Fix filemarker creation process, update error message on uninstall

internal/pkg/agent/install/install.go

@@ -102,13 +102,9 @@ func Install(cfgFile, topPath string, unprivileged bool, log *logp.Logger, pt *p
 		}
 	}
 
-	// ensure parent directory exists
-	err = os.MkdirAll(filepath.Dir(topPath), 0755)
+	err = setupInstallPath(topPath, ownership)
 	if err != nil {
-		return utils.FileOwner{}, errors.New(
-			err,
-			fmt.Sprintf("failed to create installation parent directory (%s)", filepath.Dir(topPath)),
-			errors.M("directory", filepath.Dir(topPath)))
+		return utils.FileOwner{}, fmt.Errorf("error setting up install path: %w", err)
 	}
 
 	manifest, err := readPackageManifest(dir)
@@ -173,11 +169,6 @@ func Install(cfgFile, topPath string, unprivileged bool, log *logp.Logger, pt *p
 		}
 	}
 
-	// create the install marker
-	if err := CreateInstallMarker(topPath, ownership); err != nil {
-		return utils.FileOwner{}, fmt.Errorf("failed to create install marker: %w", err)
-	}
-
 	// post install (per platform)
 	err = postInstall(topPath)
 	if err != nil {
@@ -216,6 +207,27 @@ func Install(cfgFile, topPath string, unprivileged bool, log *logp.Logger, pt *p
 	return ownership, nil
 }
 
+// setup the basic topPath, and the .installed file
+func setupInstallPath(topPath string, ownership utils.FileOwner) error {
+	// ensure parent directory exists
+	err := os.MkdirAll(filepath.Dir(topPath), 0755)
+	if err != nil {
+		return errors.New(err, fmt.Sprintf("failed to create installation parent directory (%s)", filepath.Dir(topPath)), errors.M("directory", filepath.Dir(topPath)))
+	}
+
+	// create Agent/ directory with more locked-down permissions
+	err = os.MkdirAll(topPath, 0750)
+	if err != nil {
+		return errors.New(err, fmt.Sprintf("failed to create top path (%s)", topPath), errors.M("directory", topPath))
+	}
+
+	// create the install marker
+	if err := CreateInstallMarker(topPath, ownership); err != nil {
+		return fmt.Errorf("failed to create install marker: %w", err)
+	}
+	return nil
+}
+
 func readPackageManifest(extractedPackageDir string) (*v1.PackageManifest, error) {
 	manifestFilePath := filepath.Join(extractedPackageDir, v1.ManifestFileName)
 	manifestFile, err := os.Open(manifestFilePath)
@@ -473,10 +485,14 @@ func hasAllSSDs(block ghw.BlockInfo) bool {
 	return true
 }
 
+// CreateInstallMarker creates a `.installed` file at the given install path,
+// and then calls fixInstallMarkerPermissions to set the ownership provided by `ownership`
 func CreateInstallMarker(topPath string, ownership utils.FileOwner) error {
 	markerFilePath := filepath.Join(topPath, paths.MarkerFileName)
-	if _, err := os.Create(markerFilePath); err != nil {
+	handle, err := os.Create(markerFilePath)
+	if err != nil {
 		return err
 	}
+	_ = handle.Close()
 	return fixInstallMarkerPermissions(markerFilePath, ownership)
 }

internal/pkg/agent/install/install_test.go

@@ -14,8 +14,10 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/elastic/elastic-agent/internal/pkg/agent/application/paths"
 	"github.com/elastic/elastic-agent/internal/pkg/cli"
 	v1 "github.com/elastic/elastic-agent/pkg/api/v1"
+	"github.com/elastic/elastic-agent/pkg/utils"
 )
 
 func TestHasAllSSDs(t *testing.T) {
@@ -185,3 +187,10 @@ func TestCopyFiles(t *testing.T) {
 	}
 
 }
+
+func TestSetupInstallPath(t *testing.T) {
+	tmpdir := t.TempDir()
+	err := setupInstallPath(tmpdir, utils.CurrentFileOwner())
+	require.NoError(t, err)
+	require.FileExists(t, filepath.Join(tmpdir, paths.MarkerFileName))
+}