4ef9bd22ed
Back in 2015 when I reimplemented these functions to use an AVL tree, I was annoyed by the weakness of the typing of these functions. Both tree nodes and keys are represented by 'void *', meaning that things like the documentation for these functions are an absolute train wreck. To make things worse, users of these functions need to cast the return value of tfind()/tsearch() from 'void *' to 'type_of_key **' in order to access the key. Technically speaking such casts violate aliasing rules. I've observed actual breakages as a result of this by enabling features like LTO. I've filed a bug report at the Austin Group. Looking at the way the bug got resolved, they made a pretty good step in the right direction. A new type 'posix_tnode' has been added to correspond to tree nodes. It is still defined as 'void' for source-level compatibility, but in the very far future it could be replaced by a proper structure type containing a key pointer. MFC after: 1 month Differential Revision: https://reviews.freebsd.org/D8205
132 lines
3.7 KiB
C
132 lines
3.7 KiB
C
/*-
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* Copyright (c) 2015 Nuxi, https://nuxi.nl/
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <atf-c.h>
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#define _SEARCH_PRIVATE
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#include <search.h>
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#include <stdbool.h>
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#include <stdlib.h>
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/* Validates the integrity of an AVL tree. */
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static inline unsigned int
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tnode_assert(const posix_tnode *n)
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{
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unsigned int height_left, height_right;
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int balance;
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if (n == NULL)
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return 0;
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height_left = tnode_assert(n->llink);
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height_right = tnode_assert(n->rlink);
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balance = (int)height_left - (int)height_right;
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ATF_CHECK(balance >= -1);
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ATF_CHECK(balance <= 1);
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ATF_CHECK_EQ(balance, n->balance);
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return (height_left > height_right ? height_left : height_right) + 1;
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}
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static int
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compar(const void *a, const void *b)
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{
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return *(int *)a - *(int *)b;
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}
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ATF_TC_WITHOUT_HEAD(tsearch_test);
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ATF_TC_BODY(tsearch_test, tc)
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{
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/*
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* Run the test below in a deterministic fashion to prevent this
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* test from potentially flapping. We assume that this provides
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* enough coverage.
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*/
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#if 0
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unsigned short random_state[3];
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arc4random_buf(random_state, sizeof(random_state));
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#else
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unsigned short random_state[3] = { 26554, 13330, 3246 };
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#endif
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#define NKEYS 1000
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/* Create 1000 possible keys. */
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int keys[NKEYS];
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for (int i = 0; i < NKEYS; ++i)
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keys[i] = i;
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/* Apply random operations on a binary tree and check the results. */
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posix_tnode *root = NULL;
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bool present[NKEYS] = {};
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for (int i = 0; i < NKEYS * 10; ++i) {
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int key = nrand48(random_state) % NKEYS;
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switch (nrand48(random_state) % 3) {
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case 0: /* tdelete(). */
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if (present[key]) {
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ATF_CHECK(tdelete(&key, &root, compar) != NULL);
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present[key] = false;
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} else {
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ATF_CHECK_EQ(NULL,
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tdelete(&key, &root, compar));
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}
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break;
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case 1: /* tfind(). */
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if (present[key]) {
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ATF_CHECK_EQ(&keys[key],
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*(int **)tfind(&key, &root, compar));
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} else {
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ATF_CHECK_EQ(NULL, tfind(&key, &root, compar));
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}
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break;
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case 2: /* tsearch(). */
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if (present[key]) {
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ATF_CHECK_EQ(&keys[key],
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*(int **)tsearch(&key, &root, compar));
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} else {
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ATF_CHECK_EQ(&keys[key], *(int **)tsearch(
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&keys[key], &root, compar));
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present[key] = true;
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}
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break;
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}
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tnode_assert(root);
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}
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/* Remove all entries from the tree. */
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for (int key = 0; key < NKEYS; ++key)
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if (present[key])
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ATF_CHECK(tdelete(&key, &root, compar) != NULL);
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ATF_CHECK_EQ(NULL, root);
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}
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ATF_TP_ADD_TCS(tp)
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{
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ATF_TP_ADD_TC(tp, tsearch_test);
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return (atf_no_error());
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}
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