Expand description
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.
Since version 2.0, the API is serde-based and hence you’ll find it very intuitive if you’re already familiar with serde. If you’re not familiar with serde, you may want to first read its tutorial before learning further about this crate.
Status: Stable.
Example code
Serialization and deserialization is achieved through the toplevel functions:
use std::collections::HashMap;
use zvariant::{EncodingContext as Context, from_slice, to_bytes, Type};
use serde::{Deserialize, Serialize};
use byteorder::LE;
// All serialization and deserialization API, needs a context.
let ctxt = Context::<LE>::new_dbus(0);
// You can also use the more efficient GVariant format:
// let ctxt = Context::<LE>::new_gvariant(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);
// 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");
// derive macros to handle custom types.
#[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 = Context::<LE>::new_dbus(0);
let encoded = to_bytes(ctxt, &s).unwrap();
let decoded: Struct = from_slice(&encoded, ctxt).unwrap();
assert_eq!(decoded, s);
Apart from the obvious requirement of EncodingContext
instance by the main serialization and
deserialization API, the type being serialized or deserialized must also implement Type
trait in addition to Serialize
or Deserialize
, respectively. Please refer to Type
module documentation for more details.
Most of the basic types of D-Bus match 1-1 with all the primitive Rust types. The only two
exceptions being, Signature
and ObjectPath
, which are really just strings. These types
are covered by the Basic
trait.
Similarly, most of the container types also map nicely to the usual Rust types and
collections (as can be seen in the example code above). The only note worthy exception being
ARRAY type. As arrays in Rust are fixed-sized, serde treats them as tuples and so does this
crate. This means they are encoded as STRUCT type of D-Bus. If you need to serialize to, or
deserialize from a D-Bus array, you’ll need to use a slice (array can easily be converted to a
slice), a Vec
or an arrayvec::ArrayVec
.
D-Bus string types, including Signature
and ObjectPath
, require one additional
restriction that strings in Rust do not. They must not contain any interior null bytes ('\0'
).
Encoding/Decoding strings that contain this character will return an error.
The generic D-Bus type, VARIANT
is represented by Value
, an enum that holds exactly one
value of any of the other types. Please refer to Value
module documentation for examples.
no-std
While std
is currently a hard requirement, optional no-std
support is planned in the future.
On the other hand, noalloc
support is not planned as it will be extremely difficult to
accomplish. However, community contribution can change that. 😊
Optional features
Feature | Description |
---|---|
arrayvec | Implement Type for arrayvec::ArrayVec and arrayvec::ArrayString |
enumflags2 | Implement Type for enumflags2::BitFlags<F> |
Modules
Structs
A wrapper to deserialize a value to T: Type + Deserialize
.
The encoding context to use with the serialization and deserialization API.
String that identifies objects at a given destination on the D-Bus bus.
An optional value.
Owned Signature
Owned Value
A wrapper to serialize T: Type + Serialize
as a value.
String that identifies the type of an encoded value.
A string wrapper.
Use this to efficiently build a Structure
.
Use this to deserialize a Structure
.
Enums
Our deserialization implementation.
The encoding format.
Error type used by zvariant API.
Our serialization implementation.
A generic container, in the form of an enum that holds exactly one value of any of the other types.
Constants
The prefix of ARRAY type signature, as a character. Provided for manual signature creation.
The prefix of ARRAY type signature, as a string. Provided for manual signature creation.
The closing character of DICT_ENTRY type signature. Provided for manual signature creation.
The closing character of DICT_ENTRY type signature, as a string. Provided for manual signature creation.
The opening character of DICT_ENTRY type signature. Provided for manual signature creation.
The opening character of DICT_ENTRY type signature, as a string. Provided for manual signature creation.
The prefix of MAYBE (GVariant-specific) type signature, as a character. Provided for manual signature creation.
The prefix of MAYBE (GVariant-specific) type signature, as a string. Provided for manual signature creation.
The closing character of STRUCT type signature. Provided for manual signature creation.
The closing character of STRUCT type signature, as a string. Provided for manual signature creation.
The opening character of STRUCT type signature. Provided for manual signature creation.
The opening character of STRUCT type signature, as a string. Provided for manual signature creation.
The VARIANT type signature. Provided for manual signature creation.
The VARIANT type signature, as a string. Provided for manual signature creation.
Traits
Trait for basic types.
Types that deserialize based on dynamic signatures.
Types with dynamic signatures.
Type that uses a special value to be used as none.
Trait implemented by all serializable types.
Functions
Deserialize T
from a given slice of bytes.
Deserialize T
from a given slice of bytes, containing file descriptor indices.
Deserialize T
from a given slice of bytes containing file descriptor indices, with the given
signature.
Deserialize T
from a given slice of bytes containing file descriptor indices, with the given signature.
Deserialize T
from a given slice of bytes containing file descriptor indices, using the given
seed.
Deserialize T
from a given slice of bytes containing file descriptor indices, with the given
signature.
Deserialize T
from a given slice of bytes with the given signature.
Deserialize T
from a given slice of bytes containing file descriptor indices, using the given
seed.
Calculate the serialized size of T
.
Calculate the serialized size of T
that (potentially) contains FDs.
Serialize T
as a byte vector.
Serialize T
that (potentially) contains FDs, as a byte vector.
Serialize T
that (potentially) contains FDs and has the given signature, to a new byte vector.
Serialize T
that has the given signature, to a new byte vector.
Serialize T
to the given writer
.
Serialize T
that (potentially) contains FDs, to the given writer
.
Serialize T
that (potentially) contains FDs and has the given signature, to the given writer
.
Serialize T
that has the given signature, to the given writer
.
Type Definitions
Alias for a Result
with the error type zvariant::Error
.
Derive Macros
Adds Deserialize
implementation to structs to be deserialized from a{sv}
type.
Implements conversions for your type to/from OwnedValue
.
Adds Serialize
implementation to structs to be serialized as a{sv}
type.