Fix WASM executor without instance reuse; cleanups and refactoring (#10313)

* Fix WASM executor without instance reuse; cleanups and refactoring

* Align to review comments

* Move the functions for reading/writing memory to `util.rs`

* Only `#[ignore]` the test in debug builds

* More review comments and minor extra comments

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

@@ -16,7 +16,13 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-use sp_wasm_interface::Value;
+use crate::runtime::StoreData;
+use sc_executor_common::{
+	error::{Error, Result},
+	util::checked_range,
+};
+use sp_wasm_interface::{Pointer, Value};
+use wasmtime::{AsContext, AsContextMut};
 
 /// Converts a [`wasmtime::Val`] into a substrate runtime interface [`Value`].
 ///
@@ -41,3 +47,54 @@ pub fn into_wasmtime_val(value: Value) -> wasmtime::Val {
 		Value::F64(f_bits) => wasmtime::Val::F64(f_bits),
 	}
 }
+
+/// Read data from a slice of memory into a newly allocated buffer.
+///
+/// Returns an error if the read would go out of the memory bounds.
+pub(crate) fn read_memory(
+	ctx: impl AsContext<Data = StoreData>,
+	source_addr: Pointer<u8>,
+	size: usize,
+) -> Result<Vec<u8>> {
+	let range =
+		checked_range(source_addr.into(), size, ctx.as_context().data().memory().data_size(&ctx))
+			.ok_or_else(|| Error::Other("memory read is out of bounds".into()))?;
+
+	let mut buffer = vec![0; range.len()];
+	read_memory_into(ctx, source_addr, &mut buffer)?;
+
+	Ok(buffer)
+}
+
+/// Read data from the instance memory into a slice.
+///
+/// Returns an error if the read would go out of the memory bounds.
+pub(crate) fn read_memory_into(
+	ctx: impl AsContext<Data = StoreData>,
+	address: Pointer<u8>,
+	dest: &mut [u8],
+) -> Result<()> {
+	let memory = ctx.as_context().data().memory().data(&ctx);
+
+	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 the instance memory from a slice.
+///
+/// Returns an error if the write would go out of the memory bounds.
+pub(crate) fn write_memory_from(
+	mut ctx: impl AsContextMut<Data = StoreData>,
+	address: Pointer<u8>,
+	data: &[u8],
+) -> Result<()> {
+	let memory = ctx.as_context().data().memory();
+	let memory = memory.data_mut(&mut ctx);
+
+	let range = checked_range(address.into(), data.len(), memory.len())
+		.ok_or_else(|| Error::Other("memory write is out of bounds".into()))?;
+	memory[range].copy_from_slice(data);
+	Ok(())
+}