CWCOW: roothash and graceful timeout fixes

Signed-off-by: Mahati Chamarthy <mahati.chamarthy@gmail.com>

Author: MahatiC

internal/gcs-sidecar/handlers.go

@@ -4,7 +4,7 @@
 package bridge
 
 import (
-	"encoding/base64"
+	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"os"
@@ -579,20 +579,40 @@ func (b *Bridge) modifySettings(req *request) (err error) {
 			containerID := wcowBlockCimMounts.ContainerID
 			log.G(ctx).Tracef("WCOWBlockCIMMounts { %v}", wcowBlockCimMounts)
 
-			// The block device takes some time to show up. Wait for a few seconds.
-			time.Sleep(2 * time.Second)
-
 			var layerCIMs []*cimfs.BlockCIM
 			layerHashes := make([]string, len(wcowBlockCimMounts.BlockCIMs))
 			layerDigests := make([][]byte, len(wcowBlockCimMounts.BlockCIMs))
 			for i, blockCimDevice := range wcowBlockCimMounts.BlockCIMs {
 				// Get the scsi device path for the blockCim lun
-				devNumber, err := windevice.GetDeviceNumberFromControllerLUN(
-					req.ctx,
-					0, /* controller is always 0 for wcow */
-					uint8(blockCimDevice.Lun))
-				if err != nil {
-					return fmt.Errorf("err getting scsiDevPath: %w", err)
+				// The block device takes some time to show up. Retry for up to 2 seconds.
+				var devNumber uint32
+				waitStartTime := time.Now()
+				logTime := waitStartTime.Add(time.Second)
+				logged := false
+				for {
+					devNumber, err = windevice.GetDeviceNumberFromControllerLUN(
+						req.ctx,
+						0, /* controller is always 0 for wcow */
+						uint8(blockCimDevice.Lun))
+					if err == nil {
+						break
+					}
+
+					// Check if we've exceeded max wait time
+					if time.Since(waitStartTime) >= 2*time.Second {
+						return fmt.Errorf("err getting scsiDevPath after 2s: %w", err)
+					}
+
+					// Log if taking longer than expected
+					if !logged && logTime.Before(time.Now()) {
+						log.G(ctx).WithFields(map[string]interface{}{
+							"lun":     blockCimDevice.Lun,
+							"elapsed": time.Since(waitStartTime),
+						}).Warn("waiting for block CIM device to show up")
+						logged = true
+					}
+
+					time.Sleep(10 * time.Millisecond)
 				}
 				physicalDevPath := fmt.Sprintf(devPathFormat, devNumber)
 				layerCim := cimfs.BlockCIM{
@@ -605,7 +625,7 @@ func (b *Bridge) modifySettings(req *request) (err error) {
 					return fmt.Errorf("failed to get CIM verification info: %w", err)
 				}
 				layerDigests[i] = cimRootDigestBytes
-				layerHashes[i] = base64.URLEncoding.EncodeToString(cimRootDigestBytes)
+				layerHashes[i] = hex.EncodeToString(cimRootDigestBytes)
 				layerCIMs = append(layerCIMs, &layerCim)
 
 				log.G(ctx).Debugf("block CIM layer digest %s, path: %s\n", layerHashes[i], physicalDevPath)

pkg/ociwclayer/cim/import.go

@@ -7,7 +7,7 @@ import (
 	"archive/tar"
 	"bufio"
 	"context"
-	"encoding/base64"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -98,7 +98,7 @@ func WithParentLayers(parentLayers []*cimfs.BlockCIM) BlockCIMLayerImportOpt {
 
 func writeIntegrityChecksumInfoFile(ctx context.Context, blockPath string) error {
 	log.G(ctx).Debugf("writing integrity checksum file for block CIM `%s`", blockPath)
-	// for convenience write a file that has the base64 encoded root digest of the generated verified CIM.
+	// for convenience write a file that has the hex encoded root digest of the generated verified CIM.
 	// this same base64 string can be used in the confidential policy.
 	digest, err := cimfs.GetVerificationInfo(blockPath)
 	if err != nil {
@@ -111,7 +111,7 @@ func writeIntegrityChecksumInfoFile(ctx context.Context, blockPath string) error
 	}
 	defer digestFile.Close()
 
-	digestStr := base64.URLEncoding.EncodeToString(digest)
+	digestStr := hex.EncodeToString(digest)
 	if wn, err := digestFile.WriteString(digestStr); err != nil {
 		return fmt.Errorf("failed to write verification info: %w", err)
 	} else if wn != len(digestStr) {
@@ -358,5 +358,6 @@ func MergeBlockCIMLayersWithOpts(ctx context.Context, sourceCIMs []*cimfs.BlockC
 			return fmt.Errorf("append VHD footer to block CIM: %w", err)
 		}
 	}
+
 	return nil
 }