core, core/vm, cmd/disasm: unify procedures for disassembling evm code.

cmd/disasm/main.go

@@ -18,43 +18,25 @@
 package main
 
 import (
-	"encoding/hex"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"strings"
 
-	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/core/asm"
 )
 
 func main() {
-	code, err := ioutil.ReadAll(os.Stdin)
+	in, err := ioutil.ReadAll(os.Stdin)
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
-	code, err = hex.DecodeString(strings.TrimSpace(string(code[:])))
+	code := strings.TrimSpace(string(in[:]))
+	fmt.Printf("%v\n", code)
+	err = asm.PrettyPrintDisassembledInstructions(code)
 	if err != nil {
 		fmt.Printf("Error: %v\n", err)
 		return
 	}
-	fmt.Printf("%x\n", code)
-
-	for pc := uint64(0); pc < uint64(len(code)); pc++ {
-		op := vm.OpCode(code[pc])
-
-		switch op {
-		case vm.PUSH1, vm.PUSH2, vm.PUSH3, vm.PUSH4, vm.PUSH5, vm.PUSH6, vm.PUSH7, vm.PUSH8, vm.PUSH9, vm.PUSH10, vm.PUSH11, vm.PUSH12, vm.PUSH13, vm.PUSH14, vm.PUSH15, vm.PUSH16, vm.PUSH17, vm.PUSH18, vm.PUSH19, vm.PUSH20, vm.PUSH21, vm.PUSH22, vm.PUSH23, vm.PUSH24, vm.PUSH25, vm.PUSH26, vm.PUSH27, vm.PUSH28, vm.PUSH29, vm.PUSH30, vm.PUSH31, vm.PUSH32:
-			a := uint64(op) - uint64(vm.PUSH1) + 1
-			u := pc + 1 + a
-			if uint64(len(code)) <= pc || uint64(len(code)) < u {
-				fmt.Printf("Error: incomplete push instruction at %v\n", pc)
-				return
-			}
-			fmt.Printf("%-5d  %v  => %x\n", pc, op, code[pc+1:u])
-			pc += a
-		default:
-			fmt.Printf("%-5d  %v\n", pc, op)
-		}
-	}
 }

core/asm.go

@@ -1,64 +0,0 @@
-// Copyright 2014 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library 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 Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package core
-
-import (
-	"fmt"
-	"math/big"
-
-	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/vm"
-)
-
-func Disassemble(script []byte) (asm []string) {
-	pc := new(big.Int)
-	for {
-		if pc.Cmp(big.NewInt(int64(len(script)))) >= 0 {
-			return
-		}
-
-		// Get the memory location of pc
-		val := script[pc.Int64()]
-		// Get the opcode (it must be an opcode!)
-		op := vm.OpCode(val)
-
-		asm = append(asm, fmt.Sprintf("%04v: %v", pc, op))
-
-		switch op {
-		case vm.PUSH1, vm.PUSH2, vm.PUSH3, vm.PUSH4, vm.PUSH5, vm.PUSH6, vm.PUSH7, vm.PUSH8,
-			vm.PUSH9, vm.PUSH10, vm.PUSH11, vm.PUSH12, vm.PUSH13, vm.PUSH14, vm.PUSH15,
-			vm.PUSH16, vm.PUSH17, vm.PUSH18, vm.PUSH19, vm.PUSH20, vm.PUSH21, vm.PUSH22,
-			vm.PUSH23, vm.PUSH24, vm.PUSH25, vm.PUSH26, vm.PUSH27, vm.PUSH28, vm.PUSH29,
-			vm.PUSH30, vm.PUSH31, vm.PUSH32:
-			pc.Add(pc, common.Big1)
-			a := int64(op) - int64(vm.PUSH1) + 1
-			if int(pc.Int64()+a) > len(script) {
-				return
-			}
-
-			data := script[pc.Int64() : pc.Int64()+a]
-			if len(data) == 0 {
-				data = []byte{0}
-			}
-			asm = append(asm, fmt.Sprintf("%04v: 0x%x", pc, data))
-
-			pc.Add(pc, big.NewInt(a-1))
-		}
-
-		pc.Add(pc, common.Big1)
-	}
-}

core/asm/asm.go

@@ -0,0 +1,78 @@
+// Copyright 2014, 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Provides support for dealing with EVM assembly instructions (e.g., disassembling them).
+package asm
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+// Apply function to each disassembled EVM instruction.
+func ForEachDisassembledInstruction(script []byte, fun func(uint64, vm.OpCode, []byte)) error {
+	for pc := uint64(0); pc < uint64(len(script)); pc++ {
+		op := vm.OpCode(script[pc])
+		switch op {
+		case vm.PUSH1, vm.PUSH2, vm.PUSH3, vm.PUSH4, vm.PUSH5, vm.PUSH6, vm.PUSH7, vm.PUSH8, vm.PUSH9, vm.PUSH10, vm.PUSH11, vm.PUSH12, vm.PUSH13, vm.PUSH14, vm.PUSH15, vm.PUSH16, vm.PUSH17, vm.PUSH18, vm.PUSH19, vm.PUSH20, vm.PUSH21, vm.PUSH22, vm.PUSH23, vm.PUSH24, vm.PUSH25, vm.PUSH26, vm.PUSH27, vm.PUSH28, vm.PUSH29, vm.PUSH30, vm.PUSH31, vm.PUSH32:
+			a := uint64(op) - uint64(vm.PUSH1) + 1
+			u := pc + 1 + a
+			if uint64(len(script)) <= pc || uint64(len(script)) < u {
+				return fmt.Errorf("incomplete push instruction at %v", pc)
+			}
+			fun(pc, op, script[pc+1:u])
+			pc += a
+		default:
+			fun(pc, op, make([]byte, 0))
+		}
+	}
+	return nil
+}
+
+// Pretty-print all disassembled EVM instructions to stdout.
+func PrettyPrintDisassembledInstructions(code string) error {
+	script, err := hex.DecodeString(code)
+	if err != nil {
+		return err
+	}
+
+	return ForEachDisassembledInstruction(script, func(pc uint64, op vm.OpCode, args []byte) {
+		if args != nil && 0 < len(args) {
+			fmt.Printf("%06v: %v 0x%x\n", pc, op, args)
+		} else {
+			fmt.Printf("%06v: %v\n", pc, op)
+		}
+	})
+}
+
+// Return all disassembled EVM instructions in human-readable format.
+func PrettyPrintedDisassembledInstructions(script []byte) ([]string, error) {
+	instrs := make([]string, 0)
+	err := ForEachDisassembledInstruction(script, func(pc uint64, op vm.OpCode, args []byte) {
+		if args != nil && 0 < len(args) {
+			instrs = append(instrs, fmt.Sprintf("%06v: %v 0x%x\n", pc, op, args))
+		} else {
+			instrs = append(instrs, fmt.Sprintf("%06v: %v\n", pc, op))
+		}
+	})
+
+	if err != nil {
+		return nil, err
+	}
+	return instrs, nil
+}

core/asm/asm_test.go

@@ -0,0 +1,51 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package asm
+
+import (
+	"testing"
+
+	"encoding/hex"
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+// Tests disassembling the instructions for valid evm code
+func TestForEachDisassembledInstructionValid(t *testing.T) {
+	cnt := 0
+	script, _ := hex.DecodeString("61000000")
+	err := ForEachDisassembledInstruction(script, func(pc uint64, op vm.OpCode, args []byte) {
+		cnt++
+	})
+	if err != nil {
+		t.Errorf("Expected 2, but encountered error %v instead.", err)
+	}
+	if cnt != 2 {
+		t.Errorf("Expected 2, but got %v instead.", cnt)
+	}
+}
+
+// Tests disassembling the instructions for invalid evm code
+func TestForEachDisassembledInstructionInvalid(t *testing.T) {
+	cnt := 0
+	script, _ := hex.DecodeString("6100")
+	err := ForEachDisassembledInstruction(script, func(pc uint64, op vm.OpCode, args []byte) {
+		cnt++
+	})
+	if err == nil {
+		t.Errorf("Expected an error, but got %v instead.", cnt)
+	}
+}

core/vm/asm.go

@@ -1,61 +0,0 @@
-// Copyright 2014 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library 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 Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package vm
-
-import (
-	"fmt"
-	"math/big"
-
-	"github.com/ethereum/go-ethereum/common"
-)
-
-// Disassemble disassembles the byte code and returns the string
-// representation (human readable opcodes).
-func Disassemble(script []byte) (asm []string) {
-	pc := new(big.Int)
-	for {
-		if pc.Cmp(big.NewInt(int64(len(script)))) >= 0 {
-			return
-		}
-
-		// Get the memory location of pc
-		val := script[pc.Int64()]
-		// Get the opcode (it must be an opcode!)
-		op := OpCode(val)
-
-		asm = append(asm, fmt.Sprintf("%v", op))
-
-		switch op {
-		case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
-			pc.Add(pc, common.Big1)
-			a := int64(op) - int64(PUSH1) + 1
-			if int(pc.Int64()+a) > len(script) {
-				return nil
-			}
-
-			data := script[pc.Int64() : pc.Int64()+a]
-			if len(data) == 0 {
-				data = []byte{0}
-			}
-			asm = append(asm, fmt.Sprintf("0x%x", data))
-
-			pc.Add(pc, big.NewInt(a-1))
-		}
-
-		pc.Add(pc, common.Big1)
-	}
-}

core/vm/disasm.go

@@ -1,37 +0,0 @@
-// Copyright 2015 The go-ethereum Authors
-// This file is part of the go-ethereum library.
-//
-// The go-ethereum library is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Lesser General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// The go-ethereum library 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 Lesser General Public License for more details.
-//
-// You should have received a copy of the GNU Lesser General Public License
-// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
-
-package vm
-
-import "fmt"
-
-func Disasm(code []byte) []string {
-	var out []string
-	for pc := uint64(0); pc < uint64(len(code)); pc++ {
-		op := OpCode(code[pc])
-		out = append(out, op.String())
-
-		switch op {
-		case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
-			a := uint64(op) - uint64(PUSH1) + 1
-			out = append(out, fmt.Sprintf("0x%x", code[pc+1:pc+1+a]))
-
-			pc += a
-		}
-	}
-
-	return out
-}