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gitea/vendor/go.mongodb.org/mongo-driver/bson/bsonrw/value_reader.go
2020-09-01 10:01:23 -04:00

878 lines
20 KiB
Go
Vendored

// 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.
//
// TODO(skriptble): There's a lack of symmetry between the reader and writer, since the reader takes
// a []byte while the writer takes an io.Writer. We should have two versions of each, one that takes
// a []byte and one that takes an io.Reader or io.Writer. The []byte version will need to return a
// thing that can return the finished []byte since it might be reallocated when appended to.
func NewBSONDocumentReader(b []byte) ValueReader {
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
}
vr.pop()
return b, 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
}
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) skipCString() error {
idx := bytes.IndexByte(vr.d[vr.offset:], 0x00)
if idx < 0 {
return io.EOF
}
// idx does not include the null byte
vr.offset += int64(idx) + 1
return 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
}