uefi: Return an option from LoadedImage::device

It's not guaranteed that the `device_handle` will be non-null, so return an
option.

Author: nicholasbishop

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Changed
 - `Input::wait_for_key_event` now returns an `Option<Event>`, and is no longer `const`.
+- `LoadedImage::device` now returns an `Option<Handle>`.
 
 ## uefi-macros - [Unreleased]
 

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

@@ -16,7 +16,7 @@ pub fn test(image: Handle, bt: &BootServices) {
             .expect("Failed to open LoadedImage protocol");
 
         let device_path = bt
-            .open_protocol_exclusive::<DevicePath>(loaded_image.device())
+            .open_protocol_exclusive::<DevicePath>(loaded_image.device().unwrap())
             .expect("Failed to open DevicePath protocol");
 
         let device_path_to_text = bt

uefi/src/proto/loaded_image.rs

@@ -18,7 +18,7 @@ pub struct LoadedImage {
     system_table: *const c_void,
 
     // Source location of the image
-    device_handle: Handle,
+    device_handle: Option<Handle>,
     file_path: *const FfiDevicePath,
     _reserved: *const c_void,
 
@@ -52,7 +52,7 @@ pub enum LoadOptionsError {
 impl LoadedImage {
     /// Returns a handle to the storage device on which the image is located.
     #[must_use]
-    pub const fn device(&self) -> Handle {
+    pub const fn device(&self) -> Option<Handle> {
         self.device_handle
     }
 

uefi/src/table/boot.rs

@@ -4,7 +4,7 @@ use super::Revision;
 use crate::data_types::{Align, PhysicalAddress};
 use crate::proto::device_path::DevicePath;
 use crate::proto::{Protocol, ProtocolPointer};
-use crate::{Char16, Event, Guid, Handle, Result, Status, StatusExt};
+use crate::{Char16, Error, Event, Guid, Handle, Result, Status, StatusExt};
 use core::cell::UnsafeCell;
 use core::ffi::c_void;
 use core::fmt::{Debug, Formatter};
@@ -1398,7 +1398,10 @@ impl BootServices {
     pub fn get_image_file_system(&self, image_handle: Handle) -> Result<FileSystem> {
         let loaded_image = self.open_protocol_exclusive::<LoadedImage>(image_handle)?;
 
-        let device_path = self.open_protocol_exclusive::<DevicePath>(loaded_image.device())?;
+        let device_handle = loaded_image
+            .device()
+            .ok_or(Error::new(Status::UNSUPPORTED, ()))?;
+        let device_path = self.open_protocol_exclusive::<DevicePath>(device_handle)?;
 
         let device_handle = self.locate_device_path::<SimpleFileSystem>(&mut &*device_path)?;