peridot/vendor/go.mongodb.org/mongo-driver/bson/bsonrw/value_writer.go

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2022-07-07 20:11:50 +00:00
// 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 (
"errors"
"fmt"
"io"
"math"
"strconv"
"strings"
"sync"
"go.mongodb.org/mongo-driver/bson/bsontype"
"go.mongodb.org/mongo-driver/bson/primitive"
"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
)
var _ ValueWriter = (*valueWriter)(nil)
var vwPool = sync.Pool{
New: func() interface{} {
return new(valueWriter)
},
}
// BSONValueWriterPool is a pool for BSON ValueWriters.
type BSONValueWriterPool struct {
pool sync.Pool
}
// NewBSONValueWriterPool creates a new pool for ValueWriter instances that write to BSON.
func NewBSONValueWriterPool() *BSONValueWriterPool {
return &BSONValueWriterPool{
pool: sync.Pool{
New: func() interface{} {
return new(valueWriter)
},
},
}
}
// Get retrieves a BSON ValueWriter from the pool and resets it to use w as the destination.
func (bvwp *BSONValueWriterPool) Get(w io.Writer) ValueWriter {
vw := bvwp.pool.Get().(*valueWriter)
if writer, ok := w.(*SliceWriter); ok {
vw.reset(*writer)
vw.w = writer
return vw
}
vw.buf = vw.buf[:0]
vw.w = w
return vw
}
// GetAtModeElement retrieves a ValueWriterFlusher from the pool and resets it to use w as the destination.
func (bvwp *BSONValueWriterPool) GetAtModeElement(w io.Writer) ValueWriterFlusher {
vw := bvwp.Get(w).(*valueWriter)
vw.push(mElement)
return vw
}
// Put inserts a ValueWriter into the pool. If the ValueWriter is not a BSON ValueWriter, nothing
// happens and ok will be false.
func (bvwp *BSONValueWriterPool) Put(vw ValueWriter) (ok bool) {
bvw, ok := vw.(*valueWriter)
if !ok {
return false
}
if _, ok := bvw.w.(*SliceWriter); ok {
bvw.buf = nil
}
bvw.w = nil
bvwp.pool.Put(bvw)
return true
}
// This is here so that during testing we can change it and not require
// allocating a 4GB slice.
var maxSize = math.MaxInt32
var errNilWriter = errors.New("cannot create a ValueWriter from a nil io.Writer")
type errMaxDocumentSizeExceeded struct {
size int64
}
func (mdse errMaxDocumentSizeExceeded) Error() string {
return fmt.Sprintf("document size (%d) is larger than the max int32", mdse.size)
}
type vwMode int
const (
_ vwMode = iota
vwTopLevel
vwDocument
vwArray
vwValue
vwElement
vwCodeWithScope
)
func (vm vwMode) String() string {
var str string
switch vm {
case vwTopLevel:
str = "TopLevel"
case vwDocument:
str = "DocumentMode"
case vwArray:
str = "ArrayMode"
case vwValue:
str = "ValueMode"
case vwElement:
str = "ElementMode"
case vwCodeWithScope:
str = "CodeWithScopeMode"
default:
str = "UnknownMode"
}
return str
}
type vwState struct {
mode mode
key string
arrkey int
start int32
}
type valueWriter struct {
w io.Writer
buf []byte
stack []vwState
frame int64
}
func (vw *valueWriter) advanceFrame() {
if vw.frame+1 >= int64(len(vw.stack)) { // We need to grow the stack
length := len(vw.stack)
if length+1 >= cap(vw.stack) {
// double it
buf := make([]vwState, 2*cap(vw.stack)+1)
copy(buf, vw.stack)
vw.stack = buf
}
vw.stack = vw.stack[:length+1]
}
vw.frame++
}
func (vw *valueWriter) push(m mode) {
vw.advanceFrame()
// Clean the stack
vw.stack[vw.frame].mode = m
vw.stack[vw.frame].key = ""
vw.stack[vw.frame].arrkey = 0
vw.stack[vw.frame].start = 0
vw.stack[vw.frame].mode = m
switch m {
case mDocument, mArray, mCodeWithScope:
vw.reserveLength()
}
}
func (vw *valueWriter) reserveLength() {
vw.stack[vw.frame].start = int32(len(vw.buf))
vw.buf = append(vw.buf, 0x00, 0x00, 0x00, 0x00)
}
func (vw *valueWriter) pop() {
switch vw.stack[vw.frame].mode {
case mElement, mValue:
vw.frame--
case mDocument, mArray, mCodeWithScope:
vw.frame -= 2 // we pop twice to jump over the mElement: mDocument -> mElement -> mDocument/mTopLevel/etc...
}
}
// NewBSONValueWriter creates a ValueWriter that writes BSON to w.
//
// This ValueWriter will only write entire documents to the io.Writer and it
// will buffer the document as it is built.
func NewBSONValueWriter(w io.Writer) (ValueWriter, error) {
if w == nil {
return nil, errNilWriter
}
return newValueWriter(w), nil
}
func newValueWriter(w io.Writer) *valueWriter {
vw := new(valueWriter)
stack := make([]vwState, 1, 5)
stack[0] = vwState{mode: mTopLevel}
vw.w = w
vw.stack = stack
return vw
}
func newValueWriterFromSlice(buf []byte) *valueWriter {
vw := new(valueWriter)
stack := make([]vwState, 1, 5)
stack[0] = vwState{mode: mTopLevel}
vw.stack = stack
vw.buf = buf
return vw
}
func (vw *valueWriter) reset(buf []byte) {
if vw.stack == nil {
vw.stack = make([]vwState, 1, 5)
}
vw.stack = vw.stack[:1]
vw.stack[0] = vwState{mode: mTopLevel}
vw.buf = buf
vw.frame = 0
vw.w = nil
}
func (vw *valueWriter) invalidTransitionError(destination mode, name string, modes []mode) error {
te := TransitionError{
name: name,
current: vw.stack[vw.frame].mode,
destination: destination,
modes: modes,
action: "write",
}
if vw.frame != 0 {
te.parent = vw.stack[vw.frame-1].mode
}
return te
}
func (vw *valueWriter) writeElementHeader(t bsontype.Type, destination mode, callerName string, addmodes ...mode) error {
switch vw.stack[vw.frame].mode {
case mElement:
key := vw.stack[vw.frame].key
if !isValidCString(key) {
return errors.New("BSON element key cannot contain null bytes")
}
vw.buf = bsoncore.AppendHeader(vw.buf, t, key)
case mValue:
// TODO: Do this with a cache of the first 1000 or so array keys.
vw.buf = bsoncore.AppendHeader(vw.buf, t, strconv.Itoa(vw.stack[vw.frame].arrkey))
default:
modes := []mode{mElement, mValue}
if addmodes != nil {
modes = append(modes, addmodes...)
}
return vw.invalidTransitionError(destination, callerName, modes)
}
return nil
}
func (vw *valueWriter) WriteValueBytes(t bsontype.Type, b []byte) error {
if err := vw.writeElementHeader(t, mode(0), "WriteValueBytes"); err != nil {
return err
}
vw.buf = append(vw.buf, b...)
vw.pop()
return nil
}
func (vw *valueWriter) WriteArray() (ArrayWriter, error) {
if err := vw.writeElementHeader(bsontype.Array, mArray, "WriteArray"); err != nil {
return nil, err
}
vw.push(mArray)
return vw, nil
}
func (vw *valueWriter) WriteBinary(b []byte) error {
return vw.WriteBinaryWithSubtype(b, 0x00)
}
func (vw *valueWriter) WriteBinaryWithSubtype(b []byte, btype byte) error {
if err := vw.writeElementHeader(bsontype.Binary, mode(0), "WriteBinaryWithSubtype"); err != nil {
return err
}
vw.buf = bsoncore.AppendBinary(vw.buf, btype, b)
vw.pop()
return nil
}
func (vw *valueWriter) WriteBoolean(b bool) error {
if err := vw.writeElementHeader(bsontype.Boolean, mode(0), "WriteBoolean"); err != nil {
return err
}
vw.buf = bsoncore.AppendBoolean(vw.buf, b)
vw.pop()
return nil
}
func (vw *valueWriter) WriteCodeWithScope(code string) (DocumentWriter, error) {
if err := vw.writeElementHeader(bsontype.CodeWithScope, mCodeWithScope, "WriteCodeWithScope"); err != nil {
return nil, err
}
// CodeWithScope is a different than other types because we need an extra
// frame on the stack. In the EndDocument code, we write the document
// length, pop, write the code with scope length, and pop. To simplify the
// pop code, we push a spacer frame that we'll always jump over.
vw.push(mCodeWithScope)
vw.buf = bsoncore.AppendString(vw.buf, code)
vw.push(mSpacer)
vw.push(mDocument)
return vw, nil
}
func (vw *valueWriter) WriteDBPointer(ns string, oid primitive.ObjectID) error {
if err := vw.writeElementHeader(bsontype.DBPointer, mode(0), "WriteDBPointer"); err != nil {
return err
}
vw.buf = bsoncore.AppendDBPointer(vw.buf, ns, oid)
vw.pop()
return nil
}
func (vw *valueWriter) WriteDateTime(dt int64) error {
if err := vw.writeElementHeader(bsontype.DateTime, mode(0), "WriteDateTime"); err != nil {
return err
}
vw.buf = bsoncore.AppendDateTime(vw.buf, dt)
vw.pop()
return nil
}
func (vw *valueWriter) WriteDecimal128(d128 primitive.Decimal128) error {
if err := vw.writeElementHeader(bsontype.Decimal128, mode(0), "WriteDecimal128"); err != nil {
return err
}
vw.buf = bsoncore.AppendDecimal128(vw.buf, d128)
vw.pop()
return nil
}
func (vw *valueWriter) WriteDouble(f float64) error {
if err := vw.writeElementHeader(bsontype.Double, mode(0), "WriteDouble"); err != nil {
return err
}
vw.buf = bsoncore.AppendDouble(vw.buf, f)
vw.pop()
return nil
}
func (vw *valueWriter) WriteInt32(i32 int32) error {
if err := vw.writeElementHeader(bsontype.Int32, mode(0), "WriteInt32"); err != nil {
return err
}
vw.buf = bsoncore.AppendInt32(vw.buf, i32)
vw.pop()
return nil
}
func (vw *valueWriter) WriteInt64(i64 int64) error {
if err := vw.writeElementHeader(bsontype.Int64, mode(0), "WriteInt64"); err != nil {
return err
}
vw.buf = bsoncore.AppendInt64(vw.buf, i64)
vw.pop()
return nil
}
func (vw *valueWriter) WriteJavascript(code string) error {
if err := vw.writeElementHeader(bsontype.JavaScript, mode(0), "WriteJavascript"); err != nil {
return err
}
vw.buf = bsoncore.AppendJavaScript(vw.buf, code)
vw.pop()
return nil
}
func (vw *valueWriter) WriteMaxKey() error {
if err := vw.writeElementHeader(bsontype.MaxKey, mode(0), "WriteMaxKey"); err != nil {
return err
}
vw.pop()
return nil
}
func (vw *valueWriter) WriteMinKey() error {
if err := vw.writeElementHeader(bsontype.MinKey, mode(0), "WriteMinKey"); err != nil {
return err
}
vw.pop()
return nil
}
func (vw *valueWriter) WriteNull() error {
if err := vw.writeElementHeader(bsontype.Null, mode(0), "WriteNull"); err != nil {
return err
}
vw.pop()
return nil
}
func (vw *valueWriter) WriteObjectID(oid primitive.ObjectID) error {
if err := vw.writeElementHeader(bsontype.ObjectID, mode(0), "WriteObjectID"); err != nil {
return err
}
vw.buf = bsoncore.AppendObjectID(vw.buf, oid)
vw.pop()
return nil
}
func (vw *valueWriter) WriteRegex(pattern string, options string) error {
if !isValidCString(pattern) || !isValidCString(options) {
return errors.New("BSON regex values cannot contain null bytes")
}
if err := vw.writeElementHeader(bsontype.Regex, mode(0), "WriteRegex"); err != nil {
return err
}
vw.buf = bsoncore.AppendRegex(vw.buf, pattern, sortStringAlphebeticAscending(options))
vw.pop()
return nil
}
func (vw *valueWriter) WriteString(s string) error {
if err := vw.writeElementHeader(bsontype.String, mode(0), "WriteString"); err != nil {
return err
}
vw.buf = bsoncore.AppendString(vw.buf, s)
vw.pop()
return nil
}
func (vw *valueWriter) WriteDocument() (DocumentWriter, error) {
if vw.stack[vw.frame].mode == mTopLevel {
vw.reserveLength()
return vw, nil
}
if err := vw.writeElementHeader(bsontype.EmbeddedDocument, mDocument, "WriteDocument", mTopLevel); err != nil {
return nil, err
}
vw.push(mDocument)
return vw, nil
}
func (vw *valueWriter) WriteSymbol(symbol string) error {
if err := vw.writeElementHeader(bsontype.Symbol, mode(0), "WriteSymbol"); err != nil {
return err
}
vw.buf = bsoncore.AppendSymbol(vw.buf, symbol)
vw.pop()
return nil
}
func (vw *valueWriter) WriteTimestamp(t uint32, i uint32) error {
if err := vw.writeElementHeader(bsontype.Timestamp, mode(0), "WriteTimestamp"); err != nil {
return err
}
vw.buf = bsoncore.AppendTimestamp(vw.buf, t, i)
vw.pop()
return nil
}
func (vw *valueWriter) WriteUndefined() error {
if err := vw.writeElementHeader(bsontype.Undefined, mode(0), "WriteUndefined"); err != nil {
return err
}
vw.pop()
return nil
}
func (vw *valueWriter) WriteDocumentElement(key string) (ValueWriter, error) {
switch vw.stack[vw.frame].mode {
case mTopLevel, mDocument:
default:
return nil, vw.invalidTransitionError(mElement, "WriteDocumentElement", []mode{mTopLevel, mDocument})
}
vw.push(mElement)
vw.stack[vw.frame].key = key
return vw, nil
}
func (vw *valueWriter) WriteDocumentEnd() error {
switch vw.stack[vw.frame].mode {
case mTopLevel, mDocument:
default:
return fmt.Errorf("incorrect mode to end document: %s", vw.stack[vw.frame].mode)
}
vw.buf = append(vw.buf, 0x00)
err := vw.writeLength()
if err != nil {
return err
}
if vw.stack[vw.frame].mode == mTopLevel {
if err = vw.Flush(); err != nil {
return err
}
}
vw.pop()
if vw.stack[vw.frame].mode == mCodeWithScope {
// We ignore the error here because of the gaurantee of writeLength.
// See the docs for writeLength for more info.
_ = vw.writeLength()
vw.pop()
}
return nil
}
func (vw *valueWriter) Flush() error {
if vw.w == nil {
return nil
}
if sw, ok := vw.w.(*SliceWriter); ok {
*sw = vw.buf
return nil
}
if _, err := vw.w.Write(vw.buf); err != nil {
return err
}
// reset buffer
vw.buf = vw.buf[:0]
return nil
}
func (vw *valueWriter) WriteArrayElement() (ValueWriter, error) {
if vw.stack[vw.frame].mode != mArray {
return nil, vw.invalidTransitionError(mValue, "WriteArrayElement", []mode{mArray})
}
arrkey := vw.stack[vw.frame].arrkey
vw.stack[vw.frame].arrkey++
vw.push(mValue)
vw.stack[vw.frame].arrkey = arrkey
return vw, nil
}
func (vw *valueWriter) WriteArrayEnd() error {
if vw.stack[vw.frame].mode != mArray {
return fmt.Errorf("incorrect mode to end array: %s", vw.stack[vw.frame].mode)
}
vw.buf = append(vw.buf, 0x00)
err := vw.writeLength()
if err != nil {
return err
}
vw.pop()
return nil
}
// NOTE: We assume that if we call writeLength more than once the same function
// within the same function without altering the vw.buf that this method will
// not return an error. If this changes ensure that the following methods are
// updated:
//
// - WriteDocumentEnd
func (vw *valueWriter) writeLength() error {
length := len(vw.buf)
if length > maxSize {
return errMaxDocumentSizeExceeded{size: int64(len(vw.buf))}
}
length = length - int(vw.stack[vw.frame].start)
start := vw.stack[vw.frame].start
vw.buf[start+0] = byte(length)
vw.buf[start+1] = byte(length >> 8)
vw.buf[start+2] = byte(length >> 16)
vw.buf[start+3] = byte(length >> 24)
return nil
}
func isValidCString(cs string) bool {
return !strings.ContainsRune(cs, '\x00')
}