k3s/vendor/github.com/globalsign/mgo/bson/stream.go
Darren Shepherd 8031137b79 Update vendor
2019-08-30 23:08:05 -07:00

91 lines
2.6 KiB
Go

package bson
import (
"bytes"
"encoding/binary"
"fmt"
"io"
)
const (
// MinDocumentSize is the size of the smallest possible valid BSON document:
// an int32 size header + 0x00 (end of document).
MinDocumentSize = 5
// MaxDocumentSize is the largest possible size for a BSON document allowed by MongoDB,
// that is, 16 MiB (see https://docs.mongodb.com/manual/reference/limits/).
MaxDocumentSize = 16777216
)
// ErrInvalidDocumentSize is an error returned when a BSON document's header
// contains a size smaller than MinDocumentSize or greater than MaxDocumentSize.
type ErrInvalidDocumentSize struct {
DocumentSize int32
}
func (e ErrInvalidDocumentSize) Error() string {
return fmt.Sprintf("invalid document size %d", e.DocumentSize)
}
// A Decoder reads and decodes BSON values from an input stream.
type Decoder struct {
source io.Reader
}
// NewDecoder returns a new Decoder that reads from source.
// It does not add any extra buffering, and may not read data from source beyond the BSON values requested.
func NewDecoder(source io.Reader) *Decoder {
return &Decoder{source: source}
}
// Decode reads the next BSON-encoded value from its input and stores it in the value pointed to by v.
// See the documentation for Unmarshal for details about the conversion of BSON into a Go value.
func (dec *Decoder) Decode(v interface{}) (err error) {
// BSON documents start with their size as a *signed* int32.
var docSize int32
if err = binary.Read(dec.source, binary.LittleEndian, &docSize); err != nil {
return
}
if docSize < MinDocumentSize || docSize > MaxDocumentSize {
return ErrInvalidDocumentSize{DocumentSize: docSize}
}
docBuffer := bytes.NewBuffer(make([]byte, 0, docSize))
if err = binary.Write(docBuffer, binary.LittleEndian, docSize); err != nil {
return
}
// docSize is the *full* document's size (including the 4-byte size header,
// which has already been read).
if _, err = io.CopyN(docBuffer, dec.source, int64(docSize-4)); err != nil {
return
}
// Let Unmarshal handle the rest.
defer handleErr(&err)
return Unmarshal(docBuffer.Bytes(), v)
}
// An Encoder encodes and writes BSON values to an output stream.
type Encoder struct {
target io.Writer
}
// NewEncoder returns a new Encoder that writes to target.
func NewEncoder(target io.Writer) *Encoder {
return &Encoder{target: target}
}
// Encode encodes v to BSON, and if successful writes it to the Encoder's output stream.
// See the documentation for Marshal for details about the conversion of Go values to BSON.
func (enc *Encoder) Encode(v interface{}) error {
data, err := Marshal(v)
if err != nil {
return err
}
_, err = enc.target.Write(data)
return err
}