uefi: remove duplication in DevicePathHeader; use uefi-raw type

Author: phip1611

Diff for: uefi-raw/CHANGELOG.md

@@ -14,6 +14,11 @@
 - Added `DevicePathUtilitiesProtocol`.
 - Added `UsbIoProtocol`.
 - Added `Usb2HostControllerProtocol`.
+- Added  `DevicePathProtocol::length()` properly constructing the `u16` value
+
+## Changed
+- `DevicePathProtocol` now derives
+  `Clone, Copy, Debug, Eq, PartialEq, Ord, PartialOrd, Hash`
 
 
 # uefi-raw - 0.10.0 (2025-02-07)

Diff for: uefi-raw/src/protocol/device_path.rs

@@ -8,22 +8,29 @@ pub use device_path_gen::{acpi, bios_boot_spec, end, hardware, media, messaging}
 
 /// Device path protocol.
 ///
-/// A device path contains one or more device path instances made of up
+/// A device path contains one or more device path instances made up of
 /// variable-length nodes.
 ///
 /// Note that the fields in this struct define the header at the start of each
 /// node; a device path is typically larger than these four bytes.
-#[derive(Debug)]
+#[derive(Clone, Copy, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
 #[repr(C)]
 pub struct DevicePathProtocol {
     pub major_type: DeviceType,
     pub sub_type: DeviceSubType,
+    /// Total length of the type including the fixed header as u16 in LE order.
     pub length: [u8; 2],
     // followed by payload (dynamically sized)
 }
 
 impl DevicePathProtocol {
     pub const GUID: Guid = guid!("09576e91-6d3f-11d2-8e39-00a0c969723b");
+
+    /// Returns the total length of the device path node.
+    #[must_use]
+    pub const fn length(&self) -> u16 {
+        u16::from_le_bytes(self.length)
+    }
 }
 
 newtype_enum! {
@@ -252,3 +259,17 @@ pub struct DevicePathUtilitiesProtocol {
 impl DevicePathUtilitiesProtocol {
     pub const GUID: Guid = guid!("0379be4e-d706-437d-b037-edb82fb772a4");
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use core::mem;
+
+    /// Test that ensures the struct is packed. Thus, we don't need to
+    /// explicitly specify `packed`.
+    #[test]
+    fn abi() {
+        assert_eq!(mem::size_of::<DevicePathProtocol>(), 4);
+        assert_eq!(mem::align_of::<DevicePathProtocol>(), 1);
+    }
+}

Diff for: uefi/CHANGELOG.md

@@ -27,6 +27,8 @@
   `proto::device_path::text` to `proto::device_path`.
 - **Breaking:** `exit_boot_services` now consumes a `Option<MemoryType>` which
   defaults to the recommended value of `MemoryType::LOADER_DATA`.
+- **Breaking:** Removed duplication in `DevicePathHeader`. Instead of public fields,
+  there is now a public constructor combined with public getters.
 - `boot::memory_map()` will never return `Status::BUFFER_TOO_SMALL` from now on,
   as this is considered a hard internal error where users can't do anything
   about it anyway. It will panic instead.

Diff for: uefi/src/proto/device_path/build.rs

@@ -225,7 +225,7 @@ pub unsafe trait BuildNode {
 
 unsafe impl BuildNode for &DevicePathNode {
     fn size_in_bytes(&self) -> Result<u16, BuildError> {
-        Ok(self.header.length)
+        Ok(self.header.length())
     }
 
     fn write_data(&self, out: &mut [MaybeUninit<u8>]) {