mirror of
https://github.com/nspcc-dev/neo-go.git
synced 2024-10-16 15:43:25 +00:00
f7d57e4e49
* updated readme * added basic cmd. * added seperate folders for cmd packages. * Fix netmodes in test + reverse bigint bytes * glide get deps
127 lines
2.7 KiB
Go
127 lines
2.7 KiB
Go
package vm
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import (
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"bytes"
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"encoding/binary"
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"errors"
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"fmt"
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"math/big"
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"github.com/CityOfZion/neo-go/pkg/util"
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)
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// ScriptBuilder generates bytecode and will write all
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// generated bytecode into its internal buffer.
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type ScriptBuilder struct {
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buf *bytes.Buffer
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}
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func (sb *ScriptBuilder) emit(op OpCode, b []byte) error {
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if err := sb.buf.WriteByte(byte(op)); err != nil {
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return err
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}
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_, err := sb.buf.Write(b)
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return err
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}
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func (sb *ScriptBuilder) emitPush(op OpCode) error {
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return sb.buf.WriteByte(byte(op))
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}
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func (sb *ScriptBuilder) emitPushBool(b bool) error {
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if b {
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return sb.emitPush(OpPushT)
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}
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return sb.emitPush(OpPushF)
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}
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func (sb *ScriptBuilder) emitPushInt(i int64) error {
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if i == -1 {
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return sb.emitPush(OpPushM1)
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}
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if i == 0 {
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return sb.emitPush(OpPushF)
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}
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if i > 0 && i < 16 {
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val := OpCode((int(OpPush1) - 1 + int(i)))
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return sb.emitPush(val)
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}
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bInt := big.NewInt(i)
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val := util.ToArrayReverse(bInt.Bytes())
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return sb.emitPushArray(val)
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}
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func (sb *ScriptBuilder) emitPushArray(b []byte) error {
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var (
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err error
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n = len(b)
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)
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if n == 0 {
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return errors.New("0 bytes given in pushArray")
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}
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if n <= int(OpPushBytes75) {
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return sb.emit(OpCode(n), b)
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} else if n < 0x100 {
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err = sb.emit(OpPushData1, []byte{byte(n)})
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} else if n < 0x10000 {
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buf := make([]byte, 2)
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binary.LittleEndian.PutUint16(buf, uint16(n))
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err = sb.emit(OpPushData2, buf)
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} else {
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buf := make([]byte, 4)
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binary.LittleEndian.PutUint32(buf, uint32(n))
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err = sb.emit(OpPushData4, buf)
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}
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if err != nil {
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return err
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}
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_, err = sb.buf.Write(b)
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return err
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}
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func (sb *ScriptBuilder) emitPushString(str string) error {
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return sb.emitPushArray([]byte(str))
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}
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func (sb *ScriptBuilder) emitSysCall(api string) error {
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lenAPI := len(api)
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if lenAPI == 0 {
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return errors.New("syscall argument cant be 0")
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}
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if lenAPI > 252 {
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return fmt.Errorf("invalid syscall argument: %s", api)
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}
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bapi := []byte(api)
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args := make([]byte, lenAPI+1)
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args[0] = byte(lenAPI)
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copy(args, bapi[1:])
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return sb.emit(OpSysCall, args)
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}
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func (sb *ScriptBuilder) emitPushCall(scriptHash []byte, tailCall bool) error {
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if len(scriptHash) != 20 {
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return errors.New("expected a 20 byte long scriptHash (uint160) for pushCall")
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}
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op := OpAppCall
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if tailCall {
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op = OpTailCall
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}
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return sb.emit(op, scriptHash)
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}
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func (sb *ScriptBuilder) emitJump(op OpCode, offset int16) error {
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if op != OpJMP && op != OpJMPIF && op != OpJMPIFNOT && op != OpCall {
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return fmt.Errorf("invalid jump opcode: %v", op)
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}
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return sb.emit(op, []byte{}) // convert to bits?
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}
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func (sb *ScriptBuilder) dumpOpcode() {
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buf := sb.buf.Bytes()
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for i := 0; i < len(buf); i++ {
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fmt.Printf("OPCODE AT INDEX \t %d \t 0x%2x \t %s \n", i, buf[i], OpCode(buf[i]))
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}
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}
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