1 files changed, 874 insertions, 0 deletions
diff --git a/vendor/go.mongodb.org/mongo-driver/bson/bsonrw/value_reader.go b/vendor/go.mongodb.org/mongo-driver/bson/bsonrw/value_reader.go
new file mode 100644
index 000000000..ef5d837c2
--- /dev/null
+++ b/vendor/go.mongodb.org/mongo-driver/bson/bsonrw/value_reader.go
@@ -0,0 +1,874 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package bsonrw
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"sync"
+
+	"go.mongodb.org/mongo-driver/bson/bsontype"
+	"go.mongodb.org/mongo-driver/bson/primitive"
+)
+
+var _ ValueReader = (*valueReader)(nil)
+
+var vrPool = sync.Pool{
+	New: func() interface{} {
+		return new(valueReader)
+	},
+}
+
+// BSONValueReaderPool is a pool for ValueReaders that read BSON.
+type BSONValueReaderPool struct {
+	pool sync.Pool
+}
+
+// NewBSONValueReaderPool instantiates a new BSONValueReaderPool.
+func NewBSONValueReaderPool() *BSONValueReaderPool {
+	return &BSONValueReaderPool{
+		pool: sync.Pool{
+			New: func() interface{} {
+				return new(valueReader)
+			},
+		},
+	}
+}
+
+// Get retrieves a ValueReader from the pool and uses src as the underlying BSON.
+func (bvrp *BSONValueReaderPool) Get(src []byte) ValueReader {
+	vr := bvrp.pool.Get().(*valueReader)
+	vr.reset(src)
+	return vr
+}
+
+// Put inserts a ValueReader into the pool. If the ValueReader is not a BSON ValueReader nothing
+// is inserted into the pool and ok will be false.
+func (bvrp *BSONValueReaderPool) Put(vr ValueReader) (ok bool) {
+	bvr, ok := vr.(*valueReader)
+	if !ok {
+		return false
+	}
+
+	bvr.reset(nil)
+	bvrp.pool.Put(bvr)
+	return true
+}
+
+// ErrEOA is the error returned when the end of a BSON array has been reached.
+var ErrEOA = errors.New("end of array")
+
+// ErrEOD is the error returned when the end of a BSON document has been reached.
+var ErrEOD = errors.New("end of document")
+
+type vrState struct {
+	mode  mode
+	vType bsontype.Type
+	end   int64
+}
+
+// valueReader is for reading BSON values.
+type valueReader struct {
+	offset int64
+	d      []byte
+
+	stack []vrState
+	frame int64
+}
+
+// NewBSONDocumentReader returns a ValueReader using b for the underlying BSON
+// representation. Parameter b must be a BSON Document.
+func NewBSONDocumentReader(b []byte) ValueReader {
+	// TODO(skriptble): There's a lack of symmetry between the reader and writer, since the reader takes a []byte while the
+	// TODO writer takes an io.Writer. We should have two versions of each, one that takes a []byte and one that takes an
+	// TODO io.Reader or io.Writer. The []byte version will need to return a thing that can return the finished []byte since
+	// TODO it might be reallocated when appended to.
+	return newValueReader(b)
+}
+
+// NewBSONValueReader returns a ValueReader that starts in the Value mode instead of in top
+// level document mode. This enables the creation of a ValueReader for a single BSON value.
+func NewBSONValueReader(t bsontype.Type, val []byte) ValueReader {
+	stack := make([]vrState, 1, 5)
+	stack[0] = vrState{
+		mode:  mValue,
+		vType: t,
+	}
+	return &valueReader{
+		d:     val,
+		stack: stack,
+	}
+}
+
+func newValueReader(b []byte) *valueReader {
+	stack := make([]vrState, 1, 5)
+	stack[0] = vrState{
+		mode: mTopLevel,
+	}
+	return &valueReader{
+		d:     b,
+		stack: stack,
+	}
+}
+
+func (vr *valueReader) reset(b []byte) {
+	if vr.stack == nil {
+		vr.stack = make([]vrState, 1, 5)
+	}
+	vr.stack = vr.stack[:1]
+	vr.stack[0] = vrState{mode: mTopLevel}
+	vr.d = b
+	vr.offset = 0
+	vr.frame = 0
+}
+
+func (vr *valueReader) advanceFrame() {
+	if vr.frame+1 >= int64(len(vr.stack)) { // We need to grow the stack
+		length := len(vr.stack)
+		if length+1 >= cap(vr.stack) {
+			// double it
+			buf := make([]vrState, 2*cap(vr.stack)+1)
+			copy(buf, vr.stack)
+			vr.stack = buf
+		}
+		vr.stack = vr.stack[:length+1]
+	}
+	vr.frame++
+
+	// Clean the stack
+	vr.stack[vr.frame].mode = 0
+	vr.stack[vr.frame].vType = 0
+	vr.stack[vr.frame].end = 0
+}
+
+func (vr *valueReader) pushDocument() error {
+	vr.advanceFrame()
+
+	vr.stack[vr.frame].mode = mDocument
+
+	size, err := vr.readLength()
+	if err != nil {
+		return err
+	}
+	vr.stack[vr.frame].end = int64(size) + vr.offset - 4
+
+	return nil
+}
+
+func (vr *valueReader) pushArray() error {
+	vr.advanceFrame()
+
+	vr.stack[vr.frame].mode = mArray
+
+	size, err := vr.readLength()
+	if err != nil {
+		return err
+	}
+	vr.stack[vr.frame].end = int64(size) + vr.offset - 4
+
+	return nil
+}
+
+func (vr *valueReader) pushElement(t bsontype.Type) {
+	vr.advanceFrame()
+
+	vr.stack[vr.frame].mode = mElement
+	vr.stack[vr.frame].vType = t
+}
+
+func (vr *valueReader) pushValue(t bsontype.Type) {
+	vr.advanceFrame()
+
+	vr.stack[vr.frame].mode = mValue
+	vr.stack[vr.frame].vType = t
+}
+
+func (vr *valueReader) pushCodeWithScope() (int64, error) {
+	vr.advanceFrame()
+
+	vr.stack[vr.frame].mode = mCodeWithScope
+
+	size, err := vr.readLength()
+	if err != nil {
+		return 0, err
+	}
+	vr.stack[vr.frame].end = int64(size) + vr.offset - 4
+
+	return int64(size), nil
+}
+
+func (vr *valueReader) pop() {
+	switch vr.stack[vr.frame].mode {
+	case mElement, mValue:
+		vr.frame--
+	case mDocument, mArray, mCodeWithScope:
+		vr.frame -= 2 // we pop twice to jump over the vrElement: vrDocument -> vrElement -> vrDocument/TopLevel/etc...
+	}
+}
+
+func (vr *valueReader) invalidTransitionErr(destination mode, name string, modes []mode) error {
+	te := TransitionError{
+		name:        name,
+		current:     vr.stack[vr.frame].mode,
+		destination: destination,
+		modes:       modes,
+		action:      "read",
+	}
+	if vr.frame != 0 {
+		te.parent = vr.stack[vr.frame-1].mode
+	}
+	return te
+}
+
+func (vr *valueReader) typeError(t bsontype.Type) error {
+	return fmt.Errorf("positioned on %s, but attempted to read %s", vr.stack[vr.frame].vType, t)
+}
+
+func (vr *valueReader) invalidDocumentLengthError() error {
+	return fmt.Errorf("document is invalid, end byte is at %d, but null byte found at %d", vr.stack[vr.frame].end, vr.offset)
+}
+
+func (vr *valueReader) ensureElementValue(t bsontype.Type, destination mode, callerName string) error {
+	switch vr.stack[vr.frame].mode {
+	case mElement, mValue:
+		if vr.stack[vr.frame].vType != t {
+			return vr.typeError(t)
+		}
+	default:
+		return vr.invalidTransitionErr(destination, callerName, []mode{mElement, mValue})
+	}
+
+	return nil
+}
+
+func (vr *valueReader) Type() bsontype.Type {
+	return vr.stack[vr.frame].vType
+}
+
+func (vr *valueReader) nextElementLength() (int32, error) {
+	var length int32
+	var err error
+	switch vr.stack[vr.frame].vType {
+	case bsontype.Array, bsontype.EmbeddedDocument, bsontype.CodeWithScope:
+		length, err = vr.peekLength()
+	case bsontype.Binary:
+		length, err = vr.peekLength()
+		length += 4 + 1 // binary length + subtype byte
+	case bsontype.Boolean:
+		length = 1
+	case bsontype.DBPointer:
+		length, err = vr.peekLength()
+		length += 4 + 12 // string length + ObjectID length
+	case bsontype.DateTime, bsontype.Double, bsontype.Int64, bsontype.Timestamp:
+		length = 8
+	case bsontype.Decimal128:
+		length = 16
+	case bsontype.Int32:
+		length = 4
+	case bsontype.JavaScript, bsontype.String, bsontype.Symbol:
+		length, err = vr.peekLength()
+		length += 4
+	case bsontype.MaxKey, bsontype.MinKey, bsontype.Null, bsontype.Undefined:
+		length = 0
+	case bsontype.ObjectID:
+		length = 12
+	case bsontype.Regex:
+		regex := bytes.IndexByte(vr.d[vr.offset:], 0x00)
+		if regex < 0 {
+			err = io.EOF
+			break
+		}
+		pattern := bytes.IndexByte(vr.d[vr.offset+int64(regex)+1:], 0x00)
+		if pattern < 0 {
+			err = io.EOF
+			break
+		}
+		length = int32(int64(regex) + 1 + int64(pattern) + 1)
+	default:
+		return 0, fmt.Errorf("attempted to read bytes of unknown BSON type %v", vr.stack[vr.frame].vType)
+	}
+
+	return length, err
+}
+
+func (vr *valueReader) ReadValueBytes(dst []byte) (bsontype.Type, []byte, error) {
+	switch vr.stack[vr.frame].mode {
+	case mTopLevel:
+		length, err := vr.peekLength()
+		if err != nil {
+			return bsontype.Type(0), nil, err
+		}
+		dst, err = vr.appendBytes(dst, length)
+		if err != nil {
+			return bsontype.Type(0), nil, err
+		}
+		return bsontype.Type(0), dst, nil
+	case mElement, mValue:
+		length, err := vr.nextElementLength()
+		if err != nil {
+			return bsontype.Type(0), dst, err
+		}
+
+		dst, err = vr.appendBytes(dst, length)
+		t := vr.stack[vr.frame].vType
+		vr.pop()
+		return t, dst, err
+	default:
+		return bsontype.Type(0), nil, vr.invalidTransitionErr(0, "ReadValueBytes", []mode{mElement, mValue})
+	}
+}
+
+func (vr *valueReader) Skip() error {
+	switch vr.stack[vr.frame].mode {
+	case mElement, mValue:
+	default:
+		return vr.invalidTransitionErr(0, "Skip", []mode{mElement, mValue})
+	}
+
+	length, err := vr.nextElementLength()
+	if err != nil {
+		return err
+	}
+
+	err = vr.skipBytes(length)
+	vr.pop()
+	return err
+}
+
+func (vr *valueReader) ReadArray() (ArrayReader, error) {
+	if err := vr.ensureElementValue(bsontype.Array, mArray, "ReadArray"); err != nil {
+		return nil, err
+	}
+
+	err := vr.pushArray()
+	if err != nil {
+		return nil, err
+	}
+
+	return vr, nil
+}
+
+func (vr *valueReader) ReadBinary() (b []byte, btype byte, err error) {
+	if err := vr.ensureElementValue(bsontype.Binary, 0, "ReadBinary"); err != nil {
+		return nil, 0, err
+	}
+
+	length, err := vr.readLength()
+	if err != nil {
+		return nil, 0, err
+	}
+
+	btype, err = vr.readByte()
+	if err != nil {
+		return nil, 0, err
+	}
+
+	// Check length in case it is an old binary without a length.
+	if btype == 0x02 && length > 4 {
+		length, err = vr.readLength()
+		if err != nil {
+			return nil, 0, err
+		}
+	}
+
+	b, err = vr.readBytes(length)
+	if err != nil {
+		return nil, 0, err
+	}
+	// Make a copy of the returned byte slice because it's just a subslice from the valueReader's
+	// buffer and is not safe to return in the unmarshaled value.
+	cp := make([]byte, len(b))
+	copy(cp, b)
+
+	vr.pop()
+	return cp, btype, nil
+}
+
+func (vr *valueReader) ReadBoolean() (bool, error) {
+	if err := vr.ensureElementValue(bsontype.Boolean, 0, "ReadBoolean"); err != nil {
+		return false, err
+	}
+
+	b, err := vr.readByte()
+	if err != nil {
+		return false, err
+	}
+
+	if b > 1 {
+		return false, fmt.Errorf("invalid byte for boolean, %b", b)
+	}
+
+	vr.pop()
+	return b == 1, nil
+}
+
+func (vr *valueReader) ReadDocument() (DocumentReader, error) {
+	switch vr.stack[vr.frame].mode {
+	case mTopLevel:
+		// read size
+		size, err := vr.readLength()
+		if err != nil {
+			return nil, err
+		}
+		if int(size) != len(vr.d) {
+			return nil, fmt.Errorf("invalid document length")
+		}
+		vr.stack[vr.frame].end = int64(size) + vr.offset - 4
+		return vr, nil
+	case mElement, mValue:
+		if vr.stack[vr.frame].vType != bsontype.EmbeddedDocument {
+			return nil, vr.typeError(bsontype.EmbeddedDocument)
+		}
+	default:
+		return nil, vr.invalidTransitionErr(mDocument, "ReadDocument", []mode{mTopLevel, mElement, mValue})
+	}
+
+	err := vr.pushDocument()
+	if err != nil {
+		return nil, err
+	}
+
+	return vr, nil
+}
+
+func (vr *valueReader) ReadCodeWithScope() (code string, dr DocumentReader, err error) {
+	if err := vr.ensureElementValue(bsontype.CodeWithScope, 0, "ReadCodeWithScope"); err != nil {
+		return "", nil, err
+	}
+
+	totalLength, err := vr.readLength()
+	if err != nil {
+		return "", nil, err
+	}
+	strLength, err := vr.readLength()
+	if err != nil {
+		return "", nil, err
+	}
+	if strLength <= 0 {
+		return "", nil, fmt.Errorf("invalid string length: %d", strLength)
+	}
+	strBytes, err := vr.readBytes(strLength)
+	if err != nil {
+		return "", nil, err
+	}
+	code = string(strBytes[:len(strBytes)-1])
+
+	size, err := vr.pushCodeWithScope()
+	if err != nil {
+		return "", nil, err
+	}
+
+	// The total length should equal:
+	// 4 (total length) + strLength + 4 (the length of str itself) + (document length)
+	componentsLength := int64(4+strLength+4) + size
+	if int64(totalLength) != componentsLength {
+		return "", nil, fmt.Errorf(
+			"length of CodeWithScope does not match lengths of components; total: %d; components: %d",
+			totalLength, componentsLength,
+		)
+	}
+	return code, vr, nil
+}
+
+func (vr *valueReader) ReadDBPointer() (ns string, oid primitive.ObjectID, err error) {
+	if err := vr.ensureElementValue(bsontype.DBPointer, 0, "ReadDBPointer"); err != nil {
+		return "", oid, err
+	}
+
+	ns, err = vr.readString()
+	if err != nil {
+		return "", oid, err
+	}
+
+	oidbytes, err := vr.readBytes(12)
+	if err != nil {
+		return "", oid, err
+	}
+
+	copy(oid[:], oidbytes)
+
+	vr.pop()
+	return ns, oid, nil
+}
+
+func (vr *valueReader) ReadDateTime() (int64, error) {
+	if err := vr.ensureElementValue(bsontype.DateTime, 0, "ReadDateTime"); err != nil {
+		return 0, err
+	}
+
+	i, err := vr.readi64()
+	if err != nil {
+		return 0, err
+	}
+
+	vr.pop()
+	return i, nil
+}
+
+func (vr *valueReader) ReadDecimal128() (primitive.Decimal128, error) {
+	if err := vr.ensureElementValue(bsontype.Decimal128, 0, "ReadDecimal128"); err != nil {
+		return primitive.Decimal128{}, err
+	}
+
+	b, err := vr.readBytes(16)
+	if err != nil {
+		return primitive.Decimal128{}, err
+	}
+
+	l := binary.LittleEndian.Uint64(b[0:8])
+	h := binary.LittleEndian.Uint64(b[8:16])
+
+	vr.pop()
+	return primitive.NewDecimal128(h, l), nil
+}
+
+func (vr *valueReader) ReadDouble() (float64, error) {
+	if err := vr.ensureElementValue(bsontype.Double, 0, "ReadDouble"); err != nil {
+		return 0, err
+	}
+
+	u, err := vr.readu64()
+	if err != nil {
+		return 0, err
+	}
+
+	vr.pop()
+	return math.Float64frombits(u), nil
+}
+
+func (vr *valueReader) ReadInt32() (int32, error) {
+	if err := vr.ensureElementValue(bsontype.Int32, 0, "ReadInt32"); err != nil {
+		return 0, err
+	}
+
+	vr.pop()
+	return vr.readi32()
+}
+
+func (vr *valueReader) ReadInt64() (int64, error) {
+	if err := vr.ensureElementValue(bsontype.Int64, 0, "ReadInt64"); err != nil {
+		return 0, err
+	}
+
+	vr.pop()
+	return vr.readi64()
+}
+
+func (vr *valueReader) ReadJavascript() (code string, err error) {
+	if err := vr.ensureElementValue(bsontype.JavaScript, 0, "ReadJavascript"); err != nil {
+		return "", err
+	}
+
+	vr.pop()
+	return vr.readString()
+}
+
+func (vr *valueReader) ReadMaxKey() error {
+	if err := vr.ensureElementValue(bsontype.MaxKey, 0, "ReadMaxKey"); err != nil {
+		return err
+	}
+
+	vr.pop()
+	return nil
+}
+
+func (vr *valueReader) ReadMinKey() error {
+	if err := vr.ensureElementValue(bsontype.MinKey, 0, "ReadMinKey"); err != nil {
+		return err
+	}
+
+	vr.pop()
+	return nil
+}
+
+func (vr *valueReader) ReadNull() error {
+	if err := vr.ensureElementValue(bsontype.Null, 0, "ReadNull"); err != nil {
+		return err
+	}
+
+	vr.pop()
+	return nil
+}
+
+func (vr *valueReader) ReadObjectID() (primitive.ObjectID, error) {
+	if err := vr.ensureElementValue(bsontype.ObjectID, 0, "ReadObjectID"); err != nil {
+		return primitive.ObjectID{}, err
+	}
+
+	oidbytes, err := vr.readBytes(12)
+	if err != nil {
+		return primitive.ObjectID{}, err
+	}
+
+	var oid primitive.ObjectID
+	copy(oid[:], oidbytes)
+
+	vr.pop()
+	return oid, nil
+}
+
+func (vr *valueReader) ReadRegex() (string, string, error) {
+	if err := vr.ensureElementValue(bsontype.Regex, 0, "ReadRegex"); err != nil {
+		return "", "", err
+	}
+
+	pattern, err := vr.readCString()
+	if err != nil {
+		return "", "", err
+	}
+
+	options, err := vr.readCString()
+	if err != nil {
+		return "", "", err
+	}
+
+	vr.pop()
+	return pattern, options, nil
+}
+
+func (vr *valueReader) ReadString() (string, error) {
+	if err := vr.ensureElementValue(bsontype.String, 0, "ReadString"); err != nil {
+		return "", err
+	}
+
+	vr.pop()
+	return vr.readString()
+}
+
+func (vr *valueReader) ReadSymbol() (symbol string, err error) {
+	if err := vr.ensureElementValue(bsontype.Symbol, 0, "ReadSymbol"); err != nil {
+		return "", err
+	}
+
+	vr.pop()
+	return vr.readString()
+}
+
+func (vr *valueReader) ReadTimestamp() (t uint32, i uint32, err error) {
+	if err := vr.ensureElementValue(bsontype.Timestamp, 0, "ReadTimestamp"); err != nil {
+		return 0, 0, err
+	}
+
+	i, err = vr.readu32()
+	if err != nil {
+		return 0, 0, err
+	}
+
+	t, err = vr.readu32()
+	if err != nil {
+		return 0, 0, err
+	}
+
+	vr.pop()
+	return t, i, nil
+}
+
+func (vr *valueReader) ReadUndefined() error {
+	if err := vr.ensureElementValue(bsontype.Undefined, 0, "ReadUndefined"); err != nil {
+		return err
+	}
+
+	vr.pop()
+	return nil
+}
+
+func (vr *valueReader) ReadElement() (string, ValueReader, error) {
+	switch vr.stack[vr.frame].mode {
+	case mTopLevel, mDocument, mCodeWithScope:
+	default:
+		return "", nil, vr.invalidTransitionErr(mElement, "ReadElement", []mode{mTopLevel, mDocument, mCodeWithScope})
+	}
+
+	t, err := vr.readByte()
+	if err != nil {
+		return "", nil, err
+	}
+
+	if t == 0 {
+		if vr.offset != vr.stack[vr.frame].end {
+			return "", nil, vr.invalidDocumentLengthError()
+		}
+
+		vr.pop()
+		return "", nil, ErrEOD
+	}
+
+	name, err := vr.readCString()
+	if err != nil {
+		return "", nil, err
+	}
+
+	vr.pushElement(bsontype.Type(t))
+	return name, vr, nil
+}
+
+func (vr *valueReader) ReadValue() (ValueReader, error) {
+	switch vr.stack[vr.frame].mode {
+	case mArray:
+	default:
+		return nil, vr.invalidTransitionErr(mValue, "ReadValue", []mode{mArray})
+	}
+
+	t, err := vr.readByte()
+	if err != nil {
+		return nil, err
+	}
+
+	if t == 0 {
+		if vr.offset != vr.stack[vr.frame].end {
+			return nil, vr.invalidDocumentLengthError()
+		}
+
+		vr.pop()
+		return nil, ErrEOA
+	}
+
+	_, err = vr.readCString()
+	if err != nil {
+		return nil, err
+	}
+
+	vr.pushValue(bsontype.Type(t))
+	return vr, nil
+}
+
+// readBytes reads length bytes from the valueReader starting at the current offset. Note that the
+// returned byte slice is a subslice from the valueReader buffer and must be converted or copied
+// before returning in an unmarshaled value.
+func (vr *valueReader) readBytes(length int32) ([]byte, error) {
+	if length < 0 {
+		return nil, fmt.Errorf("invalid length: %d", length)
+	}
+
+	if vr.offset+int64(length) > int64(len(vr.d)) {
+		return nil, io.EOF
+	}
+
+	start := vr.offset
+	vr.offset += int64(length)
+
+	return vr.d[start : start+int64(length)], nil
+}
+
+func (vr *valueReader) appendBytes(dst []byte, length int32) ([]byte, error) {
+	if vr.offset+int64(length) > int64(len(vr.d)) {
+		return nil, io.EOF
+	}
+
+	start := vr.offset
+	vr.offset += int64(length)
+	return append(dst, vr.d[start:start+int64(length)]...), nil
+}
+
+func (vr *valueReader) skipBytes(length int32) error {
+	if vr.offset+int64(length) > int64(len(vr.d)) {
+		return io.EOF
+	}
+
+	vr.offset += int64(length)
+	return nil
+}
+
+func (vr *valueReader) readByte() (byte, error) {
+	if vr.offset+1 > int64(len(vr.d)) {
+		return 0x0, io.EOF
+	}
+
+	vr.offset++
+	return vr.d[vr.offset-1], nil
+}
+
+func (vr *valueReader) readCString() (string, error) {
+	idx := bytes.IndexByte(vr.d[vr.offset:], 0x00)
+	if idx < 0 {
+		return "", io.EOF
+	}
+	start := vr.offset
+	// idx does not include the null byte
+	vr.offset += int64(idx) + 1
+	return string(vr.d[start : start+int64(idx)]), nil
+}
+
+func (vr *valueReader) readString() (string, error) {
+	length, err := vr.readLength()
+	if err != nil {
+		return "", err
+	}
+
+	if int64(length)+vr.offset > int64(len(vr.d)) {
+		return "", io.EOF
+	}
+
+	if length <= 0 {
+		return "", fmt.Errorf("invalid string length: %d", length)
+	}
+
+	if vr.d[vr.offset+int64(length)-1] != 0x00 {
+		return "", fmt.Errorf("string does not end with null byte, but with %v", vr.d[vr.offset+int64(length)-1])
+	}
+
+	start := vr.offset
+	vr.offset += int64(length)
+	return string(vr.d[start : start+int64(length)-1]), nil
+}
+
+func (vr *valueReader) peekLength() (int32, error) {
+	if vr.offset+4 > int64(len(vr.d)) {
+		return 0, io.EOF
+	}
+
+	idx := vr.offset
+	return (int32(vr.d[idx]) | int32(vr.d[idx+1])<<8 | int32(vr.d[idx+2])<<16 | int32(vr.d[idx+3])<<24), nil
+}
+
+func (vr *valueReader) readLength() (int32, error) { return vr.readi32() }
+
+func (vr *valueReader) readi32() (int32, error) {
+	if vr.offset+4 > int64(len(vr.d)) {
+		return 0, io.EOF
+	}
+
+	idx := vr.offset
+	vr.offset += 4
+	return (int32(vr.d[idx]) | int32(vr.d[idx+1])<<8 | int32(vr.d[idx+2])<<16 | int32(vr.d[idx+3])<<24), nil
+}
+
+func (vr *valueReader) readu32() (uint32, error) {
+	if vr.offset+4 > int64(len(vr.d)) {
+		return 0, io.EOF
+	}
+
+	idx := vr.offset
+	vr.offset += 4
+	return (uint32(vr.d[idx]) | uint32(vr.d[idx+1])<<8 | uint32(vr.d[idx+2])<<16 | uint32(vr.d[idx+3])<<24), nil
+}
+
+func (vr *valueReader) readi64() (int64, error) {
+	if vr.offset+8 > int64(len(vr.d)) {
+		return 0, io.EOF
+	}
+
+	idx := vr.offset
+	vr.offset += 8
+	return int64(vr.d[idx]) | int64(vr.d[idx+1])<<8 | int64(vr.d[idx+2])<<16 | int64(vr.d[idx+3])<<24 |
+		int64(vr.d[idx+4])<<32 | int64(vr.d[idx+5])<<40 | int64(vr.d[idx+6])<<48 | int64(vr.d[idx+7])<<56, nil
+}
+
+func (vr *valueReader) readu64() (uint64, error) {
+	if vr.offset+8 > int64(len(vr.d)) {
+		return 0, io.EOF
+	}
+
+	idx := vr.offset
+	vr.offset += 8
+	return uint64(vr.d[idx]) | uint64(vr.d[idx+1])<<8 | uint64(vr.d[idx+2])<<16 | uint64(vr.d[idx+3])<<24 |
+		uint64(vr.d[idx+4])<<32 | uint64(vr.d[idx+5])<<40 | uint64(vr.d[idx+6])<<48 | uint64(vr.d[idx+7])<<56, nil
+}