1pub(crate) mod wit;
2
3use crate::ExtensionManifest;
4use anyhow::{anyhow, bail, Context as _, Result};
5use fs::{normalize_path, Fs};
6use futures::future::LocalBoxFuture;
7use futures::{
8 channel::{
9 mpsc::{self, UnboundedSender},
10 oneshot,
11 },
12 future::BoxFuture,
13 Future, FutureExt, StreamExt as _,
14};
15use gpui::{AppContext, AsyncAppContext, BackgroundExecutor, Task};
16use http_client::HttpClient;
17use language::LanguageRegistry;
18use node_runtime::NodeRuntime;
19use release_channel::ReleaseChannel;
20use semantic_version::SemanticVersion;
21use std::{
22 path::{Path, PathBuf},
23 sync::{Arc, OnceLock},
24};
25use wasmtime::{
26 component::{Component, ResourceTable},
27 Engine, Store,
28};
29use wasmtime_wasi as wasi;
30use wit::Extension;
31
32pub(crate) struct WasmHost {
33 engine: Engine,
34 release_channel: ReleaseChannel,
35 http_client: Arc<dyn HttpClient>,
36 node_runtime: NodeRuntime,
37 pub(crate) language_registry: Arc<LanguageRegistry>,
38 fs: Arc<dyn Fs>,
39 pub(crate) work_dir: PathBuf,
40 _main_thread_message_task: Task<()>,
41 main_thread_message_tx: mpsc::UnboundedSender<MainThreadCall>,
42}
43
44#[derive(Clone)]
45pub struct WasmExtension {
46 tx: UnboundedSender<ExtensionCall>,
47 pub(crate) manifest: Arc<ExtensionManifest>,
48 #[allow(unused)]
49 pub zed_api_version: SemanticVersion,
50}
51
52pub(crate) struct WasmState {
53 manifest: Arc<ExtensionManifest>,
54 pub(crate) table: ResourceTable,
55 ctx: wasi::WasiCtx,
56 pub(crate) host: Arc<WasmHost>,
57}
58
59type MainThreadCall =
60 Box<dyn Send + for<'a> FnOnce(&'a mut AsyncAppContext) -> LocalBoxFuture<'a, ()>>;
61
62type ExtensionCall = Box<
63 dyn Send + for<'a> FnOnce(&'a mut Extension, &'a mut Store<WasmState>) -> BoxFuture<'a, ()>,
64>;
65
66fn wasm_engine() -> wasmtime::Engine {
67 static WASM_ENGINE: OnceLock<wasmtime::Engine> = OnceLock::new();
68
69 WASM_ENGINE
70 .get_or_init(|| {
71 let mut config = wasmtime::Config::new();
72 config.wasm_component_model(true);
73 config.async_support(true);
74 wasmtime::Engine::new(&config).unwrap()
75 })
76 .clone()
77}
78
79impl WasmHost {
80 pub fn new(
81 fs: Arc<dyn Fs>,
82 http_client: Arc<dyn HttpClient>,
83 node_runtime: NodeRuntime,
84 language_registry: Arc<LanguageRegistry>,
85 work_dir: PathBuf,
86 cx: &mut AppContext,
87 ) -> Arc<Self> {
88 let (tx, mut rx) = mpsc::unbounded::<MainThreadCall>();
89 let task = cx.spawn(|mut cx| async move {
90 while let Some(message) = rx.next().await {
91 message(&mut cx).await;
92 }
93 });
94 Arc::new(Self {
95 engine: wasm_engine(),
96 fs,
97 work_dir,
98 http_client,
99 node_runtime,
100 language_registry,
101 release_channel: ReleaseChannel::global(cx),
102 _main_thread_message_task: task,
103 main_thread_message_tx: tx,
104 })
105 }
106
107 pub fn load_extension(
108 self: &Arc<Self>,
109 wasm_bytes: Vec<u8>,
110 manifest: Arc<ExtensionManifest>,
111 executor: BackgroundExecutor,
112 ) -> Task<Result<WasmExtension>> {
113 let this = self.clone();
114 executor.clone().spawn(async move {
115 let zed_api_version = parse_wasm_extension_version(&manifest.id, &wasm_bytes)?;
116
117 let component = Component::from_binary(&this.engine, &wasm_bytes)
118 .context("failed to compile wasm component")?;
119
120 let mut store = wasmtime::Store::new(
121 &this.engine,
122 WasmState {
123 ctx: this.build_wasi_ctx(&manifest).await?,
124 manifest: manifest.clone(),
125 table: ResourceTable::new(),
126 host: this.clone(),
127 },
128 );
129
130 let mut extension = Extension::instantiate_async(
131 &mut store,
132 this.release_channel,
133 zed_api_version,
134 &component,
135 )
136 .await?;
137
138 extension
139 .call_init_extension(&mut store)
140 .await
141 .context("failed to initialize wasm extension")?;
142
143 let (tx, mut rx) = mpsc::unbounded::<ExtensionCall>();
144 executor
145 .spawn(async move {
146 while let Some(call) = rx.next().await {
147 (call)(&mut extension, &mut store).await;
148 }
149 })
150 .detach();
151
152 Ok(WasmExtension {
153 manifest,
154 tx,
155 zed_api_version,
156 })
157 })
158 }
159
160 async fn build_wasi_ctx(&self, manifest: &Arc<ExtensionManifest>) -> Result<wasi::WasiCtx> {
161 let extension_work_dir = self.work_dir.join(manifest.id.as_ref());
162 self.fs
163 .create_dir(&extension_work_dir)
164 .await
165 .context("failed to create extension work dir")?;
166
167 let file_perms = wasi::FilePerms::all();
168 let dir_perms = wasi::DirPerms::all();
169
170 Ok(wasi::WasiCtxBuilder::new()
171 .inherit_stdio()
172 .preopened_dir(&extension_work_dir, ".", dir_perms, file_perms)?
173 .preopened_dir(
174 &extension_work_dir,
175 extension_work_dir.to_string_lossy(),
176 dir_perms,
177 file_perms,
178 )?
179 .env("PWD", extension_work_dir.to_string_lossy())
180 .env("RUST_BACKTRACE", "full")
181 .build())
182 }
183
184 pub fn path_from_extension(&self, id: &Arc<str>, path: &Path) -> PathBuf {
185 let extension_work_dir = self.work_dir.join(id.as_ref());
186 normalize_path(&extension_work_dir.join(path))
187 }
188
189 pub fn writeable_path_from_extension(&self, id: &Arc<str>, path: &Path) -> Result<PathBuf> {
190 let extension_work_dir = self.work_dir.join(id.as_ref());
191 let path = normalize_path(&extension_work_dir.join(path));
192 if path.starts_with(&extension_work_dir) {
193 Ok(path)
194 } else {
195 Err(anyhow!("cannot write to path {}", path.display()))
196 }
197 }
198}
199
200pub fn parse_wasm_extension_version(
201 extension_id: &str,
202 wasm_bytes: &[u8],
203) -> Result<SemanticVersion> {
204 let mut version = None;
205
206 for part in wasmparser::Parser::new(0).parse_all(wasm_bytes) {
207 if let wasmparser::Payload::CustomSection(s) =
208 part.context("error parsing wasm extension")?
209 {
210 if s.name() == "zed:api-version" {
211 version = parse_wasm_extension_version_custom_section(s.data());
212 if version.is_none() {
213 bail!(
214 "extension {} has invalid zed:api-version section: {:?}",
215 extension_id,
216 s.data()
217 );
218 }
219 }
220 }
221 }
222
223 // The reason we wait until we're done parsing all of the Wasm bytes to return the version
224 // is to work around a panic that can happen inside of Wasmtime when the bytes are invalid.
225 //
226 // By parsing the entirety of the Wasm bytes before we return, we're able to detect this problem
227 // earlier as an `Err` rather than as a panic.
228 version.ok_or_else(|| anyhow!("extension {} has no zed:api-version section", extension_id))
229}
230
231fn parse_wasm_extension_version_custom_section(data: &[u8]) -> Option<SemanticVersion> {
232 if data.len() == 6 {
233 Some(SemanticVersion::new(
234 u16::from_be_bytes([data[0], data[1]]) as _,
235 u16::from_be_bytes([data[2], data[3]]) as _,
236 u16::from_be_bytes([data[4], data[5]]) as _,
237 ))
238 } else {
239 None
240 }
241}
242
243impl WasmExtension {
244 pub async fn call<T, Fn>(&self, f: Fn) -> T
245 where
246 T: 'static + Send,
247 Fn: 'static
248 + Send
249 + for<'a> FnOnce(&'a mut Extension, &'a mut Store<WasmState>) -> BoxFuture<'a, T>,
250 {
251 let (return_tx, return_rx) = oneshot::channel();
252 self.tx
253 .clone()
254 .unbounded_send(Box::new(move |extension, store| {
255 async {
256 let result = f(extension, store).await;
257 return_tx.send(result).ok();
258 }
259 .boxed()
260 }))
261 .expect("wasm extension channel should not be closed yet");
262 return_rx.await.expect("wasm extension channel")
263 }
264}
265
266impl WasmState {
267 fn on_main_thread<T, Fn>(&self, f: Fn) -> impl 'static + Future<Output = T>
268 where
269 T: 'static + Send,
270 Fn: 'static + Send + for<'a> FnOnce(&'a mut AsyncAppContext) -> LocalBoxFuture<'a, T>,
271 {
272 let (return_tx, return_rx) = oneshot::channel();
273 self.host
274 .main_thread_message_tx
275 .clone()
276 .unbounded_send(Box::new(move |cx| {
277 async {
278 let result = f(cx).await;
279 return_tx.send(result).ok();
280 }
281 .boxed_local()
282 }))
283 .expect("main thread message channel should not be closed yet");
284 async move { return_rx.await.expect("main thread message channel") }
285 }
286
287 fn work_dir(&self) -> PathBuf {
288 self.host.work_dir.join(self.manifest.id.as_ref())
289 }
290}
291
292impl wasi::WasiView for WasmState {
293 fn table(&mut self) -> &mut ResourceTable {
294 &mut self.table
295 }
296
297 fn ctx(&mut self) -> &mut wasi::WasiCtx {
298 &mut self.ctx
299 }
300}