kernel_cmdline: Add some more ergonomic/convenience methods

Implement Deref / AsRef / Clone in a few places where it makes sense.

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

Author: jeckersb

crates/kernel_cmdline/src/bytes.rs

@@ -4,6 +4,7 @@
 //! arguments, supporting both key-only switches and key-value pairs with proper quote handling.
 
 use std::borrow::Cow;
+use std::ops::Deref;
 
 use crate::{utf8, Action};
 
@@ -279,14 +280,24 @@ impl<'a, 'other> Extend<Parameter<'other>> for Cmdline<'a> {
 #[derive(Clone, Debug, Eq)]
 pub struct ParameterKey<'a>(pub(crate) &'a [u8]);
 
-impl<'a> std::ops::Deref for ParameterKey<'a> {
+impl<'a> Deref for ParameterKey<'a> {
     type Target = [u8];
 
     fn deref(&self) -> &'a Self::Target {
         self.0
     }
 }
 
+impl<'a, T> AsRef<T> for ParameterKey<'a>
+where
+    T: ?Sized,
+    <ParameterKey<'a> as Deref>::Target: AsRef<T>,
+{
+    fn as_ref(&self) -> &T {
+        self.deref().as_ref()
+    }
+}
+
 impl<'a, T: AsRef<[u8]> + ?Sized> From<&'a T> for ParameterKey<'a> {
     fn from(s: &'a T) -> Self {
         Self(s.as_ref())
@@ -318,7 +329,7 @@ impl PartialEq for ParameterKey<'_> {
 }
 
 /// A single kernel command line parameter.
-#[derive(Debug, Eq)]
+#[derive(Clone, Debug, Eq)]
 pub struct Parameter<'a> {
     /// The full original value
     parameter: &'a [u8],
@@ -424,6 +435,14 @@ impl<'a> PartialEq for Parameter<'a> {
     }
 }
 
+impl<'a> std::ops::Deref for Parameter<'a> {
+    type Target = [u8];
+
+    fn deref(&self) -> &'a Self::Target {
+        self.parameter
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -713,10 +732,7 @@ mod tests {
         let mut kargs = Cmdline::from(b"console=tty0 console=ttyS1");
 
         // add new parameter with duplicate key but different value
-        assert!(matches!(
-            kargs.add(&param("console=ttyS2")),
-            Action::Added
-        ));
+        assert!(matches!(kargs.add(&param("console=ttyS2")), Action::Added));
         let mut iter = kargs.iter();
         assert_eq!(iter.next(), Some(param("console=tty0")));
         assert_eq!(iter.next(), Some(param("console=ttyS1")));

crates/kernel_cmdline/src/utf8.rs

@@ -215,6 +215,16 @@ impl<'a> std::ops::Deref for ParameterKey<'a> {
     }
 }
 
+impl<'a, T> AsRef<T> for ParameterKey<'a>
+where
+    T: ?Sized,
+    <ParameterKey<'a> as Deref>::Target: AsRef<T>,
+{
+    fn as_ref(&self) -> &T {
+        self.deref().as_ref()
+    }
+}
+
 impl<'a> ParameterKey<'a> {
     /// Construct a utf8::ParameterKey from a bytes::ParameterKey
     ///
@@ -249,7 +259,7 @@ impl PartialEq for ParameterKey<'_> {
 }
 
 /// A single kernel command line parameter.
-#[derive(Debug, Eq)]
+#[derive(Clone, Debug, Eq)]
 pub struct Parameter<'a>(bytes::Parameter<'a>);
 
 impl<'a> Parameter<'a> {
@@ -312,6 +322,13 @@ impl<'a> Parameter<'a> {
             str::from_utf8(p).expect("We only construct the underlying bytes from valid UTF-8")
         })
     }
+
+    /// Returns the parameter as a &str
+    pub fn as_str(&'a self) -> &'a str {
+        // SAFETY: We know this is valid UTF-8 since we only
+        // construct the underlying `bytes` from valid UTF-8
+        str::from_utf8(&self.0).expect("We only construct the underlying bytes from valid UTF-8")
+    }
 }
 
 impl<'a> TryFrom<bytes::Parameter<'a>> for Parameter<'a> {
@@ -347,6 +364,16 @@ impl<'a> std::fmt::Display for Parameter<'a> {
     }
 }
 
+impl<'a> std::ops::Deref for Parameter<'a> {
+    type Target = str;
+
+    fn deref(&self) -> &Self::Target {
+        // SAFETY: We know this is valid UTF-8 since we only
+        // construct the underlying `bytes` from valid UTF-8
+        str::from_utf8(&self.0).expect("We only construct the underlying bytes from valid UTF-8")
+    }
+}
+
 impl<'a> PartialEq for Parameter<'a> {
     fn eq(&self, other: &Self) -> bool {
         self.0 == other.0
@@ -657,10 +684,7 @@ mod tests {
         let mut kargs = Cmdline::from("console=tty0 console=ttyS1");
 
         // add new parameter with duplicate key but different value
-        assert!(matches!(
-            kargs.add(&param("console=ttyS2")),
-            Action::Added
-        ));
+        assert!(matches!(kargs.add(&param("console=ttyS2")), Action::Added));
         let mut iter = kargs.iter();
         assert_eq!(iter.next(), Some(param("console=tty0")));
         assert_eq!(iter.next(), Some(param("console=ttyS1")));