[oden-js] Fix various bugs in module loader

oden-js/src/module/loader.rs

@@ -9,7 +9,7 @@ pub enum ModuleSource<'a> {
 }
 
 pub trait ModuleLoader {
-    fn load(&mut self, context: &ContextRef, name: &str) -> Result<ModuleSource>;
+    fn load(&self, context: &ContextRef, name: &str) -> Result<ModuleSource>;
 }
 
 pub struct DefaultModuleLoader {}
@@ -21,7 +21,7 @@ impl DefaultModuleLoader {
 }
 
 impl ModuleLoader for DefaultModuleLoader {
-    fn load(&mut self, _context: &ContextRef, name: &str) -> Result<ModuleSource> {
+    fn load(&self, _context: &ContextRef, name: &str) -> Result<ModuleSource> {
         // Attempt to open the file.
         let path = Path::new(name);
         match std::fs::read_to_string(path) {
@@ -34,7 +34,7 @@ impl ModuleLoader for DefaultModuleLoader {
 pub(crate) fn load_module(
     context: &ContextRef,
     name: &str,
-    loader: &mut Box<dyn ModuleLoader>,
+    loader: &Box<dyn ModuleLoader>,
 ) -> *mut sys::JSModuleDef {
     match loader.load(context, name) {
         Ok(ModuleSource::Native(native)) => native.module,

oden-js/src/runtime.rs

@@ -3,10 +3,11 @@ use crate::ContextRef;
 use oden_js_sys as sys;
 use std::cell::RefCell;
 use std::ffi::CStr;
+use std::sync::Arc;
 
 struct PrivateState {
     refs: u64,
-    loader: Box<dyn ModuleLoader>,
+    loader: Arc<Box<dyn ModuleLoader>>,
 }
 
 impl PrivateState {
@@ -20,9 +21,16 @@ impl PrivateState {
             Err(_) => return std::ptr::null_mut(),
         };
 
-        let state = opaque as *mut PrivateState;
+        let loader = unsafe {
+            let ptr = opaque as *const RefCell<PrivateState>;
+            ptr.as_ref()
+                .expect("We already know this runtime is one of ours!")
+                .borrow()
+                .loader
+                .clone()
+        };
         let context = ContextRef::from_raw(ctx);
-        load_module(&context, path, &mut (*state).loader)
+        load_module(&context, path, &loader)
     }
 }
 
@@ -39,7 +47,7 @@ impl Runtime {
     pub fn with_loader<TLoader: ModuleLoader + 'static>(loader: TLoader) -> Runtime {
         let state = Box::new(RefCell::new(PrivateState {
             refs: 1,
-            loader: Box::new(loader),
+            loader: Arc::new(Box::new(loader)),
         }));
         let rt = unsafe {
             let rt = sys::JS_NewRuntime();