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qemu/util/qtree.c
Emilio Cota 1ff4a81bd3 tcg: use QTree instead of GTree 
qemu-user can hang in a multi-threaded fork. One common
reason is that when creating a TB, between fork and exec
we manipulate a GTree whose memory allocator (GSlice) is
not fork-safe.

Although POSIX does not mandate it, the system's allocator
(e.g. tcmalloc, libc malloc) is probably fork-safe.

Fix some of these hangs by using QTree, which uses the system's
allocator regardless of the Glib version that we used at
configuration time.

Tested with the test program in the original bug report, i.e.:
```

void garble() {
  int pid = fork();
  if (pid == 0) {
    exit(0);
  } else {
    int wstatus;
    waitpid(pid, &wstatus, 0);
  }
}

void supragarble(unsigned depth) {
  if (depth == 0)
    return ;

  std::thread a(supragarble, depth-1);
  std::thread b(supragarble, depth-1);
  garble();
  a.join();
  b.join();
}

int main() {
  supragarble(10);
}
```

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/285
Reported-by: Valentin David <me@valentindavid.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Emilio Cota <cota@braap.org>
Message-Id: <20230205163758.416992-3-cota@braap.org>
[rth: Add QEMU_DISABLE_CFI for all callback using functions.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-03-28 15:23:10 -07:00

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/*
* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#include "qemu/osdep.h"
#include "qemu/qtree.h"
/**
* SECTION:trees-binary
* @title: Balanced Binary Trees
* @short_description: a sorted collection of key/value pairs optimized
* for searching and traversing in order
*
* The #QTree structure and its associated functions provide a sorted
* collection of key/value pairs optimized for searching and traversing
* in order. This means that most of the operations (access, search,
* insertion, deletion, ...) on #QTree are O(log(n)) in average and O(n)
* in worst case for time complexity. But, note that maintaining a
* balanced sorted #QTree of n elements is done in time O(n log(n)).
*
* To create a new #QTree use q_tree_new().
*
* To insert a key/value pair into a #QTree use q_tree_insert()
* (O(n log(n))).
*
* To remove a key/value pair use q_tree_remove() (O(n log(n))).
*
* To look up the value corresponding to a given key, use
* q_tree_lookup() and q_tree_lookup_extended().
*
* To find out the number of nodes in a #QTree, use q_tree_nnodes(). To
* get the height of a #QTree, use q_tree_height().
*
* To traverse a #QTree, calling a function for each node visited in
* the traversal, use q_tree_foreach().
*
* To destroy a #QTree, use q_tree_destroy().
**/
#define MAX_GTREE_HEIGHT 40
/**
* QTree:
*
* The QTree struct is an opaque data structure representing a
* [balanced binary tree][glib-Balanced-Binary-Trees]. It should be
* accessed only by using the following functions.
*/
struct _QTree {
QTreeNode *root;
GCompareDataFunc key_compare;
GDestroyNotify key_destroy_func;
GDestroyNotify value_destroy_func;
gpointer key_compare_data;
guint nnodes;
gint ref_count;
};
struct _QTreeNode {
gpointer key; /* key for this node */
gpointer value; /* value stored at this node */
QTreeNode *left; /* left subtree */
QTreeNode *right; /* right subtree */
gint8 balance; /* height (right) - height (left) */
guint8 left_child;
guint8 right_child;
};
static QTreeNode *q_tree_node_new(gpointer key,
gpointer value);
static QTreeNode *q_tree_insert_internal(QTree *tree,
gpointer key,
gpointer value,
gboolean replace);
static gboolean q_tree_remove_internal(QTree *tree,
gconstpointer key,
gboolean steal);
static QTreeNode *q_tree_node_balance(QTreeNode *node);
static QTreeNode *q_tree_find_node(QTree *tree,
gconstpointer key);
static QTreeNode *q_tree_node_search(QTreeNode *node,
GCompareFunc search_func,
gconstpointer data);
static QTreeNode *q_tree_node_rotate_left(QTreeNode *node);
static QTreeNode *q_tree_node_rotate_right(QTreeNode *node);
#ifdef Q_TREE_DEBUG
static void q_tree_node_check(QTreeNode *node);
#endif
static QTreeNode*
q_tree_node_new(gpointer key,
gpointer value)
{
QTreeNode *node = g_new(QTreeNode, 1);
node->balance = 0;
node->left = NULL;
node->right = NULL;
node->left_child = FALSE;
node->right_child = FALSE;
node->key = key;
node->value = value;
return node;
}
/**
* q_tree_new:
* @key_compare_func: the function used to order the nodes in the #QTree.
* It should return values similar to the standard strcmp() function -
* 0 if the two arguments are equal, a negative value if the first argument
* comes before the second, or a positive value if the first argument comes
* after the second.
*
* Creates a new #QTree.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new(GCompareFunc key_compare_func)
{
g_return_val_if_fail(key_compare_func != NULL, NULL);
return q_tree_new_full((GCompareDataFunc) key_compare_func, NULL,
NULL, NULL);
}
/**
* q_tree_new_with_data:
* @key_compare_func: qsort()-style comparison function
* @key_compare_data: data to pass to comparison function
*
* Creates a new #QTree with a comparison function that accepts user data.
* See q_tree_new() for more details.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new_with_data(GCompareDataFunc key_compare_func,
gpointer key_compare_data)
{
g_return_val_if_fail(key_compare_func != NULL, NULL);
return q_tree_new_full(key_compare_func, key_compare_data,
NULL, NULL);
}
/**
* q_tree_new_full:
* @key_compare_func: qsort()-style comparison function
* @key_compare_data: data to pass to comparison function
* @key_destroy_func: a function to free the memory allocated for the key
* used when removing the entry from the #QTree or %NULL if you don't
* want to supply such a function
* @value_destroy_func: a function to free the memory allocated for the
* value used when removing the entry from the #QTree or %NULL if you
* don't want to supply such a function
*
* Creates a new #QTree like q_tree_new() and allows to specify functions
* to free the memory allocated for the key and value that get called when
* removing the entry from the #QTree.
*
* Returns: a newly allocated #QTree
*/
QTree *
q_tree_new_full(GCompareDataFunc key_compare_func,
gpointer key_compare_data,
GDestroyNotify key_destroy_func,
GDestroyNotify value_destroy_func)
{
QTree *tree;
g_return_val_if_fail(key_compare_func != NULL, NULL);
tree = g_new(QTree, 1);
tree->root = NULL;
tree->key_compare = key_compare_func;
tree->key_destroy_func = key_destroy_func;
tree->value_destroy_func = value_destroy_func;
tree->key_compare_data = key_compare_data;
tree->nnodes = 0;
tree->ref_count = 1;
return tree;
}
/**
* q_tree_node_first:
* @tree: a #QTree
*
* Returns the first in-order node of the tree, or %NULL
* for an empty tree.
*
* Returns: (nullable) (transfer none): the first node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_first(QTree *tree)
{
QTreeNode *tmp;
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
return NULL;
}
tmp = tree->root;
while (tmp->left_child) {
tmp = tmp->left;
}
return tmp;
}
/**
* q_tree_node_previous
* @node: a #QTree node
*
* Returns the previous in-order node of the tree, or %NULL
* if the passed node was already the first one.
*
* Returns: (nullable) (transfer none): the previous node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_previous(QTreeNode *node)
{
QTreeNode *tmp;
g_return_val_if_fail(node != NULL, NULL);
tmp = node->left;
if (node->left_child) {
while (tmp->right_child) {
tmp = tmp->right;
}
}
return tmp;
}
/**
* q_tree_node_next
* @node: a #QTree node
*
* Returns the next in-order node of the tree, or %NULL
* if the passed node was already the last one.
*
* Returns: (nullable) (transfer none): the next node in the tree
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_node_next(QTreeNode *node)
{
QTreeNode *tmp;
g_return_val_if_fail(node != NULL, NULL);
tmp = node->right;
if (node->right_child) {
while (tmp->left_child) {
tmp = tmp->left;
}
}
return tmp;
}
/**
* q_tree_remove_all:
* @tree: a #QTree
*
* Removes all nodes from a #QTree and destroys their keys and values,
* then resets the #QTree’s root to %NULL.
*
* Since: 2.70 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static void QEMU_DISABLE_CFI
q_tree_remove_all(QTree *tree)
{
QTreeNode *node;
QTreeNode *next;
g_return_if_fail(tree != NULL);
node = q_tree_node_first(tree);
while (node) {
next = q_tree_node_next(node);
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
g_free(node);
#ifdef Q_TREE_DEBUG
g_assert(tree->nnodes > 0);
tree->nnodes--;
#endif
node = next;
}
#ifdef Q_TREE_DEBUG
g_assert(tree->nnodes == 0);
#endif
tree->root = NULL;
#ifndef Q_TREE_DEBUG
tree->nnodes = 0;
#endif
}
/**
* q_tree_ref:
* @tree: a #QTree
*
* Increments the reference count of @tree by one.
*
* It is safe to call this function from any thread.
*
* Returns: the passed in #QTree
*
* Since: 2.22
*/
QTree *
q_tree_ref(QTree *tree)
{
g_return_val_if_fail(tree != NULL, NULL);
g_atomic_int_inc(&tree->ref_count);
return tree;
}
/**
* q_tree_unref:
* @tree: a #QTree
*
* Decrements the reference count of @tree by one.
* If the reference count drops to 0, all keys and values will
* be destroyed (if destroy functions were specified) and all
* memory allocated by @tree will be released.
*
* It is safe to call this function from any thread.
*
* Since: 2.22
*/
void
q_tree_unref(QTree *tree)
{
g_return_if_fail(tree != NULL);
if (g_atomic_int_dec_and_test(&tree->ref_count)) {
q_tree_remove_all(tree);
g_free(tree);
}
}
/**
* q_tree_destroy:
* @tree: a #QTree
*
* Removes all keys and values from the #QTree and decreases its
* reference count by one. If keys and/or values are dynamically
* allocated, you should either free them first or create the #QTree
* using q_tree_new_full(). In the latter case the destroy functions
* you supplied will be called on all keys and values before destroying
* the #QTree.
*/
void
q_tree_destroy(QTree *tree)
{
g_return_if_fail(tree != NULL);
q_tree_remove_all(tree);
q_tree_unref(tree);
}
/**
* q_tree_insert_node:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a key/value pair into a #QTree.
*
* If the given key already exists in the #QTree its corresponding value
* is set to the new value. If you supplied a @value_destroy_func when
* creating the #QTree, the old value is freed using that function. If
* you supplied a @key_destroy_func when creating the #QTree, the passed
* key is freed using that function.
*
* 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.
* The cost of maintaining a balanced tree while inserting new key/value
* 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.
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_insert_node(QTree *tree,
gpointer key,
gpointer value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, NULL);
node = q_tree_insert_internal(tree, key, value, FALSE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return node;
}
/**
* q_tree_insert:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a key/value pair into a #QTree.
*
* Inserts a new key and value into a #QTree as q_tree_insert_node() does,
* only this function does not return the inserted or set node.
*/
void
q_tree_insert(QTree *tree,
gpointer key,
gpointer value)
{
q_tree_insert_node(tree, key, value);
}
/**
* q_tree_replace_node:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a new key and value into a #QTree similar to q_tree_insert_node().
* The difference is that if the key already exists in the #QTree, it gets
* replaced by the new key. If you supplied a @value_destroy_func when
* creating the #QTree, the old value is freed using that function. If you
* supplied a @key_destroy_func when creating the #QTree, the old key is
* freed using that function.
*
* 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.
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_replace_node(QTree *tree,
gpointer key,
gpointer value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, NULL);
node = q_tree_insert_internal(tree, key, value, TRUE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return node;
}
/**
* q_tree_replace:
* @tree: a #QTree
* @key: the key to insert
* @value: the value corresponding to the key
*
* Inserts a new key and value into a #QTree as q_tree_replace_node() does,
* only this function does not return the inserted or set node.
*/
void
q_tree_replace(QTree *tree,
gpointer key,
gpointer value)
{
q_tree_replace_node(tree, key, value);
}
/* internal insert routine */
static QTreeNode * QEMU_DISABLE_CFI
q_tree_insert_internal(QTree *tree,
gpointer key,
gpointer value,
gboolean replace)
{
QTreeNode *node, *retnode;
QTreeNode *path[MAX_GTREE_HEIGHT];
int idx;
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
tree->root = q_tree_node_new(key, value);
tree->nnodes++;
return tree->root;
}
idx = 0;
path[idx++] = NULL;
node = tree->root;
while (1) {
int cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
node->value = value;
if (replace) {
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
node->key = key;
} else {
/* free the passed key */
if (tree->key_destroy_func) {
tree->key_destroy_func(key);
}
}
return node;
} else if (cmp < 0) {
if (node->left_child) {
path[idx++] = node;
node = node->left;
} else {
QTreeNode *child = q_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;
}
} else {
if (node->right_child) {
path[idx++] = node;
node = node->right;
} else {
QTreeNode *child = q_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;
}
}
}
/*
* Restore balance. This is the goodness of a non-recursive
* implementation, when we are done with balancing we 'break'
* the loop and we are done.
*/
while (1) {
QTreeNode *bparent = path[--idx];
gboolean left_node = (bparent && node == bparent->left);
g_assert(!bparent || bparent->left == node || bparent->right == node);
if (node->balance < -1 || node->balance > 1) {
node = q_tree_node_balance(node);
if (bparent == NULL) {
tree->root = node;
} else if (left_node) {
bparent->left = node;
} else {
bparent->right = node;
}
}
if (node->balance == 0 || bparent == NULL) {
break;
}
if (left_node) {
bparent->balance -= 1;
} else {
bparent->balance += 1;
}
node = bparent;
}
return retnode;
}
/**
* q_tree_remove:
* @tree: a #QTree
* @key: the key to remove
*
* Removes a key/value pair from a #QTree.
*
* If the #QTree was created using q_tree_new_full(), the key and value
* are freed using the supplied destroy functions, otherwise you have to
* make sure that any dynamically allocated values are freed yourself.
* If the key does not exist in the #QTree, the function does nothing.
*
* The cost of maintaining a balanced tree while removing a key/value
* result in a O(n log(n)) operation where most of the other operations
* are O(log(n)).
*
* Returns: %TRUE if the key was found (prior to 2.8, this function
* returned nothing)
*/
gboolean
q_tree_remove(QTree *tree,
gconstpointer key)
{
gboolean removed;
g_return_val_if_fail(tree != NULL, FALSE);
removed = q_tree_remove_internal(tree, key, FALSE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return removed;
}
/**
* q_tree_steal:
* @tree: a #QTree
* @key: the key to remove
*
* Removes a key and its associated value from a #QTree without calling
* the key and value destroy functions.
*
* If the key does not exist in the #QTree, the function does nothing.
*
* Returns: %TRUE if the key was found (prior to 2.8, this function
* returned nothing)
*/
gboolean
q_tree_steal(QTree *tree,
gconstpointer key)
{
gboolean removed;
g_return_val_if_fail(tree != NULL, FALSE);
removed = q_tree_remove_internal(tree, key, TRUE);
#ifdef Q_TREE_DEBUG
q_tree_node_check(tree->root);
#endif
return removed;
}
/* internal remove routine */
static gboolean QEMU_DISABLE_CFI
q_tree_remove_internal(QTree *tree,
gconstpointer key,
gboolean steal)
{
QTreeNode *node, *parent, *balance;
QTreeNode *path[MAX_GTREE_HEIGHT];
int idx;
gboolean left_node;
g_return_val_if_fail(tree != NULL, FALSE);
if (!tree->root) {
return FALSE;
}
idx = 0;
path[idx++] = NULL;
node = tree->root;
while (1) {
int cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
break;
} else if (cmp < 0) {
if (!node->left_child) {
return FALSE;
}
path[idx++] = node;
node = node->left;
} else {
if (!node->right_child) {
return FALSE;
}
path[idx++] = node;
node = node->right;
}
}
/*
* The following code is almost equal to q_tree_remove_node,
* except that we do not have to call q_tree_node_parent.
*/
balance = parent = path[--idx];
g_assert(!parent || parent->left == node || parent->right == node);
left_node = (parent && node == parent->left);
if (!node->left_child) {
if (!node->right_child) {
if (!parent) {
tree->root = NULL;
} else if (left_node) {
parent->left_child = FALSE;
parent->left = node->left;
parent->balance += 1;
} else {
parent->right_child = FALSE;
parent->right = node->right;
parent->balance -= 1;
}
} else {
/* node has a right child */
QTreeNode *tmp = q_tree_node_next(node);
tmp->left = node->left;
if (!parent) {
tree->root = node->right;
} else if (left_node) {
parent->left = node->right;
parent->balance += 1;
} else {
parent->right = node->right;
parent->balance -= 1;
}
}
} else {
/* node has a left child */
if (!node->right_child) {
QTreeNode *tmp = q_tree_node_previous(node);
tmp->right = node->right;
if (parent == NULL) {
tree->root = node->left;
} else if (left_node) {
parent->left = node->left;
parent->balance += 1;
} else {
parent->right = node->left;
parent->balance -= 1;
}
} else {
/* node has a both children (pant, pant!) */
QTreeNode *prev = node->left;
QTreeNode *next = node->right;
QTreeNode *nextp = node;
int old_idx = idx + 1;
idx++;
/* path[idx] == parent */
/* find the immediately next node (and its parent) */
while (next->left_child) {
path[++idx] = nextp = next;
next = next->left;
}
path[old_idx] = next;
balance = path[idx];
/* remove 'next' from the tree */
if (nextp != node) {
if (next->right_child) {
nextp->left = next->right;
} else {
nextp->left_child = FALSE;
}
nextp->balance += 1;
next->right_child = TRUE;
next->right = node->right;
} else {
node->balance -= 1;
}
/* set the prev to point to the right place */
while (prev->right_child) {
prev = prev->right;
}
prev->right = next;
/* prepare 'next' to replace 'node' */
next->left_child = TRUE;
next->left = node->left;
next->balance = node->balance;
if (!parent) {
tree->root = next;
} else if (left_node) {
parent->left = next;
} else {
parent->right = next;
}
}
}
/* restore balance */
if (balance) {
while (1) {
QTreeNode *bparent = path[--idx];
g_assert(!bparent ||
bparent->left == balance ||
bparent->right == balance);
left_node = (bparent && balance == bparent->left);
if (balance->balance < -1 || balance->balance > 1) {
balance = q_tree_node_balance(balance);
if (!bparent) {
tree->root = balance;
} else if (left_node) {
bparent->left = balance;
} else {
bparent->right = balance;
}
}
if (balance->balance != 0 || !bparent) {
break;
}
if (left_node) {
bparent->balance += 1;
} else {
bparent->balance -= 1;
}
balance = bparent;
}
}
if (!steal) {
if (tree->key_destroy_func) {
tree->key_destroy_func(node->key);
}
if (tree->value_destroy_func) {
tree->value_destroy_func(node->value);
}
}
g_free(node);
tree->nnodes--;
return TRUE;
}
/**
* q_tree_lookup_node:
* @tree: a #QTree
* @key: the key to look up
*
* Gets the tree node corresponding to the given key. Since a #QTree is
* automatically balanced as key/value pairs are added, key lookup
* is O(log n) (where n is the number of key/value pairs in the tree).
*
* Returns: (nullable) (transfer none): the tree node corresponding to
* the key, or %NULL if the key was not found
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_lookup_node(QTree *tree,
gconstpointer key)
{
g_return_val_if_fail(tree != NULL, NULL);
return q_tree_find_node(tree, key);
}
/**
* q_tree_lookup:
* @tree: a #QTree
* @key: the key to look up
*
* Gets the value corresponding to the given key. Since a #QTree is
* automatically balanced as key/value pairs are added, key lookup
* is O(log n) (where n is the number of key/value pairs in the tree).
*
* Returns: the value corresponding to the key, or %NULL
* if the key was not found
*/
gpointer
q_tree_lookup(QTree *tree,
gconstpointer key)
{
QTreeNode *node;
node = q_tree_lookup_node(tree, key);
return node ? node->value : NULL;
}
/**
* q_tree_lookup_extended:
* @tree: a #QTree
* @lookup_key: the key to look up
* @orig_key: (out) (optional) (nullable): returns the original key
* @value: (out) (optional) (nullable): returns the value associated with
* the key
*
* Looks up a key in the #QTree, returning the original key and the
* associated value. This is useful if you need to free the memory
* allocated for the original key, for example before calling
* q_tree_remove().
*
* Returns: %TRUE if the key was found in the #QTree
*/
gboolean
q_tree_lookup_extended(QTree *tree,
gconstpointer lookup_key,
gpointer *orig_key,
gpointer *value)
{
QTreeNode *node;
g_return_val_if_fail(tree != NULL, FALSE);
node = q_tree_find_node(tree, lookup_key);
if (node) {
if (orig_key) {
*orig_key = node->key;
}
if (value) {
*value = node->value;
}
return TRUE;
} else {
return FALSE;
}
}
/**
* q_tree_foreach:
* @tree: a #QTree
* @func: the function to call for each node visited.
* If this function returns %TRUE, the traversal is stopped.
* @user_data: user data to pass to the function
*
* Calls the given function for each of the key/value pairs in the #QTree.
* The function is passed the key and value of each pair, and the given
* @data parameter. The tree is traversed in sorted order.
*
* The tree may not be modified while iterating over it (you can't
* add/remove items). To remove all items matching a predicate, you need
* to add each item to a list in your #GTraverseFunc as you walk over
* the tree, then walk the list and remove each item.
*/
void
q_tree_foreach(QTree *tree,
GTraverseFunc func,
gpointer user_data)
{
QTreeNode *node;
g_return_if_fail(tree != NULL);
if (!tree->root) {
return;
}
node = q_tree_node_first(tree);
while (node) {
if ((*func)(node->key, node->value, user_data)) {
break;
}
node = q_tree_node_next(node);
}
}
/**
* q_tree_search_node:
* @tree: a #QTree
* @search_func: a function used to search the #QTree
* @user_data: the data passed as the second argument to @search_func
*
* Searches a #QTree using @search_func.
*
* The @search_func is called with a pointer to the key of a key/value
* pair in the tree, and the passed in @user_data. If @search_func returns
* 0 for a key/value pair, then the corresponding node is returned as
* the result of q_tree_search(). If @search_func returns -1, searching
* will proceed among the key/value pairs that have a smaller key; if
* @search_func returns 1, searching will proceed among the key/value
* pairs that have a larger key.
*
* Returns: (nullable) (transfer none): the node corresponding to the
* found key, or %NULL if the key was not found
*
* Since: 2.68 in GLib. Internal in Qtree, i.e. not in the public API.
*/
static QTreeNode *
q_tree_search_node(QTree *tree,
GCompareFunc search_func,
gconstpointer user_data)
{
g_return_val_if_fail(tree != NULL, NULL);
if (!tree->root) {
return NULL;
}
return q_tree_node_search(tree->root, search_func, user_data);
}
/**
* q_tree_search:
* @tree: a #QTree
* @search_func: a function used to search the #QTree
* @user_data: the data passed as the second argument to @search_func
*
* Searches a #QTree using @search_func.
*
* The @search_func is called with a pointer to the key of a key/value
* pair in the tree, and the passed in @user_data. If @search_func returns
* 0 for a key/value pair, then the corresponding value is returned as
* the result of q_tree_search(). If @search_func returns -1, searching
* will proceed among the key/value pairs that have a smaller key; if
* @search_func returns 1, searching will proceed among the key/value
* pairs that have a larger key.
*
* Returns: the value corresponding to the found key, or %NULL
* if the key was not found
*/
gpointer
q_tree_search(QTree *tree,
GCompareFunc search_func,
gconstpointer user_data)
{
QTreeNode *node;
node = q_tree_search_node(tree, search_func, user_data);
return node ? node->value : NULL;
}
/**
* q_tree_height:
* @tree: a #QTree
*
* Gets the height of a #QTree.
*
* If the #QTree contains no nodes, the height is 0.
* If the #QTree contains only one root node the height is 1.
* If the root node has children the height is 2, etc.
*
* Returns: the height of @tree
*/
gint
q_tree_height(QTree *tree)
{
QTreeNode *node;
gint height;
g_return_val_if_fail(tree != NULL, 0);
if (!tree->root) {
return 0;
}
height = 0;
node = tree->root;
while (1) {
height += 1 + MAX(node->balance, 0);
if (!node->left_child) {
return height;
}
node = node->left;
}
}
/**
* q_tree_nnodes:
* @tree: a #QTree
*
* Gets the number of nodes in a #QTree.
*
* Returns: the number of nodes in @tree
*/
gint
q_tree_nnodes(QTree *tree)
{
g_return_val_if_fail(tree != NULL, 0);
return tree->nnodes;
}
static QTreeNode *
q_tree_node_balance(QTreeNode *node)
{
if (node->balance < -1) {
if (node->left->balance > 0) {
node->left = q_tree_node_rotate_left(node->left);
}
node = q_tree_node_rotate_right(node);
} else if (node->balance > 1) {
if (node->right->balance < 0) {
node->right = q_tree_node_rotate_right(node->right);
}
node = q_tree_node_rotate_left(node);
}
return node;
}
static QTreeNode * QEMU_DISABLE_CFI
q_tree_find_node(QTree *tree,
gconstpointer key)
{
QTreeNode *node;
gint cmp;
node = tree->root;
if (!node) {
return NULL;
}
while (1) {
cmp = tree->key_compare(key, node->key, tree->key_compare_data);
if (cmp == 0) {
return node;
} else if (cmp < 0) {
if (!node->left_child) {
return NULL;
}
node = node->left;
} else {
if (!node->right_child) {
return NULL;
}
node = node->right;
}
}
}
static QTreeNode *
q_tree_node_search(QTreeNode *node,
GCompareFunc search_func,
gconstpointer data)
{
gint dir;
if (!node) {
return NULL;
}
while (1) {
dir = (*search_func)(node->key, data);
if (dir == 0) {
return node;
} else if (dir < 0) {
if (!node->left_child) {
return NULL;
}
node = node->left;
} else {
if (!node->right_child) {
return NULL;
}
node = node->right;
}
}
}
static QTreeNode *
q_tree_node_rotate_left(QTreeNode *node)
{
QTreeNode *right;
gint a_bal;
gint b_bal;
right = node->right;
if (right->left_child) {
node->right = right->left;
} else {
node->right_child = FALSE;
right->left_child = TRUE;
}
right->left = node;
a_bal = node->balance;
b_bal = right->balance;
if (b_bal <= 0) {
if (a_bal >= 1) {
right->balance = b_bal - 1;
} else {
right->balance = a_bal + b_bal - 2;
}
node->balance = a_bal - 1;
} else {
if (a_bal <= b_bal) {
right->balance = a_bal - 2;
} else {
right->balance = b_bal - 1;
}
node->balance = a_bal - b_bal - 1;
}
return right;
}
static QTreeNode *
q_tree_node_rotate_right(QTreeNode *node)
{
QTreeNode *left;
gint a_bal;
gint b_bal;
left = node->left;
if (left->right_child) {
node->left = left->right;
} else {
node->left_child = FALSE;
left->right_child = TRUE;
}
left->right = node;
a_bal = node->balance;
b_bal = left->balance;
if (b_bal <= 0) {
if (b_bal > a_bal) {
left->balance = b_bal + 1;
} else {
left->balance = a_bal + 2;
}
node->balance = a_bal - b_bal + 1;
} else {
if (a_bal <= -1) {
left->balance = b_bal + 1;
} else {
left->balance = a_bal + b_bal + 2;
}
node->balance = a_bal + 1;
}
return left;
}
#ifdef Q_TREE_DEBUG
static gint
q_tree_node_height(QTreeNode *node)
{
gint left_height;
gint right_height;
if (node) {
left_height = 0;
right_height = 0;
if (node->left_child) {
left_height = q_tree_node_height(node->left);
}
if (node->right_child) {
right_height = q_tree_node_height(node->right);
}
return MAX(left_height, right_height) + 1;
}
return 0;
}
static void q_tree_node_check(QTreeNode *node)
{
gint left_height;
gint right_height;
gint balance;
QTreeNode *tmp;
if (node) {
if (node->left_child) {
tmp = q_tree_node_previous(node);
g_assert(tmp->right == node);
}
if (node->right_child) {
tmp = q_tree_node_next(node);
g_assert(tmp->left == node);
}
left_height = 0;
right_height = 0;
if (node->left_child) {
left_height = q_tree_node_height(node->left);
}
if (node->right_child) {
right_height = q_tree_node_height(node->right);
}
balance = right_height - left_height;
g_assert(balance == node->balance);
if (node->left_child) {
q_tree_node_check(node->left);
}
if (node->right_child) {
q_tree_node_check(node->right);
}
}
}
#endif
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