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GTree: Check for node counter overflow when adding new elements

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Currently, when adding new elements to GTree we blindly increment the node
counter, which is only of guint size (so 32-bit even on 64-bit Unix
platforms).

This is even more problematic because the only way to check whether
particular GTree is empty is to check whether its node count is zero.
This will obviously give wrong answer if this counter overflows.

Let's fix this by adding an appropriate check when adding a new node.

For the recently added g_tree_{insert,replace}_node () API we can simply
return NULL in such case.

However, the older g_tree_{insert,replace} () API doesn't have any ability
to return an error so for them we follow the example of
g_ptr_array_extend () and g_ptr_array_set_size () by calling g_error ()
when this happens.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
This commit is contained in:
Maciej S. Szmigiero 2023-08-08 15:51:47 +02:00
parent 1237525da2
commit f08191e398
2 changed files with 87 additions and 35 deletions
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104
glib/gtree.c
View File

@ -105,7 +105,8 @@ static GTreeNode* g_tree_node_new (gpointer key,
static GTreeNode *g_tree_insert_internal (GTree *tree,
gpointer key,
gpointer value,
gboolean replace);
gboolean replace,
gboolean null_ret_ok);
static gboolean g_tree_remove_internal (GTree *tree,
gconstpointer key,
gboolean steal);
@ -454,6 +455,26 @@ g_tree_destroy (GTree *tree)
g_tree_unref (tree);
}
static GTreeNode *
g_tree_insert_replace_node_internal (GTree *tree,
gpointer key,
gpointer value,
gboolean replace,
gboolean null_ret_ok)
{
GTreeNode *node;
g_return_val_if_fail (tree != NULL, NULL);
node = g_tree_insert_internal (tree, key, value, replace, null_ret_ok);
#ifdef G_TREE_DEBUG
g_tree_node_check (tree->root);
#endif
return node;
}
/**
* g_tree_insert_node:
* @tree: a #GTree
@ -474,7 +495,8 @@ g_tree_destroy (GTree *tree)
* result in a O(n log(n)) operation where most of the other operations
* are O(log(n)).
*
* Returns: (transfer none): the inserted (or set) node.
* Returns: (transfer none) (nullable): the inserted (or set) node or %NULL
* if insertion would overflow the tree node counter.
*
* Since: 2.68
*/
@ -483,17 +505,7 @@ g_tree_insert_node (GTree *tree,
gpointer key,
gpointer value)
{
GTreeNode *node;
g_return_val_if_fail (tree != NULL, NULL);
node = g_tree_insert_internal (tree, key, value, FALSE);
#ifdef G_TREE_DEBUG
g_tree_node_check (tree->root);
#endif
return node;
return g_tree_insert_replace_node_internal (tree, key, value, FALSE, TRUE);
}
/**
@ -512,7 +524,7 @@ g_tree_insert (GTree *tree,
gpointer key,
gpointer value)
{
g_tree_insert_node (tree, key, value);
g_tree_insert_replace_node_internal (tree, key, value, FALSE, FALSE);
}
/**
@ -531,7 +543,8 @@ g_tree_insert (GTree *tree,
* The tree is automatically 'balanced' as new key/value pairs are added,
* so that the distance from the root to every leaf is as small as possible.
*
* Returns: (transfer none): the inserted (or set) node.
* Returns: (transfer none) (nullable): the inserted (or set) node or %NULL
* if insertion would overflow the tree node counter.
*
* Since: 2.68
*/
@ -540,17 +553,7 @@ g_tree_replace_node (GTree *tree,
gpointer key,
gpointer value)
{
GTreeNode *node;
g_return_val_if_fail (tree != NULL, NULL);
node = g_tree_insert_internal (tree, key, value, TRUE);
#ifdef G_TREE_DEBUG
g_tree_node_check (tree->root);
#endif
return node;
return g_tree_insert_replace_node_internal (tree, key, value, TRUE, TRUE);
}
/**
@ -567,7 +570,26 @@ g_tree_replace (GTree *tree,
gpointer key,
gpointer value)
{
g_tree_replace_node (tree, key, value);
g_tree_insert_replace_node_internal (tree, key, value, TRUE, FALSE);
}
/* internal checked nnodes increment routine */
static gboolean
g_tree_nnodes_inc_checked (GTree *tree, gboolean overflow_fatal)
{
if (G_UNLIKELY (tree->nnodes == G_MAXUINT))
{
if (overflow_fatal)
{
g_error ("Incrementing GTree nnodes counter would overflow");
}
return FALSE;
}
tree->nnodes++;
return TRUE;
}
/* internal insert routine */
@ -575,7 +597,8 @@ static GTreeNode *
g_tree_insert_internal (GTree *tree,
gpointer key,
gpointer value,
gboolean replace)
gboolean replace,
gboolean null_ret_ok)
{
GTreeNode *node, *retnode;
GTreeNode *path[MAX_GTREE_HEIGHT];
@ -586,7 +609,12 @@ g_tree_insert_internal (GTree *tree,
if (!tree->root)
{
tree->root = g_tree_node_new (key, value);
#ifdef G_TREE_DEBUG
g_assert (tree->nnodes == 0);
#endif
tree->nnodes++;
return tree->root;
}
@ -630,16 +658,20 @@ g_tree_insert_internal (GTree *tree,
}
else
{
GTreeNode *child = g_tree_node_new (key, value);
GTreeNode *child;
if (!g_tree_nnodes_inc_checked (tree, !null_ret_ok))
{
return NULL;
}
child = g_tree_node_new (key, value);
child->left = node->left;
child->right = node;
node->left = child;
node->left_child = TRUE;
node->balance -= 1;
tree->nnodes++;
retnode = child;
break;
}
@ -653,16 +685,20 @@ g_tree_insert_internal (GTree *tree,
}
else
{
GTreeNode *child = g_tree_node_new (key, value);
GTreeNode *child;
if (!g_tree_nnodes_inc_checked (tree, !null_ret_ok))
{
return NULL;
}
child = g_tree_node_new (key, value);
child->right = node->right;
child->left = node;
node->right = child;
node->right_child = TRUE;
node->balance += 1;
tree->nnodes++;
retnode = child;
break;
}

18
glib/tests/tree.c
View File

@ -237,9 +237,10 @@ static void
test_tree_remove (void)
{
GTree *tree;
char c, d;
char c, d, e, f;
gint i;
gboolean removed;
GTreeNode *node;
gchar *remove;
tree = g_tree_new_full ((GCompareDataFunc)my_compare, NULL,
@ -263,6 +264,12 @@ test_tree_remove (void)
destroyed_key = NULL;
destroyed_value = NULL;
e = '\xff';
node = g_tree_insert_node (tree, &e, &e);
g_assert (node);
g_assert (destroyed_key == NULL);
g_assert (destroyed_value == NULL);
c = '2';
removed = g_tree_remove (tree, &c);
g_assert (removed);
@ -277,6 +284,14 @@ test_tree_remove (void)
g_assert (destroyed_key == NULL);
g_assert (destroyed_value == NULL);
f = '4';
node = g_tree_replace_node (tree, &f, &f);
g_assert (node);
g_assert (destroyed_key == &chars[4]);
g_assert (destroyed_value == &chars[4]);
destroyed_key = NULL;
destroyed_value = NULL;
remove = "omkjigfedba";
for (i = 0; remove[i]; i++)
{
@ -655,6 +670,7 @@ test_tree_bounds (void)
g_test_message ("%c ", *(char *) elem);
node = g_tree_insert_node (tree, elem, elem);
g_assert (node);
g_assert (g_tree_node_key (node) == elem);
g_assert (g_tree_node_value (node) == elem);
}