Move lowlevel binary routines into own package

binary/record.go

@@ -0,0 +1,78 @@
+package binary
+
+import (
+	"encoding/binary"
+
+	"github.com/jackc/pgio"
+	errors "golang.org/x/xerrors"
+)
+
+type RecordFieldIter struct {
+	rp  int
+	src []byte
+}
+
+// NewRecordFieldIterator creates iterator over binary representation
+// of record, aka ROW(), aka Composite
+func NewRecordFieldIterator(src []byte) (RecordFieldIter, int, error) {
+	rp := 0
+	if len(src[rp:]) < 4 {
+		return RecordFieldIter{}, 0, errors.Errorf("Record incomplete %v", src)
+	}
+
+	fieldCount := int(int32(binary.BigEndian.Uint32(src[rp:])))
+	rp += 4
+
+	return RecordFieldIter{
+		rp:  rp,
+		src: src,
+	}, fieldCount, nil
+}
+
+// Next returns next field decoded from record. eof is returned if no
+// more fields left to decode.
+func (fi *RecordFieldIter) Next() (fieldOID uint32, buf []byte, eof bool, err error) {
+	if fi.rp == len(fi.src) {
+		eof = true
+		return
+	}
+
+	if len(fi.src[fi.rp:]) < 8 {
+		err = errors.Errorf("Record incomplete %v", fi.src)
+		return
+	}
+	fieldOID = binary.BigEndian.Uint32(fi.src[fi.rp:])
+	fi.rp += 4
+
+	fieldLen := int(int32(binary.BigEndian.Uint32(fi.src[fi.rp:])))
+	fi.rp += 4
+
+	if fieldLen >= 0 {
+		if len(fi.src[fi.rp:]) < fieldLen {
+			err = errors.Errorf("Record incomplete rp=%d src=%v", fi.rp, fi.src)
+			return
+		}
+		buf = fi.src[fi.rp : fi.rp+fieldLen]
+		fi.rp += fieldLen
+	}
+
+	return
+}
+
+// RecordStart adds record header to the buf
+func RecordStart(buf []byte, fieldCount int) []byte {
+	return pgio.AppendUint32(buf, uint32(fieldCount))
+}
+
+// RecordAdd adds record field to the buf
+func RecordAdd(buf []byte, oid uint32, fieldBytes []byte) []byte {
+	buf = pgio.AppendUint32(buf, oid)
+	buf = pgio.AppendUint32(buf, uint32(len(fieldBytes)))
+	buf = append(buf, fieldBytes...)
+	return buf
+}
+
+// RecordAddNull adds null value as a field to the buf
+func RecordAddNull(buf []byte, oid uint32) []byte {
+	return pgio.AppendInt32(buf, int32(-1))
+}