feat: use refactored walrus API

After the work done upstreaming operations used in `src/walrus_ops.rs`
to walrus, the code for WASI-Virt can be updated to use the new APIs
and reduce custom code.

This commit updates the WASI-Virt codebase to use the upstreamed
functions and adds some light refactors to the more mechanical pieces
of code for stubbing/denying/stripping.

see: bytecodealliance#20

Signed-off-by: Victor Adossi <vadossi@cosmonic.com>

Cargo.toml

@@ -18,7 +18,7 @@ members = [
   "tests/components/do-everything",
   "tests/components/file-read",
   "tests/components/get-env",
-  "tests/components/stdio"
+  "tests/components/stdio",
 ]
 
 [profile.release]
@@ -33,7 +33,8 @@ anyhow = "1"
 clap = { version = "4", features = ["derive"] }
 serde = { version = "1", features = ["derive"] }
 toml = "0.7"
-walrus = "0.20.1"
+# TODO: use published version of walrus w/ improved ergonomics
+walrus = { git = "https://github.com/vados-cosmonic/walrus", branch = "refactor/improve-ergonomics-of-fn-replace" }
 wasm-compose = "0.4.2"
 wasm-metadata = "0.10.5"
 wasm-opt = "0.114.1"
@@ -45,12 +46,14 @@ anyhow = "1"
 [dev-dependencies]
 anyhow = "1"
 cap-std = "1.0.12"
-heck =  { version = "0.4" }
+heck = { version = "0.4" }
 tokio = { version = "1.30.0", features = ["macros"] }
-wasmtime = { git = "https://github.com/bytecodealliance/wasmtime", features = ["component-model"] }
+wasmtime = { git = "https://github.com/bytecodealliance/wasmtime", features = [
+  "component-model",
+] }
 wasmtime-wasi = { git = "https://github.com/bytecodealliance/wasmtime" }
 wasmparser = "0.113.1"
 
 [workspace.dependencies]
 anyhow = "1"
-wit-bindgen = "0.12.0"
+wit-bindgen = "0.12.0"

src/data.rs

@@ -1,13 +1,12 @@
-use crate::walrus_ops::{
-    bump_stack_global, get_exported_func, get_memory_id, remove_exported_func,
-};
 use anyhow::{bail, Result};
 use std::collections::HashMap;
 use walrus::{
     ActiveData, ActiveDataLocation, DataKind, ElementKind, FunctionBuilder, FunctionId,
     FunctionKind, InitExpr, Module, ValType,
 };
 
+use crate::walrus_ops::bump_stack_global;
+
 /// Data section
 /// Because data is stack-allocated we create a corresponding byte vector as large
 /// as the stack, zero fill it then populate it backwards from the
@@ -115,7 +114,7 @@ impl Data {
     }
     pub fn finish(mut self, module: &mut Module) -> Result<()> {
         // stack embedding
-        let memory = get_memory_id(module)?;
+        let memory = module.get_memory_id()?;
         let rem = (self.stack_start - self.stack_ptr) % 8;
         if rem != 0 {
             self.stack_ptr -= 8 - rem;
@@ -132,7 +131,7 @@ impl Data {
         // passive segment embedding
         // we create one function for each passive segment, due to
         if self.passive_segments.len() > 0 {
-            let alloc_fid = get_exported_func(module, "cabi_realloc")?;
+            let alloc_fid = module.exports.get_func_by_name("cabi_realloc")?;
 
             let offset_local = module.locals.add(ValType::I32);
             let len_local = module.locals.add(ValType::I32);
@@ -206,13 +205,13 @@ impl Data {
                 .call_indirect(passive_fn_alloc_type, passive_tid);
 
             // update the existing passive_alloc function export with the new function body
-            let passive_alloc_fid = get_exported_func(module, "passive_alloc")?;
+            let passive_alloc_fid = module.exports.get_func_by_name("passive_alloc")?;
             let passive_alloc_func = module.funcs.get_mut(passive_alloc_fid);
             passive_alloc_func.kind =
                 FunctionKind::Local(builder.local_func(vec![passive_idx, offset_local, len_local]));
         }
 
-        remove_exported_func(module, "passive_alloc")?;
+        module.exports.delete_func_by_name("passive_alloc")?;
 
         Ok(())
     }