bus: make sd_bus_request_name() and sd_bus_release_name() behave more like other calls

Instead of returning an enum of return codes, make them return error
codes like kdbus does internally.

Also, document this behaviour so that clients can stick to it.

(Also rework bus-control.c to always have to functions for dbus1 vs.
kernel implementation of the various calls.)

Makefile-man.am

@@ -20,6 +20,7 @@ MANPAGES += \
 	man/sd-id128.3 \
 	man/sd-journal.3 \
 	man/sd_booted.3 \
+	man/sd_bus_request_name.3 \
 	man/sd_id128_get_machine.3 \
 	man/sd_id128_randomize.3 \
 	man/sd_id128_to_string.3 \
@@ -131,6 +132,7 @@ MANPAGES_ALIAS += \
 	man/init.1 \
 	man/poweroff.8 \
 	man/reboot.8 \
+	man/sd_bus_release_name.3 \
 	man/sd_id128_equal.3 \
 	man/sd_id128_from_string.3 \
 	man/sd_id128_get_boot.3 \
@@ -232,6 +234,7 @@ man/SD_WARNING.3: man/sd-daemon.3
 man/init.1: man/systemd.1
 man/poweroff.8: man/halt.8
 man/reboot.8: man/halt.8
+man/sd_bus_release_name.3: man/sd_bus_request_name.3
 man/sd_id128_equal.3: man/sd-id128.3
 man/sd_id128_from_string.3: man/sd_id128_to_string.3
 man/sd_id128_get_boot.3: man/sd_id128_get_machine.3
@@ -389,6 +392,9 @@ man/poweroff.html: man/halt.html
 man/reboot.html: man/halt.html
 	$(html-alias)
 
+man/sd_bus_release_name.html: man/sd_bus_request_name.html
+	$(html-alias)
+
 man/sd_id128_equal.html: man/sd-id128.html
 	$(html-alias)
 

TODO

@@ -130,6 +130,7 @@ Features:
   - longer term:
     * priority queues
     * priority inheritance
+  - sort out error codes for sd_bus_release_name()
 
 * sd-event
   - allow multiple signal handlers per signal

man/sd_bus_request_name.xml

@@ -0,0 +1,213 @@
+<?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">
+
+<!--
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_bus_request_name">
+
+        <refentryinfo>
+                <title>sd_bus_request_name</title>
+                <productname>systemd</productname>
+
+                <authorgroup>
+                        <author>
+                                <contrib>Developer</contrib>
+                                <firstname>Lennart</firstname>
+                                <surname>Poettering</surname>
+                                <email>lennart@poettering.net</email>
+                        </author>
+                </authorgroup>
+        </refentryinfo>
+
+        <refmeta>
+                <refentrytitle>sd_bus_request_name</refentrytitle>
+                <manvolnum>3</manvolnum>
+        </refmeta>
+
+        <refnamediv>
+                <refname>sd_bus_request_name</refname>
+                <refname>sd_bus_release_name</refname>
+                <refpurpose>Request or release a well-known name on a bus</refpurpose>
+        </refnamediv>
+
+        <refsynopsisdiv>
+                <funcsynopsis>
+                        <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>
+
+                        <funcprototype>
+                                <funcdef>int <function>sd_bus_request_name</function></funcdef>
+                                <paramdef>sd_bus* <parameter>bus</parameter></paramdef>
+                                <paramdef>const char *<parameter>name</parameter></paramdef>
+                                <paramdef>unsigned <parameter>flags</parameter></paramdef>
+                        </funcprototype>
+
+                        <funcprototype>
+                                <funcdef>int <function>sd_bus_release_name</function></funcdef>
+                                <paramdef>sd_bus* <parameter>bus</parameter></paramdef>
+                                <paramdef>const char *<parameter>name</parameter></paramdef>
+                        </funcprototype>
+
+
+                </funcsynopsis>
+        </refsynopsisdiv>
+
+        <refsect1>
+                <title>Description</title>
+
+                <para><function>sd_bus_request_name()</function> requests
+                a well-known name on a bus. It takes a bus connection,
+                a valid bus name and a flags parameter. The flags
+                parameter is a combination of the following
+                flags:</para>
+
+                <variablelist>
+                        <varlistentry>
+                                <term><varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname></term>
+
+                                <listitem><para>After acquiring the
+                                name successuflly, permit other peers
+                                to take over the name when they try to
+                                acquire it with the
+                                <varname>SD_BUS_NAME_REPLACE_EXISTING</varname>
+                                flag set. If
+                                <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
+                                is not set on the original request
+                                such a request by other peers will be
+                                denied.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>SD_BUS_NAME_REPLACE_EXISTING</varname></term>
+
+                                <listitem><para>Take over a the name
+                                if it is already acquired by a another
+                                peer, and that other peer permitted
+                                taking it over by setting
+                                <varname>SD_BUS_NAME_ALLOW_REPLACEMENT</varname>
+                                while acquiring it.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>SD_BUS_NAME_DO_NOT_QUEUE</varname></term>
+
+                                <listitem><para>Do not queue name
+                                acquisition when the name is already
+                                taken.</para></listitem>
+                        </varlistentry>
+                </variablelist>
+
+                <para><function>sd_bus_release_name()</function> releases
+                an acquired well-known name. It takes a bus connection
+                and a valid bus name as parameters.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Return Value</title>
+
+                <para>On success, these calls return 0 or a positive
+                integer. On failure, these calls return a negative
+                errno-style error code.</para>
+
+                <para><function>sd_bus_request_name()</function> will
+                return 0 when the name is already taken by another
+                peer and the client has been added to the queue for
+                the name, unless
+                <varname>SD_BUS_NAME_DO_NOT_QUEUE</varname> has been
+                set. The caller can subscribe to
+                <literal>NameOwnerChanged</literal> signals to be
+                notified when the name is successfully
+                acquired. <function>sd_bus_request_name()</function> returns
+                &gt; 0 when the name has been
+                acquired successfully.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>Errors</title>
+
+                <para>Returned errors may indicate the following problems:</para>
+
+                <variablelist>
+                        <varlistentry>
+                                <term><varname>-EALREADY</varname></term>
+
+                                <listitem><para>The caller already is
+                                the owner of the specified
+                                name.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>-EEXIST</varname></term>
+
+                                <listitem><para>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.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>-EINVAL</varname></term>
+
+                                <listitem><para>A specified parameter
+                                is invalid.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>-ENOTCONN</varname></term>
+
+                                <listitem><para>The bus connection has
+                                been disconnected.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>-ECHILD</varname></term>
+
+                                <listitem><para>The bus connection has
+                                been created in a different process
+                                than the current.</para></listitem>
+                        </varlistentry>
+                </variablelist>
+        </refsect1>
+
+        <refsect1>
+                <title>Notes</title>
+
+                <para>The <function>sd_bus_acquire_name()</function>
+                and <function>sd_bus_release_bame()</function>
+                interfaces are available as shared library, which can
+                be compiled and linked to with the
+                <constant>libsystemd-bus</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                file.</para>
+        </refsect1>
+
+        <refsect1>
+                <title>See Also</title>
+
+                <para>
+                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                </para>
+        </refsect1>
+
+</refentry>

src/core/dbus.c

@@ -819,17 +819,12 @@ static int bus_setup_api(Manager *m, sd_bus *bus) {
          * after the new connection is set up and the name installed
          * to allow clients to synchronously wait for reexecution to
          * finish */
-        r = sd_bus_request_name(bus,"org.freedesktop.systemd1", SD_BUS_NAME_ALLOW_REPLACEMENT|SD_BUS_NAME_REPLACE_EXISTING);
+        r = sd_bus_request_name(bus,"org.freedesktop.systemd1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER) {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         bus_list_names(m, bus);
 
         log_debug("Successfully connected to API bus.");

src/hostname/hostnamed.c

@@ -574,17 +574,12 @@ static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
                 return r;
         }
 
-        r = sd_bus_request_name(bus, "org.freedesktop.hostname1", SD_BUS_NAME_DO_NOT_QUEUE);
+        r = sd_bus_request_name(bus, "org.freedesktop.hostname1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER) {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         r = sd_bus_attach_event(bus, event, 0);
         if (r < 0) {
                 log_error("Failed to attach bus to event loop: %s", strerror(-r));

src/locale/localed.c

@@ -1094,17 +1094,12 @@ static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
                 return r;
         }
 
-        r = sd_bus_request_name(bus, "org.freedesktop.locale1", SD_BUS_NAME_DO_NOT_QUEUE);
+        r = sd_bus_request_name(bus, "org.freedesktop.locale1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER) {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         r = sd_bus_attach_event(bus, event, 0);
         if (r < 0) {
                 log_error("Failed to attach bus to event loop: %s", strerror(-r));

src/login/logind.c

@@ -725,17 +725,12 @@ static int manager_connect_bus(Manager *m) {
                 return r;
         }
 
-        r = sd_bus_request_name(m->bus, "org.freedesktop.login1", SD_BUS_NAME_DO_NOT_QUEUE);
+        r = sd_bus_request_name(m->bus, "org.freedesktop.login1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER)  {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         r = sd_bus_attach_event(m->bus, m->event, 0);
         if (r < 0) {
                 log_error("Failed to attach bus to event loop: %s", strerror(-r));

src/machine/machined.c

@@ -217,17 +217,12 @@ static int manager_connect_bus(Manager *m) {
                 return r;
         }
 
-        r = sd_bus_request_name(m->bus, "org.freedesktop.machine1", SD_BUS_NAME_DO_NOT_QUEUE);
+        r = sd_bus_request_name(m->bus, "org.freedesktop.machine1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER)  {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         r = sd_bus_attach_event(m->bus, m->event, 0);
         if (r < 0) {
                 log_error("Failed to attach bus to event loop: %s", strerror(-r));

src/systemd/sd-bus.h

@@ -233,7 +233,7 @@ int sd_bus_message_rewind(sd_bus_message *m, int complete);
 /* Bus management */
 
 int sd_bus_get_unique_name(sd_bus *bus, const char **unique);
-int sd_bus_request_name(sd_bus *bus, const char *name, int flags);
+int sd_bus_request_name(sd_bus *bus, const char *name, unsigned flags);
 int sd_bus_release_name(sd_bus *bus, const char *name);
 int sd_bus_list_names(sd_bus *bus, char ***l); /* free the results */
 int sd_bus_get_owner(sd_bus *bus, const char *name, uint64_t mask, sd_bus_creds **creds); /* unref the result! */

src/timedate/timedated.c

@@ -786,17 +786,12 @@ static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
                 return r;
         }
 
-        r = sd_bus_request_name(bus, "org.freedesktop.timedate1", SD_BUS_NAME_DO_NOT_QUEUE);
+        r = sd_bus_request_name(bus, "org.freedesktop.timedate1", SD_BUS_NAME_REPLACE_EXISTING|SD_BUS_NAME_DO_NOT_QUEUE);
         if (r < 0) {
                 log_error("Failed to register name: %s", strerror(-r));
                 return r;
         }
 
-        if (r != SD_BUS_NAME_PRIMARY_OWNER) {
-                log_error("Failed to acquire name.");
-                return -EEXIST;
-        }
-
         r = sd_bus_attach_event(bus, event, 0);
         if (r < 0) {
                 log_error("Failed to attach bus to event loop: %s", strerror(-r));