add lseek

Signed-off-by: Julien CLEMENT <julien.clement@epita.fr>

src/fd/mod.rs

@@ -58,4 +58,5 @@ pub trait FileDescriptor {
     async fn write(&mut self, buf: &[u8], count: usize) -> isize;
     async fn read(&mut self, buf: &mut [u8], count: usize) -> isize;
     async fn close(&mut self);
+    async fn lseek(&mut self, offset: i32, whence: u32) -> i32;
 }

src/fs/iso/fd.rs

@@ -64,4 +64,15 @@ impl FileDescriptor for IsoFD {
     async fn close(&mut self) {
         FD_TABLE.lock().await.unregister_fd(self);
     }
+
+    async fn lseek(&mut self, offset: i32, whence: u32) -> i32 {
+        use crate::syscalls::io::*;
+        match whence {
+            w if w == SEEK_SET => self.offset = offset as u32,
+            w if w == SEEK_CUR => self.offset = (self.offset as i32 + offset) as u32,
+            w if w == SEEK_END => self.offset = (self.size as i32 + offset) as u32,
+            _ => {}
+        };
+        self.offset as i32
+    }
 }

src/lib.rs

@@ -77,5 +77,10 @@ async fn get_file() {
     serial_println!("{:?}", read);
     serial_println!("{}", alloc::str::from_utf8(&buf).unwrap());
 
+    fd.borrow_mut().lseek(10, syscalls::io::SEEK_SET).await;
+
+    fd.borrow_mut().read(&mut buf, 100).await;
+    serial_println!("{}", alloc::str::from_utf8(&buf).unwrap());
+
     fd.borrow_mut().close().await;
 }

src/syscalls/io.rs

@@ -2,9 +2,6 @@
 pub const O_RDONLY: u32 = 0;
 
 // seek flags
-#[allow(dead_code)]
 pub const SEEK_SET: u32 = 0;
-#[allow(dead_code)]
 pub const SEEK_CUR: u32 = 1;
-#[allow(dead_code)]
 pub const SEEK_END: u32 = 2;