1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
// This file is part of Substrate.

// Copyright (C) 2017-2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program 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.

// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.

use crate::{
	RuntimeInfo, error::{Error, Result},
	wasm_runtime::{RuntimeCache, WasmExecutionMethod},
};
use sp_version::{NativeVersion, RuntimeVersion};
use codec::{Decode, Encode};
use sp_core::{
	NativeOrEncoded, traits::{CodeExecutor, Externalities, RuntimeCode, MissingHostFunctions},
};
use log::trace;
use std::{result, panic::{UnwindSafe, AssertUnwindSafe}, sync::Arc};
use sp_wasm_interface::{HostFunctions, Function};
use sc_executor_common::wasm_runtime::WasmInstance;

/// Default num of pages for the heap
const DEFAULT_HEAP_PAGES: u64 = 1024;

/// Set up the externalities and safe calling environment to execute runtime calls.
///
/// If the inner closure panics, it will be caught and return an error.
pub fn with_externalities_safe<F, U>(ext: &mut dyn Externalities, f: F) -> Result<U>
	where F: UnwindSafe + FnOnce() -> U
{
	sp_externalities::set_and_run_with_externalities(
		ext,
		move || {
			// Substrate uses custom panic hook that terminates process on panic. Disable
			// termination for the native call.
			let _guard = sp_panic_handler::AbortGuard::force_unwind();
			std::panic::catch_unwind(f).map_err(|e| {
				if let Some(err) = e.downcast_ref::<String>() {
					Error::RuntimePanicked(err.clone())
				} else if let Some(err) = e.downcast_ref::<&'static str>() {
					Error::RuntimePanicked(err.to_string())
				} else {
					Error::RuntimePanicked("Unknown panic".into())
				}
			})
		},
	)
}

/// Delegate for dispatching a CodeExecutor call.
///
/// By dispatching we mean that we execute a runtime function specified by it's name.
pub trait NativeExecutionDispatch: Send + Sync {
	/// Host functions for custom runtime interfaces that should be callable from within the runtime
	/// besides the default Substrate runtime interfaces.
	type ExtendHostFunctions: HostFunctions;

	/// Dispatch a method in the runtime.
	///
	/// If the method with the specified name doesn't exist then `Err` is returned.
	fn dispatch(ext: &mut dyn Externalities, method: &str, data: &[u8]) -> Result<Vec<u8>>;

	/// Provide native runtime version.
	fn native_version() -> NativeVersion;
}

/// An abstraction over Wasm code executor. Supports selecting execution backend and
/// manages runtime cache.
#[derive(Clone)]
pub struct WasmExecutor {
	/// Method used to execute fallback Wasm code.
	method: WasmExecutionMethod,
	/// The number of 64KB pages to allocate for Wasm execution.
	default_heap_pages: u64,
	/// The host functions registered with this instance.
	host_functions: Arc<Vec<&'static dyn Function>>,
	/// WASM runtime cache.
	cache: Arc<RuntimeCache>,
	/// The size of the instances cache.
	max_runtime_instances: usize,
}

impl WasmExecutor {
	/// Create new instance.
	///
	/// # Parameters
	///
	/// `method` - Method used to execute Wasm code.
	///
	/// `default_heap_pages` - Number of 64KB pages to allocate for Wasm execution.
	/// 	Defaults to `DEFAULT_HEAP_PAGES` if `None` is provided.
	pub fn new(
		method: WasmExecutionMethod,
		default_heap_pages: Option<u64>,
		host_functions: Vec<&'static dyn Function>,
		max_runtime_instances: usize,
	) -> Self {
		WasmExecutor {
			method,
			default_heap_pages: default_heap_pages.unwrap_or(DEFAULT_HEAP_PAGES),
			host_functions: Arc::new(host_functions),
			cache: Arc::new(RuntimeCache::new(max_runtime_instances)),
			max_runtime_instances,
		}
	}

	/// Execute the given closure `f` with the latest runtime (based on `runtime_code`).
	///
	/// The closure `f` is expected to return `Err(_)` when there happened a `panic!` in native code
	/// while executing the runtime in Wasm. If a `panic!` occurred, the runtime is invalidated to
	/// prevent any poisoned state. Native runtime execution does not need to report back
	/// any `panic!`.
	///
	/// # Safety
	///
	/// `runtime` and `ext` are given as `AssertUnwindSafe` to the closure. As described above, the
	/// runtime is invalidated on any `panic!` to prevent a poisoned state. `ext` is already
	/// implicitly handled as unwind safe, as we store it in a global variable while executing the
	/// native runtime.
	fn with_instance<R, F>(
		&self,
		runtime_code: &RuntimeCode,
		ext: &mut dyn Externalities,
		allow_missing_host_functions: bool,
		f: F,
	) -> Result<R>
		where F: FnOnce(
			AssertUnwindSafe<&dyn WasmInstance>,
			Option<&RuntimeVersion>,
			AssertUnwindSafe<&mut dyn Externalities>,
		) -> Result<Result<R>>,
	{
		match self.cache.with_instance(
			runtime_code,
			ext,
			self.method,
			self.default_heap_pages,
			&*self.host_functions,
			allow_missing_host_functions,
			|instance, version, ext| {
				let instance = AssertUnwindSafe(instance);
				let ext = AssertUnwindSafe(ext);
				f(instance, version, ext)
			}
		)? {
			Ok(r) => r,
			Err(e) => Err(e),
		}
	}
}

impl sp_core::traits::CallInWasm for WasmExecutor {
	fn call_in_wasm(
		&self,
		wasm_code: &[u8],
		code_hash: Option<Vec<u8>>,
		method: &str,
		call_data: &[u8],
		ext: &mut dyn Externalities,
		missing_host_functions: MissingHostFunctions,
	) -> std::result::Result<Vec<u8>, String> {
		let allow_missing_host_functions = missing_host_functions.allowed();

		if let Some(hash) = code_hash {
			let code = RuntimeCode {
				code_fetcher: &sp_core::traits::WrappedRuntimeCode(wasm_code.into()),
				hash,
				heap_pages: None,
			};

			self.with_instance(&code, ext, allow_missing_host_functions, |instance, _, mut ext| {
				with_externalities_safe(
					&mut **ext,
					move || instance.call(method, call_data),
				)
			}).map_err(|e| e.to_string())
		} else {
			let module = crate::wasm_runtime::create_wasm_runtime_with_code(
				self.method,
				self.default_heap_pages,
				&wasm_code,
				self.host_functions.to_vec(),
				allow_missing_host_functions,
			)
				.map_err(|e| format!("Failed to create module: {:?}", e))?;

			let instance = module.new_instance()
				.map_err(|e| format!("Failed to create instance: {:?}", e))?;

			let instance = AssertUnwindSafe(instance);
			let mut ext = AssertUnwindSafe(ext);

			with_externalities_safe(
				&mut **ext,
				move || instance.call(method, call_data),
			)
			.and_then(|r| r)
			.map_err(|e| e.to_string())
		}
	}
}

/// A generic `CodeExecutor` implementation that uses a delegate to determine wasm code equivalence
/// and dispatch to native code when possible, falling back on `WasmExecutor` when not.
pub struct NativeExecutor<D> {
	/// Dummy field to avoid the compiler complaining about us not using `D`.
	_dummy: std::marker::PhantomData<D>,
	/// Native runtime version info.
	native_version: NativeVersion,
	/// Fallback wasm executor.
	wasm: WasmExecutor,
}

impl<D: NativeExecutionDispatch> NativeExecutor<D> {
	/// Create new instance.
	///
	/// # Parameters
	///
	/// `fallback_method` - Method used to execute fallback Wasm code.
	///
	/// `default_heap_pages` - Number of 64KB pages to allocate for Wasm execution.
	/// 	Defaults to `DEFAULT_HEAP_PAGES` if `None` is provided.
	pub fn new(
		fallback_method: WasmExecutionMethod,
		default_heap_pages: Option<u64>,
		max_runtime_instances: usize,
	) -> Self {
		let mut host_functions = sp_io::SubstrateHostFunctions::host_functions();

		// Add the custom host functions provided by the user.
		host_functions.extend(D::ExtendHostFunctions::host_functions());
		let wasm_executor = WasmExecutor::new(
			fallback_method,
			default_heap_pages,
			host_functions,
			max_runtime_instances,
		);

		NativeExecutor {
			_dummy: Default::default(),
			native_version: D::native_version(),
			wasm: wasm_executor,
		}
	}
}

impl<D: NativeExecutionDispatch> RuntimeInfo for NativeExecutor<D> {
	fn native_version(&self) -> &NativeVersion {
		&self.native_version
	}

	fn runtime_version(
		&self,
		ext: &mut dyn Externalities,
		runtime_code: &RuntimeCode,
	) -> Result<RuntimeVersion> {
		self.wasm.with_instance(
			runtime_code,
			ext,
			false,
			|_instance, version, _ext|
				Ok(version.cloned().ok_or_else(|| Error::ApiError("Unknown version".into()))),
		)
	}
}

impl<D: NativeExecutionDispatch + 'static> CodeExecutor for NativeExecutor<D> {
	type Error = Error;

	fn call<
		R: Decode + Encode + PartialEq,
		NC: FnOnce() -> result::Result<R, String> + UnwindSafe,
	>(
		&self,
		ext: &mut dyn Externalities,
		runtime_code: &RuntimeCode,
		method: &str,
		data: &[u8],
		use_native: bool,
		native_call: Option<NC>,
	) -> (Result<NativeOrEncoded<R>>, bool) {
		let mut used_native = false;
		let result = self.wasm.with_instance(
			runtime_code,
			ext,
			false,
			|instance, onchain_version, mut ext| {
				let onchain_version = onchain_version.ok_or_else(
					|| Error::ApiError("Unknown version".into())
				)?;
				match (
					use_native,
					onchain_version.can_call_with(&self.native_version.runtime_version),
					native_call,
				) {
					(_, false, _) => {
						trace!(
							target: "executor",
							"Request for native execution failed (native: {}, chain: {})",
							self.native_version.runtime_version,
							onchain_version,
						);

						with_externalities_safe(
							&mut **ext,
							move || instance.call(method, data).map(NativeOrEncoded::Encoded)
						)
					}
					(false, _, _) => {
						with_externalities_safe(
							&mut **ext,
							move || instance.call(method, data).map(NativeOrEncoded::Encoded)
						)
					},
					(true, true, Some(call)) => {
						trace!(
							target: "executor",
							"Request for native execution with native call succeeded \
							(native: {}, chain: {}).",
							self.native_version.runtime_version,
							onchain_version,
						);

						used_native = true;
						let res = with_externalities_safe(&mut **ext, move || (call)())
							.and_then(|r| r
								.map(NativeOrEncoded::Native)
								.map_err(|s| Error::ApiError(s.to_string()))
							);

						Ok(res)
					}
					_ => {
						trace!(
							target: "executor",
							"Request for native execution succeeded (native: {}, chain: {})",
							self.native_version.runtime_version,
							onchain_version
						);

						used_native = true;
						Ok(D::dispatch(&mut **ext, method, data).map(NativeOrEncoded::Encoded))
					}
				}
			}
		);
		(result, used_native)
	}
}

impl<D: NativeExecutionDispatch> Clone for NativeExecutor<D> {
	fn clone(&self) -> Self {
		NativeExecutor {
			_dummy: Default::default(),
			native_version: D::native_version(),
			wasm: self.wasm.clone(),
		}
	}
}

impl<D: NativeExecutionDispatch> sp_core::traits::CallInWasm for NativeExecutor<D> {
	fn call_in_wasm(
		&self,
		wasm_blob: &[u8],
		code_hash: Option<Vec<u8>>,
		method: &str,
		call_data: &[u8],
		ext: &mut dyn Externalities,
		missing_host_functions: MissingHostFunctions,
	) -> std::result::Result<Vec<u8>, String> {
		self.wasm.call_in_wasm(wasm_blob, code_hash, method, call_data, ext, missing_host_functions)
	}
}

/// Implements a `NativeExecutionDispatch` for provided parameters.
///
/// # Example
///
/// ```
/// sc_executor::native_executor_instance!(
///     pub MyExecutor,
///     substrate_test_runtime::api::dispatch,
///     substrate_test_runtime::native_version,
/// );
/// ```
///
/// # With custom host functions
///
/// When you want to use custom runtime interfaces from within your runtime, you need to make the
/// executor aware of the host functions for these interfaces.
///
/// ```
/// # use sp_runtime_interface::runtime_interface;
///
/// #[runtime_interface]
/// trait MyInterface {
///     fn say_hello_world(data: &str) {
///         println!("Hello world from: {}", data);
///     }
/// }
///
/// sc_executor::native_executor_instance!(
///     pub MyExecutor,
///     substrate_test_runtime::api::dispatch,
///     substrate_test_runtime::native_version,
///     my_interface::HostFunctions,
/// );
/// ```
///
/// When you have multiple interfaces, you can give the host functions as a tuple e.g.:
/// `(my_interface::HostFunctions, my_interface2::HostFunctions)`
///
#[macro_export]
macro_rules! native_executor_instance {
	( $pub:vis $name:ident, $dispatcher:path, $version:path $(,)?) => {
		/// A unit struct which implements `NativeExecutionDispatch` feeding in the
		/// hard-coded runtime.
		$pub struct $name;
		$crate::native_executor_instance!(IMPL $name, $dispatcher, $version, ());
	};
	( $pub:vis $name:ident, $dispatcher:path, $version:path, $custom_host_functions:ty $(,)?) => {
		/// A unit struct which implements `NativeExecutionDispatch` feeding in the
		/// hard-coded runtime.
		$pub struct $name;
		$crate::native_executor_instance!(
			IMPL $name, $dispatcher, $version, $custom_host_functions
		);
	};
	(IMPL $name:ident, $dispatcher:path, $version:path, $custom_host_functions:ty) => {
		impl $crate::NativeExecutionDispatch for $name {
			type ExtendHostFunctions = $custom_host_functions;

			fn dispatch(
				ext: &mut dyn $crate::Externalities,
				method: &str,
				data: &[u8]
			) -> $crate::error::Result<Vec<u8>> {
				$crate::with_externalities_safe(ext, move || $dispatcher(method, data))?
					.ok_or_else(|| $crate::error::Error::MethodNotFound(method.to_owned()))
			}

			fn native_version() -> $crate::NativeVersion {
				$version()
			}
		}
	}
}

#[cfg(test)]
mod tests {
	use super::*;
	use sp_runtime_interface::runtime_interface;

	#[runtime_interface]
	trait MyInterface {
		fn say_hello_world(data: &str) {
			println!("Hello world from: {}", data);
		}
	}

	native_executor_instance!(
		pub MyExecutor,
		substrate_test_runtime::api::dispatch,
		substrate_test_runtime::native_version,
		(my_interface::HostFunctions, my_interface::HostFunctions),
	);

	#[test]
	fn native_executor_registers_custom_interface() {
		let executor = NativeExecutor::<MyExecutor>::new(
			WasmExecutionMethod::Interpreted,
			None,
			8,
		);
		my_interface::HostFunctions::host_functions().iter().for_each(|function| {
			assert_eq!(
				executor.wasm.host_functions.iter().filter(|f| f == &function).count(),
				2,
			);
		});

		my_interface::say_hello_world("hey");
	}
}