1//! The WebAssembly component tooling.
2
3#![deny(missing_docs)]
4#![cfg_attr(docsrs, feature(doc_auto_cfg))]
5
6use std::str::FromStr;
7use std::{borrow::Cow, fmt::Display};
8
9use anyhow::{bail, Result};
10use wasm_encoder::{CanonicalOption, Encode, Section};
11use wit_parser::{Resolve, WorldId};
12
13mod encoding;
14mod gc;
15mod linking;
16mod printing;
17mod targets;
18mod validation;
19
20pub use encoding::{encode, ComponentEncoder};
21pub use linking::Linker;
22pub use printing::*;
23pub use targets::*;
24pub use wit_parser::decoding::{decode, decode_reader, DecodedWasm};
25
26pub mod metadata;
27
28#[cfg(feature = "dummy-module")]
29pub use dummy::dummy_module;
30#[cfg(feature = "dummy-module")]
31mod dummy;
32
33#[cfg(feature = "semver-check")]
34mod semver_check;
35#[cfg(feature = "semver-check")]
36pub use semver_check::*;
37
38/// Supported string encoding formats.
39#[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Hash)]
40pub enum StringEncoding {
41 /// Strings are encoded with UTF-8.
42 #[default]
43 UTF8,
44 /// Strings are encoded with UTF-16.
45 UTF16,
46 /// Strings are encoded with compact UTF-16 (i.e. Latin1+UTF-16).
47 CompactUTF16,
48}
49
50impl Display for StringEncoding {
51 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
52 match self {
53 StringEncoding::UTF8 => write!(f, "utf8"),
54 StringEncoding::UTF16 => write!(f, "utf16"),
55 StringEncoding::CompactUTF16 => write!(f, "compact-utf16"),
56 }
57 }
58}
59
60impl FromStr for StringEncoding {
61 type Err = anyhow::Error;
62
63 fn from_str(s: &str) -> Result<Self> {
64 match s {
65 "utf8" => Ok(StringEncoding::UTF8),
66 "utf16" => Ok(StringEncoding::UTF16),
67 "compact-utf16" => Ok(StringEncoding::CompactUTF16),
68 _ => bail!("unknown string encoding `{}`", s),
69 }
70 }
71}
72
73impl From<StringEncoding> for wasm_encoder::CanonicalOption {
74 fn from(e: StringEncoding) -> wasm_encoder::CanonicalOption {
75 match e {
76 StringEncoding::UTF8 => CanonicalOption::UTF8,
77 StringEncoding::UTF16 => CanonicalOption::UTF16,
78 StringEncoding::CompactUTF16 => CanonicalOption::CompactUTF16,
79 }
80 }
81}
82
83/// A producer section to be added to all modules and components synthesized by
84/// this crate
85pub(crate) fn base_producers() -> wasm_metadata::Producers {
86 let mut producer: Producers = wasm_metadata::Producers::empty();
87 producer.add(field:"processed-by", name:"wit-component", version:env!("CARGO_PKG_VERSION"));
88 producer
89}
90
91/// Embed component metadata in a buffer of bytes that contains a Wasm module
92pub fn embed_component_metadata(
93 bytes: &mut Vec<u8>,
94 wit_resolver: &Resolve,
95 world: WorldId,
96 encoding: StringEncoding,
97) -> Result<()> {
98 let encoded: Vec = metadata::encode(&wit_resolver, world, encoding, extra_producers:None)?;
99
100 let section: CustomSection<'_> = wasm_encoder::CustomSection {
101 name: "component-type".into(),
102 data: Cow::Borrowed(&encoded),
103 };
104 bytes.push(section.id());
105 section.encode(sink:bytes);
106
107 Ok(())
108}
109
110#[cfg(test)]
111mod tests {
112 use anyhow::Result;
113 use wasmparser::Payload;
114 use wit_parser::Resolve;
115
116 use super::{embed_component_metadata, StringEncoding};
117
118 const MODULE_WAT: &str = r#"
119(module
120 (type (;0;) (func))
121 (func (;0;) (type 0)
122 nop
123 )
124)
125"#;
126
127 const COMPONENT_WIT: &str = r#"
128package test:foo;
129world test-world {}
130"#;
131
132 #[test]
133 fn component_metadata_embedding_works() -> Result<()> {
134 let mut bytes = wat::parse_str(MODULE_WAT)?;
135
136 // Get original len & custom section count
137 let original_len = bytes.len();
138 let payloads = wasmparser::Parser::new(0).parse_all(&bytes);
139 let original_custom_section_count = payloads.fold(0, |acc, payload| {
140 if let Ok(Payload::CustomSection { .. }) = payload {
141 acc + 1
142 } else {
143 acc
144 }
145 });
146
147 // Parse pre-canned WIT to build resolver
148 let mut resolver = Resolve::default();
149 let pkg = resolver.push_str("in-code.wit", COMPONENT_WIT)?;
150 let world = resolver.select_world(pkg, Some("test-world"))?;
151
152 // Embed component metadata
153 embed_component_metadata(&mut bytes, &resolver, world, StringEncoding::UTF8)?;
154
155 // Re-retrieve custom section count, and search for the component-type custom section along the way
156 let mut found_component_section = false;
157 let new_custom_section_count =
158 wasmparser::Parser::new(0)
159 .parse_all(&bytes)
160 .fold(0, |acc, payload| {
161 if let Ok(Payload::CustomSection(reader)) = payload {
162 if reader.name() == "component-type" {
163 found_component_section = true;
164 }
165 acc + 1
166 } else {
167 acc
168 }
169 });
170
171 assert!(original_len < bytes.len());
172 assert_eq!(original_custom_section_count + 1, new_custom_section_count);
173 assert!(found_component_section);
174
175 Ok(())
176 }
177}
178