Teach updateFile to delete files

We might want to ensure a possibly pre-existing file does not exist in some
cases. updateFile could have been called with nil content, but that would only
ensure the file was empty not that it was deleted which may not always be good
enough.

Signed-off-by: Manuel Mendez <[email protected]>

Author: mmlb

lint-install.go

@@ -149,12 +149,13 @@ func updateMakefile(root string, cfg Config, dryRun bool) (string, error) {
 }
 
 // updateFile updates a configuration file within a project.
+// If the content is nil the file is removed.
 func updateFile(root string, basename string, content []byte, dryRun bool) (string, error) {
 	dest := filepath.Join(root, basename)
 	var existing []byte
-	var err error
 
-	if _, err = os.Stat(dest); err == nil {
+	f, err := os.Stat(dest)
+	if err == nil {
 		klog.Infof("Found existing %s", dest)
 		existing, err = os.ReadFile(dest)
 		if err != nil {
@@ -167,7 +168,18 @@ func updateFile(root string, basename string, content []byte, dryRun bool) (stri
 	change := gotextdiff.ToUnified(basename, basename, string(existing), edits)
 
 	if !dryRun {
-		if err := os.WriteFile(dest, content, 0o600); err != nil {
+		var err error
+		if content == nil {
+			// must be broken up, can't be conten == nil && f != nil because then
+			// the else branch will be taken if the file does *not* exist and
+			// an empty file will be written
+			if f != nil {
+				err = os.Remove(dest)
+			}
+		} else {
+			err = os.WriteFile(dest, content, 0o600)
+		}
+		if err != nil {
 			return "", err
 		}
 	}