uefi: helpers: Introduce OwnedDevicePath

This PR is split off from #135368 to reduce noise.

Rename DevicePath to OwnedDevicePath. This is to allow a non-owning
version of DevicePath in the future to work with UEFI shell APIs which
provide const pointers to device paths for UEFI shell fs mapping.

Also implement Debug for OwnedDevicePath for some quality of life
improvements.

Signed-off-by: Ayush Singh <ayush@beagleboard.org>

2 files changed, 16 insertions, 7 deletions

diff --git a/library/std/src/sys/pal/uefi/helpers.rs b/library/std/src/sys/pal/uefi/helpers.rs
index 47d9add72b5..7504a0f7ad7 100644
--- a/library/std/src/sys/pal/uefi/helpers.rs
+++ b/library/std/src/sys/pal/uefi/helpers.rs
@@ -222,14 +222,14 @@ pub(crate) fn runtime_services() -> Option<NonNull<r_efi::efi::RuntimeServices>>
     NonNull::new(runtime_services)
 }
 
-pub(crate) struct DevicePath(NonNull<r_efi::protocols::device_path::Protocol>);
+pub(crate) struct OwnedDevicePath(NonNull<r_efi::protocols::device_path::Protocol>);
 
-impl DevicePath {
+impl OwnedDevicePath {
     pub(crate) fn from_text(p: &OsStr) -> io::Result<Self> {
         fn inner(
             p: &OsStr,
             protocol: NonNull<r_efi::protocols::device_path_from_text::Protocol>,
-        ) -> io::Result<DevicePath> {
+        ) -> io::Result<OwnedDevicePath> {
             let path_vec = p.encode_wide().chain(Some(0)).collect::<Vec<u16>>();
             if path_vec[..path_vec.len() - 1].contains(&0) {
                 return Err(const_error!(
@@ -242,7 +242,7 @@ impl DevicePath {
                 unsafe { ((*protocol.as_ptr()).convert_text_to_device_path)(path_vec.as_ptr()) };
 
             NonNull::new(path)
-                .map(DevicePath)
+                .map(OwnedDevicePath)
                 .ok_or_else(|| const_error!(io::ErrorKind::InvalidFilename, "Invalid Device Path"))
         }
 
@@ -275,12 +275,12 @@ impl DevicePath {
         ))
     }
 
-    pub(crate) fn as_ptr(&self) -> *mut r_efi::protocols::device_path::Protocol {
+    pub(crate) const fn as_ptr(&self) -> *mut r_efi::protocols::device_path::Protocol {
         self.0.as_ptr()
     }
 }
 
-impl Drop for DevicePath {
+impl Drop for OwnedDevicePath {
     fn drop(&mut self) {
         if let Some(bt) = boot_services() {
             let bt: NonNull<r_efi::efi::BootServices> = bt.cast();
@@ -291,6 +291,15 @@ impl Drop for DevicePath {
     }
 }
 
+impl crate::fmt::Debug for OwnedDevicePath {
+    fn fmt(&self, f: &mut crate::fmt::Formatter<'_>) -> crate::fmt::Result {
+        match device_path_to_text(self.0) {
+            Ok(p) => p.fmt(f),
+            Err(_) => f.debug_struct("OwnedDevicePath").finish_non_exhaustive(),
+        }
+    }
+}
+
 pub(crate) struct OwnedProtocol<T> {
     guid: r_efi::efi::Guid,
     handle: NonNull<crate::ffi::c_void>,
diff --git a/library/std/src/sys/pal/uefi/process.rs b/library/std/src/sys/pal/uefi/process.rs
index 95707ebb7f0..1a0754134df 100644
--- a/library/std/src/sys/pal/uefi/process.rs
+++ b/library/std/src/sys/pal/uefi/process.rs
@@ -326,7 +326,7 @@ mod uefi_command_internal {
 
     impl Image {
         pub fn load_image(p: &OsStr) -> io::Result<Self> {
-            let path = helpers::DevicePath::from_text(p)?;
+            let path = helpers::OwnedDevicePath::from_text(p)?;
             let boot_services: NonNull<r_efi::efi::BootServices> = boot_services()
                 .ok_or_else(|| const_error!(io::ErrorKind::NotFound, "Boot Services not found"))?
                 .cast();