dbus-app-launcher

A simple service that allows executing a program via D-Bus.

Note: Allowing D-Bus clients to execute arbitrary programs may pose a security risk. Use carefully.

Installation

There is a number of ways to install. Choose one and follow the given steps.

The following installation options provide a complete package which already include a D-Bus service configuration file, so require no extra steps after installing:

• Install from the Arch User Repository (AUR):
  • dbus-app-launcher-bin (statically linked binary, recommended)
  • dbus-app-launcher (builds from source, may require re-building when dependencies are updated)

The following installation options only provide you with the executable and leave it up to you to set up the D-Bus service configuration file, for which you will need to follow the steps in the section below:

• Download a static binary from the releases page.
• Install from Hackage: dbus-app-launcher

If none of the above options work for you, you can also follow the instructions below to build the executable from source yourself.

Building from source

To build the code, you will need Haskell and the stack command line utility. Get them here.

To build and install, run stack install. This will build the code and copy the executable to ~/.local/bin.

Next, follow the steps below to set up the D-Bus service.

Build a static executable using Docker

To build a static executable (the same as made available on the releases page), you can use the following Docker command:

docker run -v $PWD:/dbus-app-launcher --rm benz0li/ghc-musl:9.8.4 sh -c "cd /dbus-app-launcher && exec stack --allow-different-user build --no-install-ghc --system-ghc --ghc-options='-static -optl-static'"

This will start a ghc-musl container, mount the current directory (where you've checked out the code) into it, and build a statically linked version of the service which should be able to run on any system with the same CPU architecture.

When the build succeeded, the executable can be found at the following path: .stack-work/dist/x86_64-linux/ghc-9.8.4/build/dbus-app-launcher/dbus-app-launcher

Setting up the D-Bus service configuration

To set up a D-Bus service description that will automatically launch the new service whenever it is accessed, create the following file:

~/.local/share/dbus-1/services/nl.dvdgiessen.dbusapplauncher.service

[D-BUS Service]
Name=nl.dvdgiessen.dbusapplauncher
Exec=/home/USERNAME/.local/bin/dbus-app-launcher

Replace the path in Exec= with the actual location of the executable.

Using the D-Bus service from your own code

The service currently exports one interface, Exec. Calling any of the methods of this interface will start the program using the exec() syscall.

• Service name: nl.dvdgiessen.dbusapplauncher
• Object path: /nl/dvdgiessen/DBusAppLauncher
• Interface: nl.dvdgiessen.dbusapplauncher.Exec
• Methods:
  • Cmd(String cmd)
  • CmdArgs(String cmd, List<String> args)
  • CmdArgsEnv(String cmd, List<String> args, Map<String,String> env)

Note: The cmd parameter is always parsed using shell-style quoting, supporting specifying environment variables by prepending them to the command (NAME=value) and arguments by appending them after the command. Other shell features such as variable interpolation are not supported.

Arguments from the optional args parameter will be added after any arguments parsed from the cmd parameter.

The launched program will inherit the environment that dbus-app-launcher itself was started with, and can be overridden by environment variables parsed from the cmd parameter. Both of those can be overriden via the env parameter.

Issues and contributing

This is my first Haskell program, so there's probably plenty that could be improved upon. Feel free to fork it or open pull requests if you find a bug.

I might add more functionality in the future, for example for running programs and returning their exit code and stdout/stderr output. Currently my own use case for this program is for starting applications from KWin scripts (see kwin-toggleterminal if you're interested in that sort of thing), so adding more functionality probably won't be a priority until I have a need for it myself.

License

dbus-app-launcher is freely distributable under the terms of the MIT license.