"is_regular_file" for FileHandle via File trait.

Author: phip1611

CHANGELOG.md

@@ -14,6 +14,8 @@
   Now you can compare everything that is `AsRef<str>` (such as `String` and `str`
   from the standard library) to uefi strings. Please head to the documentation of
   `EqStrUntilNul` to find out limitations and further information.
+- the `File` trait now knows the methods `is_regular_file` and `is_directory`.
+  Developers profit from this on the struct `FileHandle`, for example.
 
 ### Changed
 
@@ -39,7 +41,7 @@
 
 - The `no_panic_handler` feature has been replaced with an additive
   `panic_handler` feature. The new feature is enabled by default.
-  
+
 ## uefi - 0.16.1
 
 ### Added
@@ -55,7 +57,7 @@
   function pointers. This prevents potential invalid pointer access.
 - Fixed an incorrect pointer cast in the `Rng` protocol that could cause
   undefined behavior.
-  
+
 ### Changed
 
 - Relaxed the version requirements for the `bitflags` and `log`

src/proto/media/file/dir.rs

@@ -67,4 +67,12 @@ impl File for Directory {
     fn handle(&mut self) -> &mut FileHandle {
         self.0.handle()
     }
+
+    fn is_regular_file(&self) -> Result<bool> {
+        Ok(false)
+    }
+
+    fn is_directory(&self) -> Result<bool> {
+        Ok(true)
+    }
 }

src/proto/media/file/mod.rs

@@ -214,6 +214,18 @@ pub trait File: Sized {
         // global allocator.
         unsafe { Ok(Box::from_raw(info)) }
     }
+
+    /// Returns if the underlying file is a regular file.
+    /// The result is an error if the underlying file was already closed or deleted.
+    ///
+    /// UEFI file system protocol only knows "regular files" and "directories".
+    fn is_regular_file(&self) -> Result<bool>;
+
+    /// Returns if the underlying file is a directory.
+    /// The result is an error if the underlying file was already closed or deleted.
+    ///
+    /// UEFI file system protocol only knows "regular files" and "directories".
+    fn is_directory(&self) -> Result<bool>;
 }
 
 // Internal File helper methods to access the funciton pointer table.
@@ -241,16 +253,14 @@ impl FileHandle {
     }
 
     /// Converts `File` into a more specific subtype based on if it is a
-    /// directory or not. It does this via a call to `get_position`.
-    pub fn into_type(mut self) -> Result<FileType> {
+    /// directory or not. Wrapper around [Self::is_regular_file].
+    pub fn into_type(self) -> Result<FileType> {
         use FileType::*;
 
-        // get_position fails with EFI_UNSUPPORTED on directories
-        let mut pos = 0;
-        match (self.imp().get_position)(self.imp(), &mut pos) {
-            Status::SUCCESS => unsafe { Ok(Regular(RegularFile::new(self))) },
-            Status::UNSUPPORTED => unsafe { Ok(Dir(Directory::new(self))) },
-            s => Err(s.into()),
+        if self.is_regular_file()? {
+            unsafe { Ok(Regular(RegularFile::new(self))) }
+        } else {
+            unsafe { Ok(Dir(Directory::new(self))) }
         }
     }
 
@@ -280,6 +290,22 @@ impl File for FileHandle {
     fn handle(&mut self) -> &mut FileHandle {
         self
     }
+
+    fn is_regular_file(&self) -> Result<bool> {
+        let this = unsafe { self.0.as_mut().unwrap() };
+
+        // get_position fails with EFI_UNSUPPORTED on directories
+        let mut pos = 0;
+        match (this.get_position)(this, &mut pos) {
+            Status::SUCCESS => Ok(true),
+            Status::UNSUPPORTED => Ok(false),
+            s => Err(s.into()),
+        }
+    }
+
+    fn is_directory(&self) -> Result<bool> {
+        self.is_regular_file().map(|b| !b)
+    }
 }
 
 impl Drop for FileHandle {

src/proto/media/file/regular.rs

@@ -104,4 +104,12 @@ impl File for RegularFile {
     fn handle(&mut self) -> &mut FileHandle {
         &mut self.0
     }
+
+    fn is_regular_file(&self) -> Result<bool> {
+        Ok(true)
+    }
+
+    fn is_directory(&self) -> Result<bool> {
+        Ok(false)
+    }
 }