neo-go/pkg/vm/emit/emit.go

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package emit
import (
"encoding/binary"
"errors"
"fmt"
"math/big"
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"math/bits"
"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)
// Instruction emits a VM Instruction with data to the given buffer.
func Instruction(w *io.BinWriter, op opcode.Opcode, b []byte) {
w.WriteB(byte(op))
w.WriteBytes(b)
}
// Opcodes emits a single VM Instruction without arguments to the given buffer.
func Opcodes(w *io.BinWriter, ops ...opcode.Opcode) {
for _, op := range ops {
w.WriteB(byte(op))
}
}
// InitSlot emits INITSLOT instruction with the specified size of locals/args slots.
func InitSlot(w *io.BinWriter, locals, args uint8) {
Instruction(w, opcode.INITSLOT, []byte{locals, args})
}
// Bool emits a bool type to the given buffer.
func Bool(w *io.BinWriter, ok bool) {
var opVal = opcode.PUSHT
if !ok {
opVal = opcode.PUSHF
}
Opcodes(w, opVal)
}
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func padRight(s int, buf []byte) []byte {
l := len(buf)
buf = buf[:s]
if buf[l-1]&0x80 != 0 {
for i := l; i < s; i++ {
buf[i] = 0xFF
}
}
return buf
}
// Int emits an int type to the given buffer.
func Int(w *io.BinWriter, i int64) {
if smallInt(w, i) {
return
}
bigInt(w, big.NewInt(i), false)
}
// BigInt emits a big-integer to the given buffer.
func BigInt(w *io.BinWriter, n *big.Int) {
bigInt(w, n, true)
}
func smallInt(w *io.BinWriter, i int64) bool {
switch {
case i == -1:
Opcodes(w, opcode.PUSHM1)
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case i >= 0 && i < 16:
val := opcode.Opcode(int(opcode.PUSH0) + int(i))
Opcodes(w, val)
default:
return false
}
return true
}
func bigInt(w *io.BinWriter, n *big.Int, trySmall bool) {
if w.Err != nil {
return
}
if trySmall && n.IsInt64() && smallInt(w, n.Int64()) {
return
}
if err := stackitem.CheckIntegerSize(n); err != nil {
w.Err = err
return
}
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buf := bigint.ToPreallocatedBytes(n, make([]byte, 0, 32))
if len(buf) == 0 {
Opcodes(w, opcode.PUSH0)
return
}
padSize := byte(8 - bits.LeadingZeros8(byte(len(buf)-1)))
Opcodes(w, opcode.PUSHINT8+opcode.Opcode(padSize))
w.WriteBytes(padRight(1<<padSize, buf))
}
// Array emits an array of elements to the given buffer. It accepts everything that
// Any accepts.
func Array(w *io.BinWriter, es ...any) {
if len(es) == 0 {
Opcodes(w, opcode.NEWARRAY0)
return
}
for i := len(es) - 1; i >= 0; i-- {
Any(w, es[i])
}
Int(w, int64(len(es)))
Opcodes(w, opcode.PACK)
}
// Any emits element if supported. It accepts elements of the following types:
// - int8, int16, int32, int64, int
// - uint8, uint16, uint32, uint64, uint
// - *big.Int
// - string, []byte
// - util.Uint160, *util.Uint160, util.Uint256, *util.Uint256
// - bool
// - stackitem.Convertible, stackitem.Item
// - nil
// - []any
//
// [errors.ErrUnsupported] is returned for unsupported types.
func Any(w *io.BinWriter, something any) {
switch e := something.(type) {
case []any:
Array(w, e...)
case int64:
Int(w, e)
case uint64:
BigInt(w, new(big.Int).SetUint64(e))
case int32:
Int(w, int64(e))
case uint32:
Int(w, int64(e))
case int16:
Int(w, int64(e))
case uint16:
Int(w, int64(e))
case int8:
Int(w, int64(e))
case uint8:
Int(w, int64(e))
case int:
Int(w, int64(e))
case uint:
BigInt(w, new(big.Int).SetUint64(uint64(e)))
case *big.Int:
BigInt(w, e)
case string:
String(w, e)
case util.Uint160:
Bytes(w, e.BytesBE())
case util.Uint256:
Bytes(w, e.BytesBE())
case *util.Uint160:
if e == nil {
Opcodes(w, opcode.PUSHNULL)
} else {
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Bytes(w, e.BytesBE())
}
case *util.Uint256:
if e == nil {
Opcodes(w, opcode.PUSHNULL)
} else {
Bytes(w, e.BytesBE())
}
case []byte:
Bytes(w, e)
case bool:
Bool(w, e)
case stackitem.Convertible:
Convertible(w, e)
case stackitem.Item:
StackItem(w, e)
default:
if something != nil {
w.Err = fmt.Errorf("%w: %T type", errors.ErrUnsupported, e)
return
}
Opcodes(w, opcode.PUSHNULL)
}
}
// Convertible converts provided stackitem.Convertible to the stackitem.Item and
// emits the item to the given buffer.
func Convertible(w *io.BinWriter, c stackitem.Convertible) {
si, err := c.ToStackItem()
if err != nil {
w.Err = fmt.Errorf("failed to convert stackitem.Convertible to stackitem: %w", err)
return
}
StackItem(w, si)
}
// StackItem emits provided stackitem.Item to the given buffer. If it can't
// be emitted [errors.ErrUnsupported] is returned.
func StackItem(w *io.BinWriter, si stackitem.Item) {
switch t := si.Type(); t {
case stackitem.AnyT:
if si.Value() == nil {
Opcodes(w, opcode.PUSHNULL)
} else {
w.Err = fmt.Errorf("%w: %s can only be nil", errors.ErrUnsupported, t)
return
}
case stackitem.BooleanT:
Bool(w, si.Value().(bool))
case stackitem.IntegerT:
BigInt(w, si.Value().(*big.Int))
case stackitem.ByteArrayT, stackitem.BufferT:
Bytes(w, si.Value().([]byte))
case stackitem.ArrayT:
arr := si.Value().([]stackitem.Item)
arrAny := make([]any, len(arr))
for i := range arr {
arrAny[i] = arr[i]
}
Array(w, arrAny...)
case stackitem.StructT:
arr := si.Value().([]stackitem.Item)
for i := len(arr) - 1; i >= 0; i-- {
StackItem(w, arr[i])
}
Int(w, int64(len(arr)))
Opcodes(w, opcode.PACKSTRUCT)
case stackitem.MapT:
arr := si.Value().([]stackitem.MapElement)
for i := len(arr) - 1; i >= 0; i-- {
StackItem(w, arr[i].Value)
StackItem(w, arr[i].Key)
}
Int(w, int64(len(arr)))
Opcodes(w, opcode.PACKMAP)
default:
w.Err = fmt.Errorf("%w: %s type", errors.ErrUnsupported, t)
return
}
}
// String emits a string to the given buffer.
func String(w *io.BinWriter, s string) {
Bytes(w, []byte(s))
}
// Bytes emits a byte array to the given buffer.
func Bytes(w *io.BinWriter, b []byte) {
var n = len(b)
switch {
case n < 0x100:
Instruction(w, opcode.PUSHDATA1, []byte{byte(n)})
case n < 0x10000:
buf := make([]byte, 2)
binary.LittleEndian.PutUint16(buf, uint16(n))
Instruction(w, opcode.PUSHDATA2, buf)
default:
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, uint32(n))
Instruction(w, opcode.PUSHDATA4, buf)
}
w.WriteBytes(b)
}
// Syscall emits the syscall API to the given buffer.
// Syscall API string cannot be 0.
func Syscall(w *io.BinWriter, api string) {
if w.Err != nil {
return
} else if len(api) == 0 {
w.Err = errors.New("syscall api cannot be of length 0")
return
}
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, interopnames.ToID([]byte(api)))
Instruction(w, opcode.SYSCALL, buf)
}
// Call emits a call Instruction with the label to the given buffer.
func Call(w *io.BinWriter, op opcode.Opcode, label uint16) {
Jmp(w, op, label)
}
// Jmp emits a jump Instruction along with the label to the given buffer.
func Jmp(w *io.BinWriter, op opcode.Opcode, label uint16) {
if w.Err != nil {
return
} else if !isInstructionJmp(op) {
w.Err = fmt.Errorf("opcode %s is not a jump or call type", op.String())
return
}
buf := make([]byte, 4)
binary.LittleEndian.PutUint16(buf, label)
Instruction(w, op, buf)
}
// AppCallNoArgs emits a call to the provided contract.
func AppCallNoArgs(w *io.BinWriter, scriptHash util.Uint160, operation string, f callflag.CallFlag) {
Int(w, int64(f))
String(w, operation)
Bytes(w, scriptHash.BytesBE())
Syscall(w, interopnames.SystemContractCall)
}
// AppCall emits SYSCALL with System.Contract.Call parameter for given contract, operation, call flag and arguments.
func AppCall(w *io.BinWriter, scriptHash util.Uint160, operation string, f callflag.CallFlag, args ...any) {
Array(w, args...)
AppCallNoArgs(w, scriptHash, operation, f)
}
// CheckSig emits a single-key verification script using given []bytes as a key.
// It does not check for key correctness, so you can get an invalid script if the
// data passed is not really a public key.
func CheckSig(w *io.BinWriter, key []byte) {
Bytes(w, key)
Syscall(w, interopnames.SystemCryptoCheckSig)
}
func isInstructionJmp(op opcode.Opcode) bool {
return opcode.JMP <= op && op <= opcode.CALLL || op == opcode.ENDTRYL
}