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Diffstat (limited to 'Documentation/kdbus/kdbus.name.xml')
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diff --git a/Documentation/kdbus/kdbus.name.xml b/Documentation/kdbus/kdbus.name.xml new file mode 100644 index 000000000..3f5f6a6c5 --- /dev/null +++ b/Documentation/kdbus/kdbus.name.xml @@ -0,0 +1,711 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<refentry id="kdbus.name"> + + <refentryinfo> + <title>kdbus.name</title> + <productname>kdbus.name</productname> + </refentryinfo> + + <refmeta> + <refentrytitle>kdbus.name</refentrytitle> + <manvolnum>7</manvolnum> + </refmeta> + + <refnamediv> + <refname>kdbus.name</refname> + <refpurpose>kdbus.name</refpurpose> + </refnamediv> + + <refsect1> + <title>Description</title> + <para> + Each + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + instantiates a name registry to resolve well-known names into unique + connection IDs for message delivery. The registry will be queried when a + message is sent with <varname>kdbus_msg.dst_id</varname> set to + <constant>KDBUS_DST_ID_NAME</constant>, or when a registry dump is + requested with <constant>KDBUS_CMD_NAME_LIST</constant>. + </para> + + <para> + All of the below is subject to policy rules for <emphasis>SEE</emphasis> + and <emphasis>OWN</emphasis> permissions. See + <citerefentry> + <refentrytitle>kdbus.policy</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information. + </para> + </refsect1> + + <refsect1> + <title>Name validity</title> + <para> + A name has to comply with the following rules in order to be considered + valid. + </para> + + <itemizedlist> + <listitem> + <para> + The name has two or more elements separated by a + '<literal>.</literal>' (period) character. + </para> + </listitem> + <listitem> + <para> + All elements must contain at least one character. + </para> + </listitem> + <listitem> + <para> + Each element must only contain the ASCII characters + <literal>[A-Z][a-z][0-9]_</literal> and must not begin with a + digit. + </para> + </listitem> + <listitem> + <para> + The name must contain at least one '<literal>.</literal>' (period) + character (and thus at least two elements). + </para> + </listitem> + <listitem> + <para> + The name must not begin with a '<literal>.</literal>' (period) + character. + </para> + </listitem> + <listitem> + <para> + The name must not exceed <constant>255</constant> characters in + length. + </para> + </listitem> + </itemizedlist> + </refsect1> + + <refsect1> + <title>Acquiring a name</title> + <para> + To acquire a name, a client uses the + <constant>KDBUS_CMD_NAME_ACQUIRE</constant> ioctl with + <type>struct kdbus_cmd</type> as argument. + </para> + + <programlisting> +struct kdbus_cmd { + __u64 size; + __u64 flags; + __u64 return_flags; + struct kdbus_item items[0]; +}; + </programlisting> + + <para>The fields in this struct are described below.</para> + + <variablelist> + <varlistentry> + <term><varname>size</varname></term> + <listitem><para> + The overall size of the struct, including its items. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>flags</varname></term> + <listitem><para>Flags to control details in the name acquisition.</para> + <variablelist> + <varlistentry> + <term><constant>KDBUS_NAME_REPLACE_EXISTING</constant></term> + <listitem> + <para> + Acquiring a name that is already present usually fails, + unless this flag is set in the call, and + <constant>KDBUS_NAME_ALLOW_REPLACEMENT</constant> (see below) + was set when the current owner of the name acquired it, or + if the current owner is an activator connection (see + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry>). + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_NAME_ALLOW_REPLACEMENT</constant></term> + <listitem> + <para> + Allow other connections to take over this name. When this + happens, the former owner of the connection will be notified + of the name loss. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_NAME_QUEUE</constant></term> + <listitem> + <para> + A name that is already acquired by a connection can not be + acquired again (unless the + <constant>KDBUS_NAME_ALLOW_REPLACEMENT</constant> flag was + set during acquisition; see above). + However, a connection can put itself in a queue of + connections waiting for the name to be released. Once that + happens, the first connection in that queue becomes the new + owner and is notified accordingly. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_FLAG_NEGOTIATE</constant></term> + <listitem> + <para> + Request a set of valid flags for this ioctl. When this bit is + set, no action is taken; the ioctl will fail with + <errorcode>-1</errorcode>, and <varname>errno</varname> + is set to <constant>EPROTO</constant>. + Once the ioctl returned, the <varname>flags</varname> + field will have all bits set that the kernel recognizes as + valid for this command. + The <constant>KDBUS_FLAG_NEGOTIATE</constant> bit will be + cleared by the operation. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>return_flags</varname></term> + <listitem> + <para> + Flags returned by the kernel. Currently, the following may be + returned by the kernel. + </para> + <variablelist> + <varlistentry> + <term><constant>KDBUS_NAME_IN_QUEUE</constant></term> + <listitem> + <para> + The name was not acquired yet, but the connection was + placed in the queue of peers waiting for the name. + This can only happen if <constant>KDBUS_NAME_QUEUE</constant> + was set in the <varname>flags</varname> member (see above). + The connection will receive a name owner change notification + once the current owner has given up the name and its + ownership was transferred. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>items</varname></term> + <listitem> + <para> + Items to submit the name. Currently, one item of type + <constant>KDBUS_ITEM_NAME</constant> is expected and allowed, and + the contained string must be a valid bus name. + <constant>KDBUS_ITEM_NEGOTIATE</constant> may be used to probe for + valid item types. See + <citerefentry> + <refentrytitle>kdbus.item</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for a detailed description of how this item is used. + </para> + <para> + Unrecognized items are rejected, and the ioctl will fail with + <varname>errno</varname> set to <errorname>>EINVAL</errorname>. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Releasing a name</title> + <para> + A connection may release a name explicitly with the + <constant>KDBUS_CMD_NAME_RELEASE</constant> ioctl. If the connection was + an implementer of an activatable name, its pending messages are moved + back to the activator. If there are any connections queued up as waiters + for the name, the first one in the queue (the oldest entry) will become + the new owner. The same happens implicitly for all names once a + connection terminates. See + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information on connections. + </para> + <para> + The <constant>KDBUS_CMD_NAME_RELEASE</constant> ioctl uses the same data + structure as the acquisition call + (<constant>KDBUS_CMD_NAME_ACQUIRE</constant>), + but with slightly different field usage. + </para> + + <programlisting> +struct kdbus_cmd { + __u64 size; + __u64 flags; + __u64 return_flags; + struct kdbus_item items[0]; +}; + </programlisting> + + <para>The fields in this struct are described below.</para> + + <variablelist> + <varlistentry> + <term><varname>size</varname></term> + <listitem><para> + The overall size of the struct, including its items. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>flags</varname></term> + <listitem><para> + Flags to the command. Currently unused. + <constant>KDBUS_FLAG_NEGOTIATE</constant> is accepted to probe for + valid flags. If set, the ioctl will return <errorcode>0</errorcode>, + and the <varname>flags</varname> field is set to + <constant>0</constant>. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>return_flags</varname></term> + <listitem><para> + Flags returned by the kernel. Currently unused and always set to + <constant>0</constant> by the kernel. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>items</varname></term> + <listitem> + <para> + Items to submit the name. Currently, one item of type + <constant>KDBUS_ITEM_NAME</constant> is expected and allowed, and + the contained string must be a valid bus name. + <constant>KDBUS_ITEM_NEGOTIATE</constant> may be used to probe for + valid item types. See + <citerefentry> + <refentrytitle>kdbus.item</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for a detailed description of how this item is used. + </para> + <para> + Unrecognized items are rejected, and the ioctl will fail with + <varname>errno</varname> set to <constant>EINVAL</constant>. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Dumping the name registry</title> + <para> + A connection may request a complete or filtered dump of currently active + bus names with the <constant>KDBUS_CMD_LIST</constant> ioctl, which + takes a <type>struct kdbus_cmd_list</type> as argument. + </para> + + <programlisting> +struct kdbus_cmd_list { + __u64 flags; + __u64 return_flags; + __u64 offset; +}; + </programlisting> + + <para>The fields in this struct are described below.</para> + + <variablelist> + <varlistentry> + <term><varname>flags</varname></term> + <listitem> + <para> + Any combination of flags to specify which names should be dumped. + </para> + <variablelist> + <varlistentry> + <term><constant>KDBUS_LIST_UNIQUE</constant></term> + <listitem> + <para> + List the unique (numeric) IDs of the connection, whether it + owns a name or not. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_LIST_NAMES</constant></term> + <listitem> + <para> + List well-known names stored in the database which are + actively owned by a real connection (not an activator). + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_LIST_ACTIVATORS</constant></term> + <listitem> + <para> + List names that are owned by an activator. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_LIST_QUEUED</constant></term> + <listitem> + <para> + List connections that are not yet owning a name but are + waiting for it to become available. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_FLAG_NEGOTIATE</constant></term> + <listitem> + <para> + Request a set of valid flags for this ioctl. When this bit is + set, no action is taken; the ioctl will fail with + <errorcode>-1</errorcode>, and <varname>errno</varname> + is set to <constant>EPROTO</constant>. + Once the ioctl returned, the <varname>flags</varname> + field will have all bits set that the kernel recognizes as + valid for this command. + The <constant>KDBUS_FLAG_NEGOTIATE</constant> bit will be + cleared by the operation. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + + <varlistentry> + <term><varname>return_flags</varname></term> + <listitem><para> + Flags returned by the kernel. Currently unused and always set to + <constant>0</constant> by the kernel. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>offset</varname></term> + <listitem><para> + When the ioctl returns successfully, the offset to the name registry + dump inside the connection's pool will be stored in this field. + </para></listitem> + </varlistentry> + </variablelist> + + <para> + The returned list of names is stored in a <type>struct kdbus_list</type> + that in turn contains an array of type <type>struct kdbus_info</type>, + The array-size in bytes is given as <varname>list_size</varname>. + The fields inside <type>struct kdbus_info</type> is described next. + </para> + + <programlisting> +struct kdbus_info { + __u64 size; + __u64 id; + __u64 flags; + struct kdbus_item items[0]; +}; + </programlisting> + + <para>The fields in this struct are described below.</para> + + <variablelist> + <varlistentry> + <term><varname>size</varname></term> + <listitem><para> + The overall size of the struct, including its items. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>id</varname></term> + <listitem><para> + The owning connection's unique ID. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>flags</varname></term> + <listitem><para> + The flags of the owning connection. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>items</varname></term> + <listitem> + <para> + Items containing the actual name. Currently, one item of type + <constant>KDBUS_ITEM_OWNED_NAME</constant> will be attached, + including the name's flags. In that item, the flags field of the + name may carry the following bits: + </para> + <variablelist> + <varlistentry> + <term><constant>KDBUS_NAME_ALLOW_REPLACEMENT</constant></term> + <listitem> + <para> + Other connections are allowed to take over this name from the + connection that owns it. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_NAME_IN_QUEUE</constant></term> + <listitem> + <para> + When retrieving a list of currently acquired names in the + registry, this flag indicates whether the connection + actually owns the name or is currently waiting for it to + become available. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_NAME_ACTIVATOR</constant></term> + <listitem> + <para> + An activator connection owns a name as a placeholder for an + implementer, which is started on demand by programs as soon + as the first message arrives. There's some more information + on this topic in + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + . + </para> + <para> + In contrast to + <constant>KDBUS_NAME_REPLACE_EXISTING</constant>, + when a name is taken over from an activator connection, all + the messages that have been queued in the activator + connection will be moved over to the new owner. The activator + connection will still be tracked for the name and will take + control again if the implementer connection terminates. + </para> + <para> + This flag can not be used when acquiring a name, but is + implicitly set through <constant>KDBUS_CMD_HELLO</constant> + with <constant>KDBUS_HELLO_ACTIVATOR</constant> set in + <varname>kdbus_cmd_hello.conn_flags</varname>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><constant>KDBUS_FLAG_NEGOTIATE</constant></term> + <listitem> + <para> + Requests a set of valid flags for this ioctl. When this bit is + set, no action is taken; the ioctl will return + <errorcode>0</errorcode>, and the <varname>flags</varname> + field will have all bits set that are valid for this command. + The <constant>KDBUS_FLAG_NEGOTIATE</constant> bit will be + cleared by the operation. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + </variablelist> + + <para> + The returned buffer must be freed with the + <constant>KDBUS_CMD_FREE</constant> ioctl when the user is finished with + it. See + <citerefentry> + <refentrytitle>kdbus.pool</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + for more information. + </para> + </refsect1> + + <refsect1> + <title>Return value</title> + <para> + On success, all mentioned ioctl commands return <errorcode>0</errorcode>; + on error, <errorcode>-1</errorcode> is returned, and + <varname>errno</varname> is set to indicate the error. + If the issued ioctl is illegal for the file descriptor used, + <varname>errno</varname> will be set to <constant>ENOTTY</constant>. + </para> + + <refsect2> + <title> + <constant>KDBUS_CMD_NAME_ACQUIRE</constant> may fail with the following + errors + </title> + + <variablelist> + <varlistentry> + <term><constant>EINVAL</constant></term> + <listitem><para> + Illegal command flags, illegal name provided, or an activator + tried to acquire a second name. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>EPERM</constant></term> + <listitem><para> + Policy prohibited name ownership. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>EALREADY</constant></term> + <listitem><para> + Connection already owns that name. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>EEXIST</constant></term> + <listitem><para> + The name already exists and can not be taken over. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>E2BIG</constant></term> + <listitem><para> + The maximum number of well-known names per connection is exhausted. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title> + <constant>KDBUS_CMD_NAME_RELEASE</constant> + may fail with the following errors + </title> + + <variablelist> + <varlistentry> + <term><constant>EINVAL</constant></term> + <listitem><para> + Invalid command flags, or invalid name provided. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>ESRCH</constant></term> + <listitem><para> + Name is not found in the registry. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>EADDRINUSE</constant></term> + <listitem><para> + Name is owned by a different connection and can't be released. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + + <refsect2> + <title> + <constant>KDBUS_CMD_LIST</constant> may fail with the following + errors + </title> + + <variablelist> + <varlistentry> + <term><constant>EINVAL</constant></term> + <listitem><para> + Invalid command flags + </para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>ENOBUFS</constant></term> + <listitem><para> + No available memory in the connection's pool. + </para></listitem> + </varlistentry> + </variablelist> + </refsect2> + </refsect1> + + <refsect1> + <title>See Also</title> + <simplelist type="inline"> + <member> + <citerefentry> + <refentrytitle>kdbus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.bus</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.connection</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.item</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.policy</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + <member> + <citerefentry> + <refentrytitle>kdbus.pool</refentrytitle> + <manvolnum>7</manvolnum> + </citerefentry> + </member> + </simplelist> + </refsect1> +</refentry> |