1 files changed, 190 insertions, 0 deletions
diff --git a/wsutil/wmem/wmem_interval_tree.c b/wsutil/wmem/wmem_interval_tree.c
new file mode 100644
index 00000000..8b28549a
--- /dev/null
+++ b/wsutil/wmem/wmem_interval_tree.c
@@ -0,0 +1,190 @@
+/* wmem_interval_tree.c
+ * Implements an augmented interval tree
+ * Based on the red-black tree implementation in epan/wmem.*
+ * Copyright 2015, Matthieu coudron <matthieu.coudron@lip6.fr>
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "config.h"
+
+#include <inttypes.h>
+#include <string.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <glib.h>
+
+#include "wmem-int.h"
+#include "wmem_core.h"
+#include "wmem_tree-int.h"
+#include "wmem_strutl.h"
+#include "wmem_interval_tree.h"
+#include "wmem_user_cb.h"
+
+
+static void
+print_range(const void *value)
+{
+    const wmem_range_t *range = (const wmem_range_t *)value;
+    if(!value) {
+        return;
+    }
+    printf("Range: low=%" PRIu64 " high=%" PRIu64 " max_edge=%" PRIu64 "\n", range->low, range->high, range->max_edge);
+}
+
+/**
+ * In an augmented interval tree, each node saves the maximum edge of its child subtrees
+ * This function compares the children max_edge with the current max_edge
+ * and propagates any change to the parent nodes.
+ */
+static void
+update_max_edge(wmem_tree_node_t *node)
+{
+    wmem_range_t *range;
+    const wmem_range_t *range_l;
+    const wmem_range_t *range_r;
+    uint64_t maxEdge = 0;
+
+    if(!node) {
+        return ;
+    }
+
+    range = (wmem_range_t *)node->key;
+
+    range_l = (node->left) ? (const wmem_range_t *) (node->left->key) : NULL;
+    range_r = (node->right) ? (const wmem_range_t *) (node->right->key) : NULL;
+
+    maxEdge = range->high;
+
+    if(range_r) {
+        maxEdge = MAX(maxEdge, range_r->max_edge) ;
+    }
+    if(range_l) {
+        maxEdge = MAX(maxEdge, range_l->max_edge) ;
+    }
+
+    /* update the parent nodes only if a change happened (optimization) */
+    if(range->max_edge != maxEdge) {
+        range->max_edge = maxEdge;
+        update_max_edge(node->parent);
+    }
+}
+
+bool
+wmem_itree_range_overlap(const wmem_range_t *r1, const wmem_range_t *r2)
+{
+    return (r1->low <= r2->high && r2->low <= r1->high);
+}
+
+
+/* after a rotation, some of the children nodes might (dis)appear, thus we need
+ * to refresh children max_edge. Changes will propagate to parents */
+static void update_edges_after_rotation(wmem_tree_node_t *node) {
+    if(node->left)  update_max_edge(node->left);
+    if(node->right)  update_max_edge(node->right);
+}
+
+wmem_itree_t *
+wmem_itree_new(wmem_allocator_t *allocator)
+{
+    wmem_itree_t *tree      = wmem_tree_new(allocator);
+    tree->post_rotation_cb  = &update_edges_after_rotation;
+    return tree;
+}
+
+bool
+wmem_itree_is_empty(wmem_itree_t *tree)
+{
+    return wmem_tree_is_empty(tree);
+}
+
+static int
+wmem_tree_compare_ranges(const wmem_range_t *ra, const wmem_range_t *rb)
+{
+    if( ra->low == rb->low) {
+        return 0;
+    }
+    else if(ra->low < rb->low) {
+        return -1;
+    }
+    else {
+        return 1;
+    }
+}
+
+
+void
+wmem_itree_insert(wmem_itree_t *tree, const uint64_t low, const uint64_t high, void *data)
+{
+    wmem_tree_node_t *node;
+    wmem_range_t *range = (wmem_range_t *)wmem_new(tree->data_allocator, wmem_range_t);
+
+    ws_assert(low <= high);
+    range->low = low;
+    range->high = high;
+    range->max_edge = 0;
+
+    node = wmem_tree_insert(tree, range, data, (compare_func)wmem_tree_compare_ranges);
+
+    /* in absence of rotation, we still need to update max_edge */
+    update_max_edge(node);
+}
+
+
+static void
+wmem_itree_find_intervals_in_subtree(wmem_tree_node_t *node, wmem_range_t requested, wmem_list_t *results)
+{
+    const wmem_range_t* current;
+
+    if(!node) {
+        return;
+    }
+    current = (wmem_range_t*)node->key;
+
+    /* there is no child that can possibly match */
+    if(requested.low > current->max_edge) {
+        return;
+    }
+
+    if(wmem_itree_range_overlap(current, &requested)) {
+        wmem_list_prepend(results, node->data);
+    }
+
+    wmem_itree_find_intervals_in_subtree(node->left, requested, results);
+    wmem_itree_find_intervals_in_subtree(node->right, requested, results);
+}
+
+wmem_list_t *
+wmem_itree_find_intervals(wmem_itree_t *tree, wmem_allocator_t *allocator, uint64_t low, uint64_t high)
+{
+    wmem_list_t *results = NULL;
+    wmem_range_t requested = { low, high, 0 };
+    results = wmem_list_new(allocator);
+
+    wmem_itree_find_intervals_in_subtree(tree->root, requested, results);
+    return results;
+}
+
+
+void
+wmem_print_itree(wmem_tree_t *tree)
+{
+    wmem_print_tree(tree, &print_range, NULL);
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 4
+ * tab-width: 8
+ * indent-tabs-mode: nil
+ * End:
+ *
+ * vi: set shiftwidth=4 tabstop=8 expandtab:
+ * :indentSize=4:tabSize=8:noTabs=true:
+ */