From 9670737ae3fe9be30bd94ac51206160ce18f51a0 Mon Sep 17 00:00:00 2001
From: Laria Carolin Chabowski <laria@laria.me>
Date: Fri, 21 Jul 2017 08:19:56 +0200
Subject: Modified snapshot object format to prepare for snapshot signing

---
 objects/object_snapshot.go      | 64 ++++++++++++++++++++++++++++++++++-------
 objects/object_snapshot_test.go | 15 ++++++----
 2 files changed, 63 insertions(+), 16 deletions(-)

diff --git a/objects/object_snapshot.go b/objects/object_snapshot.go
index 18a534f..59c7121 100644
--- a/objects/object_snapshot.go
+++ b/objects/object_snapshot.go
@@ -9,11 +9,20 @@ import (
 	"time"
 )
 
+const (
+	snapshot_start_marker = "== BEGIN SNAPSHOT =="
+	snapshot_end_marker   = "== END SNAPSHOT =="
+
+	snapshot_start_line = snapshot_start_marker + "\n"
+	snapshot_end_line   = snapshot_end_marker + "\n"
+)
+
 type Snapshot struct {
 	Tree    ObjectId
 	Date    time.Time
 	Archive string
 	Comment string
+	Signed  bool
 }
 
 func (s Snapshot) Type() ObjectType {
@@ -29,14 +38,26 @@ func appendKVPair(b []byte, k, v string) []byte {
 }
 
 func (s Snapshot) Payload() (out []byte) {
+	out = append(out, []byte(snapshot_start_line)...)
 	out = appendKVPair(out, "archive", s.Archive)
 	out = appendKVPair(out, "date", s.Date.Format(time.RFC3339))
+	if s.Signed {
+		out = appendKVPair(out, "signed", "yes")
+	}
 	out = appendKVPair(out, "tree", s.Tree.String())
 
 	if s.Comment != "" {
+		// We must prevent that the comment includes an end marker
+		comment := strings.Replace(s.Comment, snapshot_end_marker, "~~ END SNAPSHOT ~~", -1)
+
+		if comment[len(comment)-1] != '\n' {
+			comment += "\n"
+		}
+
 		out = append(out, '\n')
-		out = append(out, []byte(s.Comment)...)
+		out = append(out, []byte(comment)...)
 	}
+	out = append(out, []byte(snapshot_end_line)...)
 
 	return out
 }
@@ -48,15 +69,39 @@ func (s *Snapshot) FromPayload(payload []byte) error {
 	seenDate := false
 	seenTree := false
 
+	start := false
+	terminated := false
+	comment := false
+
 	for {
 		line, err := r.ReadString('\n')
 		if err != nil && err != io.EOF {
 			return err
+		} else if err == io.EOF {
+			break
 		}
+
 		line = strings.TrimSpace(line)
+		if !start {
+			if line == snapshot_start_marker {
+				start = true
+			}
+			continue
+		}
+
+		if line == snapshot_end_marker {
+			terminated = true
+			break
+		}
+
+		if comment {
+			s.Comment += line + "\n"
+			continue
+		}
 
 		if line == "" {
-			break // Header read successfully
+			comment = true
+			continue
 		}
 
 		parts := strings.SplitN(line, " ", 2)
@@ -76,6 +121,8 @@ func (s *Snapshot) FromPayload(payload []byte) error {
 			}
 			s.Date = d
 			seenDate = true
+		case "signed":
+			s.Signed = headerval == "yes"
 		case "tree":
 			oid, err := ParseObjectId(headerval)
 			if err != nil {
@@ -84,22 +131,17 @@ func (s *Snapshot) FromPayload(payload []byte) error {
 			s.Tree = oid
 			seenTree = true
 		}
+	}
 
-		if err == io.EOF {
-			break
-		}
+	if !terminated {
+		return errors.New("The snapshot was not properly terminated")
 	}
 
 	if !seenArchive || !seenDate || !seenTree {
 		return errors.New("Missing archive, date or tree header")
 	}
 
-	b := new(bytes.Buffer)
-	if _, err := io.Copy(b, r); err != nil {
-		return err
-	}
-
-	s.Comment = strings.TrimSpace(string(b.Bytes()))
+	s.Comment = strings.TrimSpace(s.Comment)
 	return nil
 }
 
diff --git a/objects/object_snapshot_test.go b/objects/object_snapshot_test.go
index df150de..d62c78a 100644
--- a/objects/object_snapshot_test.go
+++ b/objects/object_snapshot_test.go
@@ -11,17 +11,21 @@ var (
 		Archive: "foo",
 		Comment: "foo\nbar\nbaz!",
 		Date:    time.Date(2017, 07, 01, 21, 40, 00, 0, time.FixedZone("", 2*60*60)),
+		Signed:  true,
 		Tree:    genId(0xff),
 	}
 
 	testSnapshotSerialization = []byte("" +
+		"== BEGIN SNAPSHOT ==\n" +
 		"archive foo\n" +
 		"date 2017-07-01T21:40:00+02:00\n" +
+		"signed yes\n" +
 		"tree sha3-256:ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff\n" +
 		"\n" +
 		"foo\n" +
 		"bar\n" +
-		"baz!")
+		"baz!\n" +
+		"== END SNAPSHOT ==\n")
 )
 
 func TestSerializeSnapshot(t *testing.T) {
@@ -46,10 +50,11 @@ func TestUnserializeSnapshot(t *testing.T) {
 func TestUnserializeSnapshotFailure(t *testing.T) {
 	subtests := []struct{ name, payload string }{
 		{"empty", ""},
-		{"missing tree", "archive foo\ndate 2017-07-01T22:02:00+02:00\n"},
-		{"missing archive", "date 2017-07-01T22:02:00+02:00\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n"},
-		{"missing date", "archive foo\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n"},
-		{"invalid date", "archive foo\ndate foobar\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n"},
+		{"missing tree", snapshot_start_line + "archive foo\ndate 2017-07-01T22:02:00+02:00\n" + snapshot_end_line},
+		{"missing archive", snapshot_start_line + "date 2017-07-01T22:02:00+02:00\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n" + snapshot_end_line},
+		{"missing date", snapshot_start_line + "archive foo\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n" + snapshot_end_line},
+		{"invalid date", snapshot_start_line + "archive foo\ndate foobar\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n" + snapshot_end_line},
+		{"End marker missing", snapshot_start_line + "archive foo\ndate 2017-07-01T22:02:00+02:00\ntree sha3-256:0000000000000000000000000000000000000000000000000000000000000000\n"},
 	}
 
 	for _, subtest := range subtests {
-- 
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