java-topology/defects/gimp/unit/GimpTest.java

import java.util.*;

/**
 * CWE-407 simulation tests for GIMP defects.
 *
 * gimp-0001: layer stack dedup — O(S² × L²) via nested g_list_find
 * gimp-0002: remove_from_layer_stack — O(C × S × L) nested g_list_remove
 */
public class GimpTest {

    // ---------------------------------------------------------------
    // gimp-0001: layer stack dedup O(S² × L²)
    // ---------------------------------------------------------------

    /** Simulate GList-based layer stack comparison (defective) */
    static long layerStackCmpDefective(List<Object> layers1, List<Object> layers2) {
        long ops = 0;
        // g_list_length — O(L) each
        ops += layers1.size(); // simulated traversal
        ops += layers2.size();
        if (layers1.size() != layers2.size())
            return ops;
        // g_list_find in loop — O(L²)
        for (Object item : layers1) {
            for (Object item2 : layers2) {
                ops++;
                if (item == item2) break;
            }
        }
        return ops;
    }

    /** Simulate GHashTable-based comparison (fixed) */
    static long layerStackCmpFixed(List<Object> layers1, List<Object> layers2) {
        long ops = 0;
        ops += layers1.size();
        ops += layers2.size();
        if (layers1.size() != layers2.size())
            return ops;
        // Build hash set from layers2: O(L)
        Set<Object> set = new HashSet<>(layers2);
        ops += layers2.size();
        // Membership test: O(L)
        for (Object item : layers1) {
            ops++;
            if (!set.contains(item)) break;
        }
        return ops;
    }

    /** Simulate rec_remove_layer_stack_dups — defective O(S² × cmp) */
    static long recRemoveDupsDefective(List<List<Object>> stack) {
        long ops = 0;
        for (int i = 0; i < stack.size(); i++) {
            // g_slist_find_custom scans remaining entries
            for (int j = i + 1; j < stack.size(); j++) {
                ops += layerStackCmpDefective(stack.get(i), stack.get(j));
            }
        }
        return ops;
    }

    /** Simulate fixed dedup — O(S × L) using hash */
    static long recRemoveDupsFixed(List<List<Object>> stack) {
        long ops = 0;
        Set<Set<Object>> seen = new HashSet<>();
        for (List<Object> entry : stack) {
            Set<Object> entrySet = new HashSet<>(entry);
            ops += entry.size(); // building set
            ops++; // hash lookup
            seen.add(entrySet);
        }
        return ops;
    }

    static void testLayerStackDedup() {
        int S = 50;  // stack entries (undo states)
        int L = 10;  // layers per selection

        // Build stack with unique selections (worst case)
        List<List<Object>> stack = new ArrayList<>();
        for (int i = 0; i < S; i++) {
            List<Object> selection = new ArrayList<>();
            for (int j = 0; j < L; j++) {
                selection.add(new Object()); // unique objects
            }
            stack.add(selection);
        }

        long defectOps = recRemoveDupsDefective(stack);
        long fixedOps = recRemoveDupsFixed(stack);
        double ratio = (double) defectOps / fixedOps;

        System.out.printf("gimp-0001 layer stack dedup:%n");
        System.out.printf("  S=%d L=%d  defect_ops=%d  fixed_ops=%d  ratio=%.1fx%n",
                S, L, defectOps, fixedOps, ratio);
        assert ratio > 20.0 : "Expected significant overhead, got " + ratio;
        System.out.println("  PASS");
    }

    // ---------------------------------------------------------------
    // gimp-0002: remove_from_layer_stack O(C × S × L)
    // ---------------------------------------------------------------

    /** Simulate defective removal: g_list_remove per child per stack entry */
    static long removeFromStackDefective(int children, int stackSize, int layersPerEntry) {
        long ops = 0;
        // For each child (plus the layer itself = children+1)
        for (int c = 0; c < children + 1; c++) {
            // For each stack entry
            for (int s = 0; s < stackSize; s++) {
                // g_list_remove scans the list: O(L)
                for (int l = 0; l < layersPerEntry; l++) {
                    ops++;
                }
            }
        }
        return ops;
    }

    /** Simulate fixed removal: hash set + single pass per stack entry */
    static long removeFromStackFixed(int children, int stackSize, int layersPerEntry) {
        long ops = 0;
        // Build hash set of all layers to remove: O(C)
        ops += children + 1;
        // Single pass over each stack entry: O(S × L)
        for (int s = 0; s < stackSize; s++) {
            for (int l = 0; l < layersPerEntry; l++) {
                ops++; // hash lookup per layer
            }
        }
        return ops;
    }

    static void testRemoveFromLayerStack() {
        int C = 20;  // children in group layer
        int S = 50;  // undo stack entries
        int L = 20;  // layers per stack entry

        long defectOps = removeFromStackDefective(C, S, L);
        long fixedOps = removeFromStackFixed(C, S, L);
        double ratio = (double) defectOps / fixedOps;

        System.out.printf("gimp-0002 remove_from_layer_stack:%n");
        System.out.printf("  C=%d S=%d L=%d  defect_ops=%d  fixed_ops=%d  ratio=%.1fx%n",
                C, S, L, defectOps, fixedOps, ratio);
        assert ratio > 10.0 : "Expected significant overhead, got " + ratio;
        System.out.println("  PASS");
    }

    // ---------------------------------------------------------------
    // Main
    // ---------------------------------------------------------------

    public static void main(String[] args) {
        testLayerStackDedup();
        testRemoveFromLayerStack();
        System.out.println("\nAll GIMP CWE-407 tests PASS");
    }
}