/zbus

This is the GitHub mirror of https://gitlab.freedesktop.org/zeenix/zbus. Please feel free to send your contributions here, if it's more convenient for you. :)

Primary LanguageRustOtherNOASSERTION

pipeline status

zbus

A Rust API for D-Bus communication. The aim is to provide a safe and simple high- and low-level API akin to GDBus, that doesn't depend on C libraries.

The project is divided into three main crates:

zbus

The zbus crate provides the main API you will use to interact with D-Bus from Rust. It takes care of the establishment of a connection, the creation, sending and receiving of different kind of D-Bus messages (method calls, signals etc) for you.

zbus crate is currently Linux-specific1.

Status: Stable2.

Dependencies

  • nix
  • byteorder
  • serde
  • serde_repr
  • enumflags2
  • derivative
  • serde-xml-rs (optional)

Getting Started

The best way to get started with zbus is the book, where we start with basic D-Bus concepts and explain with code samples, how zbus makes D-Bus easy.

Example code

Client

This code display a notification on your Freedesktop.org-compatible OS:

use std::collections::HashMap;
use std::error::Error;

use zbus::dbus_proxy;
use zvariant::Value;

#[dbus_proxy]
trait Notifications {
    fn notify(
        &self,
        app_name: &str,
        replaces_id: u32,
        app_icon: &str,
        summary: &str,
        body: &str,
        actions: &[&str],
        hints: HashMap<&str, &Value>,
        expire_timeout: i32,
    ) -> zbus::Result<u32>;
}

fn main() -> Result<(), Box<dyn Error>> {
    let connection = zbus::Connection::new_session()?;

    let proxy = NotificationsProxy::new(&connection)?;
    let reply = proxy.notify(
        "my-app",
        0,
        "dialog-information",
        "A summary",
        "Some body",
        &[],
        HashMap::new(),
        5000,
    )?;
    dbg!(reply);

    Ok(())
}

Server

A simple service that politely greets whoever calls its SayHello method:

use std::error::Error;
use std::convert::TryInto;
use zbus::{dbus_interface, fdo};

struct Greeter {
    count: u64
};

#[dbus_interface(name = "org.zbus.MyGreeter1")]
impl Greeter {
    fn say_hello(&mut self, name: &str) -> String {
        self.count += 1;
        format!("Hello {}! I have been called: {}", name, self.count)
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let connection = zbus::Connection::new_session()?;
    fdo::DBusProxy::new(&connection)?.request_name(
        "org.zbus.MyGreeter",
        fdo::RequestNameFlags::ReplaceExisting.into(),
    )?;

    let mut object_server = zbus::ObjectServer::new(&connection);
    let mut greeter = Greeter { count: 0 };
    object_server.at(&"/org/zbus/MyGreeter".try_into()?, greeter)?;
    loop {
        if let Err(err) = object_server.try_handle_next() {
            eprintln!("{}", err);
        }
    }
}

You can use the following command to test it:

$ busctl --user call org.zbus.MyGreeter /org/zbus/MyGreeter org.zbus.MyGreeter1 SayHello s "Maria"
Hello Maria!
s

zvariant

This crate provides API for encoding/decoding of data to/from D-Bus wire format. This binary wire format is simple and very efficient and hence useful outside of D-Bus context as well. A modified form of this format, GVariant is very commonly used for efficient storage of arbitrary data and is also supported by this crate.

Status: Stable.

Dependencies

  • byteorder
  • serde
  • arrayvec (optional)
  • enumflags2 (optional)

Example code

use std::collections::HashMap;
use byteorder::LE;
use zvariant::{from_slice, to_bytes};
use zvariant::EncodingContext as Context;

// All serialization and deserialization API, needs a context.
let ctxt = Context::<LE>::new_dbus(0);

// i16
let encoded = to_bytes(ctxt, &42i16).unwrap();
let decoded: i16 = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, 42);

// strings
let encoded = to_bytes(ctxt, &"hello").unwrap();
let decoded: &str = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, "hello");

// tuples
let t = ("hello", 42i32, true);
let encoded = to_bytes(ctxt, &t).unwrap();
let decoded: (&str, i32, bool) = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, t);

// Let's use the more efficient GVariant format.
let ctxt = Context::<LE>::new_gvariant(0);

// Vec
let v = vec!["hello", "world!"];
let encoded = to_bytes(ctxt, &v).unwrap();
let decoded: Vec<&str> = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, v);

// Dictionary
let mut map: HashMap<i64, &str> = HashMap::new();
map.insert(1, "123");
map.insert(2, "456");
let encoded = to_bytes(ctxt, &map).unwrap();
let decoded: HashMap<i64, &str> = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded[&1], "123");
assert_eq!(decoded[&2], "456");

zvariant_derive

This crate provides a derive macro to easily implement Type trait on structs and enums.

Status: Stable.

Dependencies

  • proc-macro2
  • syn
  • quote

Example code

use zvariant::{EncodingContext, from_slice, to_bytes};
use zvariant::{derive::Type, Type};
use serde::{Deserialize, Serialize};
use byteorder::LE;

#[derive(Deserialize, Serialize, Type, PartialEq, Debug)]
struct Struct<'s> {
    field1: u16,
    field2: i64,
    field3: &'s str,
}

assert_eq!(Struct::signature(), "(qxs)");
let s = Struct {
    field1: 42,
    field2: i64::max_value(),
    field3: "hello",
};
let ctxt = EncodingContext::<LE>::new_dbus(0);
let encoded = to_bytes(ctxt, &s).unwrap();
let decoded: Struct = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, s);

Other crates

Apart from the three crates described above, zbus project also provides a few other crates:

zbus_macros

This crate provides the convenient zbus macros that we already saw in action in the sample code above. However, zbus crate re-exports the macros for your convenience so you do not need to use this crate directly.

Status: Stable.

zbus_polkit

A crate to interact with PolicyKit, a toolkit for defining and handling authorizations. It is used for allowing unprivileged processes to speak to privileged processes.

Status: Stable.

Dependencies

  • serde
  • serde_repr
  • enumflags2

Example code

use zbus::Connection;
use zbus_polkit::policykit1::*;

let connection = Connection::new_system().unwrap();
let proxy = AuthorityProxy::new(&connection).unwrap();
let subject = Subject::new_for_owner(std::process::id(), None, None).unwrap();
let result = proxy.check_authorization(
    &subject,
    "org.zbus.BeAwesome",
    std::collections::HashMap::new(),
    CheckAuthorizationFlags::AllowUserInteraction.into(),
    "",
);

Getting Help

If you need help in using these crates, are looking for ways to contribute or just want to hang out with the cool kids, please come chat with us on our IRC channel, #zbus on irc.freenode.net. If something doesn't seem right, please file an issue.

Portability

All crates are currently Unix-only and will fail to build on non-unix. This is hopefully a temporary limitation. Moreover, integration tests of zbus crate currently require a session bus running on the build host.

License

MIT license LICENSE-MIT

Footnotes

  1. Support for other OS exist, but it is not supported to the same extent. D-Bus clients in javascript (running from any browser) do exist though. And zbus may also be working from the browser sometime in the future too, thanks to Rust 🦀 and WebAssembly 🕸. ↩

  2. We might have to change the API but zbus follows semver convention so your code won't just break out of the blue. Just make sure you depend on a specific major version of zbus. ↩