From f8e35d52f3f8f49f5d83fc60a43380c3ade3f1f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20Fern=C3=A1ndez=20L=C3=B3pez?=
 <rfernandezl@vmware.com>
Date: Tue, 3 Oct 2023 11:28:36 +0200
Subject: [PATCH] chore: better identify errors when loading core modules or
 components

---
 Cargo.lock                  |  1 +
 Cargo.toml                  |  1 +
 crates/worker/Cargo.toml    |  1 +
 crates/worker/src/errors.rs | 16 ++++++++++++++--
 crates/worker/src/lib.rs    | 23 ++++++++++++++++++-----
 5 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 87bbc95..d3994b8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4216,6 +4216,7 @@ dependencies = [
  "tokio",
  "toml 0.7.8",
  "wasi-common",
+ "wasmparser 0.113.2",
  "wasmtime",
  "wasmtime-wasi",
  "wasmtime-wasi-nn",
diff --git a/Cargo.toml b/Cargo.toml
index e308c7d..b8a8f52 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -81,6 +81,7 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0.85"
 tokio = "1.28"
 toml = "0.7.0"
+wasmparser = "0.113.2"
 wws-config = { path = "./crates/config" }
 wws-runtimes = { path = "./crates/runtimes" }
 wws-data-kv = { path = "./crates/data-kv" }
diff --git a/crates/worker/Cargo.toml b/crates/worker/Cargo.toml
index 6bade55..23aec7b 100644
--- a/crates/worker/Cargo.toml
+++ b/crates/worker/Cargo.toml
@@ -16,6 +16,7 @@ serde = { workspace = true }
 serde_json = { workspace = true }
 tokio = { workspace = true }
 toml = { workspace = true }
+wasmparser = { workspace = true }
 wasmtime = { workspace = true }
 wasmtime-wasi = { workspace = true }
 wasmtime-wasi-nn = { workspace = true }
diff --git a/crates/worker/src/errors.rs b/crates/worker/src/errors.rs
index 83d1afc..7a8a89d 100644
--- a/crates/worker/src/errors.rs
+++ b/crates/worker/src/errors.rs
@@ -7,7 +7,13 @@ pub type Result<T> = std::result::Result<T, WorkerError>;
 
 #[derive(Debug)]
 pub enum WorkerError {
-    BadWasmModuleOrComponent,
+    BadWasmCoreModule {
+        error: String,
+    },
+    BadWasmComponent {
+        error: String,
+    },
+    BadWasmCoreModuleOrComponent,
     CannotLoadConfig,
     CannotParseConfig {
         path: PathBuf,
@@ -37,7 +43,13 @@ impl From<wws_runtimes::errors::RuntimeError> for WorkerError {
 impl std::fmt::Display for WorkerError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
-            WorkerError::BadWasmModuleOrComponent => write!(f, "Bad Wasm module or component"),
+            WorkerError::BadWasmCoreModule { error } => {
+                write!(f, "Bad Wasm core module: {}", error)
+            }
+            WorkerError::BadWasmComponent { error } => write!(f, "Bad Wasm component: {}", error),
+            WorkerError::BadWasmCoreModuleOrComponent => {
+                write!(f, "Bad Wasm core module or component")
+            }
             WorkerError::CannotLoadConfig => write!(f, "Could not load configuration"),
             WorkerError::CannotParseConfig { path, error } => write!(
                 f,
diff --git a/crates/worker/src/lib.rs b/crates/worker/src/lib.rs
index 3e45c78..7a4f880 100644
--- a/crates/worker/src/lib.rs
+++ b/crates/worker/src/lib.rs
@@ -130,12 +130,25 @@ impl Worker {
         })?;
         let runtime = init_runtime(project_root, path, project_config)?;
         let bytes = runtime.module_bytes()?;
-        let module_or_component = if let Ok(module) = Module::from_binary(&engine, &bytes) {
-            Ok(ModuleOrComponent::Module(module))
-        } else if let Ok(component) = Component::from_binary(&engine, &bytes) {
-            Ok(ModuleOrComponent::Component(component))
+
+        let module_or_component = if wasmparser::Parser::is_core_wasm(&bytes) {
+            Ok(ModuleOrComponent::Module(
+                Module::from_binary(&engine, &bytes).map_err(|err| {
+                    errors::WorkerError::BadWasmCoreModule {
+                        error: format!("{:?}", err),
+                    }
+                })?,
+            ))
+        } else if wasmparser::Parser::is_component(&bytes) {
+            Ok(ModuleOrComponent::Component(
+                Component::from_binary(&engine, &bytes).map_err(|err| {
+                    errors::WorkerError::BadWasmComponent {
+                        error: format!("{:?}", err),
+                    }
+                })?,
+            ))
         } else {
-            Err(errors::WorkerError::BadWasmModuleOrComponent)
+            Err(errors::WorkerError::BadWasmCoreModuleOrComponent)
         }?;
 
         // Prepare the environment if required