Properly abort CopyFrom on reader error

copy_fail.go

@@ -0,0 +1,49 @@
+package pgproto3
+
+import (
+	"bytes"
+	"encoding/json"
+
+	"github.com/jackc/pgx/pgio"
+)
+
+type CopyFail struct {
+	Error string
+}
+
+func (*CopyFail) Frontend() {}
+func (*CopyFail) Backend()  {}
+
+func (dst *CopyFail) Decode(src []byte) error {
+	idx := bytes.IndexByte(src, 0)
+	if idx != len(src)-1 {
+		return &invalidMessageFormatErr{messageType: "CopyFail"}
+	}
+
+	dst.Error = string(src[:idx])
+
+	return nil
+}
+
+func (src *CopyFail) Encode(dst []byte) []byte {
+	dst = append(dst, 'C')
+	sp := len(dst)
+	dst = pgio.AppendInt32(dst, -1)
+
+	dst = append(dst, src.Error...)
+	dst = append(dst, 0)
+
+	pgio.SetInt32(dst[sp:], int32(len(dst[sp:])))
+
+	return dst
+}
+
+func (src *CopyFail) MarshalJSON() ([]byte, error) {
+	return json.Marshal(struct {
+		Type  string
+		Error string
+	}{
+		Type:  "CopyFail",
+		Error: src.Error,
+	})
+}