Add support for generating metadata from runtime wasm files (#1720)

closes #1660

macro/src/lib.rs

@@ -23,6 +23,9 @@ use subxt_codegen::{
 };
 use syn::{parse_macro_input, punctuated::Punctuated};
 
+#[cfg(feature = "runtime-path")]
+mod wasm_loader;
+
 #[derive(Clone, Debug)]
 struct OuterAttribute(syn::Attribute);
 
@@ -60,6 +63,9 @@ struct RuntimeMetadataArgs {
     no_default_substitutions: bool,
     #[darling(default)]
     unstable_metadata: darling::util::Flag,
+    #[cfg(feature = "runtime-path")]
+    #[darling(default)]
+    runtime_path: Option<String>,
 }
 
 #[derive(Debug, FromMeta)]
@@ -206,6 +212,22 @@ fn validate_type_path(path: &syn::Path, metadata: &Metadata) {
 fn fetch_metadata(args: &RuntimeMetadataArgs) -> Result<subxt_codegen::Metadata, TokenStream> {
     // Do we want to fetch unstable metadata? This only works if fetching from a URL.
     let unstable_metadata = args.unstable_metadata.is_present();
+
+    #[cfg(feature = "runtime-path")]
+    if let Some(path) = &args.runtime_path {
+        if args.runtime_metadata_insecure_url.is_some() || args.runtime_metadata_path.is_some() {
+            abort_call_site!(
+                "Only one of 'runtime_metadata_path', 'runtime_metadata_insecure_url' or `runtime_path` must be provided"
+            );
+        };
+        let root = std::env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".into());
+        let root_path = std::path::Path::new(&root);
+        let path = root_path.join(path);
+
+        let metadata = wasm_loader::from_wasm_file(&path).map_err(|e| e.into_compile_error())?;
+        return Ok(metadata);
+    };
+
     let metadata = match (
         &args.runtime_metadata_path,
         &args.runtime_metadata_insecure_url,
@@ -239,12 +261,26 @@ fn fetch_metadata(args: &RuntimeMetadataArgs) -> Result<subxt_codegen::Metadata,
                 .and_then(|b| subxt_codegen::Metadata::decode(&mut &*b).map_err(Into::into))
                 .map_err(|e| e.into_compile_error())?
         }
+        #[cfg(feature = "runtime-path")]
         (None, None) => {
             abort_call_site!(
-                "One of 'runtime_metadata_path' or 'runtime_metadata_insecure_url' must be provided"
+                    "At least one of 'runtime_metadata_path', 'runtime_metadata_insecure_url'  or  'runtime_path` can be provided"
+                )
+        }
+        #[cfg(not(feature = "runtime-path"))]
+        (None, None) => {
+            abort_call_site!(
+                "At least one of 'runtime_metadata_path', 'runtime_metadata_insecure_url' can be provided"
             )
         }
-        (Some(_), Some(_)) => {
+        #[cfg(feature = "runtime-path")]
+        _ => {
+            abort_call_site!(
+                    "Only one of 'runtime_metadata_path', 'runtime_metadata_insecure_url'  or  'runtime_path` can be provided"
+                )
+        }
+        #[cfg(not(feature = "runtime-path"))]
+        _ => {
             abort_call_site!(
                 "Only one of 'runtime_metadata_path' or 'runtime_metadata_insecure_url' can be provided"
             )

macro/src/wasm_loader.rs

@@ -0,0 +1,55 @@
+// Copyright 2024 Parity Technologies (UK) Ltd.
+// This file is dual-licensed as Apache-2.0 or GPL-3.0.
+// see LICENSE for license details.
+
+use std::{borrow::Cow, path::Path};
+
+use codec::Decode;
+use sc_executor::{WasmExecutionMethod, WasmExecutor};
+use sc_executor_common::runtime_blob::RuntimeBlob;
+use sp_maybe_compressed_blob::CODE_BLOB_BOMB_LIMIT;
+use subxt_codegen::{fetch_metadata::fetch_metadata_from_file_blocking, CodegenError, Metadata};
+
+/// Result type shorthand
+pub type WasmMetadataResult<A> = Result<A, CodegenError>;
+
+/// Uses wasm artifact produced by compiling the runtime to generate metadata
+pub fn from_wasm_file(wasm_file_path: &Path) -> WasmMetadataResult<Metadata> {
+    let wasm_file = fetch_metadata_from_file_blocking(wasm_file_path)
+        .map_err(Into::<CodegenError>::into)
+        .and_then(maybe_decompress)?;
+    call_and_decode(wasm_file)
+}
+
+fn call_and_decode(wasm_file: Vec<u8>) -> WasmMetadataResult<Metadata> {
+    let mut ext: sp_state_machine::BasicExternalities = Default::default();
+
+    let executor: WasmExecutor<sp_io::SubstrateHostFunctions> = WasmExecutor::builder()
+        .with_execution_method(WasmExecutionMethod::default())
+        .with_offchain_heap_alloc_strategy(sc_executor::HeapAllocStrategy::Dynamic {
+            maximum_pages: Some(64),
+        })
+        .with_max_runtime_instances(1)
+        .with_runtime_cache_size(1)
+        .build();
+
+    let runtime_blob =
+        RuntimeBlob::new(&wasm_file).map_err(|e| CodegenError::Wasm(e.to_string()))?;
+    let metadata_encoded = executor
+        .uncached_call(runtime_blob, &mut ext, true, "Metadata_metadata", &[])
+        .map_err(|_| CodegenError::Wasm("method \"Metadata_metadata\" doesnt exist".to_owned()))?;
+
+    let metadata = <Vec<u8>>::decode(&mut &metadata_encoded[..]).map_err(CodegenError::Decode)?;
+
+    decode(metadata)
+}
+
+fn decode(encoded_metadata: Vec<u8>) -> WasmMetadataResult<Metadata> {
+    Metadata::decode(&mut encoded_metadata.as_ref()).map_err(Into::into)
+}
+
+fn maybe_decompress(file_contents: Vec<u8>) -> WasmMetadataResult<Vec<u8>> {
+    sp_maybe_compressed_blob::decompress(file_contents.as_ref(), CODE_BLOB_BOMB_LIMIT)
+        .map_err(|e| CodegenError::Wasm(e.to_string()))
+        .map(Cow::into_owned)
+}