Introduce pgproto3 package

pgproto3 will wrap the message encoding and decoding for the PostgreSQL
frontend/backend protocol version 3.

copy_both_response.go

@@ -0,0 +1,64 @@
+package pgproto3
+
+import (
+	"bytes"
+	"encoding/binary"
+	"encoding/json"
+)
+
+type CopyBothResponse struct {
+	OverallFormat     byte
+	ColumnFormatCodes []uint16
+}
+
+func (*CopyBothResponse) Backend() {}
+
+func (dst *CopyBothResponse) UnmarshalBinary(src []byte) error {
+	buf := bytes.NewBuffer(src)
+
+	if buf.Len() < 3 {
+		return &invalidMessageFormatErr{messageType: "CopyBothResponse"}
+	}
+
+	overallFormat := buf.Next(1)[0]
+
+	columnCount := int(binary.BigEndian.Uint16(buf.Next(2)))
+	if buf.Len() != columnCount*2 {
+		return &invalidMessageFormatErr{messageType: "CopyBothResponse"}
+	}
+
+	columnFormatCodes := make([]uint16, columnCount)
+	for i := 0; i < columnCount; i++ {
+		columnFormatCodes[i] = binary.BigEndian.Uint16(buf.Next(2))
+	}
+
+	*dst = CopyBothResponse{OverallFormat: overallFormat, ColumnFormatCodes: columnFormatCodes}
+
+	return nil
+}
+
+func (src *CopyBothResponse) MarshalBinary() ([]byte, error) {
+	var bigEndian BigEndianBuf
+	buf := &bytes.Buffer{}
+
+	buf.WriteByte('W')
+	buf.Write(bigEndian.Uint32(uint32(4 + 1 + 2 + 2*len(src.ColumnFormatCodes))))
+
+	buf.Write(bigEndian.Uint16(uint16(len(src.ColumnFormatCodes))))
+
+	for _, fc := range src.ColumnFormatCodes {
+		buf.Write(bigEndian.Uint16(fc))
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (src *CopyBothResponse) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type              string
+		ColumnFormatCodes []uint16
+	}{
+		Type:              "CopyBothResponse",
+		ColumnFormatCodes: src.ColumnFormatCodes,
+	})
+}