java-topology/defects/dosbox-x/test/DosboxXOverlayCacheTest.java

import java.util.*;

/**
 * Unit tests for DOSBox-X CWE-407 defects in overlay drive caching.
 *
 * dosbox-x-0001: add_DOSname_to_cache linear vector dedup O(N^2)
 * dosbox-x-0002: is_deleted_file linear vector scan O(N) per call
 *
 * Models the C++ std::vector<std::string> with strcasecmp dedup pattern
 * and demonstrates the fix using HashSet with case-insensitive semantics.
 */
public class DosboxXOverlayCacheTest {

    // ---------------------------------------------------------------
    // dosbox-x-0001: DOSnames_cache vector dedup
    // ---------------------------------------------------------------

    /** DEFECTIVE: O(N) linear scan per insertion → O(N^2) total */
    static List<String> addDOSname_defective(List<String> cache, String name) {
        for (String entry : cache) {
            if (entry.equalsIgnoreCase(name)) return cache;
        }
        cache.add(name);
        return cache;
    }

    /** FIXED: O(1) amortized insertion with case-insensitive HashSet */
    static Set<String> addDOSname_fixed(Set<String> cache, String name) {
        cache.add(name.toUpperCase());
        return cache;
    }

    // ---------------------------------------------------------------
    // dosbox-x-0002: is_deleted_file linear vector scan
    // ---------------------------------------------------------------

    /** DEFECTIVE: O(N) linear scan through deleted_files_in_base */
    static boolean isDeletedFile_defective(List<String> deletedFiles, String name) {
        for (String f : deletedFiles) {
            if (f.equalsIgnoreCase(name)) return true;
        }
        return false;
    }

    /** FIXED: O(1) hash lookup */
    static boolean isDeletedFile_fixed(Set<String> deletedFiles, String name) {
        return deletedFiles.contains(name.toUpperCase());
    }

    public static void main(String[] args) {
        int N = 5000;
        int passed = 0;
        int failed = 0;

        // --- Test 1: dosbox-x-0001 correctness ---
        {
            List<String> defectCache = new ArrayList<>();
            Set<String> fixedCache = new HashSet<>();
            for (int i = 0; i < 100; i++) {
                String name = "FILE" + i + ".TXT";
                addDOSname_defective(defectCache, name);
                addDOSname_defective(defectCache, name.toLowerCase()); // case-insensitive dedup
                addDOSname_fixed(fixedCache, name);
                addDOSname_fixed(fixedCache, name.toLowerCase());
            }
            boolean ok = defectCache.size() == 100 && fixedCache.size() == 100;
            System.out.println((ok ? "PASS" : "FAIL") + " dosbox-x-0001 correctness: dedup 100 names (case-insensitive)");
            if (ok) passed++; else failed++;
        }

        // --- Test 2: dosbox-x-0001 performance ---
        {
            List<String> defectCache = new ArrayList<>();
            Set<String> fixedCache = new HashSet<>();

            long t0 = System.nanoTime();
            for (int i = 0; i < N; i++) {
                addDOSname_defective(defectCache, "NAME" + i + ".DOS");
            }
            long defectNs = System.nanoTime() - t0;

            t0 = System.nanoTime();
            for (int i = 0; i < N; i++) {
                addDOSname_fixed(fixedCache, "NAME" + i + ".DOS");
            }
            long fixedNs = System.nanoTime() - t0;

            double ratio = (double) defectNs / Math.max(fixedNs, 1);
            boolean ok = ratio > 5.0;
            System.out.printf("%s dosbox-x-0001 performance: N=%d defect=%.1fms fixed=%.1fms ratio=%.1fx%n",
                    ok ? "PASS" : "FAIL", N,
                    defectNs / 1e6, fixedNs / 1e6, ratio);
            if (ok) passed++; else failed++;
        }

        // --- Test 3: dosbox-x-0002 correctness ---
        {
            List<String> defectList = new ArrayList<>();
            Set<String> fixedSet = new HashSet<>();
            for (int i = 0; i < 100; i++) {
                String name = "DELETED" + i + ".TMP";
                defectList.add(name);
                fixedSet.add(name.toUpperCase());
            }
            boolean allMatch = true;
            for (int i = 0; i < 100; i++) {
                String query = "deleted" + i + ".tmp"; // lowercase query
                boolean d = isDeletedFile_defective(defectList, query);
                boolean f = isDeletedFile_fixed(fixedSet, query);
                if (d != f) { allMatch = false; break; }
            }
            // Also check non-existent
            boolean dNeg = isDeletedFile_defective(defectList, "NOTHERE.TXT");
            boolean fNeg = isDeletedFile_fixed(fixedSet, "NOTHERE.TXT");
            boolean ok = allMatch && !dNeg && !fNeg;
            System.out.println((ok ? "PASS" : "FAIL") + " dosbox-x-0002 correctness: deleted file lookup");
            if (ok) passed++; else failed++;
        }

        // --- Test 4: dosbox-x-0002 performance ---
        {
            List<String> defectList = new ArrayList<>();
            Set<String> fixedSet = new HashSet<>();
            for (int i = 0; i < N; i++) {
                String name = "BASE\\OVERLAY\\FILE" + i + ".DAT";
                defectList.add(name);
                fixedSet.add(name.toUpperCase());
            }

            long t0 = System.nanoTime();
            for (int i = 0; i < N; i++) {
                isDeletedFile_defective(defectList, "BASE\\OVERLAY\\FILE" + (N - 1 - i) + ".DAT");
            }
            long defectNs = System.nanoTime() - t0;

            t0 = System.nanoTime();
            for (int i = 0; i < N; i++) {
                isDeletedFile_fixed(fixedSet, "BASE\\OVERLAY\\FILE" + (N - 1 - i) + ".DAT");
            }
            long fixedNs = System.nanoTime() - t0;

            double ratio = (double) defectNs / Math.max(fixedNs, 1);
            boolean ok = ratio > 5.0;
            System.out.printf("%s dosbox-x-0002 performance: N=%d defect=%.1fms fixed=%.1fms ratio=%.1fx%n",
                    ok ? "PASS" : "FAIL", N,
                    defectNs / 1e6, fixedNs / 1e6, ratio);
            if (ok) passed++; else failed++;
        }

        System.out.printf("%n%d/%d tests passed%n", passed, passed + failed);
        if (failed > 0) System.exit(1);
    }
}