fix export isolation issues

Signed-off-by: Henry Gressmann <mail@henrygressmann.de>

8 files changed, 200 insertions, 328 deletions

diff --git a/crates/tinywasm/src/export.rs b/crates/tinywasm/src/export.rs
index 52adc6f..8b13789 100644
--- a/crates/tinywasm/src/export.rs
+++ b/crates/tinywasm/src/export.rs
@@ -1,18 +1 @@
-use alloc::boxed::Box;
-use tinywasm_types::{Export, ExternalKind};
 
-#[derive(Debug)]
-/// Exports of a module instance
-// TODO: Maybe use a BTreeMap instead?
-pub struct ExportInstance(pub(crate) Box<[Export]>);
-
-impl ExportInstance {
-    /// Get an export by name
-    pub fn get(&self, name: &str, ty: ExternalKind) -> Option<&Export> {
-        self.0.iter().find(|e| e.name == name.into() && e.kind == ty)
-    }
-
-    pub(crate) fn get_untyped(&self, name: &str) -> Option<&Export> {
-        self.0.iter().find(|e| e.name == name.into())
-    }
-}
diff --git a/crates/tinywasm/src/imports.rs b/crates/tinywasm/src/imports.rs
index e7f9b81..f89ba64 100644
--- a/crates/tinywasm/src/imports.rs
+++ b/crates/tinywasm/src/imports.rs
@@ -11,12 +11,12 @@ use alloc::{
     vec::Vec,
 };
 use tinywasm_types::{
-    ExternVal, ExternalKind, FuncAddr, GlobalAddr, GlobalType, Import, MemAddr, MemoryType, ModuleInstanceAddr,
-    TableAddr, TableType, WasmFunction, WasmValue,
+    Addr, Export, ExternVal, ExternalKind, FuncAddr, GlobalAddr, GlobalType, Import, MemAddr, MemoryType,
+    ModuleInstanceAddr, TableAddr, TableType, WasmFunction, WasmValue,
 };
 
 /// The internal representation of a function
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum Function {
     /// A host function
     Host(HostFunction),
@@ -26,6 +26,7 @@ pub enum Function {
 }
 
 /// A host function
+#[derive(Clone)]
 pub struct HostFunction {
     pub(crate) ty: tinywasm_types::FuncType,
     pub(crate) func: Arc<dyn Fn(&mut crate::Store, &[WasmValue]) -> Result<Vec<WasmValue>> + 'static + Send + Sync>,
@@ -33,14 +34,11 @@ pub struct HostFunction {
 
 impl Debug for HostFunction {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        f.debug_struct("HostFunction")
-            .field("ty", &self.ty)
-            .field("func", &"...")
-            .finish()
+        f.debug_struct("HostFunction").field("ty", &self.ty).field("func", &"...").finish()
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 #[non_exhaustive]
 /// An external value
 pub enum Extern {
@@ -58,25 +56,25 @@ pub enum Extern {
 }
 
 /// A function
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ExternFunc(pub(crate) HostFunction);
 
 /// A global value
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ExternGlobal {
     pub(crate) ty: GlobalType,
     pub(crate) val: WasmValue,
 }
 
 /// A table
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ExternTable {
     pub(crate) ty: TableType,
     pub(crate) val: WasmValue,
 }
 
 /// A memory
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ExternMemory {
     pub(crate) ty: MemoryType,
 }
@@ -84,13 +82,7 @@ pub struct ExternMemory {
 impl Extern {
     /// Create a new global import
     pub fn global(val: WasmValue, mutable: bool) -> Self {
-        Self::Global(ExternGlobal {
-            ty: GlobalType {
-                ty: val.val_type(),
-                mutable,
-            },
-            val,
-        })
+        Self::Global(ExternGlobal { ty: GlobalType { ty: val.val_type(), mutable }, val })
     }
 
     /// Create a new table import
@@ -113,10 +105,7 @@ impl Extern {
             func(store, &args)
         };
 
-        Self::Func(Function::Host(HostFunction {
-            func: Arc::new(inner_func),
-            ty: ty.clone(),
-        }))
+        Self::Func(Function::Host(HostFunction { func: Arc::new(inner_func), ty: ty.clone() }))
     }
 
     /// Create a new typed function import
@@ -131,15 +120,9 @@ impl Extern {
             Ok(result.into_wasm_value_tuple())
         };
 
-        let ty = tinywasm_types::FuncType {
-            params: P::val_types(),
-            results: R::val_types(),
-        };
+        let ty = tinywasm_types::FuncType { params: P::val_types(), results: R::val_types() };
 
-        Self::Func(Function::Host(HostFunction {
-            func: Arc::new(inner_func),
-            ty,
-        }))
+        Self::Func(Function::Host(HostFunction { func: Arc::new(inner_func), ty }))
     }
 
     pub(crate) fn kind(&self) -> ExternalKind {
@@ -161,10 +144,7 @@ pub struct ExternName {
 
 impl From<&Import> for ExternName {
     fn from(import: &Import) -> Self {
-        Self {
-            module: import.module.to_string(),
-            name: import.name.to_string(),
-        }
+        Self { module: import.module.to_string(), name: import.name.to_string() }
     }
 }
 
@@ -183,79 +163,23 @@ pub(crate) enum ResolvedExtern<S, V> {
     Extern(V),
 }
 
-pub(crate) enum ResolvedImport {
-    Extern(Extern),
-    Store(ExternVal),
-}
-
-impl ResolvedImport {
-    fn initialize(self, store: &mut crate::Store, idx: ModuleInstanceAddr) -> Result<ExternVal> {
-        match self {
-            Self::Extern(extern_) => match extern_ {
-                Extern::Global(global) => {
-                    let addr = store.add_global(global.ty, global.val.into(), idx)?;
-                    Ok(ExternVal::Global(addr))
-                }
-                Extern::Table(table) => {
-                    // todo: do something with the initial value
-                    let addr = store.add_table(table.ty, idx)?;
-                    Ok(ExternVal::Table(addr))
-                }
-                Extern::Memory(memory) => {
-                    let addr = store.add_mem(memory.ty, idx)?;
-                    Ok(ExternVal::Mem(addr))
-                }
-                Extern::Func(func) => {
-                    let addr = store.add_func(func, idx)?;
-                    Ok(ExternVal::Func(addr))
-                }
-            },
-            Self::Store(extern_val) => Ok(extern_val.clone()),
-        }
-    }
-}
-
 pub(crate) struct ResolvedImports {
-    pub(crate) globals: Vec<ResolvedExtern<GlobalAddr, ExternGlobal>>,
-    pub(crate) tables: Vec<ResolvedExtern<TableAddr, ExternTable>>,
-    pub(crate) mems: Vec<ResolvedExtern<MemAddr, ExternMemory>>,
-    pub(crate) funcs: Vec<ResolvedExtern<FuncAddr, ExternFunc>>,
+    pub(crate) globals: Vec<GlobalAddr>,
+    pub(crate) tables: Vec<TableAddr>,
+    pub(crate) mems: Vec<MemAddr>,
+    pub(crate) funcs: Vec<FuncAddr>,
 }
 
 impl ResolvedImports {
     pub(crate) fn new() -> Self {
-        Self {
-            globals: Vec::new(),
-            tables: Vec::new(),
-            mems: Vec::new(),
-            funcs: Vec::new(),
-        }
-    }
-
-    pub(crate) fn globals(&self) -> &[ResolvedExtern<GlobalAddr, ExternGlobal>] {
-        &self.globals
-    }
-
-    pub(crate) fn tables(&self) -> &[ResolvedExtern<TableAddr, ExternTable>] {
-        &self.tables
-    }
-
-    pub(crate) fn mems(&self) -> &[ResolvedExtern<MemAddr, ExternMemory>] {
-        &self.mems
-    }
-
-    pub(crate) fn funcs(&self) -> &[ResolvedExtern<FuncAddr, ExternFunc>] {
-        &self.funcs
+        Self { globals: Vec::new(), tables: Vec::new(), mems: Vec::new(), funcs: Vec::new() }
     }
 }
 
 impl Imports {
     /// Create a new empty import set
     pub fn new() -> Self {
-        Imports {
-            values: BTreeMap::new(),
-            modules: BTreeMap::new(),
-        }
+        Imports { values: BTreeMap::new(), modules: BTreeMap::new() }
     }
 
     /// Link a module
@@ -268,39 +192,43 @@ impl Imports {
 
     /// Define an import
     pub fn define(&mut self, module: &str, name: &str, value: Extern) -> Result<&mut Self> {
-        self.values.insert(
-            ExternName {
-                module: module.to_string(),
-                name: name.to_string(),
-            },
-            value,
-        );
+        self.values.insert(ExternName { module: module.to_string(), name: name.to_string() }, value);
         Ok(self)
     }
 
-    pub(crate) fn take(&mut self, store: &mut crate::Store, import: &Import) -> Option<ResolvedImport> {
-        // TODO: compare types
-
+    pub(crate) fn take(
+        &mut self,
+        store: &mut crate::Store,
+        import: &Import,
+    ) -> Option<ResolvedExtern<ExternVal, Extern>> {
         let name = ExternName::from(import);
-        if let Some(v) = self.values.remove(&name) {
-            return Some(ResolvedImport::Extern(v));
+        log::error!("provided externs: {:?}", self.values.keys());
+        if let Some(v) = self.values.get(&name) {
+            return Some(ResolvedExtern::Extern(v.clone()));
         }
+        log::error!("failed to resolve import: {:?}", name);
+        // TODO:
+        // if let Some(addr) = self.modules.get(&name.module) {
+        //     let instance = store.get_module_instance(*addr)?;
+        //     let exports = instance.exports();
 
-        return None;
-
-        // TODO: allow linking to other modules
-        // if let Some(module_addr) = self.modules.get(&name.module) {
-        //     let Some(module) = store.get_module_instance(*module_addr) else {
-        //         return None;
+        //     let export = exports.get_untyped(&import.name)?;
+        //     let addr = match export.kind {
+        //         ExternalKind::Global(g) => ExternVal::Global(),
         //     };
 
-        //     let export = module.exports().get_untyped(&name.name)?;
-        // };
+        //     return Some(ResolvedExtern::Store());
+        // }
 
-        // then check if the import is defined
+        None
     }
 
-    pub(crate) fn link(mut self, store: &mut crate::Store, module: &crate::Module) -> Result<ResolvedImports> {
+    pub(crate) fn link(
+        mut self,
+        store: &mut crate::Store,
+        module: &crate::Module,
+        idx: ModuleInstanceAddr,
+    ) -> Result<ResolvedImports> {
         let mut imports = ResolvedImports::new();
 
         for import in module.data.imports.iter() {
@@ -311,28 +239,57 @@ impl Imports {
                 });
             };
 
-            // validate import
-            // if export.kind != (&import.kind).into() {
-            //     return Err(crate::Error::InvalidImportType {
-            //         module: import.module.to_string(),
-            //         name: import.name.to_string(),
-            //     });
-            // }
+            match val {
+                // A link to something that needs to be added to the store
+                ResolvedExtern::Extern(ex) => {
+                    // check if the kind matches
+                    let kind = ex.kind();
+                    if kind != (&import.kind).into() {
+                        return Err(crate::Error::InvalidImportType {
+                            module: import.module.to_string(),
+                            name: import.name.to_string(),
+                        });
+                    }
+
+                    // TODO: check if the type matches
 
-            // let val = match export.kind {
-            //     ExternalKind::Func => ExternVal::Func(export.index),
-            //     ExternalKind::Global => ExternVal::Global(export.index),
-            //     ExternalKind::Table => ExternVal::Table(export.index),
-            //     ExternalKind::Memory => ExternVal::Mem(export.index),
-            // };
+                    // add it to the store and get the address
+                    let addr = match ex {
+                        Extern::Global(g) => store.add_global(g.ty, g.val.into(), idx)?,
+                        Extern::Table(t) => store.add_table(t.ty, idx)?,
+                        Extern::Memory(m) => store.add_mem(m.ty, idx)?,
+                        Extern::Func(f) => store.add_func(f, idx)?,
+                    };
+
+                    // store the link
+                    match &kind {
+                        ExternalKind::Global => imports.globals.push(addr),
+                        ExternalKind::Table => imports.tables.push(addr),
+                        ExternalKind::Memory => imports.mems.push(addr),
+                        ExternalKind::Func => imports.funcs.push(addr),
+                    }
+                }
 
-            // imports.0.insert(
-            //     ExternName {
-            //         module: import.module.to_string(),
-            //         name: import.name.to_string(),
-            //     },
-            //     ResolvedImport::Store(val),
-            // );
+                // A link to something already in the store
+                ResolvedExtern::Store(val) => {
+                    // check if the kind matches
+                    if val.kind() != (&import.kind).into() {
+                        return Err(crate::Error::InvalidImportType {
+                            module: import.module.to_string(),
+                            name: import.name.to_string(),
+                        });
+                    }
+
+                    // TODO: check if the type matches
+
+                    match val {
+                        ExternVal::Global(g) => imports.globals.push(g),
+                        ExternVal::Table(t) => imports.tables.push(t),
+                        ExternVal::Mem(m) => imports.mems.push(m),
+                        ExternVal::Func(f) => imports.funcs.push(f),
+                    }
+                }
+            }
         }
 
         Ok(imports)
diff --git a/crates/tinywasm/src/instance.rs b/crates/tinywasm/src/instance.rs
index b8f87d7..92db518 100644
--- a/crates/tinywasm/src/instance.rs
+++ b/crates/tinywasm/src/instance.rs
@@ -1,11 +1,12 @@
 use alloc::{boxed::Box, format, string::ToString, sync::Arc, vec::Vec};
 use tinywasm_types::{
-    DataAddr, ElemAddr, ExternalKind, FuncAddr, FuncType, GlobalAddr, Import, MemAddr, ModuleInstanceAddr, TableAddr,
+    DataAddr, ElemAddr, Export, ExternVal, ExternalKind, FuncAddr, FuncType, GlobalAddr, Import, MemAddr,
+    ModuleInstanceAddr, TableAddr,
 };
 
 use crate::{
     func::{FromWasmValueTuple, IntoWasmValueTuple},
-    Error, ExportInstance, FuncHandle, Imports, Module, Result, Store, TypedFuncHandle,
+    Error, FuncHandle, Imports, Module, Result, Store, TypedFuncHandle,
 };
 
 /// A WebAssembly Module Instance
@@ -32,7 +33,7 @@ pub(crate) struct ModuleInstanceInner {
 
     pub(crate) func_start: Option<FuncAddr>,
     pub(crate) imports: Box<[Import]>,
-    pub(crate) exports: ExportInstance,
+    pub(crate) exports: Box<[Export]>,
 }
 
 impl ModuleInstance {
@@ -52,36 +53,33 @@ impl ModuleInstance {
         let idx = store.next_module_instance_idx();
         let imports = imports.unwrap_or_default();
 
-        let linked_imports = imports.link(store, &module)?;
-        let global_addrs = store.add_globals(module.data.globals.into(), idx)?;
+        let mut addrs = imports.link(store, &module, idx)?;
+        let data = module.data;
 
-        // TODO: imported functions missing
-        let func_addrs = store.add_funcs(module.data.funcs.into(), idx)?;
+        addrs.globals.extend(store.init_globals(data.globals.into(), idx)?);
+        addrs.funcs.extend(store.init_funcs(data.funcs.into(), idx)?);
+        addrs.tables.extend(store.init_tables(data.table_types.into(), idx)?);
+        addrs.mems.extend(store.init_mems(data.memory_types.into(), idx)?);
 
-        let table_addrs = store.add_tables(module.data.table_types.into(), idx)?;
-        let mem_addrs = store.add_mems(module.data.memory_types.into(), idx)?;
-
-        // TODO: active/declared elems need to be initialized
-        let elem_addrs = store.add_elems(module.data.elements.into(), idx)?;
-
-        // TODO: active data segments need to be initialized
-        let data_addrs = store.add_datas(module.data.data.into(), idx)?;
+        let elem_addrs = store.add_elems(data.elements.into(), idx)?;
+        let data_addrs = store.add_datas(data.data.into(), idx)?;
 
         let instance = ModuleInstanceInner {
             store_id: store.id(),
             idx,
 
-            types: module.data.func_types,
-            func_addrs,
-            table_addrs,
-            mem_addrs,
-            global_addrs,
+            types: data.func_types,
+
+            func_addrs: addrs.funcs,
+            table_addrs: addrs.tables,
+            mem_addrs: addrs.mems,
+            global_addrs: addrs.globals,
             elem_addrs,
             data_addrs,
 
-            func_start: module.data.start_func,
-            imports: module.data.imports,
-            exports: crate::ExportInstance(module.data.exports),
+            func_start: data.start_func,
+            imports: data.imports,
+            exports: data.exports,
         };
 
         let instance = ModuleInstance::new(instance);
@@ -91,8 +89,17 @@ impl ModuleInstance {
     }
 
     /// Get the module's exports
-    pub fn exports(&self) -> &ExportInstance {
-        &self.0.exports
+    pub(crate) fn export(&self, name: &str) -> Option<ExternVal> {
+        let exports = self.0.exports.iter().find(|e| e.name == name.into())?;
+        let kind = exports.kind.clone();
+        let addr = match kind {
+            ExternalKind::Func => self.0.func_addrs.get(exports.index as usize)?,
+            ExternalKind::Table => self.0.table_addrs.get(exports.index as usize)?,
+            ExternalKind::Memory => self.0.mem_addrs.get(exports.index as usize)?,
+            ExternalKind::Global => self.0.global_addrs.get(exports.index as usize)?,
+        };
+
+        Some(ExternVal::new(kind, *addr))
     }
 
     pub(crate) fn func_addrs(&self) -> &[FuncAddr] {
@@ -145,28 +152,21 @@ impl ModuleInstance {
             return Err(Error::InvalidStore);
         }
 
-        let export = self
-            .0
-            .exports
-            .get(name, ExternalKind::Func)
-            .ok_or_else(|| Error::Other(format!("Export not found: {}", name)))?;
-
-        let func_addr = self
-            .0
-            .func_addrs
-            .get(export.index as usize)
-            .expect("No func addr for export, this is a bug");
+        let export = self.export(name).ok_or_else(|| Error::Other(format!("Export not found: {}", name)))?;
+        let ExternVal::Func(func_addr) = export else {
+            return Err(Error::Other(format!("Export is not a function: {}", name)));
+        };
 
-        let func_inst = store.get_func(*func_addr as usize)?;
+        let func_inst = store.get_func(func_addr as usize)?;
         let func = func_inst.assert_wasm()?;
-        let ty = self.0.types[func.ty_addr as usize].clone();
+        let ty = self
+            .0
+            .types
+            .get(func.ty_addr as usize)
+            .ok_or_else(|| Error::Other(format!("Invalid function type address: {}", func.ty_addr)))?
+            .clone();
 
-        Ok(FuncHandle {
-            addr: export.index,
-            module: self.clone(),
-            name: Some(name.to_string()),
-            ty,
-        })
+        Ok(FuncHandle { addr: func_addr, module: self.clone(), name: Some(name.to_string()), ty })
     }
 
     /// Get a typed exported function by name
@@ -176,10 +176,7 @@ impl ModuleInstance {
         R: FromWasmValueTuple,
     {
         let func = self.exported_func_by_name(store, name)?;
-        Ok(TypedFuncHandle {
-            func,
-            marker: core::marker::PhantomData,
-        })
+        Ok(TypedFuncHandle { func, marker: core::marker::PhantomData })
     }
 
     /// Get the start function of the module
@@ -198,30 +195,21 @@ impl ModuleInstance {
             Some(func_index) => func_index,
             None => {
                 // alternatively, check for a _start function in the exports
-                let Some(start) = self.0.exports.get("_start", ExternalKind::Func) else {
+                let Some(ExternVal::Func(func_addr)) = self.export("_start") else {
                     return Ok(None);
                 };
 
-                start.index
+                func_addr
             }
         };
 
-        let func_addr = self
-            .0
-            .func_addrs
-            .get(func_index as usize)
-            .expect("No func addr for start func, this is a bug");
+        let func_addr = self.0.func_addrs.get(func_index as usize).expect("No func addr for start func, this is a bug");
 
         let func_inst = store.get_func(*func_addr as usize)?;
         let func = func_inst.assert_wasm()?;
         let ty = self.0.types[func.ty_addr as usize].clone();
 
-        Ok(Some(FuncHandle {
-            module: self.clone(),
-            addr: *func_addr,
-            ty,
-            name: None,
-        }))
+        Ok(Some(FuncHandle { module: self.clone(), addr: *func_addr, ty, name: None }))
     }
 
     /// Invoke the start function of the module
diff --git a/crates/tinywasm/src/lib.rs b/crates/tinywasm/src/lib.rs
index 0c1863f..64d34df 100644
--- a/crates/tinywasm/src/lib.rs
+++ b/crates/tinywasm/src/lib.rs
@@ -2,10 +2,7 @@
 #![forbid(unsafe_code)]
 #![doc(test(
     no_crate_inject,
-    attr(
-        deny(warnings, rust_2018_idioms),
-        allow(dead_code, unused_assignments, unused_variables)
-    )
+    attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_assignments, unused_variables))
 ))]
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms, unreachable_pub)]
 #![cfg_attr(nightly, feature(error_in_core))]
@@ -89,9 +86,6 @@ pub use module::Module;
 mod instance;
 pub use instance::ModuleInstance;
 
-mod export;
-pub use export::ExportInstance;
-
 mod func;
 pub use func::{FuncHandle, TypedFuncHandle};
 
diff --git a/crates/tinywasm/src/runtime/executor/mod.rs b/crates/tinywasm/src/runtime/executor/mod.rs
index 5e191cc..62f17e7 100644
--- a/crates/tinywasm/src/runtime/executor/mod.rs
+++ b/crates/tinywasm/src/runtime/executor/mod.rs
@@ -16,7 +16,6 @@ use traits::*;
 
 impl DefaultRuntime {
     pub(crate) fn exec(&self, store: &mut Store, stack: &mut Stack, module: ModuleInstance) -> Result<()> {
-        log::debug!("exports: {:?}", module.exports());
         log::debug!("func_addrs: {:?}", module.func_addrs());
         log::debug!("func_ty_addrs: {:?}", module.func_ty_addrs().len());
         log::debug!("store funcs: {:?}", store.data.funcs.len());
@@ -162,11 +161,9 @@ fn exec_one(
             let func_ty = module.func_ty(func.ty_addr);
 
             if func_ty != call_ty {
-                return Err(Trap::IndirectCallTypeMismatch {
-                    actual: func_ty.clone(),
-                    expected: call_ty.clone(),
-                }
-                .into());
+                return Err(
+                    Trap::IndirectCallTypeMismatch { actual: func_ty.clone(), expected: call_ty.clone() }.into()
+                );
             }
 
             let params = stack.values.pop_n(func_ty.params.len())?;
@@ -569,10 +566,7 @@ fn exec_one(
 
         i => {
             log::error!("unimplemented instruction: {:?}", i);
-            return Err(Error::UnsupportedFeature(alloc::format!(
-                "unimplemented instruction: {:?}",
-                i
-            )));
+            return Err(Error::UnsupportedFeature(alloc::format!("unimplemented instruction: {:?}", i)));
         }
     };
 
diff --git a/crates/tinywasm/src/store.rs b/crates/tinywasm/src/store.rs
index 9b2f711..426ca78 100644
--- a/crates/tinywasm/src/store.rs
+++ b/crates/tinywasm/src/store.rs
@@ -7,7 +7,7 @@ use core::{
 
 use alloc::{format, rc::Rc, string::ToString, vec, vec::Vec};
 use tinywasm_types::{
-    Addr, Data, DataAddr, ElemAddr, Element, ElementKind, FuncAddr, Global, GlobalType, Import, MemAddr, MemoryArch,
+    Addr, Data, DataAddr, ElemAddr, Element, ElementKind, FuncAddr, Global, GlobalType, MemAddr, MemoryArch,
     MemoryType, ModuleInstanceAddr, TableAddr, TableType, WasmFunction,
 };
 
@@ -114,7 +114,7 @@ impl Store {
     }
 
     /// Add functions to the store, returning their addresses in the store
-    pub(crate) fn add_funcs(&mut self, funcs: Vec<WasmFunction>, idx: ModuleInstanceAddr) -> Result<Vec<FuncAddr>> {
+    pub(crate) fn init_funcs(&mut self, funcs: Vec<WasmFunction>, idx: ModuleInstanceAddr) -> Result<Vec<FuncAddr>> {
         let func_count = self.data.funcs.len();
         let mut func_addrs = Vec::with_capacity(func_count);
         for func in funcs.into_iter() {
@@ -124,7 +124,7 @@ impl Store {
     }
 
     /// Add tables to the store, returning their addresses in the store
-    pub(crate) fn add_tables(&mut self, tables: Vec<TableType>, idx: ModuleInstanceAddr) -> Result<Vec<TableAddr>> {
+    pub(crate) fn init_tables(&mut self, tables: Vec<TableType>, idx: ModuleInstanceAddr) -> Result<Vec<TableAddr>> {
         let table_count = self.data.tables.len();
         let mut table_addrs = Vec::with_capacity(table_count);
         for (i, table) in tables.into_iter().enumerate() {
@@ -134,7 +134,7 @@ impl Store {
     }
 
     /// Add memories to the store, returning their addresses in the store
-    pub(crate) fn add_mems(&mut self, mems: Vec<MemoryType>, idx: ModuleInstanceAddr) -> Result<Vec<MemAddr>> {
+    pub(crate) fn init_mems(&mut self, mems: Vec<MemoryType>, idx: ModuleInstanceAddr) -> Result<Vec<MemAddr>> {
         let mem_count = self.data.mems.len();
         let mut mem_addrs = Vec::with_capacity(mem_count);
         for (i, mem) in mems.into_iter().enumerate() {
@@ -144,7 +144,7 @@ impl Store {
     }
 
     /// Add globals to the store, returning their addresses in the store
-    pub(crate) fn add_globals(&mut self, globals: Vec<Global>, idx: ModuleInstanceAddr) -> Result<Vec<Addr>> {
+    pub(crate) fn init_globals(&mut self, globals: Vec<Global>, idx: ModuleInstanceAddr) -> Result<Vec<Addr>> {
         let global_count = self.data.globals.len();
         let mut global_addrs = Vec::with_capacity(global_count);
         // then add the module globals
@@ -156,16 +156,12 @@ impl Store {
     }
 
     pub(crate) fn add_global(&mut self, ty: GlobalType, value: RawWasmValue, idx: ModuleInstanceAddr) -> Result<Addr> {
-        self.data
-            .globals
-            .push(Rc::new(RefCell::new(GlobalInstance::new(ty, value, idx))));
+        self.data.globals.push(Rc::new(RefCell::new(GlobalInstance::new(ty, value, idx))));
         Ok(self.data.globals.len() as Addr - 1)
     }
 
     pub(crate) fn add_table(&mut self, table: TableType, idx: ModuleInstanceAddr) -> Result<TableAddr> {
-        self.data
-            .tables
-            .push(Rc::new(RefCell::new(TableInstance::new(table, idx))));
+        self.data.tables.push(Rc::new(RefCell::new(TableInstance::new(table, idx))));
         Ok(self.data.tables.len() as TableAddr - 1)
     }
 
@@ -173,9 +169,7 @@ impl Store {
         if let MemoryArch::I64 = mem.arch {
             return Err(Error::UnsupportedFeature("64-bit memories".to_string()));
         }
-        self.data
-            .mems
-            .push(Rc::new(RefCell::new(MemoryInstance::new(mem, idx))));
+        self.data.mems.push(Rc::new(RefCell::new(MemoryInstance::new(mem, idx))));
         Ok(self.data.mems.len() as MemAddr - 1)
     }
 
@@ -203,6 +197,7 @@ impl Store {
         Ok(self.data.funcs.len() as FuncAddr - 1)
     }
 
+    /// Evaluate a constant expression, only supporting i32 globals and i32.const
     pub(crate) fn eval_i32_const(&self, const_instr: &tinywasm_types::ConstInstruction) -> Result<i32> {
         use tinywasm_types::ConstInstruction::*;
         let val = match const_instr {
@@ -218,6 +213,7 @@ impl Store {
         Ok(val)
     }
 
+    /// Evaluate a constant expression
     pub(crate) fn eval_const(&self, const_instr: &tinywasm_types::ConstInstruction) -> Result<RawWasmValue> {
         use tinywasm_types::ConstInstruction::*;
         let val = match const_instr {
@@ -300,9 +296,7 @@ impl Store {
                 Active { mem: mem_addr, offset } => {
                     // a. Assert: memidx == 0
                     if mem_addr != 0 {
-                        return Err(Error::UnsupportedFeature(
-                            "data segments for non-zero memories".to_string(),
-                        ));
+                        return Err(Error::UnsupportedFeature("data segments for non-zero memories".to_string()));
                     }
 
                     let offset = self.eval_i32_const(&offset)?;
@@ -328,33 +322,21 @@ impl Store {
 
     /// Get the function at the actual index in the store
     pub(crate) fn get_func(&self, addr: usize) -> Result<&Rc<FunctionInstance>> {
-        self.data
-            .funcs
-            .get(addr)
-            .ok_or_else(|| Error::Other(format!("function {} not found", addr)))
+        self.data.funcs.get(addr).ok_or_else(|| Error::Other(format!("function {} not found", addr)))
     }
 
     /// Get the memory at the actual index in the store
     pub(crate) fn get_mem(&self, addr: usize) -> Result<&Rc<RefCell<MemoryInstance>>> {
-        self.data
-            .mems
-            .get(addr)
-            .ok_or_else(|| Error::Other(format!("memory {} not found", addr)))
+        self.data.mems.get(addr).ok_or_else(|| Error::Other(format!("memory {} not found", addr)))
     }
 
     /// Get the table at the actual index in the store
     pub(crate) fn get_table(&self, addr: usize) -> Result<&Rc<RefCell<TableInstance>>> {
-        self.data
-            .tables
-            .get(addr)
-            .ok_or_else(|| Error::Other(format!("table {} not found", addr)))
+        self.data.tables.get(addr).ok_or_else(|| Error::Other(format!("table {} not found", addr)))
     }
 
     pub(crate) fn get_elem(&self, addr: usize) -> Result<&ElemInstance> {
-        self.data
-            .elems
-            .get(addr)
-            .ok_or_else(|| Error::Other(format!("element {} not found", addr)))
+        self.data.elems.get(addr).ok_or_else(|| Error::Other(format!("element {} not found", addr)))
     }
 
     /// Get the global at the actual index in the store
@@ -413,18 +395,11 @@ pub(crate) struct TableInstance {
 
 impl TableInstance {
     pub(crate) fn new(kind: TableType, owner: ModuleInstanceAddr) -> Self {
-        Self {
-            elements: vec![0; kind.size_initial as usize],
-            kind,
-            owner,
-        }
+        Self { elements: vec![0; kind.size_initial as usize], kind, owner }
     }
 
     pub(crate) fn get(&self, addr: usize) -> Result<Addr> {
-        self.elements
-            .get(addr)
-            .copied()
-            .ok_or_else(|| Trap::UndefinedElement { index: addr }.into())
+        self.elements.get(addr).copied().ok_or_else(|| Trap::UndefinedElement { index: addr }.into())
     }
 
     pub(crate) fn set(&mut self, addr: usize, value: Addr) -> Result<()> {
@@ -442,20 +417,11 @@ impl TableInstance {
     pub(crate) fn init(&mut self, offset: i32, init: &[Addr]) -> Result<()> {
         let offset = offset as usize;
         let end = offset.checked_add(init.len()).ok_or_else(|| {
-            Error::Trap(crate::Trap::TableOutOfBounds {
-                offset,
-                len: init.len(),
-                max: self.elements.len(),
-            })
+            Error::Trap(crate::Trap::TableOutOfBounds { offset, len: init.len(), max: self.elements.len() })
         })?;
 
         if end > self.elements.len() || end < offset {
-            return Err(crate::Trap::TableOutOfBounds {
-                offset,
-                len: init.len(),
-                max: self.elements.len(),
-            }
-            .into());
+            return Err(crate::Trap::TableOutOfBounds { offset, len: init.len(), max: self.elements.len() }.into());
         }
 
         self.elements[offset..end].copy_from_slice(init);
@@ -493,11 +459,7 @@ impl MemoryInstance {
 
     pub(crate) fn store(&mut self, addr: usize, _align: usize, data: &[u8]) -> Result<()> {
         let end = addr.checked_add(data.len()).ok_or_else(|| {
-            Error::Trap(crate::Trap::MemoryOutOfBounds {
-                offset: addr,
-                len: data.len(),
-                max: self.data.len(),
-            })
+            Error::Trap(crate::Trap::MemoryOutOfBounds { offset: addr, len: data.len(), max: self.data.len() })
         })?;
 
         if end > self.data.len() || end < addr {
@@ -518,20 +480,12 @@ impl MemoryInstance {
     }
 
     pub(crate) fn load(&self, addr: usize, _align: usize, len: usize) -> Result<&[u8]> {
-        let end = addr.checked_add(len).ok_or_else(|| {
-            Error::Trap(crate::Trap::MemoryOutOfBounds {
-                offset: addr,
-                len,
-                max: self.max_pages(),
-            })
-        })?;
+        let end = addr
+            .checked_add(len)
+            .ok_or_else(|| Error::Trap(crate::Trap::MemoryOutOfBounds { offset: addr, len, max: self.max_pages() }))?;
 
         if end > self.data.len() {
-            return Err(Error::Trap(crate::Trap::MemoryOutOfBounds {
-                offset: addr,
-                len,
-                max: self.data.len(),
-            }));
+            return Err(Error::Trap(crate::Trap::MemoryOutOfBounds { offset: addr, len, max: self.data.len() }));
         }
 
         // WebAssembly doesn't require alignment for loads
diff --git a/crates/tinywasm/tests/generated/mvp.csv b/crates/tinywasm/tests/generated/mvp.csv
index e175639..a1eaf8c 100644
--- a/crates/tinywasm/tests/generated/mvp.csv
+++ b/crates/tinywasm/tests/generated/mvp.csv
@@ -2,4 +2,4 @@
 0.0.5,11135,9093,[{"name":"address.wast","passed":1,"failed":259},{"name":"align.wast","passed":108,"failed":48},{"name":"binary-leb128.wast","passed":78,"failed":13},{"name":"binary.wast","passed":107,"failed":5},{"name":"block.wast","passed":170,"failed":53},{"name":"br.wast","passed":20,"failed":77},{"name":"br_if.wast","passed":29,"failed":89},{"name":"br_table.wast","passed":24,"failed":150},{"name":"call.wast","passed":18,"failed":73},{"name":"call_indirect.wast","passed":34,"failed":136},{"name":"comments.wast","passed":5,"failed":3},{"name":"const.wast","passed":778,"failed":0},{"name":"conversions.wast","passed":25,"failed":594},{"name":"custom.wast","passed":10,"failed":1},{"name":"data.wast","passed":22,"failed":39},{"name":"elem.wast","passed":27,"failed":72},{"name":"endianness.wast","passed":1,"failed":68},{"name":"exports.wast","passed":90,"failed":6},{"name":"f32.wast","passed":1018,"failed":1496},{"name":"f32_bitwise.wast","passed":4,"failed":360},{"name":"f32_cmp.wast","passed":2407,"failed":0},{"name":"f64.wast","passed":1018,"failed":1496},{"name":"f64_bitwise.wast","passed":4,"failed":360},{"name":"f64_cmp.wast","passed":2407,"failed":0},{"name":"fac.wast","passed":1,"failed":7},{"name":"float_exprs.wast","passed":275,"failed":625},{"name":"float_literals.wast","passed":112,"failed":51},{"name":"float_memory.wast","passed":0,"failed":90},{"name":"float_misc.wast","passed":138,"failed":303},{"name":"forward.wast","passed":1,"failed":4},{"name":"func.wast","passed":81,"failed":91},{"name":"func_ptrs.wast","passed":7,"failed":29},{"name":"global.wast","passed":50,"failed":60},{"name":"i32.wast","passed":85,"failed":375},{"name":"i64.wast","passed":31,"failed":385},{"name":"if.wast","passed":116,"failed":125},{"name":"imports.wast","passed":23,"failed":160},{"name":"inline-module.wast","passed":1,"failed":0},{"name":"int_exprs.wast","passed":38,"failed":70},{"name":"int_literals.wast","passed":25,"failed":26},{"name":"labels.wast","passed":13,"failed":16},{"name":"left-to-right.wast","passed":0,"failed":96},{"name":"linking.wast","passed":5,"failed":127},{"name":"load.wast","passed":59,"failed":38},{"name":"local_get.wast","passed":18,"failed":18},{"name":"local_set.wast","passed":38,"failed":15},{"name":"local_tee.wast","passed":41,"failed":56},{"name":"loop.wast","passed":42,"failed":78},{"name":"memory.wast","passed":30,"failed":49},{"name":"memory_grow.wast","passed":11,"failed":85},{"name":"memory_redundancy.wast","passed":1,"failed":7},{"name":"memory_size.wast","passed":6,"failed":36},{"name":"memory_trap.wast","passed":1,"failed":181},{"name":"names.wast","passed":484,"failed":2},{"name":"nop.wast","passed":4,"failed":84},{"name":"return.wast","passed":20,"failed":64},{"name":"select.wast","passed":28,"failed":120},{"name":"skip-stack-guard-page.wast","passed":1,"failed":10},{"name":"stack.wast","passed":2,"failed":5},{"name":"start.wast","passed":4,"failed":16},{"name":"store.wast","passed":59,"failed":9},{"name":"switch.wast","passed":2,"failed":26},{"name":"token.wast","passed":39,"failed":19},{"name":"traps.wast","passed":4,"failed":32},{"name":"type.wast","passed":3,"failed":0},{"name":"unreachable.wast","passed":0,"failed":64},{"name":"unreached-invalid.wast","passed":118,"failed":0},{"name":"unwind.wast","passed":9,"failed":41},{"name":"utf8-custom-section-id.wast","passed":176,"failed":0},{"name":"utf8-import-field.wast","passed":176,"failed":0},{"name":"utf8-import-module.wast","passed":176,"failed":0},{"name":"utf8-invalid-encoding.wast","passed":176,"failed":0}]
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diff --git a/crates/types/src/lib.rs b/crates/types/src/lib.rs
index ac7f854..4d3c59a 100644
--- a/crates/types/src/lib.rs
+++ b/crates/types/src/lib.rs
@@ -2,10 +2,7 @@
 #![forbid(unsafe_code)]
 #![doc(test(
     no_crate_inject,
-    attr(
-        deny(warnings, rust_2018_idioms),
-        allow(dead_code, unused_assignments, unused_variables)
-    )
+    attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_assignments, unused_variables))
 ))]
 #![warn(missing_debug_implementations, rust_2018_idioms, unreachable_pub)]
 
@@ -314,6 +311,26 @@ pub enum ExternVal {
     Global(GlobalAddr),
 }
 
+impl ExternVal {
+    pub fn kind(&self) -> ExternalKind {
+        match self {
+            Self::Func(_) => ExternalKind::Func,
+            Self::Table(_) => ExternalKind::Table,
+            Self::Mem(_) => ExternalKind::Memory,
+            Self::Global(_) => ExternalKind::Global,
+        }
+    }
+
+    pub fn new(kind: ExternalKind, addr: Addr) -> Self {
+        match kind {
+            ExternalKind::Func => Self::Func(addr),
+            ExternalKind::Table => Self::Table(addr),
+            ExternalKind::Memory => Self::Mem(addr),
+            ExternalKind::Global => Self::Global(addr),
+        }
+    }
+}
+
 /// The type of a WebAssembly Function.
 ///
 /// See <https://webassembly.github.io/spec/core/syntax/types.html#function-types>
@@ -326,10 +343,7 @@ pub struct FuncType {
 impl FuncType {
     /// Get the number of parameters of a function type.
     pub fn empty() -> Self {
-        Self {
-            params: Box::new([]),
-            results: Box::new([]),
-        }
+        Self { params: Box::new([]), results: Box::new([]) }
     }
 }
 
@@ -372,19 +386,11 @@ pub struct TableType {
 
 impl TableType {
     pub fn empty() -> Self {
-        Self {
-            element_type: ValType::FuncRef,
-            size_initial: 0,
-            size_max: None,
-        }
+        Self { element_type: ValType::FuncRef, size_initial: 0, size_max: None }
     }
 
     pub fn new(element_type: ValType, size_initial: u32, size_max: Option<u32>) -> Self {
-        Self {
-            element_type,
-            size_initial,
-            size_max,
-        }
+        Self { element_type, size_initial, size_max }
     }
 }
 
@@ -400,11 +406,7 @@ pub struct MemoryType {
 
 impl MemoryType {
     pub fn new_32(page_count_initial: u64, page_count_max: Option<u64>) -> Self {
-        Self {
-            arch: MemoryArch::I32,
-            page_count_initial,
-            page_count_max,
-        }
+        Self { arch: MemoryArch::I32, page_count_initial, page_count_max }
     }
 
     // pub fn new_64(page_count_initial: u64, page_count_max: Option<u64>) -> Self {