[v16] Fix Windows permission error with self remove

integration/autoupdate/tools/main_test.go

@@ -61,6 +61,7 @@ var (
 
 func TestMain(m *testing.M) {
 	modules.SetInsecureTestMode(true)
+	modules.SetModules(&modules.TestModules{TestBuildType: modules.BuildCommunity})
 	ctx := context.Background()
 	tmp, err := os.MkdirTemp(os.TempDir(), testBinaryName)
 	if err != nil {

integration/autoupdate/tools/updater/modules.go

@@ -65,12 +65,12 @@ func (p *TestModules) BuildType() string {
 	return "CLI"
 }
 
-// IsEnterpriseBuild returns false for [TestModules].
+// IsEnterpriseBuild returns true if `UPDATER_TEST_BUILD` env is set `ent` for [TestModules].
 func (p *TestModules) IsEnterpriseBuild() bool {
 	return os.Getenv(TestBuild) == modules.BuildEnterprise
 }
 
-// IsOSSBuild returns false for [TestModules].
+// IsOSSBuild returns true if `UPDATER_TEST_BUILD` env is set `oss` for [TestModules].
 func (p *TestModules) IsOSSBuild() bool {
 	return os.Getenv(TestBuild) == modules.BuildOSS
 }

integration/autoupdate/tools/updater_tsh_test.go

@@ -1,3 +1,5 @@
+//go:build !windows
+
 /*
  * Teleport
  * Copyright (C) 2024  Gravitational, Inc.

lib/utils/fs.go

@@ -422,15 +422,19 @@ func RecursiveChown(dir string, uid, gid int) error {
 	return nil
 }
 
-func CopyFile(src, dest string, perm os.FileMode) error {
+func CopyFile(src, dest string, perm os.FileMode) (err error) {
 	srcFile, err := os.Open(src)
 	if err != nil {
 		return trace.ConvertSystemError(err)
 	}
+	defer srcFile.Close()
 	destFile, err := os.OpenFile(dest, os.O_RDWR|os.O_CREATE|os.O_TRUNC, perm)
 	if err != nil {
 		return trace.ConvertSystemError(err)
 	}
+	defer func() {
+		err = trace.NewAggregate(err, trace.Wrap(destFile.Close()))
+	}()
 	_, err = destFile.ReadFrom(srcFile)
 	if err != nil {
 		return trace.ConvertSystemError(err)

lib/utils/packaging/unarchive.go

@@ -129,12 +129,10 @@ func replaceZip(toolsDir string, archivePath string, extractDir string, execName
 				return trace.Wrap(err)
 			}
 			appPath := filepath.Join(toolsDir, baseName)
-			if err := os.Remove(appPath); err != nil && !os.IsNotExist(err) {
-				return trace.Wrap(err)
-			}
-			// For the Windows build we have to copy binary to be able
-			// to do this without administrative access as it required
-			// for symlinks.
+			// For the Windows build, we need to copy the binary to perform updates without requiring
+			// administrative access, which would otherwise be needed for creating symlinks.
+			// Since symlinks are not used on the Windows platform, there's no need to remove appPath
+			// before copying the new binary — it will simply be replaced.
 			if err := utils.CopyFile(dest, appPath, 0o755); err != nil {
 				return trace.Wrap(err)
 			}