Gaming Linux® From Scratch (System V Edition) - Version #b31d

Chapter 3. Shared Dependencies

dbus-1.16.0

Introduction to D-Bus

D-Bus was already compiled before, but not a useful program, dbus-launch. This pass will cover it, and some setup required.

D-Bus Dependencies

Recommended

Xorg Libraries (for dbus-launch program)

Installation of D-Bus

Install D-Bus by running the following commands (you may wish to review the meson_options.txt file first and add any desired parameters to the meson command shown below): 

rm -rf build &&
mkdir  build &&
cd     build &&

meson setup --prefix=/usr          \
            --buildtype=release    \
            --wrap-mode=nofallback \
            -D systemd=disabled    \
            .. &&

ninja

Now, as the root user: 

ninja install

If you are using a DESTDIR install, dbus-daemon-launch-helper needs to be fixed afterwards. Issue, as root user: 

chown -v root:messagebus /usr/libexec/dbus-daemon-launch-helper &&
chmod -v      4750       /usr/libexec/dbus-daemon-launch-helper

Command Explanations

--wrap-mode=nofallback: This switch prevents meson from using subproject fallbacks for any dependency declarations in the build files, stopping it downloading any optional dependency which is not installed on the system.

-D systemd=disabled: Don't install systemd support files even if libsystemd exists (i.e. the elogind-255.17 package is installed).

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

To automatically start dbus-daemon when the system is rebooted, install the /etc/rc.d/init.d/dbus bootscript from the blfs-bootscripts package. 

make install-dbus

Note that this boot script only starts the system-wide D-Bus daemon. Each user requiring access to D-Bus services will also need to run a session daemon as well. 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 gdm 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-x11 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

Now would be a good idea to reboot and test to see if D-Bus, elogind, etc. works, and you can login. Run the command loginctl after ensuring D-Bus is running. The result should indicate that a SESSION and a SEAT have been created.

Contents

Installed Programs: dbus-cleanup-sockets, dbus-daemon, dbus-launch, dbus-monitor, dbus-run-session, dbus-send, dbus-test-tool, dbus-update-activation-environment, and dbus-uuidgen
Installed Library: libdbus-1.so
Installed Directories: /etc/dbus-1, /usr/{include,lib}/dbus-1.0, /usr/lib/cmake/DBus1, /usr/share/dbus-1, /usr/share/xml/dbus-1, /usr/share/doc/dbus-1.16.0, and /var/{lib,run}/dbus

Short Descriptions

dbus-cleanup-sockets

is used to clean up leftover sockets in a directory

dbus-daemon

is the D-Bus message bus daemon

dbus-launch

is used to start dbus-daemon from a shell script. It would normally be called from a user's login scripts

dbus-monitor

is used to monitor messages going through a D-Bus message bus

dbus-run-session

starts a process as a new D-Bus session

dbus-send

is used to send a message to a D-Bus message bus

dbus-test-tool

is a D-Bus traffic generator and test tool; it is a multi-purpose tool for debugging and profiling D-Bus

dbus-update-activation-environment

is used to update the environment used for D-Bus session services; it updates the list of environment variables used by dbus-daemon --session when it activates session services without using systemd

dbus-uuidgen

is used to generate a universally unique ID

libdbus-1.so

contains the API functions used by the D-Bus message daemon. D-Bus is first a library that provides one-to-one communication between any two applications; dbus-daemon is an application that uses this library to implement a message bus daemon