Adds --no-validator CLI flag (#3348)

* Implement `is_validator` for offchain-workers

* Introduce `--no-validator` flag

* Don't run babe/grandpa/im-online when `--no-validator` is given

* Fixes compilation

* Bump spec version

* Improve error handling in executor

* Add missing extern function

* Revert making error public

* Remove `--no-validator` CLI

substrate/core/executor/src/error.rs

@@ -38,8 +38,8 @@ pub enum Error {
 	#[display(fmt="Method not found: '{}'", _0)]
 	MethodNotFound(String),
 	/// Code is invalid (expected single byte)
-	#[display(fmt="Invalid Code")]
-	InvalidCode,
+	#[display(fmt="Invalid Code: {}", _0)]
+	InvalidCode(String),
 	/// Could not get runtime version.
 	#[display(fmt="On-chain runtime does not specify version")]
 	VersionInvalid,

substrate/core/executor/src/native_executor.rs

@@ -22,7 +22,7 @@ use runtime_version::{NativeVersion, RuntimeVersion};
 use codec::{Decode, Encode};
 use crate::RuntimeInfo;
 use primitives::{Blake2Hasher, NativeOrEncoded};
-use log::trace;
+use log::{trace, warn};
 
 use crate::RuntimesCache;
 
@@ -107,8 +107,14 @@ impl<D: NativeExecutionDispatch> RuntimeInfo for NativeExecutor<D> {
 	) -> Option<RuntimeVersion> {
 		RUNTIMES_CACHE.with(|cache| {
 			let cache = &mut cache.borrow_mut();
-			cache.fetch_runtime(&self.fallback, ext, self.default_heap_pages)
-				.ok()?.version().clone()
+
+			match cache.fetch_runtime(&self.fallback, ext, self.default_heap_pages) {
+				Ok(runtime) => runtime.version(),
+				Err(e) => {
+					warn!(target: "executor", "Failed to fetch runtime: {:?}", e);
+					None
+				}
+			}
 		})
 	}
 }

substrate/core/executor/src/wasm_executor.rs

@@ -876,6 +876,13 @@ impl_function_executor!(this: FunctionExecutor<'e, E>,
 
 		Ok(0)
 	},
+	ext_is_validator() -> u32 => {
+		Ok(if runtime_io::is_validator() {
+			1
+		} else {
+			0
+		})
+	},
 	ext_submit_transaction(msg_data: *const u8, len: u32) -> u32 => {
 		let extrinsic = this.memory.get(msg_data, len as usize)
 			.map_err(|_| "OOB while ext_submit_transaction: wasm")?;

substrate/core/executor/src/wasm_runtimes_cache.rs

@@ -248,12 +248,12 @@ impl RuntimesCache {
 	) -> Result<Rc<CachedRuntime>, Error> {
 		let code_hash = ext
 			.original_storage_hash(well_known_keys::CODE)
-			.ok_or(Error::InvalidCode)?;
+			.ok_or(Error::InvalidCode("`CODE` not found in storage.".into()))?;
 
 		// This is direct result from fighting with borrowck.
 		let handle_result =
 			|cached_result: &Result<Rc<CachedRuntime>, CacheError>| match *cached_result {
-				Err(_) => Err(Error::InvalidCode),
+				Err(ref e) => Err(Error::InvalidCode(format!("{:?}", e))),
 				Ok(ref cached_runtime) => Ok(Rc::clone(cached_runtime)),
 			};