syscall/class1: Implement opendir() and readdir()

Implement the OPENDIR and READDIR syscall interface in user space.

Co-developed-by: Vijay Dhanraj <[email protected]>
Signed-off-by: Peter Fang <[email protected]>

syscall/src/class1.rs

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2024 Intel Corporation.
+//
+// Author: Peter Fang <[email protected]>
+
+use super::call::{syscall1, syscall3, SysCallError};
+use super::def::{SYS_OPENDIR, SYS_READDIR};
+use super::{DirEnt, Obj, ObjHandle};
+use core::ffi::CStr;
+
+#[derive(Debug)]
+pub struct FsObjHandle(ObjHandle);
+
+impl Obj for FsObjHandle {
+    fn id(&self) -> u32 {
+        u32::from(&self.0)
+    }
+}
+
+pub fn opendir(path: &CStr) -> Result<FsObjHandle, SysCallError> {
+    unsafe {
+        syscall1(SYS_OPENDIR, path.as_ptr() as u64)
+            .map(|ret| FsObjHandle(ObjHandle::new(ret as u32)))
+    }
+}
+
+pub fn readdir(fs: &FsObjHandle, dirents: &mut [DirEnt]) -> Result<usize, SysCallError> {
+    unsafe {
+        syscall3(
+            SYS_READDIR,
+            fs.id().into(),
+            dirents.as_mut_ptr() as u64,
+            dirents.len() as u64,
+        )
+        .map(|ret| ret.try_into().unwrap())
+    }
+}

syscall/src/lib.rs

@@ -7,10 +7,12 @@
 
 mod call;
 mod class0;
+mod class1;
 mod def;
 mod obj;
 
 pub use call::SysCallError;
 pub use class0::*;
+pub use class1::*;
 pub use def::*;
 pub use obj::*;

syscall/src/obj.rs

@@ -18,7 +18,6 @@ use super::SYS_CLOSE;
 pub struct ObjHandle(u32);
 
 impl ObjHandle {
-    #[expect(dead_code)]
     pub(crate) fn new(id: u32) -> Self {
         Self(id)
     }