feat(ext4): seek, rmdir (e2fsck-clean)

crates/servers/storage-server/src/tests/ext4_real.rs

@@ -183,3 +183,38 @@ fn holes_read_as_zeros() {
     let mut fs = Ext4::mount(FileDisk(img)).expect("mount");
     assert_eq!(read_all(&mut fs, b"sparse.bin"), data);
 }
+
+#[test]
+fn an_empty_directory_goes_and_e2fsck_agrees() {
+    let Some((dir, img)) = setup("rmdir") else { return };
+    let mut fs = Ext4::mount(FileDisk(img)).expect("mount");
+    assert!(fs.mkdir(b"/gone"));
+    assert!(fs.mkdir(b"/gone/deeper"));
+    let h = fs.create(b"/gone/deeper/f").expect("create");
+    fs.close(h);
+    assert!(!fs.rmdir(b"/gone"), "not empty");
+    assert!(fs.delete(b"/gone/deeper/f"));
+    assert!(fs.rmdir(b"/gone/deeper"));
+    assert!(fs.rmdir(b"/gone"));
+    assert!(!names(&mut fs, b"/").iter().any(|n| n == "gone"));
+    assert!(!fs.rmdir(b"/hello.txt"), "a file is not a directory");
+    let (clean, report) = fsck_clean(&dir, &fs.into_device().0);
+    assert!(clean, "e2fsck: {report}");
+}
+
+#[test]
+fn writes_land_where_seek_says() {
+    let Some((dir, img)) = setup("seek") else { return };
+    let mut fs = Ext4::mount(FileDisk(img)).expect("mount");
+    let h = fs.create(b"/f").expect("create");
+    assert_eq!(fs.write(h, &[b'a'; 5000]), Some(5000));
+    assert!(fs.seek(h, 4090));
+    assert_eq!(fs.write(h, b"XYZXYZXYZXYZ"), Some(12));
+    assert!(!fs.seek(h, 6000), "not past the end");
+    fs.close(h);
+    let back = read_all(&mut fs, b"/f");
+    assert_eq!(back.len(), 5000);
+    assert_eq!(&back[4088..4104], b"aaXYZXYZXYZXYZaa");
+    let (clean, report) = fsck_clean(&dir, &fs.into_device().0);
+    assert!(clean, "e2fsck: {report}");
+}