daemon: make error message explicit

When we are skipping the mcd binary write when it already
exists. Today this is the case for RHEL worker node during upgrade.
Explicitly make sure that we are skipping because file doesn't exist

pkg/daemon/daemon.go

@@ -466,7 +466,7 @@ func ReexecuteForTargetRoot(target string) error {
 			// Otherwise, we assume that there's no suffixing needed.  Hopefully
 			// by RHEL10 the MCD will have fundamentally changed and we won't be doing the
 			// chroot() thing anymore.
-			klog.Info("not chrooting for source=rhel-%s target=rhel-%s", sourceMajor, targetMajor)
+			klog.Infof("not chrooting for source=rhel-%s target=rhel-%s", sourceMajor, targetMajor)
 		}
 	} else {
 		klog.Info("assuming we can use container binary chroot() to host")
@@ -476,7 +476,11 @@ func ReexecuteForTargetRoot(target string) error {
 	targetBin := filepath.Join(target, targetBinBase)
 
 	// Be idempotent
-	if _, err := os.Stat(targetBin); err != nil {
+	targetBinExist, err := fileExists(targetBin)
+	if err != nil {
+		return err
+	}
+	if !targetBinExist {
 		sourceBinary := "/usr/bin/machine-config-daemon" + sourceBinarySuffix
 		src, err := os.Open(sourceBinary)
 		if err != nil {
@@ -485,7 +489,12 @@ func ReexecuteForTargetRoot(target string) error {
 		defer src.Close()
 
 		targetBinDir := filepath.Dir(targetBin)
-		if _, err := os.Stat(targetBinDir); err != nil {
+		// Before creating targetBinDir, ensure that it doesn't exist
+		targetBinDirExist, err := directoryExists(targetBinDir)
+		if err != nil {
+			return err
+		}
+		if !targetBinDirExist {
 			if err := os.Mkdir(targetBinDir, 0o755); err != nil {
 				return fmt.Errorf("mkdir %s: %w", targetBinDir, err)
 			}

pkg/daemon/update.go

@@ -1648,6 +1648,27 @@ func fileExists(path string) (bool, error) {
 	return false, fmt.Errorf("cannot stat file: %w", err)
 }
 
+// Determines if a directory exists by checking the returned error when we stat the file.
+// Also, check that it is a directory.
+func directoryExists(path string) (bool, error) {
+	info, err := os.Stat(path)
+	// If there is no error, check if it is a directory
+	if err == nil {
+		if info.IsDir() {
+			return true, nil
+		}
+		return false, fmt.Errorf("%s exists but it is not a directory", path)
+	}
+
+	// If the error matches fs.ErrNotExist, file definitely does not exist.
+	if errors.Is(err, fs.ErrNotExist) {
+		return false, nil
+	}
+
+	// An unexpected error occurred.
+	return false, fmt.Errorf("cannot stat file: %w", err)
+}
+
 // Removes the old SSH key path (/home/core/.ssh/authorized_keys), if found.
 func cleanSSHKeyPaths() error {
 	oldKeyExists, err := fileExists(constants.RHCOS8SSHKeyPath)