238 lines
7.1 KiB
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238 lines
7.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SD_BUS_REQUEST_NAME</TITLE>
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</HEAD><BODY>
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<H1>SD_BUS_REQUEST_NAME</H1>
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Section: sd_bus_request_name (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sd_bus_request_name, sd_bus_request_name_async, sd_bus_release_name, sd_bus_release_name_async - Request or release a well-known service name on a bus
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<P>
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<B>
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</B><PRE>
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#include <<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>>
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</PRE>
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<DL COMPACT>
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<DT id="1">
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<B>int sd_bus_request_name(sd_bus *</B><I>bus</I><B>, const char *</B><I>name</I><B>, uint64_t </B><I>flags</I><B>);</B>
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<DT id="2">
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<B>int sd_bus_request_name_async(sd_bus *</B><I>bus</I><B>, sd_bus_slot **</B><I>slot</I><B>, const char *</B><I>name</I><B>, uint64_t </B><I>flags</I><B>, sd_bus_message_handler_t </B><I>callback</I><B>, void *</B><I>userdata</I><B>);</B>
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<DT id="3">
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<B>int sd_bus_release_name(sd_bus *</B><I>bus</I><B>, const char *</B><I>name</I><B>);</B>
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<DT id="4">
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<B>int sd_bus_release_name_async(sd_bus *</B><I>bus</I><B>, sd_bus_slot **</B><I>slot</I><B>, const char *</B><I>name</I><B>, sd_bus_message_handler_t </B><I>callback</I><B>, void *</B><I>userdata</I><B>);</B>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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<B>sd_bus_request_name()</B>
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<DD>requests a well-known service name on a bus. It takes a bus connection, a valid bus name, and a flags parameter. The flags parameter is a combination of zero or more of the following flags:
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<P>
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<B>SD_BUS_NAME_ALLOW_REPLACEMENT</B>
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<DL COMPACT><DT id="5"><DD>
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After acquiring the name successfully, permit other peers to take over the name when they try to acquire it with the
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<B>SD_BUS_NAME_REPLACE_EXISTING</B>
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flag set. If
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<B>SD_BUS_NAME_ALLOW_REPLACEMENT</B>
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is not set on the original request, such a request by other peers will be denied.
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</DL>
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<P>
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<B>SD_BUS_NAME_REPLACE_EXISTING</B>
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<DL COMPACT><DT id="6"><DD>
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Take over the name if it was already acquired by another peer, and that other peer has permitted takeover by setting
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<B>SD_BUS_NAME_ALLOW_REPLACEMENT</B>
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while acquiring it.
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</DL>
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<P>
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<B>SD_BUS_NAME_QUEUE</B>
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<DL COMPACT><DT id="7"><DD>
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Queue the acquisition of the name when the name is already taken.
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</DL>
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<P>
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<B>sd_bus_request_name()</B>
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operates in a synchronous fashion: a message requesting the name is sent to the bus broker, and the call waits until the broker responds.
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<P>
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<B>sd_bus_request_name_async()</B>
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is an asynchronous version of
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<B>sd_bus_release_name()</B>. Instead of waiting for the request to complete, the request message is enqueued. The specified
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<I>callback</I>
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will be called when the broker's response is received. If the parameter is specified as
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<B>NULL</B>
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a default implementation is used instead which will terminate the connection when the name cannot be acquired. The function returns a slot object in its
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<I>slot</I>
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parameter --- if it is passed as non-<B>NULL</B>
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--- which may be used as a reference to the name request operation. Use
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_slot_unref">sd_bus_slot_unref</A></B>(3)
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to destroy this reference. Note that destroying the reference will not unregister the name, but simply ensure the specified callback is no longer called.
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<P>
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<B>sd_bus_release_name()</B>
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releases an acquired well-known name. It takes a bus connection and a valid bus name as parameters. This function operates synchronously, sending a release request message to the bus broker and waiting for it to reply.
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<P>
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<B>sd_bus_release_name_async()</B>
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is an asynchronous version of
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<B>sd_bus_release_name()</B>. The specified
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<I>callback</I>
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function is called when the name has been released successfully. If specified as
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<B>NULL</B>
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a generic implementation is used that ignores the result of the operation. As above, the
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<I>slot</I>
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(if non-<B>NULL</B>) is set to an object that may be used to reference the operation.
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<P>
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These functions are supported only on bus connections, i.e. connections to a bus broker and not on direct connections.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<P>
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On success, these calls return 0 or a positive integer. On failure, these calls return a negative errno-style error code.
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<P>
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If
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<B>SD_BUS_NAME_QUEUE</B>
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is specified,
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<B>sd_bus_request_name()</B>
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will return 0 when the name is already taken by another peer and the client has been added to the queue for the name. In that case, the caller can subscribe to
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"NameOwnerChanged"
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signals to be notified when the name is successfully acquired.
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<B>sd_bus_request_name()</B>
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returns > 0 when the name has immediately been acquired successfully.
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<A NAME="lbAF"> </A>
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<H3>Errors</H3>
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<P>
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Returned errors may indicate the following problems:
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<P>
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<B>-EALREADY</B>
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<DL COMPACT><DT id="8"><DD>
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The caller already is the owner of the specified name.
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</DL>
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<P>
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<B>-EEXIST</B>
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<DL COMPACT><DT id="9"><DD>
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The name has already been acquired by a different peer, and SD_BUS_NAME_REPLACE_EXISTING was not specified or the other peer did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the name.
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</DL>
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<P>
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<B>-ESRCH</B>
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<DL COMPACT><DT id="10"><DD>
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It was attempted to release a name that is currently not registered on the bus.
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</DL>
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<P>
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<B>-EADDRINUSE</B>
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<DL COMPACT><DT id="11"><DD>
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It was attempted to release a name that is owned by a different peer on the bus.
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</DL>
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<P>
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<B>-EINVAL</B>
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<DL COMPACT><DT id="12"><DD>
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A specified parameter is invalid. This is also generated when the requested name is a special service name reserved by the D-Bus specification, or when the operation is requested on a connection that does not refer to a bus.
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</DL>
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<P>
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<B>-ENOTCONN</B>
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<DL COMPACT><DT id="13"><DD>
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The bus connection has been disconnected.
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</DL>
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<P>
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<B>-ECHILD</B>
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<DL COMPACT><DT id="14"><DD>
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The bus connection has been created in a different process than the current one.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>NOTES</H2>
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<P>
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These APIs are implemented as a shared library, which can be compiled and linked to with the
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<B>libsystemd</B> <B><A HREF="/cgi-bin/man/man2html?1+pkg-config">pkg-config</A></B>(1)
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file.
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<A NAME="lbAH"> </A>
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<H2>SEE ALSO</H2>
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<P>
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<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_new">sd_bus_new</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sd_bus_slot_unref">sd_bus_slot_unref</A></B>(3)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="15"><A HREF="#lbAB">NAME</A><DD>
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<DT id="16"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="17"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="18"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DL>
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<DT id="19"><A HREF="#lbAF">Errors</A><DD>
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</DL>
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<DT id="20"><A HREF="#lbAG">NOTES</A><DD>
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<DT id="21"><A HREF="#lbAH">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:55 GMT, March 31, 2021
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</BODY>
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