seal_delegate_call api function (support for library contracts) (#1…

…0617)

* seal_call_code implementation

- tests
- benchmark

* Addressing @xgreenx's comments

* Fix test-linux-stable-int

* Rename seal_call_code to seal_delegate_call

* Pass value unchanged into lib contract

* Address @athei's comments

- whitespace .wat issues
- wrong/missing .wat comments
- redundant .wat calls/declarations

- change order of functions (seal_delegate_call right after seal_call)
  in decls, tests, benchmark
- fix comments, move doc comments to enum variants
- remove unnecessary empty lines

- rename runtime cost DelegateCall to DelegateCallBase
- do not set CallFlags::ALLOW_REENTRY for delegate_call

* Do not pass CallFlags::ALLOWS_REENTRY for delegate_call

* Update comment for seal_delegate_call and CallFlags

* Addressing @athei's comments (minor)

* Allow reentry for a new frame after delegate_call (revert)

* Same seal_caller and seal_value_transferred for lib contract

- test
- refactor frame args due to review
- logic for seal_caller (please review)

* Put caller on frame for delegate_call, minor fixes

* Update comment for delegate_call

* Addressing @athei's comments

* Update weights generated by benchmark

* Improve comments

* Address @HCastano's comments

* Update weights, thanks @joao-paulo-parity

* Improve InvalidCallFlags error comment

frame/contracts/fixtures/delegate_call.wat

@@ -0,0 +1,111 @@
+(module
+	(import "seal0" "seal_input" (func $seal_input (param i32 i32)))
+	(import "seal0" "seal_get_storage" (func $seal_get_storage (param i32 i32 i32) (result i32)))
+	(import "seal0" "seal_set_storage" (func $seal_set_storage (param i32 i32 i32)))
+	(import "__unstable__" "seal_delegate_call" (func $seal_delegate_call (param i32 i32 i32 i32 i32 i32) (result i32)))
+	(import "env" "memory" (memory 3 3))
+
+	;; [0, 32) storage key
+	(data (i32.const 0) "\01")
+
+	;; [32, 64) storage key
+	(data (i32.const 32) "\02")
+
+	;; [64, 96) buffer where input is copied
+
+	;; [96, 100) size of the input buffer
+	(data (i32.const 96) "\20")
+
+	;; [100, 104) size of buffer for seal_get_storage
+	(data (i32.const 100) "\20")
+
+	;; [104, 136) seal_get_storage buffer
+
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
+	(func (export "call")
+		(local $exit_code i32)
+
+		;; Reading "callee" code_hash
+		(call $seal_input (i32.const 64) (i32.const 96))
+
+		;; assert input size == 32
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 96))
+				(i32.const 32)
+			)
+		)
+
+		;; place a value in storage, the size of which is specified by the call input.
+		(call $seal_set_storage
+			(i32.const 0)		;; Pointer to storage key
+			(i32.const 32)		;; Pointer to initial value
+		    (i32.load (i32.const 100))		;; Size of value
+		)
+
+		(call $assert
+			(i32.eq
+		        (call $seal_get_storage
+		        	(i32.const 0)		;; Pointer to storage key
+		        	(i32.const 104)		;; buffer where to copy result
+		        	(i32.const 100)		;; pointer to size of buffer
+		        )
+				(i32.const 0) ;; ReturnCode::Success
+			)
+		)
+
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 104))		;; value received from storage
+				(i32.load (i32.const 32))		;; initial value
+			)
+		)
+
+		;; Call deployed library contract code.
+		(set_local $exit_code
+			(call $seal_delegate_call
+				(i32.const 0)	;; Set no call flags
+				(i32.const 64)	;; Pointer to "callee" code_hash.
+				(i32.const 0)	;; Input is ignored
+				(i32.const 0)	;; Length of the input
+				(i32.const 4294967295)	;; u32 max sentinel value: do not copy output
+				(i32.const 0)	;; Length is ignored in this case
+			)
+		)
+
+		;; Check for success exit status.
+		(call $assert
+			(i32.eq (get_local $exit_code) (i32.const 0)) ;; ReturnCode::Success
+		)
+
+		(call $assert
+			(i32.eq
+				(call $seal_get_storage
+					(i32.const 0)		;; Pointer to storage key
+					(i32.const 104)		;; buffer where to copy result
+					(i32.const 100)		;; pointer to size of buffer
+				)
+				(i32.const 0) ;; ReturnCode::Success
+			)
+		)
+
+		;; Make sure that 'callee' code changed the value
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 104))
+				(i32.const 1)
+			)
+		)
+	)
+
+	(func (export "deploy"))
+
+)

frame/contracts/fixtures/delegate_call_lib.wat

@@ -0,0 +1,79 @@
+(module
+	(import "seal0" "seal_set_storage" (func $seal_set_storage (param i32 i32 i32)))
+	(import "seal0" "seal_caller" (func $seal_caller (param i32 i32)))
+	(import "seal0" "seal_value_transferred" (func $seal_value_transferred (param i32 i32)))
+	(import "env" "memory" (memory 1 1))
+
+	;; [0, 32) storage key
+	(data (i32.const 0) "\01")
+
+	;; [32, 64) buffer for transferred value
+
+	;; [64, 96) size of the buffer for transferred value
+	(data (i32.const 64) "\20")
+
+	;; [96, 128) buffer for the caller
+
+	;; [128, 160) size of the buffer for caller
+	(data (i32.const 128) "\20")
+
+	(func $assert (param i32)
+		(block $ok
+			(br_if $ok
+				(get_local 0)
+			)
+			(unreachable)
+		)
+	)
+
+	(func (export "call")
+		;; place a value in storage
+		(call $seal_set_storage
+			(i32.const 0)		;; Pointer to storage key
+			(i32.const 0)		;; Pointer to value
+			(i32.const 32)		;; Size of value
+		)
+
+		;; This stores the value transferred in the buffer
+		(call $seal_value_transferred (i32.const 32) (i32.const 64))
+
+		;; assert len == 8
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 64))
+				(i32.const 8)
+			)
+		)
+
+		;; assert that contents of the buffer is equal to the value
+		;; passed to the `caller` contract: 1337
+		(call $assert
+			(i64.eq
+				(i64.load (i32.const 32))
+				(i64.const 1337)
+			)
+		)
+
+		;; fill the buffer with the caller.
+		(call $seal_caller (i32.const 96) (i32.const 128))
+
+		;; assert len == 32
+		(call $assert
+			(i32.eq
+				(i32.load (i32.const 128))
+				(i32.const 32)
+			)
+		)
+
+		;; assert that the first 64 byte are the beginning of "ALICE",
+		;; who is the caller of the `caller` contract
+		(call $assert
+			(i64.eq
+				(i64.load (i32.const 96))
+				(i64.const 0x0101010101010101)
+			)
+		)
+	)
+
+	(func (export "deploy"))
+)

frame/contracts/src/benchmarking/mod.rs

@@ -1474,6 +1474,58 @@ benchmarks! {
 		let origin = RawOrigin::Signed(instance.caller.clone());
 	}: call(origin, instance.addr, 0u32.into(), Weight::MAX, None, vec![])
 
+	seal_delegate_call {
+		let r in 0 .. API_BENCHMARK_BATCHES;
+		let hashes = (0..r * API_BENCHMARK_BATCH_SIZE)
+			.map(|i| {
+				let code = WasmModule::<T>::dummy_with_bytes(i);
+				Contracts::<T>::store_code_raw(code.code, whitelisted_caller())?;
+				Ok(code.hash)
+			})
+			.collect::<Result<Vec<_>, &'static str>>()?;
+		let hash_len = hashes.get(0).map(|x| x.encode().len()).unwrap_or(0);
+		let hashes_bytes = hashes.iter().flat_map(|x| x.encode()).collect::<Vec<_>>();
+		let hashes_len = hashes_bytes.len();
+		let hashes_offset = 0;
+
+		let code = WasmModule::<T>::from(ModuleDefinition {
+			memory: Some(ImportedMemory::max::<T>()),
+			imported_functions: vec![ImportedFunction {
+				module: "__unstable__",
+				name: "seal_delegate_call",
+				params: vec![
+					ValueType::I32,
+					ValueType::I32,
+					ValueType::I32,
+					ValueType::I32,
+					ValueType::I32,
+					ValueType::I32,
+				],
+				return_type: Some(ValueType::I32),
+			}],
+			data_segments: vec![
+				DataSegment {
+					offset: hashes_offset as u32,
+					value: hashes_bytes,
+				},
+			],
+			call_body: Some(body::repeated_dyn(r * API_BENCHMARK_BATCH_SIZE, vec![
+				Regular(Instruction::I32Const(0)), // flags
+				Counter(hashes_offset as u32, hash_len as u32), // code_hash_ptr
+				Regular(Instruction::I32Const(0)), // input_data_ptr
+				Regular(Instruction::I32Const(0)), // input_data_len
+				Regular(Instruction::I32Const(u32::max_value() as i32)), // output_ptr
+				Regular(Instruction::I32Const(0)), // output_len_ptr
+				Regular(Instruction::Call(0)),
+				Regular(Instruction::Drop),
+			])),
+			.. Default::default()
+		});
+		let instance = Contract::<T>::new(code, vec![])?;
+		let callee = instance.addr.clone();
+		let origin = RawOrigin::Signed(instance.caller.clone());
+	}: call(origin, callee, 0u32.into(), Weight::MAX, None, vec![])
+
 	seal_call_per_transfer_input_output_kb {
 		let t in 0 .. 1;
 		let i in 0 .. code::max_pages::<T>() * 64;