Improved Emscripten / WASI autodetection

lib/emscripten/src/utils.rs

@@ -24,7 +24,9 @@ pub fn is_emscripten_module(module: &Module) -> bool {
             .namespace_table
             .get(import_name.namespace_index);
         let field = module.info().name_table.get(import_name.name_index);
-        if (field == "_emscripten_memcpy_big" || field == "emscripten_memcpy_big")
+        if (field == "_emscripten_memcpy_big"
+            || field == "emscripten_memcpy_big"
+            || field == "__map_file")
             && namespace == "env"
         {
             return true;

lib/runtime-core/src/structures/map.rs

@@ -39,6 +39,10 @@ where
         self.elems.len()
     }
 
+    pub fn is_empty(&self) -> bool {
+        self.elems.is_empty()
+    }
+
     pub fn push(&mut self, value: V) -> K {
         let len = self.len();
         self.elems.push(value);

lib/wasi/src/utils.rs

@@ -2,14 +2,17 @@ use wasmer_runtime_core::module::Module;
 
 /// Check if a provided module is compiled with WASI support
 pub fn is_wasi_module(module: &Module) -> bool {
+    if module.info().imported_functions.is_empty() {
+        return false;
+    }
     for (_, import_name) in &module.info().imported_functions {
         let namespace = module
             .info()
             .namespace_table
             .get(import_name.namespace_index);
-        if namespace == "wasi_unstable" {
-            return true;
+        if namespace != "wasi_unstable" {
+            return false;
         }
     }
-    false
+    true
 }

src/bin/wasmer.rs

@@ -512,7 +512,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
         import_object.allow_missing_functions = true; // Import initialization might be left to the loader.
         let instance = module
             .instantiate(&import_object)
-            .map_err(|e| format!("Can't instantiate module: {:?}", e))?;
+            .map_err(|e| format!("Can't instantiate loader module: {:?}", e))?;
 
         let args: Vec<Value> = options
             .args
@@ -551,7 +551,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
         let import_object = wasmer_emscripten::generate_emscripten_env(&mut emscripten_globals);
         let mut instance = module
             .instantiate(&import_object)
-            .map_err(|e| format!("Can't instantiate module: {:?}", e))?;
+            .map_err(|e| format!("Can't instantiate emscripten module: {:?}", e))?;
 
         wasmer_emscripten::run_emscripten_instance(
             &module,
@@ -591,7 +591,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
             #[allow(unused_mut)] // mut used in feature
             let mut instance = module
                 .instantiate(&import_object)
-                .map_err(|e| format!("Can't instantiate module: {:?}", e))?;
+                .map_err(|e| format!("Can't instantiate WASI module: {:?}", e))?;
 
             let start: Func<(), ()> = instance.func("_start").map_err(|e| format!("{:?}", e))?;