Adds validate_block support for runtime

runtime/src/validate_block/mod.rs

@@ -0,0 +1,105 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Cumulus. If not, see <http://www.gnu.org/licenses/>.
+
+//! A module that enables a runtime to work as parachain.
+
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+pub use rstd::slice;
+
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+pub mod storage_functions;
+#[cfg(test)]
+mod tests;
+
+/// Register the `validate_block` function that is used by parachains to validate blocks on a validator.
+///
+/// Does *nothing* when `std` feature is enabled.
+///
+/// Expects as parameters the block and the block executor.
+///
+/// # Example
+///
+/// ```
+///     struct Block;
+///     struct BlockExecutor;
+///
+///     srml_parachain::register_validate_block!(Block, BlockExecutor);
+///
+/// # fn main() {}
+/// ```
+#[macro_export]
+macro_rules! register_validate_block {
+	($block:ty, $block_executor:ty) => {
+		$crate::register_validate_block_impl!($block, $block_executor);
+	};
+}
+
+/// The actual implementation of `register_validate_block` for `no_std`.
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! register_validate_block_impl {
+	($block:ty, $block_executor:ty) => {
+		#[doc(hidden)]
+		mod parachain_validate_block {
+			use super::*;
+
+			#[no_mangle]
+			unsafe fn validate_block(block: *const u8, block_len: u64, prev_head: *const u8, prev_head_len: u64) {
+				let block = $crate::slice::from_raw_parts(block, block_len as usize);
+				let prev_head = $crate::slice::from_raw_parts(prev_head, prev_head_len as usize);
+
+				$crate::validate_block::validate_block::<$block, $block_executor>(block, prev_head);
+			}
+		}
+	};
+}
+
+/// The actual implementation of `register_validate_block` for `std`.
+#[cfg(feature = "std")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! register_validate_block_impl {
+	($block:ty, $block_executor:ty) => {};
+}
+
+/// Validate a given parachain block on a validator.
+#[cfg(not(feature = "std"))]
+#[doc(hidden)]
+pub fn validate_block<Block: BlockT, E: ExecuteBlock<Block>>(mut block: &[u8], mut prev_head: &[u8]) {
+	use codec::Decode;
+
+	let block = ParachainBlock::<Block>::decode(&mut block).expect("Could not decode parachain block.");
+	let parent_header = <<Block as BlockT>::Header as Decode>::decode(&mut prev_head).expect("Could not decode parent header.");
+
+	let _guard = unsafe {
+		use storage_functions as storage;
+		STORAGE = Some(block.witness_data);
+		(
+			// Replace storage calls with our own implementations
+			rio::ext_get_allocated_storage.replace_implementation(storage::ext_get_allocated_storage),
+			rio::ext_get_storage_into.replace_implementation(storage::ext_get_storage_into),
+			rio::ext_set_storage.replace_implementation(storage::ext_set_storage),
+			rio::ext_exists_storage.replace_implementation(storage::ext_exists_storage),
+			rio::ext_clear_storage.replace_implementation(storage::ext_clear_storage),
+		)
+	};
+
+	let block_number = *parent_header.number() + One::one();
+	E::execute_extrinsics_without_checks(block_number, block.extrinsics);
+}