rm: don't treat symlinks as write-protected

Detect symlinks in prompt_file() using fs::symlink_metadata() and handle them differently:
- InteractiveMode::Always should still prompt with "remove symbolic link ...?".
- For all other interactive modes, do not follow the symlink target or use the target's permissions to decide a write-protected prompt.

Adds a unit test test_symlink_not_write_protected_prompt to verify that a symlink to a read-only file is not treated as a write-protected regular file.

Author: GomesGoncalo

src/uu/rm/src/rm.rs

@@ -800,11 +800,10 @@ fn prompt_file(path: &Path, options: &Options) -> bool {
         return true;
     }
     // If interactive is Always we want to check if the file is symlink to prompt the right message
-    if options.interactive == InteractiveMode::Always {
-        if let Ok(metadata) = fs::symlink_metadata(path) {
-            if metadata.is_symlink() {
-                return prompt_yes!("remove symbolic link {}?", path.quote());
-            }
+    if let Ok(symlink_md) = fs::symlink_metadata(path) {
+        if symlink_md.file_type().is_symlink() {
+            return options.interactive != InteractiveMode::Always
+                || prompt_yes!("remove symbolic link {}?", path.quote());
         }
     }
 
@@ -819,6 +818,7 @@ fn prompt_file(path: &Path, options: &Options) -> bool {
             prompt_yes!("remove file {}?", path.quote())
         };
     }
+
     prompt_file_permission_readonly(path, options)
 }
 
@@ -975,4 +975,34 @@ mod tests {
 
         assert_eq!(Path::new("/"), clean_trailing_slashes(path));
     }
+
+    #[test]
+    #[cfg(unix)]
+    fn test_symlink_not_write_protected_prompt() {
+        use std::fs::{self, File};
+        use std::os::unix::fs::{PermissionsExt, symlink};
+        use tempfile::tempdir;
+
+        use crate::InteractiveMode;
+        use crate::Options;
+        use crate::prompt_file;
+
+        let dir = tempdir().expect("temp dir");
+        let foo = dir.path().join("foo");
+        File::create(&foo).expect("create foo");
+
+        let mut perms = fs::metadata(&foo).expect("meta").permissions();
+        perms.set_mode(0o444);
+        fs::set_permissions(&foo, perms).expect("set perms");
+
+        let bar = dir.path().join("bar");
+        symlink(&foo, &bar).expect("symlink");
+
+        let options = Options {
+            __presume_input_tty: None,
+            interactive: InteractiveMode::PromptProtected,
+            ..Options::default()
+        };
+        assert!(prompt_file(&bar, &options));
+    }
 }