add filetable state logging at EBADF point

src/syscall/fs.rs

@@ -79,7 +79,24 @@ pub fn openat(
         let (context, mut token) = current.token_split();
         let name = context.name;
         let pipe = context.get_file(fh, &mut token).ok_or_else(|| {
-            info!("openat: EBADF fh={:#x} ctx='{}'", fh.get(), name);
+            let ft = context.files.read(token.token());
+            let raw = fh.get();
+            let stripped = raw & !syscall::UPPER_FDTBL_TAG;
+            let is_upper = raw & syscall::UPPER_FDTBL_TAG != 0;
+            let upper_len = ft.upper_fdtbl.len();
+            let upper_at_idx = if is_upper && stripped < ft.upper_fdtbl.len() {
+                ft.upper_fdtbl[stripped].is_some()
+            } else {
+                false
+            };
+            let upper_present: String = ft.upper_fdtbl.iter().enumerate()
+                .filter(|(_, f)| f.is_some())
+                .map(|(i, _)| i.to_string())
+                .collect::<Vec<_>>().join(",");
+            info!(
+                "openat: EBADF fh={:#x} ctx='{}' is_upper={} idx={} upper_len={} upper_at_idx={} upper_present=[{}]",
+                raw, name, is_upper, stripped, upper_len, upper_at_idx, upper_present
+            );
             Error::new(EBADF)
         })?;
         let desc = pipe.description.read(token.token());