encoding/protojson/decode.go - protobuf - Git at Google

 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package protojson

 import (
 	"encoding/base64"
 	"fmt"
 	"math"
 	"strconv"
 	"strings"

 	"google.golang.org/protobuf/internal/encoding/json"
 	"google.golang.org/protobuf/internal/encoding/messageset"
 	"google.golang.org/protobuf/internal/errors"
 	"google.golang.org/protobuf/internal/flags"
 	"google.golang.org/protobuf/internal/pragma"
 	"google.golang.org/protobuf/internal/set"
 	"google.golang.org/protobuf/proto"
 	pref "google.golang.org/protobuf/reflect/protoreflect"
 	"google.golang.org/protobuf/reflect/protoregistry"
 )

 // Unmarshal reads the given []byte into the given proto.Message.
 func Unmarshal(b []byte, m proto.Message) error {
 	return UnmarshalOptions{}.Unmarshal(b, m)
 }

 // UnmarshalOptions is a configurable JSON format parser.
 type UnmarshalOptions struct {
 	pragma.NoUnkeyedLiterals

 	// If AllowPartial is set, input for messages that will result in missing
 	// required fields will not return an error.
 	AllowPartial bool

 	// If DiscardUnknown is set, unknown fields are ignored.
 	DiscardUnknown bool

 	// Resolver is used for looking up types when unmarshaling
 	// google.protobuf.Any messages or extension fields.
 	// If nil, this defaults to using protoregistry.GlobalTypes.
 	Resolver interface {
 		protoregistry.MessageTypeResolver
 		protoregistry.ExtensionTypeResolver
 	}

 	decoder *json.Decoder
 }

 // Unmarshal reads the given []byte and populates the given proto.Message using
 // options in UnmarshalOptions object. It will clear the message first before
 // setting the fields. If it returns an error, the given message may be
 // partially set.
 func (o UnmarshalOptions) Unmarshal(b []byte, m proto.Message) error {
 	proto.Reset(m)

 	if o.Resolver == nil {
 		o.Resolver = protoregistry.GlobalTypes
 	}
 	o.decoder = json.NewDecoder(b)

 	if err := o.unmarshalMessage(m.ProtoReflect(), false); err != nil {
 		return err
 	}

 	// Check for EOF.
 	val, err := o.decoder.Read()
 	if err != nil {
 		return err
 	}
 	if val.Type() != json.EOF {
 		return unexpectedJSONError{val}
 	}

 	if o.AllowPartial {
 		return nil
 	}
 	return proto.IsInitialized(m)
 }

 // unexpectedJSONError is an error that contains the unexpected json.Value. This
 // is returned by methods to provide callers the read json.Value that it did not
 // expect.
 // TODO: Consider moving this to internal/encoding/json for consistency with
 // errors that package returns.
 type unexpectedJSONError struct {
 	value json.Value
 }

 func (e unexpectedJSONError) Error() string {
 	return newError("unexpected value %s", e.value).Error()
 }

 // newError returns an error object. If one of the values passed in is of
 // json.Value type, it produces an error with position info.
 func newError(f string, x ...interface{}) error {
 	var hasValue bool
 	var line, column int
 	for i := 0; i < len(x); i++ {
 		if val, ok := x[i].(json.Value); ok {
 			line, column = val.Position()
 			hasValue = true
 			break
 		}
 	}
 	e := errors.New(f, x...)
 	if hasValue {
 		return errors.New("(line %d:%d): %v", line, column, e)
 	}
 	return e
 }

 // unmarshalMessage unmarshals a message into the given protoreflect.Message.
 func (o UnmarshalOptions) unmarshalMessage(m pref.Message, skipTypeURL bool) error {
 	if isCustomType(m.Descriptor().FullName()) {
 		return o.unmarshalCustomType(m)
 	}

 	jval, err := o.decoder.Read()
 	if err != nil {
 		return err
 	}
 	if jval.Type() != json.StartObject {
 		return unexpectedJSONError{jval}
 	}

 	if err := o.unmarshalFields(m, skipTypeURL); err != nil {
 		return err
 	}

 	return nil
 }

 // unmarshalFields unmarshals the fields into the given protoreflect.Message.
 func (o UnmarshalOptions) unmarshalFields(m pref.Message, skipTypeURL bool) error {
 	messageDesc := m.Descriptor()
 	if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
 		return errors.New("no support for proto1 MessageSets")
 	}

 	var seenNums set.Ints
 	var seenOneofs set.Ints
 	fieldDescs := messageDesc.Fields()
 	for {
 		// Read field name.
 		jval, err := o.decoder.Read()
 		if err != nil {
 			return err
 		}
 		switch jval.Type() {
 		default:
 			return unexpectedJSONError{jval}
 		case json.EndObject:
 			return nil
 		case json.Name:
 			// Continue below.
 		}

 		name, err := jval.Name()
 		if err != nil {
 			return err
 		}
 		// Unmarshaling a non-custom embedded message in Any will contain the
 		// JSON field "@type" which should be skipped because it is not a field
 		// of the embedded message, but simply an artifact of the Any format.
 		if skipTypeURL && name == "@type" {
 			o.decoder.Read()
 			continue
 		}

 		// Get the FieldDescriptor.
 		var fd pref.FieldDescriptor
 		if strings.HasPrefix(name, "[") && strings.HasSuffix(name, "]") {
 			// Only extension names are in [name] format.
 			extName := pref.FullName(name[1 : len(name)-1])
 			extType, err := o.findExtension(extName)
 			if err != nil && err != protoregistry.NotFound {
 				return errors.New("unable to resolve [%v]: %v", extName, err)
 			}
 			if extType != nil {
 				fd = extType.TypeDescriptor()
 				if !messageDesc.ExtensionRanges().Has(fd.Number()) || fd.ContainingMessage().FullName() != messageDesc.FullName() {
 					return errors.New("message %v cannot be extended by %v", messageDesc.FullName(), fd.FullName())
 				}
 			}
 		} else {
 			// The name can either be the JSON name or the proto field name.
 			fd = fieldDescs.ByJSONName(name)
 			if fd == nil {
 				fd = fieldDescs.ByName(pref.Name(name))
 				if fd == nil {
 					// The proto name of a group field is in all lowercase,
 					// while the textual field name is the group message name.
 					gd := fieldDescs.ByName(pref.Name(strings.ToLower(name)))
 					if gd != nil && gd.Kind() == pref.GroupKind && gd.Message().Name() == pref.Name(name) {
 						fd = gd
 					}
 				} else if fd.Kind() == pref.GroupKind && fd.Message().Name() != pref.Name(name) {
 					fd = nil // reset since field name is actually the message name
 				}
 			}
 		}
 		if flags.ProtoLegacy {
 			if fd != nil && fd.IsWeak() && fd.Message().IsPlaceholder() {
 				fd = nil // reset since the weak reference is not linked in
 			}
 		}

 		if fd == nil {
 			// Field is unknown.
 			if o.DiscardUnknown {
 				if err := skipJSONValue(o.decoder); err != nil {
 					return err
 				}
 				continue
 			}
 			return newError("%v contains unknown field %s", messageDesc.FullName(), jval)
 		}

 		// Do not allow duplicate fields.
 		num := uint64(fd.Number())
 		if seenNums.Has(num) {
 			return newError("%v contains repeated field %s", messageDesc.FullName(), jval)
 		}
 		seenNums.Set(num)

 		// No need to set values for JSON null unless the field type is
 		// google.protobuf.Value or google.protobuf.NullValue.
 		if o.decoder.Peek() == json.Null && !isKnownValue(fd) && !isNullValue(fd) {
 			o.decoder.Read()
 			continue
 		}

 		switch {
 		case fd.IsList():
 			list := m.Mutable(fd).List()
 			if err := o.unmarshalList(list, fd); err != nil {
 				return errors.New("%v|%q: %v", fd.FullName(), name, err)
 			}
 		case fd.IsMap():
 			mmap := m.Mutable(fd).Map()
 			if err := o.unmarshalMap(mmap, fd); err != nil {
 				return errors.New("%v|%q: %v", fd.FullName(), name, err)
 			}
 		default:
 			// If field is a oneof, check if it has already been set.
 			if od := fd.ContainingOneof(); od != nil {
 				idx := uint64(od.Index())
 				if seenOneofs.Has(idx) {
 					return errors.New("%v: oneof is already set", od.FullName())
 				}
 				seenOneofs.Set(idx)
 			}

 			// Required or optional fields.
 			if err := o.unmarshalSingular(m, fd); err != nil {
 				return errors.New("%v|%q: %v", fd.FullName(), name, err)
 			}
 		}
 	}
 }

 // findExtension returns protoreflect.ExtensionType from the resolver if found.
 func (o UnmarshalOptions) findExtension(xtName pref.FullName) (pref.ExtensionType, error) {
 	xt, err := o.Resolver.FindExtensionByName(xtName)
 	if err == nil {
 		return xt, nil
 	}
 	return messageset.FindMessageSetExtension(o.Resolver, xtName)
 }

 func isKnownValue(fd pref.FieldDescriptor) bool {
 	md := fd.Message()
 	return md != nil && md.FullName() == "google.protobuf.Value"
 }

 func isNullValue(fd pref.FieldDescriptor) bool {
 	ed := fd.Enum()
 	return ed != nil && ed.FullName() == "google.protobuf.NullValue"
 }

 // unmarshalSingular unmarshals to the non-repeated field specified by the given
 // FieldDescriptor.
 func (o UnmarshalOptions) unmarshalSingular(m pref.Message, fd pref.FieldDescriptor) error {
 	var val pref.Value
 	var err error
 	switch fd.Kind() {
 	case pref.MessageKind, pref.GroupKind:
 		val = m.NewField(fd)
 		err = o.unmarshalMessage(val.Message(), false)
 	default:
 		val, err = o.unmarshalScalar(fd)
 	}

 	if err != nil {
 		return err
 	}
 	m.Set(fd, val)
 	return nil
 }

 // unmarshalScalar unmarshals to a scalar/enum protoreflect.Value specified by
 // the given FieldDescriptor.
 func (o UnmarshalOptions) unmarshalScalar(fd pref.FieldDescriptor) (pref.Value, error) {
 	const b32 int = 32
 	const b64 int = 64

 	jval, err := o.decoder.Read()
 	if err != nil {
 		return pref.Value{}, err
 	}

 	kind := fd.Kind()
 	switch kind {
 	case pref.BoolKind:
 		return unmarshalBool(jval)

 	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
 		return unmarshalInt(jval, b32)

 	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
 		return unmarshalInt(jval, b64)

 	case pref.Uint32Kind, pref.Fixed32Kind:
 		return unmarshalUint(jval, b32)

 	case pref.Uint64Kind, pref.Fixed64Kind:
 		return unmarshalUint(jval, b64)

 	case pref.FloatKind:
 		return unmarshalFloat(jval, b32)

 	case pref.DoubleKind:
 		return unmarshalFloat(jval, b64)

 	case pref.StringKind:
 		pval, err := unmarshalString(jval)
 		if err != nil {
 			return pval, err
 		}
 		return pval, nil

 	case pref.BytesKind:
 		return unmarshalBytes(jval)

 	case pref.EnumKind:
 		return unmarshalEnum(jval, fd)
 	}

 	panic(fmt.Sprintf("invalid scalar kind %v", kind))
 }

 func unmarshalBool(jval json.Value) (pref.Value, error) {
 	if jval.Type() != json.Bool {
 		return pref.Value{}, unexpectedJSONError{jval}
 	}
 	b, err := jval.Bool()
 	return pref.ValueOfBool(b), err
 }

 func unmarshalInt(jval json.Value, bitSize int) (pref.Value, error) {
 	switch jval.Type() {
 	case json.Number:
 		return getInt(jval, bitSize)

 	case json.String:
 		// Decode number from string.
 		s := strings.TrimSpace(jval.String())
 		if len(s) != len(jval.String()) {
 			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
 		}
 		dec := json.NewDecoder([]byte(s))
 		jval, err := dec.Read()
 		if err != nil {
 			return pref.Value{}, err
 		}
 		return getInt(jval, bitSize)
 	}
 	return pref.Value{}, unexpectedJSONError{jval}
 }

 func getInt(jval json.Value, bitSize int) (pref.Value, error) {
 	n, err := jval.Int(bitSize)
 	if err != nil {
 		return pref.Value{}, err
 	}
 	if bitSize == 32 {
 		return pref.ValueOfInt32(int32(n)), nil
 	}
 	return pref.ValueOfInt64(n), nil
 }

 func unmarshalUint(jval json.Value, bitSize int) (pref.Value, error) {
 	switch jval.Type() {
 	case json.Number:
 		return getUint(jval, bitSize)

 	case json.String:
 		// Decode number from string.
 		s := strings.TrimSpace(jval.String())
 		if len(s) != len(jval.String()) {
 			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
 		}
 		dec := json.NewDecoder([]byte(s))
 		jval, err := dec.Read()
 		if err != nil {
 			return pref.Value{}, err
 		}
 		return getUint(jval, bitSize)
 	}
 	return pref.Value{}, unexpectedJSONError{jval}
 }

 func getUint(jval json.Value, bitSize int) (pref.Value, error) {
 	n, err := jval.Uint(bitSize)
 	if err != nil {
 		return pref.Value{}, err
 	}
 	if bitSize == 32 {
 		return pref.ValueOfUint32(uint32(n)), nil
 	}
 	return pref.ValueOfUint64(n), nil
 }

 func unmarshalFloat(jval json.Value, bitSize int) (pref.Value, error) {
 	switch jval.Type() {
 	case json.Number:
 		return getFloat(jval, bitSize)

 	case json.String:
 		s := jval.String()
 		switch s {
 		case "NaN":
 			if bitSize == 32 {
 				return pref.ValueOfFloat32(float32(math.NaN())), nil
 			}
 			return pref.ValueOfFloat64(math.NaN()), nil
 		case "Infinity":
 			if bitSize == 32 {
 				return pref.ValueOfFloat32(float32(math.Inf(+1))), nil
 			}
 			return pref.ValueOfFloat64(math.Inf(+1)), nil
 		case "-Infinity":
 			if bitSize == 32 {
 				return pref.ValueOfFloat32(float32(math.Inf(-1))), nil
 			}
 			return pref.ValueOfFloat64(math.Inf(-1)), nil
 		}
 		// Decode number from string.
 		if len(s) != len(strings.TrimSpace(s)) {
 			return pref.Value{}, errors.New("invalid number %v", jval.Raw())
 		}
 		dec := json.NewDecoder([]byte(s))
 		jval, err := dec.Read()
 		if err != nil {
 			return pref.Value{}, err
 		}
 		return getFloat(jval, bitSize)
 	}
 	return pref.Value{}, unexpectedJSONError{jval}
 }

 func getFloat(jval json.Value, bitSize int) (pref.Value, error) {
 	n, err := jval.Float(bitSize)
 	if err != nil {
 		return pref.Value{}, err
 	}
 	if bitSize == 32 {
 		return pref.ValueOfFloat32(float32(n)), nil
 	}
 	return pref.ValueOfFloat64(n), nil
 }

 func unmarshalString(jval json.Value) (pref.Value, error) {
 	if jval.Type() != json.String {
 		return pref.Value{}, unexpectedJSONError{jval}
 	}
 	return pref.ValueOfString(jval.String()), nil
 }

 func unmarshalBytes(jval json.Value) (pref.Value, error) {
 	if jval.Type() != json.String {
 		return pref.Value{}, unexpectedJSONError{jval}
 	}

 	s := jval.String()
 	enc := base64.StdEncoding
 	if strings.ContainsAny(s, "-_") {
 		enc = base64.URLEncoding
 	}
 	if len(s)%4 != 0 {
 		enc = enc.WithPadding(base64.NoPadding)
 	}
 	b, err := enc.DecodeString(s)
 	if err != nil {
 		return pref.Value{}, err
 	}
 	return pref.ValueOfBytes(b), nil
 }

 func unmarshalEnum(jval json.Value, fd pref.FieldDescriptor) (pref.Value, error) {
 	switch jval.Type() {
 	case json.String:
 		// Lookup EnumNumber based on name.
 		s := jval.String()
 		if enumVal := fd.Enum().Values().ByName(pref.Name(s)); enumVal != nil {
 			return pref.ValueOfEnum(enumVal.Number()), nil
 		}
 		return pref.Value{}, newError("invalid enum value %q", jval)

 	case json.Number:
 		n, err := jval.Int(32)
 		if err != nil {
 			return pref.Value{}, err
 		}
 		return pref.ValueOfEnum(pref.EnumNumber(n)), nil

 	case json.Null:
 		// This is only valid for google.protobuf.NullValue.
 		if isNullValue(fd) {
 			return pref.ValueOfEnum(0), nil
 		}
 	}

 	return pref.Value{}, unexpectedJSONError{jval}
 }

 func (o UnmarshalOptions) unmarshalList(list pref.List, fd pref.FieldDescriptor) error {
 	jval, err := o.decoder.Read()
 	if err != nil {
 		return err
 	}
 	if jval.Type() != json.StartArray {
 		return unexpectedJSONError{jval}
 	}

 	switch fd.Kind() {
 	case pref.MessageKind, pref.GroupKind:
 		for {
 			val := list.NewElement()
 			err := o.unmarshalMessage(val.Message(), false)
 			if err != nil {
 				if e, ok := err.(unexpectedJSONError); ok {
 					if e.value.Type() == json.EndArray {
 						// Done with list.
 						return nil
 					}
 				}
 				return err
 			}
 			list.Append(val)
 		}
 	default:
 		for {
 			val, err := o.unmarshalScalar(fd)
 			if err != nil {
 				if e, ok := err.(unexpectedJSONError); ok {
 					if e.value.Type() == json.EndArray {
 						// Done with list.
 						return nil
 					}
 				}
 				return err
 			}
 			list.Append(val)
 		}
 	}
 	return nil
 }

 func (o UnmarshalOptions) unmarshalMap(mmap pref.Map, fd pref.FieldDescriptor) error {
 	jval, err := o.decoder.Read()
 	if err != nil {
 		return err
 	}
 	if jval.Type() != json.StartObject {
 		return unexpectedJSONError{jval}
 	}

 	// Determine ahead whether map entry is a scalar type or a message type in
 	// order to call the appropriate unmarshalMapValue func inside the for loop
 	// below.
 	var unmarshalMapValue func() (pref.Value, error)
 	switch fd.MapValue().Kind() {
 	case pref.MessageKind, pref.GroupKind:
 		unmarshalMapValue = func() (pref.Value, error) {
 			val := mmap.NewValue()
 			if err := o.unmarshalMessage(val.Message(), false); err != nil {
 				return pref.Value{}, err
 			}
 			return val, nil
 		}
 	default:
 		unmarshalMapValue = func() (pref.Value, error) {
 			return o.unmarshalScalar(fd.MapValue())
 		}
 	}

 Loop:
 	for {
 		// Read field name.
 		jval, err := o.decoder.Read()
 		if err != nil {
 			return err
 		}
 		switch jval.Type() {
 		default:
 			return unexpectedJSONError{jval}
 		case json.EndObject:
 			break Loop
 		case json.Name:
 			// Continue.
 		}

 		name, err := jval.Name()
 		if err != nil {
 			return err
 		}

 		// Unmarshal field name.
 		pkey, err := unmarshalMapKey(name, fd.MapKey())
 		if err != nil {
 			return err
 		}

 		// Check for duplicate field name.
 		if mmap.Has(pkey) {
 			return newError("duplicate map key %q", jval)
 		}

 		// Read and unmarshal field value.
 		pval, err := unmarshalMapValue()
 		if err != nil {
 			return err
 		}

 		mmap.Set(pkey, pval)
 	}

 	return nil
 }

 // unmarshalMapKey converts given string into a protoreflect.MapKey. A map key type is any
 // integral or string type.
 func unmarshalMapKey(name string, fd pref.FieldDescriptor) (pref.MapKey, error) {
 	const b32 = 32
 	const b64 = 64
 	const base10 = 10

 	kind := fd.Kind()
 	switch kind {
 	case pref.StringKind:
 		return pref.ValueOfString(name).MapKey(), nil

 	case pref.BoolKind:
 		switch name {
 		case "true":
 			return pref.ValueOfBool(true).MapKey(), nil
 		case "false":
 			return pref.ValueOfBool(false).MapKey(), nil
 		}
 		return pref.MapKey{}, errors.New("invalid value for boolean key %q", name)

 	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
 		n, err := strconv.ParseInt(name, base10, b32)
 		if err != nil {
 			return pref.MapKey{}, err
 		}
 		return pref.ValueOfInt32(int32(n)).MapKey(), nil

 	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
 		n, err := strconv.ParseInt(name, base10, b64)
 		if err != nil {
 			return pref.MapKey{}, err
 		}
 		return pref.ValueOfInt64(int64(n)).MapKey(), nil

 	case pref.Uint32Kind, pref.Fixed32Kind:
 		n, err := strconv.ParseUint(name, base10, b32)
 		if err != nil {
 			return pref.MapKey{}, err
 		}
 		return pref.ValueOfUint32(uint32(n)).MapKey(), nil

 	case pref.Uint64Kind, pref.Fixed64Kind:
 		n, err := strconv.ParseUint(name, base10, b64)
 		if err != nil {
 			return pref.MapKey{}, err
 		}
 		return pref.ValueOfUint64(uint64(n)).MapKey(), nil
 	}

 	panic(fmt.Sprintf("%s: invalid kind %s for map key", fd.FullName(), kind))
 }
	// Copyright 2019 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package protojson

	import (
	"encoding/base64"
	"fmt"
	"math"
	"strconv"
	"strings"

	"google.golang.org/protobuf/internal/encoding/json"
	"google.golang.org/protobuf/internal/encoding/messageset"
	"google.golang.org/protobuf/internal/errors"
	"google.golang.org/protobuf/internal/flags"
	"google.golang.org/protobuf/internal/pragma"
	"google.golang.org/protobuf/internal/set"
	"google.golang.org/protobuf/proto"
	pref "google.golang.org/protobuf/reflect/protoreflect"
	"google.golang.org/protobuf/reflect/protoregistry"
	)

	// Unmarshal reads the given []byte into the given proto.Message.
	func Unmarshal(b []byte, m proto.Message) error {
	return UnmarshalOptions{}.Unmarshal(b, m)
	}

	// UnmarshalOptions is a configurable JSON format parser.
	type UnmarshalOptions struct {
	pragma.NoUnkeyedLiterals

	// If AllowPartial is set, input for messages that will result in missing
	// required fields will not return an error.
	AllowPartial bool

	// If DiscardUnknown is set, unknown fields are ignored.
	DiscardUnknown bool

	// Resolver is used for looking up types when unmarshaling
	// google.protobuf.Any messages or extension fields.
	// If nil, this defaults to using protoregistry.GlobalTypes.
	Resolver interface {
	protoregistry.MessageTypeResolver
	protoregistry.ExtensionTypeResolver
	}

	decoder *json.Decoder
	}

	// Unmarshal reads the given []byte and populates the given proto.Message using
	// options in UnmarshalOptions object. It will clear the message first before
	// setting the fields. If it returns an error, the given message may be
	// partially set.
	func (o UnmarshalOptions) Unmarshal(b []byte, m proto.Message) error {
	proto.Reset(m)

	if o.Resolver == nil {
	o.Resolver = protoregistry.GlobalTypes
	}
	o.decoder = json.NewDecoder(b)

	if err := o.unmarshalMessage(m.ProtoReflect(), false); err != nil {
	return err
	}

	// Check for EOF.
	val, err := o.decoder.Read()
	if err != nil {
	return err
	}
	if val.Type() != json.EOF {
	return unexpectedJSONError{val}
	}

	if o.AllowPartial {
	return nil
	}
	return proto.IsInitialized(m)
	}

	// unexpectedJSONError is an error that contains the unexpected json.Value. This
	// is returned by methods to provide callers the read json.Value that it did not
	// expect.
	// TODO: Consider moving this to internal/encoding/json for consistency with
	// errors that package returns.
	type unexpectedJSONError struct {
	value json.Value
	}

	func (e unexpectedJSONError) Error() string {
	return newError("unexpected value %s", e.value).Error()
	}

	// newError returns an error object. If one of the values passed in is of
	// json.Value type, it produces an error with position info.
	func newError(f string, x ...interface{}) error {
	var hasValue bool
	var line, column int
	for i := 0; i < len(x); i++ {
	if val, ok := x[i].(json.Value); ok {
	line, column = val.Position()
	hasValue = true
	break
	}
	}
	e := errors.New(f, x...)
	if hasValue {
	return errors.New("(line %d:%d): %v", line, column, e)
	}
	return e
	}

	// unmarshalMessage unmarshals a message into the given protoreflect.Message.
	func (o UnmarshalOptions) unmarshalMessage(m pref.Message, skipTypeURL bool) error {
	if isCustomType(m.Descriptor().FullName()) {
	return o.unmarshalCustomType(m)
	}

	jval, err := o.decoder.Read()
	if err != nil {
	return err
	}
	if jval.Type() != json.StartObject {
	return unexpectedJSONError{jval}
	}

	if err := o.unmarshalFields(m, skipTypeURL); err != nil {
	return err
	}

	return nil
	}

	// unmarshalFields unmarshals the fields into the given protoreflect.Message.
	func (o UnmarshalOptions) unmarshalFields(m pref.Message, skipTypeURL bool) error {
	messageDesc := m.Descriptor()
	if !flags.ProtoLegacy && messageset.IsMessageSet(messageDesc) {
	return errors.New("no support for proto1 MessageSets")
	}

	var seenNums set.Ints
	var seenOneofs set.Ints
	fieldDescs := messageDesc.Fields()
	for {
	// Read field name.
	jval, err := o.decoder.Read()
	if err != nil {
	return err
	}
	switch jval.Type() {
	default:
	return unexpectedJSONError{jval}
	case json.EndObject:
	return nil
	case json.Name:
	// Continue below.
	}

	name, err := jval.Name()
	if err != nil {
	return err
	}
	// Unmarshaling a non-custom embedded message in Any will contain the
	// JSON field "@type" which should be skipped because it is not a field
	// of the embedded message, but simply an artifact of the Any format.
	if skipTypeURL && name == "@type" {
	o.decoder.Read()
	continue
	}

	// Get the FieldDescriptor.
	var fd pref.FieldDescriptor
	if strings.HasPrefix(name, "[") && strings.HasSuffix(name, "]") {
	// Only extension names are in [name] format.
	extName := pref.FullName(name[1 : len(name)-1])
	extType, err := o.findExtension(extName)
	if err != nil && err != protoregistry.NotFound {
	return errors.New("unable to resolve [%v]: %v", extName, err)
	}
	if extType != nil {
	fd = extType.TypeDescriptor()
	if !messageDesc.ExtensionRanges().Has(fd.Number()) \|\| fd.ContainingMessage().FullName() != messageDesc.FullName() {
	return errors.New("message %v cannot be extended by %v", messageDesc.FullName(), fd.FullName())
	}
	}
	} else {
	// The name can either be the JSON name or the proto field name.
	fd = fieldDescs.ByJSONName(name)
	if fd == nil {
	fd = fieldDescs.ByName(pref.Name(name))
	if fd == nil {
	// The proto name of a group field is in all lowercase,
	// while the textual field name is the group message name.
	gd := fieldDescs.ByName(pref.Name(strings.ToLower(name)))
	if gd != nil && gd.Kind() == pref.GroupKind && gd.Message().Name() == pref.Name(name) {
	fd = gd
	}
	} else if fd.Kind() == pref.GroupKind && fd.Message().Name() != pref.Name(name) {
	fd = nil // reset since field name is actually the message name
	}
	}
	}
	if flags.ProtoLegacy {
	if fd != nil && fd.IsWeak() && fd.Message().IsPlaceholder() {
	fd = nil // reset since the weak reference is not linked in
	}
	}

	if fd == nil {
	// Field is unknown.
	if o.DiscardUnknown {
	if err := skipJSONValue(o.decoder); err != nil {
	return err
	}
	continue
	}
	return newError("%v contains unknown field %s", messageDesc.FullName(), jval)
	}

	// Do not allow duplicate fields.
	num := uint64(fd.Number())
	if seenNums.Has(num) {
	return newError("%v contains repeated field %s", messageDesc.FullName(), jval)
	}
	seenNums.Set(num)

	// No need to set values for JSON null unless the field type is
	// google.protobuf.Value or google.protobuf.NullValue.
	if o.decoder.Peek() == json.Null && !isKnownValue(fd) && !isNullValue(fd) {
	o.decoder.Read()
	continue
	}

	switch {
	case fd.IsList():
	list := m.Mutable(fd).List()
	if err := o.unmarshalList(list, fd); err != nil {
	return errors.New("%v\|%q: %v", fd.FullName(), name, err)
	}
	case fd.IsMap():
	mmap := m.Mutable(fd).Map()
	if err := o.unmarshalMap(mmap, fd); err != nil {
	return errors.New("%v\|%q: %v", fd.FullName(), name, err)
	}
	default:
	// If field is a oneof, check if it has already been set.
	if od := fd.ContainingOneof(); od != nil {
	idx := uint64(od.Index())
	if seenOneofs.Has(idx) {
	return errors.New("%v: oneof is already set", od.FullName())
	}
	seenOneofs.Set(idx)
	}

	// Required or optional fields.
	if err := o.unmarshalSingular(m, fd); err != nil {
	return errors.New("%v\|%q: %v", fd.FullName(), name, err)
	}
	}
	}
	}

	// findExtension returns protoreflect.ExtensionType from the resolver if found.
	func (o UnmarshalOptions) findExtension(xtName pref.FullName) (pref.ExtensionType, error) {
	xt, err := o.Resolver.FindExtensionByName(xtName)
	if err == nil {
	return xt, nil
	}
	return messageset.FindMessageSetExtension(o.Resolver, xtName)
	}

	func isKnownValue(fd pref.FieldDescriptor) bool {
	md := fd.Message()
	return md != nil && md.FullName() == "google.protobuf.Value"
	}

	func isNullValue(fd pref.FieldDescriptor) bool {
	ed := fd.Enum()
	return ed != nil && ed.FullName() == "google.protobuf.NullValue"
	}

	// unmarshalSingular unmarshals to the non-repeated field specified by the given
	// FieldDescriptor.
	func (o UnmarshalOptions) unmarshalSingular(m pref.Message, fd pref.FieldDescriptor) error {
	var val pref.Value
	var err error
	switch fd.Kind() {
	case pref.MessageKind, pref.GroupKind:
	val = m.NewField(fd)
	err = o.unmarshalMessage(val.Message(), false)
	default:
	val, err = o.unmarshalScalar(fd)
	}

	if err != nil {
	return err
	}
	m.Set(fd, val)
	return nil
	}

	// unmarshalScalar unmarshals to a scalar/enum protoreflect.Value specified by
	// the given FieldDescriptor.
	func (o UnmarshalOptions) unmarshalScalar(fd pref.FieldDescriptor) (pref.Value, error) {
	const b32 int = 32
	const b64 int = 64

	jval, err := o.decoder.Read()
	if err != nil {
	return pref.Value{}, err
	}

	kind := fd.Kind()
	switch kind {
	case pref.BoolKind:
	return unmarshalBool(jval)

	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
	return unmarshalInt(jval, b32)

	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
	return unmarshalInt(jval, b64)

	case pref.Uint32Kind, pref.Fixed32Kind:
	return unmarshalUint(jval, b32)

	case pref.Uint64Kind, pref.Fixed64Kind:
	return unmarshalUint(jval, b64)

	case pref.FloatKind:
	return unmarshalFloat(jval, b32)

	case pref.DoubleKind:
	return unmarshalFloat(jval, b64)

	case pref.StringKind:
	pval, err := unmarshalString(jval)
	if err != nil {
	return pval, err
	}
	return pval, nil

	case pref.BytesKind:
	return unmarshalBytes(jval)

	case pref.EnumKind:
	return unmarshalEnum(jval, fd)
	}

	panic(fmt.Sprintf("invalid scalar kind %v", kind))
	}

	func unmarshalBool(jval json.Value) (pref.Value, error) {
	if jval.Type() != json.Bool {
	return pref.Value{}, unexpectedJSONError{jval}
	}
	b, err := jval.Bool()
	return pref.ValueOfBool(b), err
	}

	func unmarshalInt(jval json.Value, bitSize int) (pref.Value, error) {
	switch jval.Type() {
	case json.Number:
	return getInt(jval, bitSize)

	case json.String:
	// Decode number from string.
	s := strings.TrimSpace(jval.String())
	if len(s) != len(jval.String()) {
	return pref.Value{}, errors.New("invalid number %v", jval.Raw())
	}
	dec := json.NewDecoder([]byte(s))
	jval, err := dec.Read()
	if err != nil {
	return pref.Value{}, err
	}
	return getInt(jval, bitSize)
	}
	return pref.Value{}, unexpectedJSONError{jval}
	}

	func getInt(jval json.Value, bitSize int) (pref.Value, error) {
	n, err := jval.Int(bitSize)
	if err != nil {
	return pref.Value{}, err
	}
	if bitSize == 32 {
	return pref.ValueOfInt32(int32(n)), nil
	}
	return pref.ValueOfInt64(n), nil
	}

	func unmarshalUint(jval json.Value, bitSize int) (pref.Value, error) {
	switch jval.Type() {
	case json.Number:
	return getUint(jval, bitSize)

	case json.String:
	// Decode number from string.
	s := strings.TrimSpace(jval.String())
	if len(s) != len(jval.String()) {
	return pref.Value{}, errors.New("invalid number %v", jval.Raw())
	}
	dec := json.NewDecoder([]byte(s))
	jval, err := dec.Read()
	if err != nil {
	return pref.Value{}, err
	}
	return getUint(jval, bitSize)
	}
	return pref.Value{}, unexpectedJSONError{jval}
	}

	func getUint(jval json.Value, bitSize int) (pref.Value, error) {
	n, err := jval.Uint(bitSize)
	if err != nil {
	return pref.Value{}, err
	}
	if bitSize == 32 {
	return pref.ValueOfUint32(uint32(n)), nil
	}
	return pref.ValueOfUint64(n), nil
	}

	func unmarshalFloat(jval json.Value, bitSize int) (pref.Value, error) {
	switch jval.Type() {
	case json.Number:
	return getFloat(jval, bitSize)

	case json.String:
	s := jval.String()
	switch s {
	case "NaN":
	if bitSize == 32 {
	return pref.ValueOfFloat32(float32(math.NaN())), nil
	}
	return pref.ValueOfFloat64(math.NaN()), nil
	case "Infinity":
	if bitSize == 32 {
	return pref.ValueOfFloat32(float32(math.Inf(+1))), nil
	}
	return pref.ValueOfFloat64(math.Inf(+1)), nil
	case "-Infinity":
	if bitSize == 32 {
	return pref.ValueOfFloat32(float32(math.Inf(-1))), nil
	}
	return pref.ValueOfFloat64(math.Inf(-1)), nil
	}
	// Decode number from string.
	if len(s) != len(strings.TrimSpace(s)) {
	return pref.Value{}, errors.New("invalid number %v", jval.Raw())
	}
	dec := json.NewDecoder([]byte(s))
	jval, err := dec.Read()
	if err != nil {
	return pref.Value{}, err
	}
	return getFloat(jval, bitSize)
	}
	return pref.Value{}, unexpectedJSONError{jval}
	}

	func getFloat(jval json.Value, bitSize int) (pref.Value, error) {
	n, err := jval.Float(bitSize)
	if err != nil {
	return pref.Value{}, err
	}
	if bitSize == 32 {
	return pref.ValueOfFloat32(float32(n)), nil
	}
	return pref.ValueOfFloat64(n), nil
	}

	func unmarshalString(jval json.Value) (pref.Value, error) {
	if jval.Type() != json.String {
	return pref.Value{}, unexpectedJSONError{jval}
	}
	return pref.ValueOfString(jval.String()), nil
	}

	func unmarshalBytes(jval json.Value) (pref.Value, error) {
	if jval.Type() != json.String {
	return pref.Value{}, unexpectedJSONError{jval}
	}

	s := jval.String()
	enc := base64.StdEncoding
	if strings.ContainsAny(s, "-_") {
	enc = base64.URLEncoding
	}
	if len(s)%4 != 0 {
	enc = enc.WithPadding(base64.NoPadding)
	}
	b, err := enc.DecodeString(s)
	if err != nil {
	return pref.Value{}, err
	}
	return pref.ValueOfBytes(b), nil
	}

	func unmarshalEnum(jval json.Value, fd pref.FieldDescriptor) (pref.Value, error) {
	switch jval.Type() {
	case json.String:
	// Lookup EnumNumber based on name.
	s := jval.String()
	if enumVal := fd.Enum().Values().ByName(pref.Name(s)); enumVal != nil {
	return pref.ValueOfEnum(enumVal.Number()), nil
	}
	return pref.Value{}, newError("invalid enum value %q", jval)

	case json.Number:
	n, err := jval.Int(32)
	if err != nil {
	return pref.Value{}, err
	}
	return pref.ValueOfEnum(pref.EnumNumber(n)), nil

	case json.Null:
	// This is only valid for google.protobuf.NullValue.
	if isNullValue(fd) {
	return pref.ValueOfEnum(0), nil
	}
	}

	return pref.Value{}, unexpectedJSONError{jval}
	}

	func (o UnmarshalOptions) unmarshalList(list pref.List, fd pref.FieldDescriptor) error {
	jval, err := o.decoder.Read()
	if err != nil {
	return err
	}
	if jval.Type() != json.StartArray {
	return unexpectedJSONError{jval}
	}

	switch fd.Kind() {
	case pref.MessageKind, pref.GroupKind:
	for {
	val := list.NewElement()
	err := o.unmarshalMessage(val.Message(), false)
	if err != nil {
	if e, ok := err.(unexpectedJSONError); ok {
	if e.value.Type() == json.EndArray {
	// Done with list.
	return nil
	}
	}
	return err
	}
	list.Append(val)
	}
	default:
	for {
	val, err := o.unmarshalScalar(fd)
	if err != nil {
	if e, ok := err.(unexpectedJSONError); ok {
	if e.value.Type() == json.EndArray {
	// Done with list.
	return nil
	}
	}
	return err
	}
	list.Append(val)
	}
	}
	return nil
	}

	func (o UnmarshalOptions) unmarshalMap(mmap pref.Map, fd pref.FieldDescriptor) error {
	jval, err := o.decoder.Read()
	if err != nil {
	return err
	}
	if jval.Type() != json.StartObject {
	return unexpectedJSONError{jval}
	}

	// Determine ahead whether map entry is a scalar type or a message type in
	// order to call the appropriate unmarshalMapValue func inside the for loop
	// below.
	var unmarshalMapValue func() (pref.Value, error)
	switch fd.MapValue().Kind() {
	case pref.MessageKind, pref.GroupKind:
	unmarshalMapValue = func() (pref.Value, error) {
	val := mmap.NewValue()
	if err := o.unmarshalMessage(val.Message(), false); err != nil {
	return pref.Value{}, err
	}
	return val, nil
	}
	default:
	unmarshalMapValue = func() (pref.Value, error) {
	return o.unmarshalScalar(fd.MapValue())
	}
	}

	Loop:
	for {
	// Read field name.
	jval, err := o.decoder.Read()
	if err != nil {
	return err
	}
	switch jval.Type() {
	default:
	return unexpectedJSONError{jval}
	case json.EndObject:
	break Loop
	case json.Name:
	// Continue.
	}

	name, err := jval.Name()
	if err != nil {
	return err
	}

	// Unmarshal field name.
	pkey, err := unmarshalMapKey(name, fd.MapKey())
	if err != nil {
	return err
	}

	// Check for duplicate field name.
	if mmap.Has(pkey) {
	return newError("duplicate map key %q", jval)
	}

	// Read and unmarshal field value.
	pval, err := unmarshalMapValue()
	if err != nil {
	return err
	}

	mmap.Set(pkey, pval)
	}

	return nil
	}

	// unmarshalMapKey converts given string into a protoreflect.MapKey. A map key type is any
	// integral or string type.
	func unmarshalMapKey(name string, fd pref.FieldDescriptor) (pref.MapKey, error) {
	const b32 = 32
	const b64 = 64
	const base10 = 10

	kind := fd.Kind()
	switch kind {
	case pref.StringKind:
	return pref.ValueOfString(name).MapKey(), nil

	case pref.BoolKind:
	switch name {
	case "true":
	return pref.ValueOfBool(true).MapKey(), nil
	case "false":
	return pref.ValueOfBool(false).MapKey(), nil
	}
	return pref.MapKey{}, errors.New("invalid value for boolean key %q", name)

	case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
	n, err := strconv.ParseInt(name, base10, b32)
	if err != nil {
	return pref.MapKey{}, err
	}
	return pref.ValueOfInt32(int32(n)).MapKey(), nil

	case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
	n, err := strconv.ParseInt(name, base10, b64)
	if err != nil {
	return pref.MapKey{}, err
	}
	return pref.ValueOfInt64(int64(n)).MapKey(), nil

	case pref.Uint32Kind, pref.Fixed32Kind:
	n, err := strconv.ParseUint(name, base10, b32)
	if err != nil {
	return pref.MapKey{}, err
	}
	return pref.ValueOfUint32(uint32(n)).MapKey(), nil

	case pref.Uint64Kind, pref.Fixed64Kind:
	n, err := strconv.ParseUint(name, base10, b64)
	if err != nil {
	return pref.MapKey{}, err
	}
	return pref.ValueOfUint64(uint64(n)).MapKey(), nil
	}

	panic(fmt.Sprintf("%s: invalid kind %s for map key", fd.FullName(), kind))
	}