Fix openat for incorrect conversion

kernel/src/syscall/fs.rs

@@ -263,12 +263,16 @@ impl Syscall<'_> {
     }
 
     pub fn sys_open(&mut self, path: *const u8, flags: usize, mode: usize) -> SysResult {
+        info!(
+            "open: path: {:?}, flags: {:?}, mode: {:#o}",
+            path, flags, mode
+        );
         self.sys_openat(AT_FDCWD, path, flags, mode)
     }
 
     pub fn sys_openat(
         &mut self,
-        dir_fd: usize,
+        in_dir_fd: usize,
         path: *const u8,
         flags: usize,
         mode: usize,
@@ -276,6 +280,12 @@ impl Syscall<'_> {
         let mut proc = self.process();
         let path = check_and_clone_cstr(path)?;
         let flags = OpenFlags::from_bits_truncate(flags);
+        let dir_fd = if in_dir_fd == 4294967196 {
+            AT_FDCWD as usize
+        } else {
+            in_dir_fd
+        };
+
         info!(
             "openat: dir_fd: {}, path: {:?}, flags: {:?}, mode: {:#o}",
             dir_fd as isize, path, flags, mode