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
// This file is part of Substrate.

// Copyright (C) 2019-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Provides the [`PassBy`](PassBy) trait to simplify the implementation of the
//! runtime interface traits for custom types.
//!
//! [`Codec`], [`Inner`] and [`Enum`] are the provided strategy implementations.

use crate::{
	util::{pack_ptr_and_len, unpack_ptr_and_len},
	RIType,
};

#[cfg(feature = "std")]
use crate::host::*;
#[cfg(not(feature = "std"))]
use crate::wasm::*;

#[cfg(feature = "std")]
use sp_wasm_interface::{FunctionContext, Pointer, Result};

use sp_std::{convert::TryFrom, marker::PhantomData};

#[cfg(not(feature = "std"))]
use sp_std::vec::Vec;

/// Derive macro for implementing [`PassBy`] with the [`Codec`] strategy.
///
/// This requires that the type implements [`Encode`](codec::Encode) and
/// [`Decode`](codec::Decode) from `parity-scale-codec`.
///
/// # Example
///
/// ```
/// # use sp_runtime_interface::pass_by::PassByCodec;
/// # use codec::{Encode, Decode};
/// #[derive(PassByCodec, Encode, Decode)]
/// struct EncodableType {
///     name: Vec<u8>,
///     param: u32,
/// }
/// ```
pub use sp_runtime_interface_proc_macro::PassByCodec;

/// Derive macro for implementing [`PassBy`] with the [`Inner`] strategy.
///
/// Besides implementing [`PassBy`], this derive also implements the helper trait
/// [`PassByInner`].
///
/// The type is required to be a struct with just one field. The field type needs to implement
/// the required traits to pass it between the wasm and the native side. (See the runtime
/// interface crate for more information about these traits.)
///
/// # Example
///
/// ```
/// # use sp_runtime_interface::pass_by::PassByInner;
/// #[derive(PassByInner)]
/// struct Data([u8; 32]);
/// ```
///
/// ```
/// # use sp_runtime_interface::pass_by::PassByInner;
/// #[derive(PassByInner)]
/// struct Data {
///     data: [u8; 32],
/// }
/// ```
pub use sp_runtime_interface_proc_macro::PassByInner;

/// Derive macro for implementing [`PassBy`] with the [`Enum`] strategy.
///
/// Besides implementing [`PassBy`], this derive also implements `TryFrom<u8>` and
/// `From<Self> for u8` for the type.
///
/// The type is required to be an enum with only unit variants and at maximum `256` variants.
/// Also it is required that the type implements `Copy`.
///
/// # Example
///
/// ```
/// # use sp_runtime_interface::pass_by::PassByEnum;
/// #[derive(PassByEnum, Copy, Clone)]
/// enum Data {
///     Okay,
///     NotOkay,
///     // This will not work with the derive.
///     //Why(u32),
/// }
/// ```
pub use sp_runtime_interface_proc_macro::PassByEnum;

/// Something that should be passed between wasm and the host using the given strategy.
///
/// See [`Codec`], [`Inner`] or [`Enum`] for more information about the provided strategies.
pub trait PassBy: Sized {
	/// The strategy that should be used to pass the type.
	type PassBy: PassByImpl<Self>;
}

/// Something that provides a strategy for passing a type between wasm and the host.
///
/// This trait exposes the same functionality as [`crate::host::IntoFFIValue`] and
/// [`crate::host::FromFFIValue`] to delegate the implementation for a type to a different type.
///
/// This trait is used for the host implementation.
#[cfg(feature = "std")]
pub trait PassByImpl<T>: RIType {
	/// Convert the given instance to the ffi value.
	///
	/// For more information see: [`crate::host::IntoFFIValue::into_ffi_value`]
	fn into_ffi_value(instance: T, context: &mut dyn FunctionContext) -> Result<Self::FFIType>;

	/// Create `T` from the given ffi value.
	///
	/// For more information see: [`crate::host::FromFFIValue::from_ffi_value`]
	fn from_ffi_value(context: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T>;
}

/// Something that provides a strategy for passing a type between wasm and the host.
///
/// This trait exposes the same functionality as [`crate::wasm::IntoFFIValue`] and
/// [`crate::wasm::FromFFIValue`] to delegate the implementation for a type to a different type.
///
/// This trait is used for the wasm implementation.
#[cfg(not(feature = "std"))]
pub trait PassByImpl<T>: RIType {
	/// The owned rust type that is stored with the ffi value in [`crate::wasm::WrappedFFIValue`].
	type Owned;

	/// Convert the given `instance` into [`crate::wasm::WrappedFFIValue`].
	///
	/// For more information see: [`crate::wasm::IntoFFIValue::into_ffi_value`]
	fn into_ffi_value(instance: &T) -> WrappedFFIValue<Self::FFIType, Self::Owned>;

	/// Create `T` from the given ffi value.
	///
	/// For more information see: [`crate::wasm::FromFFIValue::from_ffi_value`]
	fn from_ffi_value(arg: Self::FFIType) -> T;
}

impl<T: PassBy> RIType for T {
	type FFIType = <T::PassBy as RIType>::FFIType;
}

#[cfg(feature = "std")]
impl<T: PassBy> IntoFFIValue for T {
	fn into_ffi_value(
		self,
		context: &mut dyn FunctionContext,
	) -> Result<<T::PassBy as RIType>::FFIType> {
		T::PassBy::into_ffi_value(self, context)
	}
}

#[cfg(feature = "std")]
impl<T: PassBy> FromFFIValue for T {
	type SelfInstance = Self;

	fn from_ffi_value(
		context: &mut dyn FunctionContext,
		arg: <T::PassBy as RIType>::FFIType,
	) -> Result<Self> {
		T::PassBy::from_ffi_value(context, arg)
	}
}

#[cfg(not(feature = "std"))]
impl<T: PassBy> IntoFFIValue for T {
	type Owned = <T::PassBy as PassByImpl<T>>::Owned;

	fn into_ffi_value(&self) -> WrappedFFIValue<<T::PassBy as RIType>::FFIType, Self::Owned> {
		T::PassBy::into_ffi_value(self)
	}
}

#[cfg(not(feature = "std"))]
impl<T: PassBy> FromFFIValue for T {
	fn from_ffi_value(arg: <T::PassBy as RIType>::FFIType) -> Self {
		T::PassBy::from_ffi_value(arg)
	}
}

/// The implementation of the pass by codec strategy. This strategy uses a SCALE encoded
/// representation of the type between wasm and the host.
///
/// Use this type as associated type for [`PassBy`] to implement this strategy for a type.
///
/// This type expects the type that wants to implement this strategy as generic parameter.
///
/// [`PassByCodec`](derive.PassByCodec.html) is a derive macro to implement this strategy.
///
/// # Example
/// ```
/// # use sp_runtime_interface::pass_by::{PassBy, Codec};
/// #[derive(codec::Encode, codec::Decode)]
/// struct Test;
///
/// impl PassBy for Test {
///     type PassBy = Codec<Self>;
/// }
/// ```
pub struct Codec<T: codec::Codec>(PhantomData<T>);

#[cfg(feature = "std")]
impl<T: codec::Codec> PassByImpl<T> for Codec<T> {
	fn into_ffi_value(instance: T, context: &mut dyn FunctionContext) -> Result<Self::FFIType> {
		let vec = instance.encode();
		let ptr = context.allocate_memory(vec.len() as u32)?;
		context.write_memory(ptr, &vec)?;

		Ok(pack_ptr_and_len(ptr.into(), vec.len() as u32))
	}

	fn from_ffi_value(context: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T> {
		let (ptr, len) = unpack_ptr_and_len(arg);
		let vec = context.read_memory(Pointer::new(ptr), len)?;
		T::decode(&mut &vec[..]).map_err(|e| format!("Could not decode value from wasm: {}", e))
	}
}

#[cfg(not(feature = "std"))]
impl<T: codec::Codec> PassByImpl<T> for Codec<T> {
	type Owned = Vec<u8>;

	fn into_ffi_value(instance: &T) -> WrappedFFIValue<Self::FFIType, Self::Owned> {
		let data = instance.encode();
		let ffi_value = pack_ptr_and_len(data.as_ptr() as u32, data.len() as u32);
		(ffi_value, data).into()
	}

	fn from_ffi_value(arg: Self::FFIType) -> T {
		let (ptr, len) = unpack_ptr_and_len(arg);
		let len = len as usize;

		let encoded = if len == 0 {
			Vec::new()
		} else {
			unsafe { Vec::from_raw_parts(ptr as *mut u8, len, len) }
		};

		T::decode(&mut &encoded[..]).expect("Host to wasm values are encoded correctly; qed")
	}
}

/// The type is passed as `u64`.
///
/// The `u64` value is build by `length 32bit << 32 | pointer 32bit`
///
/// `Self` is encoded and the length and the pointer are taken from the encoded vector.
impl<T: codec::Codec> RIType for Codec<T> {
	type FFIType = u64;
}

/// Trait that needs to be implemented by a type that should be passed between wasm and the host,
/// by using the inner type. See [`Inner`] for more information.
pub trait PassByInner: Sized {
	/// The inner type that is wrapped by `Self`.
	type Inner: RIType;

	/// Consumes `self` and returns the inner type.
	fn into_inner(self) -> Self::Inner;

	/// Returns the reference to the inner type.
	fn inner(&self) -> &Self::Inner;

	/// Construct `Self` from the given `inner`.
	fn from_inner(inner: Self::Inner) -> Self;
}

/// The implementation of the pass by inner type strategy. The type that uses this strategy will be
/// passed between wasm and the host by using the wrapped inner type. So, this strategy is only
/// usable by newtype structs.
///
/// Use this type as associated type for [`PassBy`] to implement this strategy for a type. Besides
/// that the `PassByInner` trait need to be implemented as well.
///
/// This type expects the type that wants to use this strategy as generic parameter `T` and the
/// inner type as generic parameter `I`.
///
/// [`PassByInner`](derive.PassByInner.html) is a derive macro to implement this strategy.
///
/// # Example
/// ```
/// # use sp_runtime_interface::pass_by::{PassBy, Inner, PassByInner};
/// struct Test([u8; 32]);
///
/// impl PassBy for Test {
///     type PassBy = Inner<Self, [u8; 32]>;
/// }
///
/// impl PassByInner for Test {
///     type Inner = [u8; 32];
///
///     fn into_inner(self) -> [u8; 32] {
///         self.0
///     }
///     fn inner(&self) -> &[u8; 32] {
///         &self.0
///     }
///     fn from_inner(inner: [u8; 32]) -> Self {
///         Self(inner)
///     }
/// }
/// ```
pub struct Inner<T: PassByInner<Inner = I>, I: RIType>(PhantomData<(T, I)>);

#[cfg(feature = "std")]
impl<T: PassByInner<Inner = I>, I: RIType> PassByImpl<T> for Inner<T, I>
where
	I: IntoFFIValue + FromFFIValue<SelfInstance = I>,
{
	fn into_ffi_value(instance: T, context: &mut dyn FunctionContext) -> Result<Self::FFIType> {
		instance.into_inner().into_ffi_value(context)
	}

	fn from_ffi_value(context: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T> {
		I::from_ffi_value(context, arg).map(T::from_inner)
	}
}

#[cfg(not(feature = "std"))]
impl<T: PassByInner<Inner = I>, I: RIType> PassByImpl<T> for Inner<T, I>
where
	I: IntoFFIValue + FromFFIValue,
{
	type Owned = I::Owned;

	fn into_ffi_value(instance: &T) -> WrappedFFIValue<Self::FFIType, Self::Owned> {
		instance.inner().into_ffi_value()
	}

	fn from_ffi_value(arg: Self::FFIType) -> T {
		T::from_inner(I::from_ffi_value(arg))
	}
}

/// The type is passed as the inner type.
impl<T: PassByInner<Inner = I>, I: RIType> RIType for Inner<T, I> {
	type FFIType = I::FFIType;
}

/// The implementation of the pass by enum strategy. This strategy uses an `u8` internally to pass
/// the enum between wasm and the host. So, this strategy only supports enums with unit variants.
///
/// Use this type as associated type for [`PassBy`] to implement this strategy for a type.
///
/// This type expects the type that wants to implement this strategy as generic parameter. Besides
/// that the type needs to implement `TryFrom<u8>` and `From<Self> for u8`.
///
/// [`PassByEnum`](derive.PassByEnum.html) is a derive macro to implement this strategy.
///
/// # Example
/// ```
/// # use sp_runtime_interface::pass_by::{PassBy, Enum};
/// #[derive(Clone, Copy)]
/// enum Test {
///     Test1,
///     Test2,
/// }
///
/// impl From<Test> for u8 {
///     fn from(val: Test) -> u8 {
///         match val {
///             Test::Test1 => 0,
///             Test::Test2 => 1,
///         }
///     }
/// }
///
/// impl std::convert::TryFrom<u8> for Test {
///     type Error = ();
///
///     fn try_from(val: u8) -> Result<Test, ()> {
///         match val {
///             0 => Ok(Test::Test1),
///             1 => Ok(Test::Test2),
///             _ => Err(()),
///         }
///     }
/// }
///
/// impl PassBy for Test {
///     type PassBy = Enum<Self>;
/// }
/// ```
pub struct Enum<T: Copy + Into<u8> + TryFrom<u8>>(PhantomData<T>);

#[cfg(feature = "std")]
impl<T: Copy + Into<u8> + TryFrom<u8>> PassByImpl<T> for Enum<T> {
	fn into_ffi_value(instance: T, _: &mut dyn FunctionContext) -> Result<Self::FFIType> {
		Ok(instance.into())
	}

	fn from_ffi_value(_: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T> {
		T::try_from(arg).map_err(|_| format!("Invalid enum discriminant: {}", arg))
	}
}

#[cfg(not(feature = "std"))]
impl<T: Copy + Into<u8> + TryFrom<u8, Error = ()>> PassByImpl<T> for Enum<T> {
	type Owned = ();

	fn into_ffi_value(instance: &T) -> WrappedFFIValue<Self::FFIType, Self::Owned> {
		let value: u8 = (*instance).into();
		value.into()
	}

	fn from_ffi_value(arg: Self::FFIType) -> T {
		T::try_from(arg).expect("Host to wasm provides a valid enum discriminant; qed")
	}
}

/// The type is passed as `u8`.
///
/// The value is corresponds to the discriminant of the variant.
impl<T: Copy + Into<u8> + TryFrom<u8>> RIType for Enum<T> {
	type FFIType = u8;
}