INFRA-4180: Replace BSONElementSize implementation

Author: bozaro

bson/decode.go

@@ -28,7 +28,6 @@
 package bson
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -38,6 +37,8 @@ import (
 	"sync"
 	"time"
 
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+
 	"go.mongodb.org/mongo-driver/bson"
 	"go.mongodb.org/mongo-driver/bson/bsontype"
 	"go.mongodb.org/mongo-driver/bson/primitive"
@@ -404,104 +405,11 @@ func (d *decoder) readSliceDoc(t reflect.Type) interface{} {
 }
 
 func BSONElementSize(kind bsontype.Type, offset int, buffer []byte) (int, error) {
-	switch kind {
-	case ElementFloat64: // Float64
-		return 8, nil
-	case ElementJavaScriptWithoutScope: // JavaScript without scope
-		fallthrough
-	case ElementSymbol: // Symbol
-		fallthrough
-	case ElementString: // UTF-8 string
-		size, err := getSize(offset, buffer)
-		if err != nil {
-			return 0, err
-		}
-		if size < 1 {
-			return 0, errors.New("String size can't be less then one byte")
-		}
-		size += 4
-		if offset+size > len(buffer) {
-			return 0, io.ErrUnexpectedEOF
-		}
-		if buffer[offset+size-1] != 0 {
-			return 0, errors.New("Invalid string: non zero-terminated")
-		}
-		return size, nil
-	case ElementArray: // Array
-		fallthrough
-	case ElementDocument: // Document
-		size, err := getSize(offset, buffer)
-		if err != nil {
-			return 0, err
-		}
-		if size < 5 {
-			return 0, errors.New("Declared document size is too small")
-		}
-		return size, nil
-	case ElementBinary: // Binary
-		size, err := getSize(offset, buffer)
-		if err != nil {
-			return 0, err
-		}
-		if size < 0 {
-			return 0, errors.New("Binary data size can't be negative")
-		}
-		return size + 5, nil
-	case Element06: // Undefined (obsolete, but still seen in the wild)
-		return 0, nil
-	case ElementObjectId: // ObjectId
-		return 12, nil
-	case ElementBool: // Bool
-		return 1, nil
-	case ElementDatetime: // Timestamp
-		return 8, nil
-	case ElementNil: // Nil
-		return 0, nil
-	case ElementRegEx: // RegEx
-		end := offset
-		for i := 0; i < 2; i++ {
-			for end < len(buffer) && buffer[end] != '\x00' {
-				end++
-			}
-			end++
-		}
-		if end > len(buffer) {
-			return 0, io.ErrUnexpectedEOF
-		}
-		return end - offset, nil
-	case ElementDBPointer: // DBPointer
-		size, err := getSize(offset, buffer)
-		if err != nil {
-			return 0, err
-		}
-		if size < 1 {
-			return 0, errors.New("String size can't be less then one byte")
-		}
-		return size + 12 + 4, nil
-	case ElementJavaScriptWithScope: // JavaScript with scope
-		size, err := getSize(offset, buffer)
-		if err != nil {
-			return 0, err
-		}
-		if size < 4+5+5 {
-			return 0, errors.New("Declared document element is too small")
-		}
-		return size, nil
-	case ElementInt32: // Int32
-		return 4, nil
-	case ElementTimestamp: // Mongo-specific timestamp
-		return 8, nil
-	case ElementInt64: // Int64
-		return 8, nil
-	case ElementDecimal128: // Decimal128
-		return 16, nil
-	case ElementMaxKey: // Max key
-		return 0, nil
-	case ElementMinKey: // Min key
-		return 0, nil
-	default:
-		return 0, errors.New(fmt.Sprintf("Unknown element kind (0x%02X)", byte(kind)))
+	value, _, ok := bsoncore.ReadValue(buffer[offset:], kind)
+	if !ok {
+		return 0, bsoncore.ErrCorruptedDocument
 	}
+	return len(value.Data), nil
 }
 
 func (d *decoder) readRaw(kind bsontype.Type) Raw {