Add LoadedImageDevicePath protocol

This protocol is the same as `DevicePath`, but only available on image handles.

Author: nicholasbishop

uefi-test-runner/src/proto/device_path.rs

@@ -1,6 +1,6 @@
 use uefi::prelude::*;
 use uefi::proto::device_path::text::*;
-use uefi::proto::device_path::DevicePath;
+use uefi::proto::device_path::{DevicePath, LoadedImageDevicePath};
 use uefi::proto::loaded_image::LoadedImage;
 use uefi::table::boot::BootServices;
 
@@ -48,4 +48,16 @@ pub fn test(image: Handle, bt: &BootServices) {
             .expect("Failed to convert text to device path");
         assert_eq!(path, convert);
     }
+
+    // Get the `LoadedImageDevicePath`. Verify it start with the same nodes as
+    // `device_path`.
+    let loaded_image_device_path = bt
+        .open_protocol_exclusive::<LoadedImageDevicePath>(image)
+        .expect("Failed to open LoadedImageDevicePath protocol");
+    for (n1, n2) in device_path
+        .node_iter()
+        .zip(loaded_image_device_path.node_iter())
+    {
+        assert_eq!(n1, n2);
+    }
 }

uefi/src/proto/device_path/mod.rs

@@ -85,6 +85,7 @@ use crate::proto::{unsafe_protocol, ProtocolPointer};
 use core::ffi::c_void;
 use core::fmt::{self, Debug, Formatter};
 use core::mem;
+use core::ops::Deref;
 use ptr_meta::Pointee;
 
 opaque_type! {
@@ -610,6 +611,35 @@ pub enum NodeConversionError {
     UnsupportedType,
 }
 
+/// Protocol for accessing the device path that was passed in to [`load_image`]
+/// when loading a PE/COFF image.
+///
+/// The layout of this type is the same as a [`DevicePath`].
+///
+/// [`load_image`]: crate::table::boot::BootServices::load_image
+#[repr(transparent)]
+#[unsafe_protocol("bc62157e-3e33-4fec-9920-2d3b36d750df")]
+#[derive(Pointee)]
+pub struct LoadedImageDevicePath(DevicePath);
+
+impl ProtocolPointer for LoadedImageDevicePath {
+    unsafe fn ptr_from_ffi(ptr: *const c_void) -> *const Self {
+        ptr_meta::from_raw_parts(ptr.cast(), DevicePath::size_in_bytes_from_ptr(ptr))
+    }
+
+    unsafe fn mut_ptr_from_ffi(ptr: *mut c_void) -> *mut Self {
+        ptr_meta::from_raw_parts_mut(ptr.cast(), DevicePath::size_in_bytes_from_ptr(ptr))
+    }
+}
+
+impl Deref for LoadedImageDevicePath {
+    type Target = DevicePath;
+
+    fn deref(&self) -> &DevicePath {
+        &self.0
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

uefi/src/table/boot.rs

@@ -986,10 +986,11 @@ impl BootServices {
     /// image.
     ///
     /// If the image is successfully loaded, a [`Handle`] supporting the
-    /// [`LoadedImage`] and `LoadedImageDevicePath` protocols is
+    /// [`LoadedImage`] and [`LoadedImageDevicePath`] protocols is
     /// returned. The image can be started with [`start_image`] or
     /// unloaded with [`unload_image`].
     ///
+    /// [`LoadedImageDevicePath`]: crate::proto::device_path::LoadedImageDevicePath
     /// [`start_image`]: BootServices::start_image
     /// [`unload_image`]: BootServices::unload_image
     ///