Extract execution engines definitions into their own crates (#4489)

* Clean imports in wasmi_execution

* Replace `interpret_runtime_api_result` with `pointer_and_len_from_u64`.

* Extract sc-executor-common crate

* Extract `sc-executor-wasmi` into its own crate

* Extract `sc-executor-wasmtime` into its own crate.

* Add missing headers.

* Clean and docs

* Docs for sc-executor-wasmi

* Expand a comment about sandboxing

* Fix assert_matches

* Rename (un)pack_ptr_and_len and move them into util module

* Remove wasmtime errors in sc-executor-common

substrate/client/executor/wasmtime/src/util.rs

@@ -0,0 +1,113 @@
+// 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 Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use sc_executor_common::error::{Error, Result};
+
+use cranelift_codegen::{ir, isa};
+use std::ops::Range;
+use sp_wasm_interface::{Pointer, Signature, ValueType};
+
+/// Read data from a slice of memory into a destination buffer.
+///
+/// Returns an error if the read would go out of the memory bounds.
+pub fn read_memory_into(memory: &[u8], address: Pointer<u8>, dest: &mut [u8]) -> Result<()> {
+	let range = checked_range(address.into(), dest.len(), memory.len())
+		.ok_or_else(|| Error::Other("memory read is out of bounds".into()))?;
+	dest.copy_from_slice(&memory[range]);
+	Ok(())
+}
+
+/// Write data to a slice of memory.
+///
+/// Returns an error if the write would go out of the memory bounds.
+pub fn write_memory_from(memory: &mut [u8], address: Pointer<u8>, data: &[u8]) -> Result<()> {
+	let range = checked_range(address.into(), data.len(), memory.len())
+		.ok_or_else(|| Error::Other("memory write is out of bounds".into()))?;
+	&mut memory[range].copy_from_slice(data);
+	Ok(())
+}
+
+/// Construct a range from an offset to a data length after the offset.
+/// Returns None if the end of the range would exceed some maximum offset.
+pub fn checked_range(offset: usize, len: usize, max: usize) -> Option<Range<usize>> {
+	let end = offset.checked_add(len)?;
+	if end <= max {
+		Some(offset..end)
+	} else {
+		None
+	}
+}
+
+/// Convert a wasm_interface Signature into a cranelift_codegen Signature.
+pub fn cranelift_ir_signature(signature: Signature, call_conv: &isa::CallConv) -> ir::Signature {
+	ir::Signature {
+		params: signature.args.iter()
+			.map(cranelift_ir_type)
+			.map(ir::AbiParam::new)
+			.collect(),
+		returns: signature.return_value.iter()
+			.map(cranelift_ir_type)
+			.map(ir::AbiParam::new)
+			.collect(),
+		call_conv: call_conv.clone(),
+	}
+}
+
+/// Convert a wasm_interface ValueType into a cranelift_codegen Type.
+pub fn cranelift_ir_type(value_type: &ValueType) -> ir::types::Type {
+	match value_type {
+		ValueType::I32 => ir::types::I32,
+		ValueType::I64 => ir::types::I64,
+		ValueType::F32 => ir::types::F32,
+		ValueType::F64 => ir::types::F64,
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use assert_matches::assert_matches;
+
+	#[test]
+	fn test_read_memory_into() {
+		let mut memory = [0; 20];
+		let mut dest = [0; 5];
+
+		&mut memory[15..20].copy_from_slice(b"hello");
+
+		read_memory_into(&memory[..], Pointer::new(15), &mut dest[..]).unwrap();
+
+		// Test that out of bounds read fails.
+		assert_matches!(
+			read_memory_into(&memory[..], Pointer::new(16), &mut dest[..]),
+			Err(Error::Other(_))
+		)
+	}
+
+	#[test]
+	fn test_write_memory_from() {
+		let mut memory = [0; 20];
+		let data = b"hello";
+
+		write_memory_from(&mut memory[..], Pointer::new(15), data).unwrap();
+
+		// Test that out of bounds write fails.
+		assert_matches!(
+			write_memory_from(&mut memory[..], Pointer::new(16), data),
+			Err(Error::Other(_))
+		)
+	}
+}