forked from TrueCloudLab/neoneo-go
231 lines
6.7 KiB
Go
231 lines
6.7 KiB
Go
package nef
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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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"strconv"
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"strings"
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"github.com/nspcc-dev/neo-go/pkg/config"
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"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
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"github.com/nspcc-dev/neo-go/pkg/io"
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"github.com/nspcc-dev/neo-go/pkg/util"
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)
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// NEO Executable Format 3 (NEF3)
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// Standard: https://github.com/neo-project/proposals/pull/121/files
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// Implementation: https://github.com/neo-project/neo/blob/v3.0.0-preview2/src/neo/SmartContract/NefFile.cs#L8
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// +------------+-----------+------------------------------------------------------------+
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// | Field | Length | Comment |
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// +------------+-----------+------------------------------------------------------------+
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// | Magic | 4 bytes | Magic header |
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// | Compiler | 32 bytes | Compiler used |
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// | Version | 16 bytes | Compiler version (Major, Minor, Build, Version) |
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// | ScriptHash | 20 bytes | ScriptHash for the script (BE) |
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// +------------+-----------+------------------------------------------------------------+
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// | Checksum | 4 bytes | First four bytes of double SHA256 hash of the header |
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// +------------+-----------+------------------------------------------------------------+
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// | Script | Var bytes | Var bytes for the payload |
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// +------------+-----------+------------------------------------------------------------+
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const (
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// Magic is a magic File header constant.
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Magic uint32 = 0x3346454E
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// MaxScriptLength is the maximum allowed contract script length.
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MaxScriptLength = 1024 * 1024
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// compilerFieldSize is the length of `Compiler` File header field in bytes.
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compilerFieldSize = 32
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)
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// File represents compiled contract file structure according to the NEF3 standard.
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type File struct {
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Header Header
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Checksum uint32
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Script []byte
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}
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// Header represents File header.
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type Header struct {
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Magic uint32
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Compiler string
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Version Version
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ScriptHash util.Uint160
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}
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// Version represents compiler version.
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type Version struct {
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Major int32
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Minor int32
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Build int32
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Revision int32
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}
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// NewFile returns new NEF3 file with script specified.
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func NewFile(script []byte) (File, error) {
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file := File{
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Header: Header{
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Magic: Magic,
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Compiler: "neo-go",
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ScriptHash: hash.Hash160(script),
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},
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Script: script,
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}
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v, err := GetVersion(config.Version)
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if err != nil {
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return file, err
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}
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file.Header.Version = v
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file.Checksum = file.Header.CalculateChecksum()
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return file, nil
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}
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// GetVersion returns Version from the given string. It accepts the following formats:
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// `major[-...].minor[-...].build[-...]` and `major[-...].minor[-...].build[-...].revision[-...]`
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// where `major`, `minor`, `build` and `revision` are 32-bit integers with base=10
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func GetVersion(version string) (Version, error) {
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var (
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result Version
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err error
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)
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versions := strings.SplitN(version, ".", 4)
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if len(versions) < 3 {
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return result, errors.New("invalid version format")
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}
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result.Major, err = parseDashedVersion(versions[0])
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if err != nil {
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return result, fmt.Errorf("failed to parse major version: %w", err)
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}
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result.Minor, err = parseDashedVersion(versions[1])
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if err != nil {
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return result, fmt.Errorf("failed to parse minor version: %w", err)
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}
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result.Build, err = parseDashedVersion(versions[2])
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if err != nil {
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return result, fmt.Errorf("failed to parse build version: %w", err)
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}
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if len(versions) == 4 {
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result.Revision, err = parseDashedVersion(versions[3])
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if err != nil {
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return result, fmt.Errorf("failed to parse revision version: %w", err)
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}
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}
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return result, nil
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}
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// parseDashedVersion extracts int from string of the format `int[-...]` where `int` is
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// a 32-bit integer with base=10.
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func parseDashedVersion(version string) (int32, error) {
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version = strings.SplitN(version, "-", 2)[0]
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result, err := strconv.ParseInt(version, 10, 32)
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if err != nil {
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return 0, err
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}
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return int32(result), nil
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}
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// EncodeBinary implements io.Serializable interface.
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func (v *Version) EncodeBinary(w *io.BinWriter) {
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w.WriteU32LE(uint32(v.Major))
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w.WriteU32LE(uint32(v.Minor))
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w.WriteU32LE(uint32(v.Build))
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w.WriteU32LE(uint32(v.Revision))
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}
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// DecodeBinary implements io.Serializable interface.
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func (v *Version) DecodeBinary(r *io.BinReader) {
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v.Major = int32(r.ReadU32LE())
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v.Minor = int32(r.ReadU32LE())
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v.Build = int32(r.ReadU32LE())
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v.Revision = int32(r.ReadU32LE())
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}
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// EncodeBinary implements io.Serializable interface.
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func (h *Header) EncodeBinary(w *io.BinWriter) {
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w.WriteU32LE(h.Magic)
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if len(h.Compiler) > compilerFieldSize {
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w.Err = errors.New("invalid compiler name length")
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return
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}
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bytes := []byte(h.Compiler)
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w.WriteBytes(bytes)
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if len(bytes) < compilerFieldSize {
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w.WriteBytes(make([]byte, compilerFieldSize-len(bytes)))
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}
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h.Version.EncodeBinary(w)
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h.ScriptHash.EncodeBinary(w)
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}
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// DecodeBinary implements io.Serializable interface.
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func (h *Header) DecodeBinary(r *io.BinReader) {
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h.Magic = r.ReadU32LE()
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if h.Magic != Magic {
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r.Err = errors.New("invalid Magic")
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return
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}
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buf := make([]byte, compilerFieldSize)
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r.ReadBytes(buf)
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buf = bytes.TrimRightFunc(buf, func(r rune) bool {
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return r == 0
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})
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h.Compiler = string(buf)
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h.Version.DecodeBinary(r)
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h.ScriptHash.DecodeBinary(r)
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}
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// CalculateChecksum returns first 4 bytes of double-SHA256(Header) converted to uint32.
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func (h *Header) CalculateChecksum() uint32 {
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buf := io.NewBufBinWriter()
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h.EncodeBinary(buf.BinWriter)
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if buf.Err != nil {
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panic(buf.Err)
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}
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return binary.LittleEndian.Uint32(hash.Checksum(buf.Bytes()))
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}
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// EncodeBinary implements io.Serializable interface.
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func (n *File) EncodeBinary(w *io.BinWriter) {
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n.Header.EncodeBinary(w)
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w.WriteU32LE(n.Checksum)
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w.WriteVarBytes(n.Script)
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}
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// DecodeBinary implements io.Serializable interface.
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func (n *File) DecodeBinary(r *io.BinReader) {
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n.Header.DecodeBinary(r)
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n.Checksum = r.ReadU32LE()
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checksum := n.Header.CalculateChecksum()
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if checksum != n.Checksum {
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r.Err = errors.New("CRC verification fail")
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return
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}
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n.Script = r.ReadVarBytes(MaxScriptLength)
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if !hash.Hash160(n.Script).Equals(n.Header.ScriptHash) {
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r.Err = errors.New("script hashes mismatch")
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return
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}
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}
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// Bytes returns byte array with serialized NEF File.
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func (n File) Bytes() ([]byte, error) {
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buf := io.NewBufBinWriter()
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n.EncodeBinary(buf.BinWriter)
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if buf.Err != nil {
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return nil, buf.Err
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}
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return buf.Bytes(), nil
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}
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// FileFromBytes returns NEF File deserialized from given bytes.
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func FileFromBytes(source []byte) (File, error) {
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result := File{}
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r := io.NewBinReaderFromBuf(source)
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result.DecodeBinary(r)
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if r.Err != nil {
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return result, r.Err
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}
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return result, nil
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}
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