Remove host function definition region dependency

[jsturtevant]

Instead of using a shared memory region or a host function callback
to provide host function definitions to the guest, the host now pushes
the serialized definitions directly as a parameter to InitWasmRuntime.

fixes #388

[ludfjig]

I think this looks good

[ludfjig]

Not strictly related to your PR, but can we use the #[guest_func] macro on init_wasm_runtime instead of manually calling register_function?

[ludfjig]

maybe teh same applies to all usages of register_function

[Copilot]

Pull request overview

This PR removes the guest’s dependency on a dedicated “host function definition region” by having the host serialize host function definitions and pass them directly into the guest’s InitWasmRuntime call, aligning with upstream HL-core changes (issue #388).

Changes:

• Update the guest wasm runtime to parse HostFunctionDetails from InitWasmRuntime parameters (VecBytes) instead of reading from a shared region / callback.
• Update the host sandbox initialization to track + serialize registered host function definitions and pass them into InitWasmRuntime.
• Remove SandboxBuilder::with_function_definition_size and document the breaking change; add [workspace] stanzas to excluded crates to avoid workspace resolution issues.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/wasm_runtime/src/module.rs	InitWasmRuntime now expects a VecBytes parameter containing serialized host function details and registers host funcs from it.
src/wasm_runtime/src/hostfuncs.rs	Removes the old get_host_function_details() path.
src/wasm_runtime/src/component.rs	Updates InitWasmRuntime signature in the component runtime interface (now takes VecBytes).
src/hyperlight_wasm/src/sandbox/proto_wasm_sandbox.rs	Tracks host function definitions as they’re registered; serializes and passes them to InitWasmRuntime.
src/hyperlight_wasm/src/sandbox/sandbox_builder.rs	Removes the builder API for host function definition region sizing.
src/hyperlight_wasm/src/sandbox/loaded_wasm_sandbox.rs	Adds a regression test ensuring missing host functions fail module load.
src/hyperlight_wasm/Cargo.toml	Adds hyperlight-common dependency used for flatbuffer wrapper types.
Cargo.toml	Adds hyperlight-common to workspace dependencies.
Cargo.lock	Locks hyperlight-common dependency.
src/rust_wasm_samples/Cargo.toml	Adds [workspace] to make the crate a standalone workspace root when built directly.
src/hyperlight_wasm_macro/Cargo.toml	Adds [workspace] to make the crate a standalone workspace root when built directly.
src/component_sample/Cargo.toml	Adds [workspace] to make the crate a standalone workspace root when built directly.
CHANGELOG.md	Documents the breaking removal of SandboxBuilder::with_function_definition_size.

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[Copilot]

host_function_definitions is built by blindly pushing entries, but you also pre-seed it with a HostPrint definition in new(). If a caller later registers a host function named HostPrint via register(...)/register_host_function(...), the list will contain duplicates and the guest init_wasm_runtime will attempt to linker.func_new the same name twice, which should error and prevent the runtime from loading. Consider enforcing uniqueness by name (e.g., replace existing definition instead of pushing, or special-case HostPrint).

Suggested change

	// Track the host function definition for pushing to guest at load time
	self.host_function_definitions.push(HostFunctionDefinition {
	function_name: name.to_string(),
	parameter_types: Some(Args::TYPE.to_vec()),
	return_type: Output::TYPE,
	});
	// Track the host function definition for pushing to guest at load time,
	// ensuring uniqueness by function name.
	if let Some(existing) = self
	.host_function_definitions
	.iter_mut()
	.find(|def| def.function_name == name)
	{
	existing.parameter_types = Some(Args::TYPE.to_vec());
	existing.return_type = Output::TYPE;
	} else {
	self.host_function_definitions
	.push(HostFunctionDefinition {
	function_name: name.to_string(),
	parameter_types: Some(Args::TYPE.to_vec()),
	return_type: Output::TYPE,
	});
	}

[jsturtevant]

I did think about this, but wasn't sure what the best thing to do was. Anyone have any thoughts? This feels like it could lead to some strange bugs as well

[Copilot]

The logic to append a HostFunctionDefinition is duplicated in both Registerable::register_host_function and the inherent ProtoWasmSandbox::register method. This duplication makes it easy for the two paths to drift (e.g., one adds de-dup or normalization and the other doesn’t). Consider extracting a small helper (or having one method delegate to the other) so the tracking behavior stays consistent.

[Copilot]

When parameters is present but empty, this returns "InitWasmRuntime: first parameter must be VecBytes", which is a bit misleading (the real issue is that no parameters were provided). Consider explicitly handling the empty-vec case and returning a clearer error (e.g., "expected 1 parameter") to make debugging host/guest ABI mismatches easier.

Suggested change

	_ => {
	return Err(HyperlightGuestError::new(
	ErrorCode::GuestFunctionParameterTypeMismatch,
	"InitWasmRuntime: first parameter must be VecBytes".to_string(),
	))
	}
	Some(_) => {
	return Err(HyperlightGuestError::new(
	ErrorCode::GuestFunctionParameterTypeMismatch,
	"InitWasmRuntime: first parameter must be VecBytes".to_string(),
	))
	}
	None => {
	return Err(HyperlightGuestError::new(
	ErrorCode::GuestFunctionParameterTypeMismatch,
	"InitWasmRuntime: expected 1 parameter".to_string(),
	))
	}