DevicePathToText and DevicePathFromText Protocol

src/proto/device_path.rs → src/proto/device_path/mod.rs

@@ -16,6 +16,8 @@
 //! the rest of the structure, and the `length` field indicates the
 //! total size of the Node including the header.
 
+pub mod text;
+
 use crate::{proto::Protocol, unsafe_guid};
 use core::slice;
 
@@ -36,7 +38,7 @@ pub struct DevicePathHeader {
 /// This can be opened on a `LoadedImage.device()` handle using the `HandleProtocol` boot service.
 #[repr(C, packed)]
 #[unsafe_guid("09576e91-6d3f-11d2-8e39-00a0c969723b")]
-#[derive(Eq, Protocol)]
+#[derive(Debug, Eq, Protocol)]
 pub struct DevicePath {
     header: DevicePathHeader,
 }

src/proto/device_path/text.rs

@@ -0,0 +1,165 @@
+//! `DevicePathToText` and `DevicePathFromText` Protocol
+
+use crate::{
+    proto::{device_path::DevicePath, Protocol},
+    table::boot::BootServices,
+    unsafe_guid, CStr16, Char16,
+};
+use core::ops::Deref;
+
+/// This struct is a wrapper of `display_only` parameter
+/// used by Device Path to Text protocol.
+///
+/// The `display_only` parameter controls whether the longer
+/// (parseable)  or shorter (display-only) form of the conversion
+/// is used. If `display_only` is TRUE, then the shorter text
+/// representation of the display node is used, where applicable.
+/// If `display_only` is FALSE, then the longer text representation
+/// of the display node is used.
+#[derive(Clone, Copy)]
+pub struct DisplayOnly(pub bool);
+
+/// This struct is a wrapper of `allow_shortcuts` parameter
+/// used by Device Path to Text protocol.
+///
+/// The `allow_shortcuts` is FALSE, then the shortcut forms of
+/// text representation for a device node cannot be used. A
+/// shortcut form is one which uses information other than the
+/// type or subtype. If `allow_shortcuts is TRUE, then the
+/// shortcut forms of text representation for a device node
+/// can be used, where applicable.
+#[derive(Clone, Copy)]
+pub struct AllowShortcuts(pub bool);
+
+/// Wrapper for a string internally allocated from
+/// UEFI boot services memory.
+pub struct PoolString<'a> {
+    boot_services: &'a BootServices,
+    text: *const Char16,
+}
+
+impl<'a> PoolString<'a> {
+    fn new(boot_services: &'a BootServices, text: *const Char16) -> Option<Self> {
+        if text.is_null() {
+            None
+        } else {
+            Some(Self {
+                boot_services,
+                text,
+            })
+        }
+    }
+}
+
+impl<'a> Deref for PoolString<'a> {
+    type Target = CStr16;
+
+    fn deref(&self) -> &Self::Target {
+        unsafe { CStr16::from_ptr(self.text) }
+    }
+}
+
+impl Drop for PoolString<'_> {
+    fn drop(&mut self) {
+        let addr = self.text as *mut u8;
+        self.boot_services
+            .free_pool(addr)
+            .expect("Failed to free pool [{addr:#?}]");
+    }
+}
+
+/// Device Path to Text protocol.
+///
+/// This protocol provides common utility functions for converting device
+/// nodes and device paths to a text representation.
+#[repr(C)]
+#[unsafe_guid("8b843e20-8132-4852-90cc-551a4e4a7f1c")]
+#[derive(Protocol)]
+pub struct DevicePathToText {
+    convert_device_node_to_text: unsafe extern "efiapi" fn(
+        device_node: *const DevicePath,
+        display_only: bool,
+        allow_shortcuts: bool,
+    ) -> *const Char16,
+    convert_device_path_to_text: unsafe extern "efiapi" fn(
+        device_path: *const DevicePath,
+        display_only: bool,
+        allow_shortcuts: bool,
+    ) -> *const Char16,
+}
+
+impl DevicePathToText {
+    /// Convert a device node to its text representation.
+    ///
+    /// Returns `None` if `device_node` was NULL or there was
+    /// insufficient memory.
+    pub fn convert_device_node_to_text<'boot>(
+        &self,
+        boot_services: &'boot BootServices,
+        device_node: &DevicePath,
+        display_only: DisplayOnly,
+        allow_shortcuts: AllowShortcuts,
+    ) -> Option<PoolString<'boot>> {
+        let text_device_node = unsafe {
+            (self.convert_device_node_to_text)(device_node, display_only.0, allow_shortcuts.0)
+        };
+        PoolString::new(boot_services, text_device_node)
+    }
+
+    /// Convert a device path to its text representation.
+    ///
+    /// Returns `None` if `device_path` was NULL or there was
+    /// insufficient memory.
+    pub fn convert_device_path_to_text<'boot>(
+        &self,
+        boot_services: &'boot BootServices,
+        device_path: &DevicePath,
+        display_only: DisplayOnly,
+        allow_shortcuts: AllowShortcuts,
+    ) -> Option<PoolString<'boot>> {
+        let text_device_path = unsafe {
+            (self.convert_device_path_to_text)(device_path, display_only.0, allow_shortcuts.0)
+        };
+        PoolString::new(boot_services, text_device_path)
+    }
+}
+
+/// Device Path from Text protocol.
+///
+/// This protocol provides common utilities for converting text to
+/// device paths and device nodes.
+#[repr(C)]
+#[unsafe_guid("05c99a21-c70f-4ad2-8a5f-35df3343f51e")]
+#[derive(Protocol)]
+pub struct DevicePathFromText {
+    convert_text_to_device_node:
+        unsafe extern "efiapi" fn(text_device_node: *const Char16) -> *const DevicePath,
+    convert_text_to_device_path:
+        unsafe extern "efiapi" fn(text_device_path: *const Char16) -> *const DevicePath,
+}
+
+impl DevicePathFromText {
+    /// Convert text to the binary representation of a device node.
+    ///
+    /// `text_device_node` is the text representation of a device node.
+    /// Conversion starts with the first character and continues until
+    /// the first non-device node character.
+    ///
+    /// Returns `None` if `text_device_node` was NULL or there was
+    /// insufficient memory.
+    pub fn convert_text_to_device_node(&self, text_device_node: &CStr16) -> Option<&DevicePath> {
+        unsafe { (self.convert_text_to_device_node)(text_device_node.as_ptr()).as_ref() }
+    }
+
+    /// Convert a text to its binary device path representation.
+    ///
+    /// `text_device_path` is the text representation of a device path.
+    /// Conversion starts with the first character and continues until
+    /// the first non-device path character.
+    ///
+    /// Returns `None` if `text_device_path` was NULL or there was
+    /// insufficient memory.
+    pub fn convert_text_to_device_path(&self, text_device_path: &CStr16) -> Option<&DevicePath> {
+        unsafe { (self.convert_text_to_device_path)(text_device_path.as_ptr()).as_ref() }
+    }
+}

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

@@ -1,5 +1,5 @@
 use uefi::prelude::*;
-use uefi::proto::device_path::DevicePath;
+use uefi::proto::device_path::{text::*, DevicePath};
 use uefi::proto::loaded_image::LoadedImage;
 use uefi::table::boot::{BootServices, OpenProtocolAttributes, OpenProtocolParams};
 
@@ -30,12 +30,33 @@ pub fn test(image: Handle, bt: &BootServices) {
         .expect("Failed to open DevicePath protocol");
     let device_path = unsafe { &*device_path.interface.get() };
 
+    let device_path_to_text = bt
+        .locate_protocol::<DevicePathToText>()
+        .expect("Failed to open DevicePathToText protocol");
+    let device_path_to_text = unsafe { &*device_path_to_text.get() };
+
+    let device_path_from_text = bt
+        .locate_protocol::<DevicePathFromText>()
+        .expect("Failed to open DevicePathFromText protocol");
+    let device_path_from_text = unsafe { &*device_path_from_text.get() };
+
     for path in device_path.iter() {
         info!(
             "path: type={:?}, subtype={:?}, length={}",
             path.device_type(),
             path.sub_type(),
             path.length(),
         );
+
+        let text = device_path_to_text
+            .convert_device_path_to_text(bt, path, DisplayOnly(true), AllowShortcuts(false))
+            .expect("Failed to convert device path to text");
+        let text = &*text;
+        info!("path name: {text}");
+
+        let convert = device_path_from_text
+            .convert_text_to_device_path(text)
+            .expect("Failed to convert text to device path");
+        assert_eq!(path, convert);
     }
 }