neoneo-go/pkg/vm/emit/emit.go

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package emit
import (
"crypto/sha256"
"encoding/binary"
"errors"
"fmt"
"math/big"
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"math/bits"
"github.com/nspcc-dev/neo-go/pkg/io"
"github.com/nspcc-dev/neo-go/pkg/util"
"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
)
// 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)
}
// Opcode emits a single VM Instruction without arguments to the given buffer.
func Opcode(w *io.BinWriter, op opcode.Opcode) {
w.WriteB(byte(op))
}
// Bool emits a bool type the given buffer.
func Bool(w *io.BinWriter, ok bool) {
if ok {
Opcode(w, opcode.PUSHT)
return
}
Opcode(w, opcode.PUSHF)
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Instruction(w, opcode.CONVERT, []byte{0x20}) // 0x20 for Boolean type
}
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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 a int type to the given buffer.
func Int(w *io.BinWriter, i int64) {
switch {
case i == -1:
Opcode(w, opcode.PUSHM1)
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case i >= 0 && i < 16:
val := opcode.Opcode(int(opcode.PUSH1) - 1 + int(i))
Opcode(w, val)
default:
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buf := intToBytes(big.NewInt(i), make([]byte, 0, 32))
// l != 0 becase of switch
padSize := byte(8 - bits.LeadingZeros8(byte(len(buf)-1)))
Opcode(w, opcode.PUSHINT8+opcode.Opcode(padSize))
w.WriteBytes(padRight(1<<padSize, buf))
}
}
// Array emits array of elements to the given buffer.
func Array(w *io.BinWriter, es ...interface{}) {
for i := len(es) - 1; i >= 0; i-- {
switch e := es[i].(type) {
case int64:
Int(w, e)
case string:
String(w, e)
case util.Uint160:
Bytes(w, e.BytesBE())
case []byte:
Bytes(w, e)
case bool:
Bool(w, e)
default:
w.Err = errors.New("unsupported type")
return
}
}
Int(w, int64(len(es)))
Opcode(w, opcode.PACK)
}
// 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, InteropNameToID([]byte(api)))
Instruction(w, opcode.SYSCALL, buf)
}
// Call emits a call Instruction with 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 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)
}
// AppCall emits an appcall, if tailCall is true, tailCall opcode will be
// emitted instead.
func AppCall(w *io.BinWriter, scriptHash util.Uint160, tailCall bool) {
op := opcode.APPCALL
if tailCall {
op = opcode.TAILCALL
}
Instruction(w, op, scriptHash.BytesBE())
}
// AppCallWithOperationAndArgs emits an APPCALL with the given operation and arguments.
func AppCallWithOperationAndArgs(w *io.BinWriter, scriptHash util.Uint160, operation string, args ...interface{}) {
Array(w, args...)
String(w, operation)
AppCall(w, scriptHash, false)
}
// AppCallWithOperationAndData emits an appcall with the given operation and data.
func AppCallWithOperationAndData(w *io.BinWriter, scriptHash util.Uint160, operation string, data []byte) {
Bytes(w, data)
String(w, operation)
AppCall(w, scriptHash, false)
}
// AppCallWithOperation emits an appcall with the given operation.
func AppCallWithOperation(w *io.BinWriter, scriptHash util.Uint160, operation string) {
Bool(w, false)
String(w, operation)
AppCall(w, scriptHash, false)
}
func isInstructionJmp(op opcode.Opcode) bool {
return opcode.JMP <= op && op <= opcode.CALLL
}
// InteropNameToID returns an identificator of the method based on its name.
func InteropNameToID(name []byte) uint32 {
h := sha256.Sum256(name)
return binary.LittleEndian.Uint32(h[:4])
}