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//! fastnbt aims for fast deserializing and serializing of NBT data from
//! *Minecraft: Java Edition*. This format is used by the game to store various
//! things, such as the world data and player inventories.
//!
//! * For documentation and examples of serde deserialization, see [`de`].
//! * For documentation and examples of serde serialization, see [`ser`].
//! * For a `serde_json`-like `Value` type see [`Value`].
//! * For NBT array types see [`ByteArray`], [`IntArray`], and [`LongArray`].
//! * For 'zero-copy' NBT array types see [`borrow`].
//!
//! Both this and related crates are under one [fastnbt Github
//! repository](https://github.com/owengage/fastnbt)
//!
//! ```toml
//! [dependencies]
//! fastnbt = "2"
//! ```
//!
//! # Byte, Int and Long array types
//!
//! There are three array types in NBT. To capture these, use [`ByteArray`],
//! [`IntArray`], and [`LongArray`]. in order to preserve the information from
//! the original NBT, these NBT types do not deserialize straight into serde
//! sequences like `Vec`. Without these types, it is not possible to tell if
//! some data came from a NBT List or an NBT Array.
//!
//! A limitation of these array types is that they cannot be used with serde's
//! untagged enums. If this is important to you please open an issue.
//!
//! Use these in your own data structures. They all implement
//! [`Deref`][`std::ops::Deref`] for dereferencing into a slice`.
//!
//! For versions that borrow their data, see [`borrow`].
//!
//! An example of deserializing a section of a chunk:
//!
//! ```no_run
//! use fastnbt::LongArray;
//! use serde::Deserialize;
//!
//! #[derive(Deserialize)]
//! #[serde(rename_all = "PascalCase")]
//! pub struct Section {
//! pub block_states: Option<LongArray>,
//! pub y: i8,
//! }
//!
//!# fn main(){
//! let buf: &[u8] = unimplemented!("get a buffer from somewhere");
//! let section: Section = fastnbt::from_bytes(buf).unwrap();
//! let states = section.block_states.unwrap();
//!
//! for long in states.iter() {
//! // do something
//! }
//! # }
//! ```
//!
//! # Example: Player inventory
//!
//! This example demonstrates printing out a players inventory and ender chest
//! contents from the [player dat
//! files](https://minecraft.gamepedia.com/Player.dat_format) found in worlds.
//!
//! Here we
//! * use serde's renaming attributes to have rustfmt conformant field names,
//! * use lifetimes to save on some string allocations (see [`de`] for more
//! info), and
//! * use the `Value` type to deserialize a field we don't know the exact
//! structure of.
//!
//!```no_run
//! use std::borrow::Cow;
//! use fastnbt::error::Result;
//! use fastnbt::{from_bytes, Value};
//! use flate2::read::GzDecoder;
//! use serde::Deserialize;
//! use std::io::Read;
//!
//! #[derive(Deserialize, Debug)]
//! #[serde(rename_all = "PascalCase")]
//! struct PlayerDat<'a> {
//! data_version: i32,
//!
//! #[serde(borrow)]
//! inventory: Vec<InventorySlot<'a>>,
//! ender_items: Vec<InventorySlot<'a>>,
//! }
//!
//! #[derive(Deserialize, Debug)]
//! struct InventorySlot<'a> {
//! // We typically avoid allocating a string here.
//! // See `fastnbt::de` docs for more info.
//! id: Cow<'a, str>,
//!
//! // Also get the less structured properties of the object.
//! tag: Option<Value>,
//!
//! // We need to rename fields a lot.
//! #[serde(rename = "Count")]
//! count: i8,
//! }
//!
//!# fn main() {
//! let args: Vec<_> = std::env::args().skip(1).collect();
//! let file = std::fs::File::open(args[0].clone()).unwrap();
//!
//! // Player dat files are compressed with GZip.
//! let mut decoder = GzDecoder::new(file);
//! let mut data = vec![];
//! decoder.read_to_end(&mut data).unwrap();
//!
//! let player: Result<PlayerDat> = from_bytes(data.as_slice());
//!
//! println!("{:#?}", player);
//!# }
//! ```
//!
//! # `Read` based parser
//!
//! A lower level parser also exists in the `stream` module that only requires
//! the `Read` trait on the input. This parser however doesn't support
//! deserializing to Rust objects directly.
//!
use ser::{Serializer, State};
use serde::{de as serde_de, Deserialize, Serialize};
pub mod borrow;
pub mod de;
pub mod error;
pub mod ser;
pub mod stream;
mod arrays;
mod de_arrays;
mod value;
pub use arrays::*;
pub use value::*;
#[cfg(test)]
mod test;
use crate::{
de::Deserializer,
error::{Error, Result},
};
use std::{convert::TryFrom, fmt::Display, io::Write};
/// An NBT tag. This does not carry the value or the name of the data.
#[derive(Deserialize, Debug, PartialEq, Clone, Copy)]
#[cfg_attr(feature = "arbitrary1", derive(arbitrary::Arbitrary))]
#[repr(u8)]
pub enum Tag {
/// Represents the end of a Compound object.
End = 0,
/// Equivalent to i8.
Byte = 1,
/// Equivalent to i16.
Short = 2,
/// Equivalent to i32.
Int = 3,
/// Equivalent to i64
Long = 4,
/// Equivalent to f32.
Float = 5,
/// Equivalent to f64.
Double = 6,
/// Represents as array of Byte (i8).
ByteArray = 7,
/// Represents a Unicode string.
String = 8,
/// Represents a list of other objects, elements are not required to be the same type.
List = 9,
/// Represents a struct-like structure.
Compound = 10,
/// Represents as array of Int (i32).
IntArray = 11,
/// Represents as array of Long (i64).
LongArray = 12,
}
// Crates exist to generate this code for us, but would add to our compile
// times, so we instead write it out manually, the tags will very rarely change
// so isn't a massive burden, but saves a significant amount of compile time.
impl TryFrom<u8> for Tag {
type Error = ();
fn try_from(value: u8) -> std::result::Result<Self, ()> {
use Tag::*;
Ok(match value {
0 => End,
1 => Byte,
2 => Short,
3 => Int,
4 => Long,
5 => Float,
6 => Double,
7 => ByteArray,
8 => String,
9 => List,
10 => Compound,
11 => IntArray,
12 => LongArray,
13..=u8::MAX => return Err(()),
})
}
}
impl From<Tag> for u8 {
fn from(tag: Tag) -> Self {
match tag {
Tag::End => 0,
Tag::Byte => 1,
Tag::Short => 2,
Tag::Int => 3,
Tag::Long => 4,
Tag::Float => 5,
Tag::Double => 6,
Tag::ByteArray => 7,
Tag::String => 8,
Tag::List => 9,
Tag::Compound => 10,
Tag::IntArray => 11,
Tag::LongArray => 12,
}
}
}
impl Display for Tag {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let s = match self {
Tag::End => "end",
Tag::Byte => "byte",
Tag::Short => "short",
Tag::Int => "int",
Tag::Long => "long",
Tag::Float => "float",
Tag::Double => "double",
Tag::ByteArray => "byte-array",
Tag::String => "string",
Tag::List => "list",
Tag::Compound => "compound",
Tag::IntArray => "int-array",
Tag::LongArray => "long-array",
};
f.write_str(s)
}
}
/// Serialize some `T` into NBT data. See the [`ser`] module for more
/// information.
pub fn to_bytes<T: Serialize>(v: &T) -> Result<Vec<u8>> {
let mut result = vec![];
let mut serializer = Serializer {
writer: &mut result,
state: State::Compound {
current_field: String::new(),
},
};
v.serialize(&mut serializer)?;
Ok(result)
}
/// Serialize some `T` into NBT data. See the [`ser`] module for more
/// information.
pub fn to_writer<T: Serialize, W: Write>(writer: W, v: &T) -> Result<()> {
let mut serializer = Serializer {
writer,
state: State::Compound {
current_field: String::new(),
},
};
v.serialize(&mut serializer)?;
Ok(())
}
/// Deserialize into a `T` from some NBT data. See the [`de`] module for more
/// information.
///
/// ```no_run
/// # use fastnbt::Value;
/// # use flate2::read::GzDecoder;
/// # use std::io;
/// # use std::io::Read;
/// # use fastnbt::error::Result;
/// # fn main() -> Result<()> {
/// # let some_reader = io::stdin();
/// let mut decoder = GzDecoder::new(some_reader);
/// let mut buf = vec![];
/// decoder.read_to_end(&mut buf).unwrap();
///
/// let val: Value = fastnbt::from_bytes(buf.as_slice())?;
/// # Ok(())
/// # }
/// ```
///
/// [`de`]: ./index.html
pub fn from_bytes<'a, T>(input: &'a [u8]) -> Result<T>
where
T: serde_de::Deserialize<'a>,
{
from_bytes_with_opts(input, Default::default())
}
/// Options for customozing deserialization.
pub struct DeOpts {
/// Maximum number of bytes a list or array can be.
max_seq_len: usize,
}
impl DeOpts {
/// Create new options. This object follows a builder pattern.
pub fn new() -> Self {
Default::default()
}
/// Set the maximum length any given sequence can be, eg lists. This does
/// not apply to NBT array types. This can help prevent panics on malformed
/// data.
pub fn max_seq_len(mut self, value: usize) -> Self {
self.max_seq_len = value;
self
}
}
impl Default for DeOpts {
fn default() -> Self {
Self {
max_seq_len: 100_000,
}
}
}
/// Similar to [`from_bytes`] but with options.
pub fn from_bytes_with_opts<'a, T>(input: &'a [u8], opts: DeOpts) -> Result<T>
where
T: serde_de::Deserialize<'a>,
{
const GZIP_MAGIC_BYTES: [u8; 2] = [0x1f, 0x8b];
// Provide freindly error for the common case of passing GZip data to
// `from_bytes`. This would be invalid starting data for NBT anyway.
if input.starts_with(&GZIP_MAGIC_BYTES) {
return Err(Error::bespoke(
"from_bytes expects raw NBT, but input appears to be gzipped".to_string(),
));
}
let mut des = Deserializer::from_bytes(input, opts);
let t = T::deserialize(&mut des)?;
Ok(t)
}