Beyond Linux® From Scratch (systemd edition) - Version 7.6-systemd

Chapter 12. System Utilities

D-Bus

Introduction to D-Bus

Even though D-Bus was built in LFS, there are some features provided by the package that some BLFS packages need, but their dependencies didn't fit into LFS.

Unlike other packages in BLFS, there is no set version of D-Bus in this page's title and no set version specified for download. Version updates to D-Bus make it possible that the user's system may have a D-Bus version different from the one in the current LFS book. Therefore, users should use the version of D-Bus that is currently installed on their system.

This package is known to build and work properly using an LFS-7.6 systemd platform using dbus-1.8.6 source.

Package Information

[Note]

Note

If you are unsure which version needs to be downloaded, issue dbus-daemon --version in order to find out. Some of the commands below might need the version information. Issue the following command to store the D-Bus version number into an environment variable: 

export DBUS_VERSION=$(dbus-daemon --version | head -n1 | awk '{print $5}')

D-Bus Dependencies

Required

Xorg Libraries (for X11 autolaunch support)

Optional

For the tests: dbus-glib-0.102, D-Bus Python-1.2.0, and PyGObject-2.28.6; for the API documentation: Doxygen-1.8.8; for man pages and XML/HTML documentation: xmlto-0.0.26

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/dbus

Installation of D-Bus

Rebuild D-Bus by running the following commands: 

./configure --prefix=/usr                        \
            --sysconfdir=/etc                    \
            --localstatedir=/var                 \
            --with-console-auth-dir=/run/console \
            --docdir=/usr/share/doc/dbus-${DBUS_VERSION} &&
make

See below for test instructions.

[Warning]

Warning

Installing the package will override all files installed by D-Bus in LFS. It is critical that nothing uses D-Bus libraries or programs during the installation phrase. Best way to achieve that is to do the installation in the rescue mode. To switch to the rescue mode, issue the following command as the root user from a TTY: 

systemctl start rescue.target

Now, as the root user: 

make install

The shared library needs to be moved to /lib, and as a result the .so file in /usr/lib will need to be recreated. Run the following command as the root user: 

mv -v /usr/lib/libdbus-1.so.* /lib
ln -sfv ../../lib/$(readlink /usr/lib/libdbus-1.so) /usr/lib/libdbus-1.so

The D-Bus tests cannot be run until after dbus-glib-0.102 has been installed. They must be run as an unprivileged user from a local session. If you want to run only the unit tests, replace --enable-tests in the command below by --enable-embedded-tests, otherwise D-Bus Python-1.2.0 has to be installed before the tests are run. The tests require passing additional parameters to configure and exposing additional functionality in the binaries. These interfaces are not intended to be used in a production build of D-Bus. If you would like to run the tests, issue the following commands: 

make distclean                              &&
./configure --enable-tests --enable-asserts &&
make                                        &&
make check                                  &&
make distclean

If run-test.sh fails, it can be disabled with the following sed, before running the commands for the tests: 

sed -i -e 's:run-test.sh:$(NULL):g' test/name-test/Makefile.in

Note there has been a report that the tests may fail if running inside a Midnight Commander shell. You may get out-of-memory error messages when running the tests. These are normal and can be safely ignored.

Command Explanations

--enable-tests: Build extra parts of the code to support all tests. Configure will end with a NOTE warning about increased size of libraries and decreased security.

--enable-embedded-tests: Build extra parts of the code to support only unit tests. Configure will end with a NOTE warning about increased size of libraries and decreased security.

--enable-asserts: Enable debugging code to run assertions for statements normally assumed to be true. This prevents a warning that '--enable-tests' on its own is only useful for profiling and might not give true results for all tests, but adds its own NOTE that this should not be used in a production build.

Configuring D-Bus

Config Files

/etc/dbus-1/session.conf, /etc/dbus-1/system.conf and /etc/dbus-1/system.d/*

Configuration Information

The configuration files listed above should probably not be modified. If changes are required, you should create /etc/dbus-1/session-local.conf and/or /etc/dbus-1/system-local.conf and make any desired changes to these files.

If any packages install a D-Bus .service file outside of the standard /usr/share/dbus-1/services directory, that directory should be added to the local session configuration. For instance, /usr/local/share/dbus-1/services can be added by performing the following commands as the root user: 

cat > /etc/dbus-1/session-local.conf << "EOF"
<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>

  <!-- Search for .service files in /usr/local -->
  <servicedir>/usr/local/share/dbus-1/services</servicedir>

</busconfig>
EOF

D-Bus Session Daemon

There are many methods you can use to start a session daemon using the dbus-launch command. Review the dbus-launch man page for details about the available parameters and options. Here are some suggestions and examples:

  • Add dbus-launch to the line in the ~/.xinitrc file that starts your graphical desktop environment.

  • If you use xdm or some other display manager that calls the ~/.xsession file, you can add dbus-launch to the line in your ~/.xsession file that starts your graphical desktop environment. The syntax would be similar to the example in the ~/.xinitrc file.

  • The examples shown previously use dbus-launch to specify a program to be run. This has the benefit (when also using the --exit-with-session parameter) of stopping the session daemon when the specified program is stopped. You can also start the session daemon in your system or personal startup scripts by adding the following lines: 

    # Start the D-Bus session daemon
eval `dbus-launch`
export DBUS_SESSION_BUS_ADDRESS

    This method will not stop the session daemon when you exit your shell, therefore you should add the following line to your ~/.bash_logout file: 

    # Kill the D-Bus session daemon
kill $DBUS_SESSION_BUS_PID

  • A hint has been written that provides ways to start scripts using the KDM session manager of KDE. The concepts in this hint could possibly be used with other session managers as well. The hint is located at http://www.linuxfromscratch.org/hints/downloads/files/execute-session-scripts-using-kdm.txt.

Contents

A list of the installed files, along with their short descriptions can be found at ../../../../lfs/view/7.6-systemd/chapter06/dbus.html#contents-dbus.

Last updated on 2014-08-22 13:59:17 -0700