <systemd/sd-bus.h>

       int sd_bus_new(sd_bus **bus);

       sd_bus *sd_bus_ref(sd_bus *bus);

       sd_bus *sd_bus_unref(sd_bus *bus);

       sd_bus *sd_bus_close_unref(sd_bus *bus);

       sd_bus *sd_bus_flush_close_unref(sd_bus *bus);

       void sd_bus_unrefp(sd_bus **busp);

       void sd_bus_close_unrefp(sd_bus **busp);

       void sd_bus_flush_close_unrefp(sd_bus **busp);

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Описание (Description)

sd_bus_new() creates a new bus object. This object is
       reference-counted, and will be destroyed when all references are
       gone. Initially, the caller of this function owns the sole
       reference and the bus object will not be connected to any bus. To
       connect it to a bus, make sure to set an address with
       sd_bus_set_address(3) or a related call, and then start the
       connection with sd_bus_start(3).

       In most cases, it is better to use sd_bus_default_user(3),
       sd_bus_default_system(3) or related calls instead of the more
       low-level sd_bus_new() and sd_bus_start(). The higher-level
       functions not only allocate a bus object but also start the
       connection to a well-known bus in a single function call.

       sd_bus_ref() increases the reference counter of bus by one.

       sd_bus_unref() decreases the reference counter of bus by one.
       Once the reference count has dropped to zero, bus is destroyed
       and cannot be used anymore, so further calls to sd_bus_ref() or
       sd_bus_unref() are illegal.

       sd_bus_unrefp() is similar to sd_bus_unref() but takes a pointer
       to a pointer to an sd_bus object. This call is useful in
       conjunction with GCC's and LLVM's Clean-up Variable Attribute[1].
       Note that this function is defined as inline function. Use a
       declaration like the following, in order to allocate a bus object
       that is freed automatically as the code block is left:

           {
             __attribute__((cleanup(sd_bus_unrefp))) sd_bus *bus = NULL;
             int r;
             ...
             r = sd_bus_default(&bus);
             if (r < 0)
               fprintf(stderr, "Failed to allocate bus: %s\n", strerror(-r));
             ...
           }

       sd_bus_ref() and sd_bus_unref() execute no operation if the
       passed in bus object address is NULL.  sd_bus_unrefp() will first
       dereference its argument, which must not be NULL, and will
       execute no operation if that is NULL.

       sd_bus_close_unref() is similar to sd_bus_unref(), but first
       executes sd_bus_close(3), ensuring that the connection is
       terminated before the reference to the connection is dropped and
       possibly the object freed.

       sd_bus_flush_close_unref() is similar to sd_bus_unref(), but
       first executes sd_bus_flush(3) as well as sd_bus_close(3),
       ensuring that any pending messages are synchronously flushed out
       before the reference to the connection is dropped and possibly
       the object freed. This call is particularly useful immediately
       before exiting from a program as it ensures that any pending
       outgoing messages are written out, and unprocessed but queued
       incoming messages released before the connection is terminated
       and released.

       sd_bus_close_unrefp() is similar to sd_bus_close_unref(), but may
       be used in GCC's and LLVM's Clean-up Variable Attribute, see
       above. Similarly, sd_bus_flush_close_unrefp() is similar to
       sd_bus_flush_close_unref().

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Возвращаемое значение (Return value)

On success, sd_bus_new() returns 0 or a positive integer. On
       failure, it returns a negative errno-style error code.

       sd_bus_ref() always returns the argument.

       sd_bus_unref() and sd_bus_flush_close_unref() always return NULL.

   Errors
       Returned errors may indicate the following problems:

       -ENOMEM
           Memory allocation failed.

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Примечание (Note)

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

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Смотри также (See also)

systemd(1), sd-bus(3), sd_bus_default_user(3),
       sd_bus_default_system(3), sd_bus_open_user(3),
       sd_bus_open_system(3), sd_bus_close(3)

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Примечание (Note)

1. Clean-up Variable Attribute
           https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html

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