kernel_cmdline: Simplify Display impl for utf8::Parameter

Really we want to just return the original slice that the Parameter
was created from.  This also aligns with how Cmdline and ParameterKey
impl Display.

Where this really matters the most is to ensure we retain the quoting
that the parameter was created with, so I added a test just to sanity
check that.  Before this change the test would fail because "foo"
would be stripped of its quotes and just rendered as foo unquoted.

Signed-off-by: John Eckersberg <[email protected]>

Author: jeckersb

crates/kernel_cmdline/src/utf8.rs

@@ -368,16 +368,8 @@ impl<'a> TryFrom<bytes::Parameter<'a>> for Parameter<'a> {
 
 impl<'a> std::fmt::Display for Parameter<'a> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
-        match self.value() {
-            Some(v) => {
-                if v.contains(|ch: char| ch.is_ascii_whitespace()) {
-                    write!(f, "{}=\"{}\"", self.key(), v)
-                } else {
-                    write!(f, "{}={}", self.key(), v)
-                }
-            }
-            None => write!(f, "{}", self.key()),
-        }
+        let as_str: &str = self.as_ref();
+        write!(f, "{as_str}")
     }
 }
 
@@ -449,6 +441,18 @@ mod tests {
         assert_eq!(outside_quoted, value_quoted);
     }
 
+    #[test]
+    fn test_parameter_display() {
+        // Basically this should always return the original data
+        // without modification.
+
+        // unquoted stays unquoted
+        assert_eq!(param("foo").to_string(), "foo");
+
+        // quoted stays quoted
+        assert_eq!(param("\"foo\"").to_string(), "\"foo\"");
+    }
+
     #[test]
     fn test_parameter_extra_whitespace() {
         let p = param("  foo=bar  ");