Function refcount_subbyte_max_values

block/src/qcow/mod.rs:2872–2893

()

    /// Test sub-byte refcount read/write roundtrip with max values.
    #[test]
    fn refcount_subbyte_max_values() {
        for (bits, max_val) in [(1u64, 1u64), (2, 3), (4, 15)] {
            let file = vmm_sys_util::tempfile::TempFile::new().unwrap().into_file();
            let cluster_size = 0x10000u64;
            file.set_len(cluster_size * 2).unwrap();
            let raw = RawFile::new(file, false);
            let mut qcow_raw = QcowRawFile::from(raw, cluster_size, bits).unwrap();

            let entries = (cluster_size * 8 / bits) as usize;
            let mut table: Vec<u64> = (0..entries as u64).map(|i| i % (max_val + 1)).collect();
            table[0] = max_val;
            table[entries - 1] = max_val;

            qcow_raw.write_refcount_block(cluster_size, &table).unwrap();
            let read_table = qcow_raw.read_refcount_block(cluster_size).unwrap();

            assert_eq!(read_table.len(), entries);
            for (i, (&written, &read)) in table.iter().zip(read_table.iter()).enumerate() {
                assert_eq!(read, written & max_val, "{bits}-bit entry {i} mismatch");
            }
        }
    }

    /// Test byte-aligned refcounts with max values.
    #[test]