swupd: add minversion header to MoM

An upcoming improvement to swupd-client requires the minversion header
to exist in the MoM in order to determine the strategy with which to
update files in the update.

When the minVersion argument is provided to createManifests populate a
header in the MoM with this version. If no flag is provided and the
previous MoM had a minversion set populate the new MoM with this
version.

Write the minversion to the manifest header when the minversion != 0.
Since we only set minversion for the MoM the minversion will only be
written to the MoM and not to bundle manifests.

Signed-off-by: Matthew Johnson <matthew.johnson@intel.com>

swupd/create_manifests.go

@@ -410,12 +410,18 @@ func CreateManifests(version uint32, minVersion uint32, format uint, statedir st
 	newMoM := Manifest{
 		Name: "MoM",
 		Header: ManifestHeader{
-			Format:    format,
-			Version:   version,
-			Previous:  lastVersion,
-			TimeStamp: timeStamp,
+			Format:     format,
+			Version:    version,
+			MinVersion: minVersion,
+			Previous:   lastVersion,
+			TimeStamp:  timeStamp,
 		},
 	}
+	// if min-version wasn't explicitly set we need to carry the header forward
+	// from the old MoM
+	if newMoM.Header.MinVersion == 0 && oldMoM.Header.MinVersion > 0 {
+		newMoM.Header.MinVersion = oldMoM.Header.MinVersion
+	}
 
 	fmt.Println("Writing manifest files...")
 	newFull, err := newMoM.writeBundleManifests(newManifests, verOutput)

swupd/manifest.go

@@ -49,6 +49,7 @@ type ManifestHeader struct {
 	Format      uint
 	Version     uint32
 	Previous    uint32
+	MinVersion  uint32
 	FileCount   uint32
 	TimeStamp   time.Time
 	ContentSize uint64
@@ -99,6 +100,11 @@ func readManifestFileHeaderLine(fields []string, m *Manifest) error {
 			return fmt.Errorf("invalid manifest, %v", err)
 		}
 		m.Header.Previous = uint32(parsed)
+	case "minversion:":
+		if parsed, err = strconv.ParseUint(fields[1], 10, 32); err != nil {
+			return fmt.Errorf("invalid manifest, %v", err)
+		}
+		m.Header.MinVersion = uint32(parsed)
 	case "filecount:":
 		if parsed, err = strconv.ParseUint(fields[1], 10, 32); err != nil {
 			return fmt.Errorf("invalid manifest, %v", err)
@@ -294,7 +300,8 @@ var manifestTemplate = template.Must(template.New("manifest").Parse(`
 MANIFEST	{{.Format}}
 version:	{{.Version}}
 previous:	{{.Previous}}
-filecount:	{{.FileCount}}
+{{ if ne .MinVersion 0 }}minversion:	{{.MinVersion}}
+{{ end }}filecount:	{{.FileCount}}
 timestamp:	{{(.TimeStamp.Unix)}}
 contentsize:	{{.ContentSize -}}
 {{range .Includes}}