Decode contract bytearray in fate bytecode (#279)

src/ContractEncoder.js

@@ -1,13 +1,14 @@
-const RLP = require('rlp')
 const ApiEncoder = require('./ApiEncoder')
 const Serializer = require('./Serializer')
-const BytecodeSerializer = require('./Serializers/BytecodeSerializer')
-const {byteArray2Int, byteArray2Hex} = require('./utils/int2ByteArray')
+const ContractBytecodeSerializer = require('./Serializers/ContractBytecodeSerializer')
+const IntSerializer = require('./Serializers/IntSerializer')
+const FateTag = require('./FateTag')
 
 class ContractEncoder {
     constructor() {
         this._apiEncoder = new ApiEncoder()
-        this._bytecodeSerializer = new BytecodeSerializer(new Serializer())
+        this._contractBytecodeSerializer = new ContractBytecodeSerializer(new Serializer())
+        this._intSerializer = new IntSerializer()
     }
 
     /**
@@ -17,19 +18,15 @@ class ContractEncoder {
      * @returns {Object} Decoded contract metadata as POJO.
     */
     decode(data) {
-        const binData = this._apiEncoder.decodeWithType(data, 'contract_bytearray')
-        const decoded = RLP.decode(binData, true)
-        const stringDecoder = new TextDecoder()
+        const bytecode = this._apiEncoder.decodeWithType(data, 'contract_bytearray')
 
-        return {
-            tag: byteArray2Int(decoded.data[0]),
-            vsn: byteArray2Int(decoded.data[1]),
-            sourceHash: byteArray2Hex(decoded.data[2]),
-            aevmTypeInfo: decoded.data[3],
-            compilerVersion: stringDecoder.decode(decoded.data[5]),
-            payable: Boolean(decoded.data[6][0]),
-            bytecode: this._bytecodeSerializer.deserialize(new Uint8Array(decoded.data[4]))
-        }
+        const fateContractBytearray = new Uint8Array([
+            FateTag.CONTRACT_BYTEARRAY,
+            ...this._intSerializer.serialize(bytecode.length),
+            ...bytecode,
+        ])
+
+        return this._contractBytecodeSerializer.deserialize(fateContractBytearray)
     }
 }
 

src/FateTag.js

@@ -42,7 +42,7 @@ module.exports = Object.freeze({
     EMPTY_STRING : 0b01011111, // 0101 1111
     POS_BIG_INT  : 0b01101111, // 0110 1111 | RLP encoded (integer - 64)
     FALSE        : 0b01111111, // 0111 1111
-                               // 1000 1111 - FREE (Possibly for bytecode in the future.)
+    CONTRACT_BYTEARRAY: 0b10001111, // 1000 1111
     OBJECT       : 0b10011111, // 1001 1111 | ObjectType | RLP encoded Array
     VARIANT      : 0b10101111, // 1010 1111 | [encoded arities] | encoded tag | [encoded values]
     MAP_ID       : 0b10111111, // 1011 1111 | RLP encoded integer (store map id)

src/FateTypes.js

@@ -247,6 +247,10 @@ const FateTypeCalldata = (functionName, argumentTypes) => {
     }
 }
 
+const FateTypeContractBytearray = () => {
+    return {name: 'contract_bytearray'}
+}
+
 const FateTypeVar = (id) => {
     return {
         name: 'tvar',
@@ -293,6 +297,7 @@ module.exports = {
     FateTypeBls12381Fr,
     FateTypeBls12381Fp,
     FateTypeCalldata,
+    FateTypeContractBytearray,
     FateTypeVar,
     FateTypeAny,
 }

src/Serializer.js

@@ -20,6 +20,7 @@ const TupleSerializer = require('./Serializers/TupleSerializer')
 const VariantSerializer = require('./Serializers/VariantSerializer')
 const Bls12381FieldSerializer = require('./Serializers/Bls12381FieldSerializer')
 const CalldataSerializer = require('./Serializers/CalldataSerializer')
+const ContractBytecodeSerializer = require('./Serializers/ContractBytecodeSerializer')
 const TypeSerializer = require('./Serializers/TypeSerializer')
 const SerializerError = require('./Errors/SerializerError')
 
@@ -52,6 +53,7 @@ class Serializer extends BaseSerializer {
             'bls12_381.fr': new Bls12381FieldSerializer(),
             'bls12_381.fp': new Bls12381FieldSerializer(),
             'calldata': new CalldataSerializer(this),
+            'contract_bytearray': new ContractBytecodeSerializer(this),
             'type': new TypeSerializer(),
         }
     }

src/Serializers/BytecodeSerializer.js

@@ -69,7 +69,7 @@ class BytecodeSerializer extends BaseSerializer {
         const id = byteArray2Hex(data.slice(1, 5))
 
         if (prefix !== 0xfe) {
-            throw new Error(`Wrong function prefix, expeted 0xfe got 0x${data[0].toString(16)}`)
+            throw new Error(`Wrong function prefix, expected 0xfe got 0x${data[0].toString(16)}`)
         }
 
         const name = symbols[id]

src/Serializers/ContractBytecodeSerializer.js

@@ -0,0 +1,35 @@
+const RLP = require('rlp')
+const BaseSerializer = require('./BaseSerializer')
+const BytecodeSerializer = require('./BytecodeSerializer')
+const IntSerializer = require('./IntSerializer')
+const {byteArray2Int, byteArray2Hex} = require('../utils/int2ByteArray')
+
+class ContractBytecodeSerializer extends BaseSerializer {
+    constructor(globalSerializer) {
+        super()
+        this._bytecodeSerializer = new BytecodeSerializer(globalSerializer)
+        this._intSerializer = new IntSerializer()
+    }
+
+    deserializeStream(data) {
+        const buffer = new Uint8Array(data)
+        const [fateInt, remainder] = this._intSerializer.deserializeStream(buffer.slice(1))
+        const overallSize = Number(fateInt)
+        const decoded = RLP.decode(remainder.slice(0, overallSize))
+        const stringEncoder = new TextDecoder()
+        return [
+            {
+                tag: byteArray2Int(decoded[0]),
+                vsn: byteArray2Int(decoded[1]),
+                sourceHash: byteArray2Hex(decoded[2]),
+                aevmTypeInfo: decoded[3],
+                bytecode: this._bytecodeSerializer.deserialize(decoded[4]),
+                compilerVersion: stringEncoder.decode(decoded[5]),
+                payable: Boolean(decoded[6][0]),
+            },
+            remainder.slice(overallSize),
+        ]
+    }
+}
+
+module.exports = ContractBytecodeSerializer

src/TypeFactory.js

@@ -16,6 +16,7 @@ const {
     FateTypeMap,
     FateTypeTuple,
     FateTypeVariant,
+    FateTypeContractBytearray,
     FateTypeType,
 } = require('./FateTypes')
 
@@ -80,6 +81,10 @@ class TypeFactory {
             return OBJECT_TYPES[obj]
         }
 
+        if (tag === FateTag.CONTRACT_BYTEARRAY) {
+            return FateTypeContractBytearray()
+        }
+
         if (tag === FateTag.TYPE_INTEGER
             || tag === FateTag.TYPE_BOOLEAN
             || tag === FateTag.TYPE_LIST

tests/ContractEncoder.js

@@ -57,6 +57,27 @@ test('Decode basic contract', t => {
     })
 })
 
+test('Decode contract with Chain.create', t => {
+    t.plan(1)
+
+    const contract = encoder.decode('cb_+NBGA6D+x/gUE1YYLmvMJDIzJK2ZFJyOM5sXubwJy+9TVt/ib8C4n7iE/kTWRB8ANwA3ABoOgj8BAz/+m66dXgA3AQdHAgwBAAwDAAwDNwEHDAOPbxX4U0YDoJg7mklGIIWH49uiZBksC7yUEVO88y4D7lTd8+T4TMK2wKOS/kTWRB8ANwEHNwAaBoIAAQM/jC8BEUTWRB8RaW5pdIIvAIk4LjAuMC1yYzEAowAAlS8CEUTWRB8RaW5pdBGbrp1eDW5ld4IvAIk4LjAuMC1yYzEAaSb5ng==')
+
+    t.like(contract.bytecode.functions[1].instructions[0][3], {
+        mnemonic: 'PUSH',
+        args: [{
+            mod: 'immediate',
+            arg: {
+                tag: 70n,
+                vsn: 3n,
+                sourceHash: '983b9a4946208587e3dba264192c0bbc941153bcf32e03ee54ddf3e4f84cc2b6',
+                aevmTypeInfo: [],
+                compilerVersion: '8.0.0-rc1',
+                payable: false
+            }
+        }],
+    })
+})
+
 test('Decode full featured contract', t => {
     const contract = encoder.decode(testContract.toString())