docs: design merge

crates/interpreter/src/lib.rs

@@ -157,3 +157,4 @@ pub use syntax::{
     FuncType, GlobalType, ImportDesc, Limits, Mut, RefType, ResultType, TableType, ValType,
 };
 pub use valid::prepare;
+pub use valid::merge;

crates/interpreter/src/valid.rs

@@ -25,6 +25,15 @@ use crate::syntax::*;
 use crate::toctou::*;
 use crate::util::*;
 use crate::*;
+use crate::Error::Invalid;
+
+pub fn merge(binary: &[u8], side_table: Vec<MetadataEntry>) -> Result<Vec<u8>, Error> {
+    // Convert Vec<MetadataEntry> to Vec<u8>.
+    // Create a custom section at the beginning of the binary,
+    // and put the serialized `side_table` in it.
+    // Return the new module.
+    Err(Invalid)
+}
 
 /// Checks whether a WASM module in binary format is valid, and returns the side table.
 pub fn prepare(binary: &[u8]) -> Result<Vec<MetadataEntry>, Error> {

crates/interpreter/tests/spec.rs

@@ -164,8 +164,10 @@ impl<'m> Env<'m> {
     }
 
     fn maybe_instantiate(&mut self, name: &str, wasm: &[u8]) -> Result<InstId, Error> {
-        let module = self.alloc(wasm.len());
-        module.copy_from_slice(wasm);
+        let side_table = prepare(wasm)?;
+        let wasm_with_side_table = merge(wasm, side_table)?.as_slice();
+        let module = self.alloc(wasm_with_side_table.len());
+        module.copy_from_slice(wasm_with_side_table);
         let module = Module::new(module)?;
         let memory = self.alloc(mem_size(name));
         self.store.instantiate(module, memory)