feat(dir2config): defaults

vendor/gopkg.in/src-d/go-git.v4/plumbing/protocol/packp/srvresp.go

@@ -0,0 +1,127 @@
+package packp
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/pktline"
+)
+
+const ackLineLen = 44
+
+// ServerResponse object acknowledgement from upload-pack service
+type ServerResponse struct {
+	ACKs []plumbing.Hash
+}
+
+// Decode decodes the response into the struct, isMultiACK should be true, if
+// the request was done with multi_ack or multi_ack_detailed capabilities.
+func (r *ServerResponse) Decode(reader *bufio.Reader, isMultiACK bool) error {
+	// TODO: implement support for multi_ack or multi_ack_detailed responses
+	if isMultiACK {
+		return errors.New("multi_ack and multi_ack_detailed are not supported")
+	}
+
+	s := pktline.NewScanner(reader)
+
+	for s.Scan() {
+		line := s.Bytes()
+
+		if err := r.decodeLine(line); err != nil {
+			return err
+		}
+
+		// we need to detect when the end of a response header and the beginning
+		// of a packfile header happened, some requests to the git daemon
+		// produces a duplicate ACK header even when multi_ack is not supported.
+		stop, err := r.stopReading(reader)
+		if err != nil {
+			return err
+		}
+
+		if stop {
+			break
+		}
+	}
+
+	return s.Err()
+}
+
+// stopReading detects when a valid command such as ACK or NAK is found to be
+// read in the buffer without moving the read pointer.
+func (r *ServerResponse) stopReading(reader *bufio.Reader) (bool, error) {
+	ahead, err := reader.Peek(7)
+	if err == io.EOF {
+		return true, nil
+	}
+
+	if err != nil {
+		return false, err
+	}
+
+	if len(ahead) > 4 && r.isValidCommand(ahead[0:3]) {
+		return false, nil
+	}
+
+	if len(ahead) == 7 && r.isValidCommand(ahead[4:]) {
+		return false, nil
+	}
+
+	return true, nil
+}
+
+func (r *ServerResponse) isValidCommand(b []byte) bool {
+	commands := [][]byte{ack, nak}
+	for _, c := range commands {
+		if bytes.Equal(b, c) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (r *ServerResponse) decodeLine(line []byte) error {
+	if len(line) == 0 {
+		return fmt.Errorf("unexpected flush")
+	}
+
+	if bytes.Equal(line[0:3], ack) {
+		return r.decodeACKLine(line)
+	}
+
+	if bytes.Equal(line[0:3], nak) {
+		return nil
+	}
+
+	return fmt.Errorf("unexpected content %q", string(line))
+}
+
+func (r *ServerResponse) decodeACKLine(line []byte) error {
+	if len(line) < ackLineLen {
+		return fmt.Errorf("malformed ACK %q", line)
+	}
+
+	sp := bytes.Index(line, []byte(" "))
+	h := plumbing.NewHash(string(line[sp+1 : sp+41]))
+	r.ACKs = append(r.ACKs, h)
+	return nil
+}
+
+// Encode encodes the ServerResponse into a writer.
+func (r *ServerResponse) Encode(w io.Writer) error {
+	if len(r.ACKs) > 1 {
+		return errors.New("multi_ack and multi_ack_detailed are not supported")
+	}
+
+	e := pktline.NewEncoder(w)
+	if len(r.ACKs) == 0 {
+		return e.Encodef("%s\n", nak)
+	}
+
+	return e.Encodef("%s %s\n", ack, r.ACKs[0].String())
+}