Implement twalk(3), add unit tests.

I've also added insque(3) and remque(3) (from NetBSD because the OpenBSD
ones are currently broken for non-circular lists).

I've not added the three hash table functions that should be in this header
because they operate on a single global hash table and thus aren't likely
to be useful.

Bug: https://code.google.com/p/android/issues/detail?id=73719
Change-Id: I97397a7b921e2e860fd9c8032cafd9097380498a

libc/upstream-openbsd/lib/libc/stdlib/lsearch.c

@@ -0,0 +1,84 @@
+/*	$OpenBSD: lsearch.c,v 1.5 2014/07/18 04:16:09 matthew Exp $	*/
+
+/*
+ * Copyright (c) 1989, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Roger L. Snyder.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <string.h>
+#include <search.h>
+
+typedef int (*cmp_fn_t)(const void *, const void *);
+static void *linear_base(const void *, const void *, size_t *, size_t,
+    cmp_fn_t, int);
+
+void *
+lsearch(const void *key, void *base, size_t *nelp, size_t width,
+    	cmp_fn_t compar)
+{
+
+	return(linear_base(key, base, nelp, width, compar, 1));
+}
+
+void *
+lfind(const void *key, const void *base, size_t *nelp, size_t width,
+	cmp_fn_t compar)
+{
+	return(linear_base(key, base, nelp, width, compar, 0));
+}
+
+static void *
+linear_base(const void *key, const void *base, size_t *nelp, size_t width,
+	cmp_fn_t compar, int add_flag)
+{
+	const char *element, *end;
+
+	end = (const char *)base + *nelp * width;
+	for (element = base; element < end; element += width)
+		if (!compar(key, element))		/* key found */
+			return((void *)element);
+
+	if (!add_flag)					/* key not found */
+		return(NULL);
+
+	/*
+	 * The UNIX System User's Manual, 1986 edition claims that
+	 * a NULL pointer is returned by lsearch with errno set
+	 * appropriately, if there is not enough room in the table
+	 * to add a new item.  This can't be done as none of these
+	 * routines have any method of determining the size of the
+	 * table.  This comment isn't in the 1986-87 System V
+	 * manual.
+	 */
+	++*nelp;
+	memcpy((void *)end, key, width);
+	return((void *)end);
+}

libc/upstream-openbsd/lib/libc/stdlib/tfind.c

@@ -0,0 +1,41 @@
+/*	$OpenBSD: tfind.c,v 1.6 2014/03/16 18:38:30 guenther Exp $	*/
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+/*LINTLIBRARY*/
+#include <search.h>
+
+typedef struct node_t
+{
+    char	  *key;
+    struct node_t *llink, *rlink;
+} node;
+
+/* find a node, or return 0 */
+void *
+tfind(const void *vkey, void * const *vrootp,
+    int (*compar)(const void *, const void *))
+{
+    char *key = (char *)vkey;
+    node **rootp = (node **)vrootp;
+
+    if (rootp == (struct node_t **)0)
+	return ((struct node_t *)0);
+    while (*rootp != (struct node_t *)0) {	/* T1: */
+	int r;
+	if ((r = (*compar)(key, (*rootp)->key)) == 0)	/* T2: */
+	    return (*rootp);		/* key found */
+	rootp = (r < 0) ?
+	    &(*rootp)->llink :		/* T3: follow left branch */
+	    &(*rootp)->rlink;		/* T4: follow right branch */
+    }
+    return (node *)0;
+}

libc/upstream-openbsd/lib/libc/stdlib/tsearch.c

@@ -0,0 +1,119 @@
+/*	$OpenBSD: tsearch.c,v 1.8 2014/03/16 18:38:30 guenther Exp $	*/
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+/*LINTLIBRARY*/
+
+#include <search.h>
+#include <stdlib.h>
+
+typedef struct node_t {
+    char	  *key;
+    struct node_t *left, *right;
+} node;
+
+/* find or insert datum into search tree */
+void *
+tsearch(const void *vkey, void **vrootp,
+    int (*compar)(const void *, const void *))
+{
+    node *q;
+    char *key = (char *)vkey;
+    node **rootp = (node **)vrootp;
+
+    if (rootp == (struct node_t **)0)
+	return ((void *)0);
+    while (*rootp != (struct node_t *)0) {	/* Knuth's T1: */
+	int r;
+
+	if ((r = (*compar)(key, (*rootp)->key)) == 0)	/* T2: */
+	    return ((void *)*rootp);		/* we found it! */
+	rootp = (r < 0) ?
+	    &(*rootp)->left :		/* T3: follow left branch */
+	    &(*rootp)->right;		/* T4: follow right branch */
+    }
+    q = (node *) malloc(sizeof(node));	/* T5: key not found */
+    if (q != (struct node_t *)0) {	/* make new node */
+	*rootp = q;			/* link new node to old */
+	q->key = key;			/* initialize new node */
+	q->left = q->right = (struct node_t *)0;
+    }
+    return ((void *)q);
+}
+
+/* delete node with given key */
+void *
+tdelete(const void *vkey, void **vrootp,
+    int (*compar)(const void *, const void *))
+{
+    node **rootp = (node **)vrootp;
+    char *key = (char *)vkey;
+    node *p = (node *)1;
+    node *q;
+    node *r;
+    int cmp;
+
+    if (rootp == (struct node_t **)0 || *rootp == (struct node_t *)0)
+	return ((struct node_t *)0);
+    while ((cmp = (*compar)(key, (*rootp)->key)) != 0) {
+	p = *rootp;
+	rootp = (cmp < 0) ?
+	    &(*rootp)->left :		/* follow left branch */
+	    &(*rootp)->right;		/* follow right branch */
+	if (*rootp == (struct node_t *)0)
+	    return ((void *)0);		/* key not found */
+    }
+    r = (*rootp)->right;			/* D1: */
+    if ((q = (*rootp)->left) == (struct node_t *)0)	/* Left (struct node_t *)0? */
+	q = r;
+    else if (r != (struct node_t *)0) {		/* Right link is null? */
+	if (r->left == (struct node_t *)0) {	/* D2: Find successor */
+	    r->left = q;
+	    q = r;
+	} else {			/* D3: Find (struct node_t *)0 link */
+	    for (q = r->left; q->left != (struct node_t *)0; q = r->left)
+		r = q;
+	    r->left = q->right;
+	    q->left = (*rootp)->left;
+	    q->right = (*rootp)->right;
+	}
+    }
+    free((struct node_t *) *rootp);	/* D4: Free node */
+    *rootp = q;				/* link parent to new node */
+    return(p);
+}
+
+/* Walk the nodes of a tree */
+static void
+trecurse(node *root, void (*action)(const void *, VISIT, int), int level)
+{
+    if (root->left == (struct node_t *)0 && root->right == (struct node_t *)0)
+	(*action)(root, leaf, level);
+    else {
+	(*action)(root, preorder, level);
+	if (root->left != (struct node_t *)0)
+	    trecurse(root->left, action, level + 1);
+	(*action)(root, postorder, level);
+	if (root->right != (struct node_t *)0)
+	    trecurse(root->right, action, level + 1);
+	(*action)(root, endorder, level);
+    }
+}
+
+/* Walk the nodes of a tree */
+void
+twalk(const void *vroot, void (*action)(const void *, VISIT, int))
+{
+    node *root = (node *)vroot;
+
+    if (root != (node *)0 && action != (void (*)(const void *, VISIT, int))0)
+	trecurse(root, action, 0);
+}