pillar: Encode media type in verifier filenames.

Implemented a feature to save the media type hashed in the
verifier filename. This enhancement is used in both config and
status, ensuring that the media type is persistently available and
survives reboots. Modified several functions in verifier.go to
include media type in the filename generation. Also updated
related structures in verifiertypes.go to include the media type.

Issue: lf-edge#3704

Signed-off-by: Avi Deitcher <avi@deitcher.net>

pkg/pillar/cmd/verifier/verifier.go

@@ -14,6 +14,7 @@ package verifier
 import (
 	"flag"
 	"fmt"
+	"net/url"
 	"os"
 	"path"
 	"strings"
@@ -308,6 +309,7 @@ func handleCreate(ctx *verifierContext,
 	status := types.VerifyImageStatus{
 		Name:        config.Name,
 		ImageSha256: config.ImageSha256,
+		MediaType:   config.MediaType,
 		PendingAdd:  true,
 		State:       types.VERIFYING,
 		RefCount:    config.RefCount,
@@ -500,12 +502,20 @@ func handleGlobalConfigDelete(ctxArg interface{}, key string,
 }
 
 // ImageVerifierFilenames - Returns pendingFilename, verifierFilename, verifiedFilename
-// for the image
-func ImageVerifierFilenames(infile, sha256, tmpID string) (string, string, string) {
+// for the image. The verifierFilename and verifiedFilename always will have an extension
+// of the media-type, e.g. abcdeff112.application-vnd.oci.image.manifest.v1+json
+// This is because we need the media-type to process the blob. Normally, we carry
+// it around in the status (DownloadStatus -> BlobStatus), but those are ephemeral and
+// lost during a reboot. We need that information to be persistent and survive reboot,
+// so we can reconstruct it. Hence, we preserve it in the filename. It is PathEscape'd
+// so it is filename-safe.
+func ImageVerifierFilenames(infile, sha256, tmpID, mediaType string) (string, string, string) {
 	verifierDirname, verifiedDirname := getVerifierDir(), getVerifiedDir()
 	// Handle names which are paths
-	verified := tmpID + "." + sha256
-	return infile, path.Join(verifierDirname, verified), path.Join(verifiedDirname, sha256)
+	mediaTypeSafe := url.PathEscape(mediaType)
+	verifierFilename := strings.Join([]string{tmpID, sha256, mediaTypeSafe}, ".")
+	verifiedFilename := strings.Join([]string{sha256, mediaTypeSafe}, ".")
+	return infile, path.Join(verifierDirname, verifierFilename), path.Join(verifiedDirname, verifiedFilename)
 }
 
 // Returns ok, size of object
@@ -514,7 +524,7 @@ func markObjectAsVerifying(ctx *verifierContext,
 	status *types.VerifyImageStatus, tmpID uuid.UUID) (bool, int64) {
 
 	verifierDirname := getVerifierDir()
-	pendingFilename, verifierFilename, _ := ImageVerifierFilenames(config.FileLocation, config.ImageSha256, tmpID.String())
+	pendingFilename, verifierFilename, _ := ImageVerifierFilenames(config.FileLocation, config.ImageSha256, tmpID.String(), config.MediaType)
 
 	// Move to verifier directory which is RO
 	// XXX should have dom0 do this and/or have RO mounts
@@ -561,7 +571,7 @@ func markObjectAsVerifying(ctx *verifierContext,
 func markObjectAsVerified(config *types.VerifyImageConfig, status *types.VerifyImageStatus, tmpID uuid.UUID) {
 
 	verifiedDirname := getVerifiedDir()
-	_, verifierFilename, verifiedFilename := ImageVerifierFilenames(config.FileLocation, config.ImageSha256, tmpID.String())
+	_, verifierFilename, verifiedFilename := ImageVerifierFilenames(config.FileLocation, config.ImageSha256, tmpID.String(), config.MediaType)
 	// Move directory from DownloadDirname/verifier to
 	// DownloadDirname/verified
 	// XXX should have dom0 do this and/or have RO mounts
@@ -609,10 +619,22 @@ func handleInitVerifiedObjects(ctx *verifierContext) {
 func verifyImageStatusFromImageFile(imageFileName string,
 	size int64, pathname string) *types.VerifyImageStatus {
 
+	// filename might have two parts, separated by '.': digest and PathEscape(mediaType)
+	var (
+		mediaType string
+		digest    string
+	)
+	parts := strings.SplitN(imageFileName, ".", 2)
+	digest = parts[0]
+	if len(parts) == 2 {
+		// just ignore the error and treat mediaType as empty
+		mediaType, _ = url.PathUnescape(parts[1])
+	}
 	status := types.VerifyImageStatus{
 		Name:         imageFileName,
 		FileLocation: pathname,
-		ImageSha256:  imageFileName,
+		ImageSha256:  digest,
+		MediaType:    mediaType,
 		Size:         size,
 		State:        types.VERIFIED,
 		RefCount:     0,

pkg/pillar/cmd/volumemgr/handleverifier.go

@@ -71,6 +71,7 @@ func MaybeAddVerifyImageConfigBlob(ctx *volumemgrContext, blob types.BlobStatus)
 			ImageSha256:  blob.Sha256, // the sha to verify
 			Name:         blob.Sha256, // we are just going to use the sha for the verifier display
 			RefCount:     refcount,
+			MediaType:    blob.MediaType,
 		}
 		log.Tracef("MaybeAddVerifyImageConfigBlob - config: %+v", vic)
 	}

pkg/pillar/types/verifiertypes.go

@@ -21,6 +21,7 @@ import (
 type VerifyImageConfig struct {
 	ImageSha256  string // sha256 of immutable image
 	Name         string
+	MediaType    string // MIME type
 	FileLocation string // Current location; should be info about file
 	Size         int64  //FileLocation size
 	RefCount     uint
@@ -91,6 +92,7 @@ type VerifyImageStatus struct {
 	Name          string
 	FileLocation  string // Current location
 	Size          int64
+	MediaType     string // MIME type
 	PendingAdd    bool
 	PendingModify bool
 	PendingDelete bool