Remote Debugger

.devcontainer/Dockerfile

@@ -45,5 +45,11 @@ RUN pip3 --disable-pip-version-check --no-cache-dir install mypy wasmtime \
 
 # configure rust
 RUN rustup target add wasm32-unknown-unknown wasm32-wasi
-RUN cargo install twiggy cargo-wasi cargo-expand mdbook
+RUN cargo install           \
+    twiggy                  \
+    cargo-wasi              \
+    cargo-expand            \
+    mdbook                  \
+    cargo-get               \
+    cargo-workspaces
 RUN cargo install --git https://github.com/bytecodealliance/wit-bindgen wit-bindgen-cli

.devcontainer/devcontainer.json

@@ -15,6 +15,9 @@
     }
   },
 
+  // needed for debugging
+  "runArgs": ["--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined"],
+
   // Set *default* container specific settings.json values on container create.
   "settings": {
     "python.defaultInterpreterPath": "/usr/local/bin/python",

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "lldb",
+      "request": "attach",
+      "name": "Debug",
+      "program": "${workspaceFolder}/target/debug/debugger",
+      "preLaunchTask": "setup: debugger",
+      "postDebugTask": "Terminate All Tasks"
+    }
+  ]
+}

.vscode/tasks.json

@@ -0,0 +1,68 @@
+{
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "type": "cargo",
+      "group": "build",
+      "label": "build: debugger",
+      "command": "build",
+      "args": ["-p", "debugger"],
+      "problemMatcher": ["$rustc"]
+    },
+    {
+      "type": "cargo",
+      "group": "build",
+      "label": "build: rust wasm modules",
+      "command": "build",
+      "args": [
+        "--target=wasm32-wasi",
+        "--workspace",
+        "--exclude",
+        "debugger",
+        "--exclude",
+        "debugger-macro"
+      ],
+      "problemMatcher": ["$rustc"]
+    },
+    {
+      "group": "build",
+      "label": "setup: debugger",
+      "dependsOn": ["build: debugger", "build: rust wasm modules"],
+      "type": "process",
+      "command": "scripts/debug",
+      "args": ["${fileDirname}"],
+      "isBackground": true,
+      "problemMatcher": [
+        {
+          "pattern": [
+            {
+              "regexp": ".",
+              "file": 1,
+              "location": 2,
+              "message": 3
+            }
+          ],
+          "background": {
+            "activeOnStart": true,
+            "beginsPattern": ".",
+            "endsPattern": "."
+          }
+        }
+      ]
+    },
+    {
+      "label": "Terminate All Tasks",
+      "command": "echo ${input:terminate}",
+      "type": "shell",
+      "problemMatcher": []
+    }
+  ],
+  "inputs": [
+    {
+      "id": "terminate",
+      "type": "command",
+      "command": "workbench.action.tasks.terminate",
+      "args": "terminateAll"
+    }
+  ]
+}

Cargo.toml

@@ -1,2 +1,2 @@
 [workspace]
-members = ["examples/rust/*"]
+members = ["examples/rust/*", "crates/*"]

crates/debugger-macro-impl/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "debugger-macro-impl"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "1.0", features = [
+    "full",
+    "printing",
+    "visit",
+    "extra-traits",
+    "parsing",
+] }
+quote = "1.0"
+proc-macro2 = "1.0"

crates/debugger-macro-impl/src/lib.rs

@@ -0,0 +1,84 @@
+use proc_macro::TokenStream;
+use proc_macro2::TokenStream as TokenStream2;
+use quote::quote;
+use syn::{parse_macro_input, visit::Visit};
+
+struct Handler {
+    name: String,
+    src: TokenStream2,
+}
+
+struct HandleVisitor {
+    impl_trait: syn::Path,
+    impl_type: syn::Type,
+    handlers: Vec<Handler>,
+}
+
+impl<'ast> Visit<'ast> for HandleVisitor {
+    fn visit_impl_item_method(&mut self, node: &'ast syn::ImplItemMethod) {
+        let sig = &node.sig;
+        let name = &sig.ident;
+
+        let typed_args = sig.inputs.iter().filter_map(|input| match input {
+            syn::FnArg::Typed(x) => Some((*x.ty).clone()),
+            _ => None,
+        });
+        let indexes = (0..typed_args.clone().count()).map(syn::Index::from);
+
+        let args = quote! { (#(#typed_args,)*) };
+        let args_splat = quote! { #(args.#indexes),* };
+
+        let impl_trait = &self.impl_trait;
+        let impl_type = &self.impl_type;
+
+        self.handlers.push(Handler {
+            name: name.to_string(),
+            src: quote! {
+                let args: #args = serde_json::from_slice(&json).unwrap();
+                let result = <#impl_type as #impl_trait>::#name(#args_splat);
+                serde_json::to_vec(&result).unwrap()
+            },
+        });
+
+        syn::visit::visit_impl_item_method(self, node);
+    }
+}
+
+#[proc_macro_attribute]
+pub fn export_debug_handler(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(item as syn::ItemImpl);
+
+    let (_, path, _) = input.trait_.as_ref().expect("expected trait");
+
+    let mut visitor = HandleVisitor {
+        impl_trait: path.clone(),
+        impl_type: (*input.self_ty).clone(),
+        handlers: vec![],
+    };
+    visitor.visit_item_impl(&input);
+
+    let handle_names = visitor.handlers.iter().map(|h| &h.name);
+    let handle_srcs = visitor.handlers.iter().map(|h| &h.src);
+
+    let debugger_wit = include_str!("../../debugger/debugger.wit");
+
+    quote! {
+        #input
+
+        use ::debugger_macro::serde_json;
+
+        struct DebuggerImpl;
+        wit_bindgen_rust::export!({
+            src["debugger_impl"]: #debugger_wit
+        });
+        impl debugger_impl::DebuggerImpl for DebuggerImpl {
+            fn handle_json(name: String, json: Vec<u8>) -> Vec<u8> {
+                match name.as_str() {
+                    #(#handle_names => {#handle_srcs})*
+                    _ => panic!("unknown handler")
+                }
+            }
+        }
+    }
+    .into()
+}

crates/debugger-macro/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "debugger-macro"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+debugger-macro-impl = { path = "../debugger-macro-impl" }

crates/debugger-macro/src/lib.rs

@@ -0,0 +1,2 @@
+pub use ::serde_json;
+pub use debugger_macro_impl::export_debug_handler;

crates/debugger/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "debugger"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = "1"
+anyhow = "1.0"
+wasmtime = "0.35.3"
+wasmtime-wasi = "0.35.3"
+wit-bindgen-wasmtime = { git = "https://github.com/bytecodealliance/wit-bindgen.git" }
+tide = "0.16.0"
+async-std = { version = "1.8.0", features = ["attributes"] }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"