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::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: Arc<dyn 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: Arc<dyn 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, instance) = 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 let _instance = instance;
147 while let Some(call) = rx.next().await {
148 (call)(&mut extension, &mut store).await;
149 }
150 })
151 .detach();
152
153 Ok(WasmExtension {
154 manifest,
155 tx,
156 zed_api_version,
157 })
158 })
159 }
160
161 async fn build_wasi_ctx(&self, manifest: &Arc<ExtensionManifest>) -> Result<wasi::WasiCtx> {
162 use cap_std::{ambient_authority, fs::Dir};
163
164 let extension_work_dir = self.work_dir.join(manifest.id.as_ref());
165 self.fs
166 .create_dir(&extension_work_dir)
167 .await
168 .context("failed to create extension work dir")?;
169
170 let work_dir_preopen = Dir::open_ambient_dir(&extension_work_dir, ambient_authority())
171 .context("failed to preopen extension work directory")?;
172 let current_dir_preopen = work_dir_preopen
173 .try_clone()
174 .context("failed to preopen extension current directory")?;
175 let extension_work_dir = extension_work_dir.to_string_lossy();
176
177 let perms = wasi::FilePerms::all();
178 let dir_perms = wasi::DirPerms::all();
179
180 Ok(wasi::WasiCtxBuilder::new()
181 .inherit_stdio()
182 .preopened_dir(current_dir_preopen, dir_perms, perms, ".")
183 .preopened_dir(work_dir_preopen, dir_perms, perms, &extension_work_dir)
184 .env("PWD", &extension_work_dir)
185 .env("RUST_BACKTRACE", "full")
186 .build())
187 }
188
189 pub fn path_from_extension(&self, id: &Arc<str>, path: &Path) -> PathBuf {
190 let extension_work_dir = self.work_dir.join(id.as_ref());
191 normalize_path(&extension_work_dir.join(path))
192 }
193
194 pub fn writeable_path_from_extension(&self, id: &Arc<str>, path: &Path) -> Result<PathBuf> {
195 let extension_work_dir = self.work_dir.join(id.as_ref());
196 let path = normalize_path(&extension_work_dir.join(path));
197 if path.starts_with(&extension_work_dir) {
198 Ok(path)
199 } else {
200 Err(anyhow!("cannot write to path {}", path.display()))
201 }
202 }
203}
204
205pub fn parse_wasm_extension_version(
206 extension_id: &str,
207 wasm_bytes: &[u8],
208) -> Result<SemanticVersion> {
209 let mut version = None;
210
211 for part in wasmparser::Parser::new(0).parse_all(wasm_bytes) {
212 if let wasmparser::Payload::CustomSection(s) =
213 part.context("error parsing wasm extension")?
214 {
215 if s.name() == "zed:api-version" {
216 version = parse_wasm_extension_version_custom_section(s.data());
217 if version.is_none() {
218 bail!(
219 "extension {} has invalid zed:api-version section: {:?}",
220 extension_id,
221 s.data()
222 );
223 }
224 }
225 }
226 }
227
228 // The reason we wait until we're done parsing all of the Wasm bytes to return the version
229 // is to work around a panic that can happen inside of Wasmtime when the bytes are invalid.
230 //
231 // By parsing the entirety of the Wasm bytes before we return, we're able to detect this problem
232 // earlier as an `Err` rather than as a panic.
233 version.ok_or_else(|| anyhow!("extension {} has no zed:api-version section", extension_id))
234}
235
236fn parse_wasm_extension_version_custom_section(data: &[u8]) -> Option<SemanticVersion> {
237 if data.len() == 6 {
238 Some(SemanticVersion::new(
239 u16::from_be_bytes([data[0], data[1]]) as _,
240 u16::from_be_bytes([data[2], data[3]]) as _,
241 u16::from_be_bytes([data[4], data[5]]) as _,
242 ))
243 } else {
244 None
245 }
246}
247
248impl WasmExtension {
249 pub async fn call<T, Fn>(&self, f: Fn) -> T
250 where
251 T: 'static + Send,
252 Fn: 'static
253 + Send
254 + for<'a> FnOnce(&'a mut Extension, &'a mut Store<WasmState>) -> BoxFuture<'a, T>,
255 {
256 let (return_tx, return_rx) = oneshot::channel();
257 self.tx
258 .clone()
259 .unbounded_send(Box::new(move |extension, store| {
260 async {
261 let result = f(extension, store).await;
262 return_tx.send(result).ok();
263 }
264 .boxed()
265 }))
266 .expect("wasm extension channel should not be closed yet");
267 return_rx.await.expect("wasm extension channel")
268 }
269}
270
271impl WasmState {
272 fn on_main_thread<T, Fn>(&self, f: Fn) -> impl 'static + Future<Output = T>
273 where
274 T: 'static + Send,
275 Fn: 'static + Send + for<'a> FnOnce(&'a mut AsyncAppContext) -> LocalBoxFuture<'a, T>,
276 {
277 let (return_tx, return_rx) = oneshot::channel();
278 self.host
279 .main_thread_message_tx
280 .clone()
281 .unbounded_send(Box::new(move |cx| {
282 async {
283 let result = f(cx).await;
284 return_tx.send(result).ok();
285 }
286 .boxed_local()
287 }))
288 .expect("main thread message channel should not be closed yet");
289 async move { return_rx.await.expect("main thread message channel") }
290 }
291
292 fn work_dir(&self) -> PathBuf {
293 self.host.work_dir.join(self.manifest.id.as_ref())
294 }
295}
296
297impl wasi::WasiView for WasmState {
298 fn table(&mut self) -> &mut ResourceTable {
299 &mut self.table
300 }
301
302 fn ctx(&mut self) -> &mut wasi::WasiCtx {
303 &mut self.ctx
304 }
305}