Select should not return ETIME

kernel/aster-nix/src/syscall/select.rs

@@ -52,13 +52,26 @@ pub fn sys_select(
         nfds, readfds, writefds, exceptfds, timeout
     );
 
-    let num_revents = do_select(
+    let num_revents = match do_select(
         nfds,
         readfds.as_mut(),
         writefds.as_mut(),
         exceptfds.as_mut(),
         timeout,
-    )?;
+    ) {
+        Ok(num_revents) => num_revents,
+        Err(e) if e.error() == Errno::ETIME => {
+            // The return value is zero if the timeout expires
+            // before any file descriptors became ready
+            return Ok(SyscallReturn::Return(0));
+        }
+        Err(e) => return Err(e),
+    };
+
+    // FIXME: The Linux select() and pselect6() system call
+    // modifies its timeout argument to reflect the amount of time not slept.
+    // However, the glibc wrapper function hides this behavior.
+    // Maybe we should follow the Linux behavior.
 
     let set_fdset = |fdset_addr: Vaddr, fdset: Option<FdSet>| -> Result<()> {
         if let Some(fdset) = fdset {