I tried to file this as a pr yesterday, but can't due to mail not being
set up properly on my machine.

Here was the message text:



-- 
Neil A. Carson
Category: Bug
Release: NetBSD-current

Greetings,

In search.h, tsearch() is defined. BUt no code exists in the C
library!!!
Can someone commit this stuff for me, please? It went from libposix
(written by some dude I can't remember the name of) via OpenBSD.

	Neil


/*
 * 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, lint doesn't grok it.
 *
 * 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(vkey, vrootp, compar)
	const void	*vkey;		/* key to be found */
	void		*const *vrootp;	/* address of the tree root */
	int		(*compar) __P((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;
}
/*
 * 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, lint doesn't grok it.
 *
 * 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(vkey, vrootp, compar)
	const void 	*vkey;		/* key to be located */
	void		**vrootp;	/* address of tree root */
	int		(*compar) __P((const void *, const void *));
{
    register 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(vkey, vrootp, compar)
	const void	*vkey;		/* key to be deleted */
	void		**vrootp;	/* address of the root of tree */
	int		(*compar) __P((const void *, const void *));
{
    node **rootp = (node **)vrootp;
    char *key = (char *)vkey;
    node *p;
    register node *q;
    register node *r;
    int cmp;

    if (rootp == (struct node_t **)0 || (p = *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(root, action, level)
	register node	*root;		/* Root of the tree to be walked */
	register void	(*action)();	/* Function to be called at each node */
	register 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(vroot, action)
	const void	*vroot;		/* Root of the tree to be walked */
	void		(*action) __P((const void *, VISIT, int));
{
    node *root = (node *)vroot;

    if (root != (node *)0 && action != (void(*)())0)
	trecurse(root, action, 0);
}
.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
.\" All rights reserved.
.\"
.\" 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. The name of the author may not be used to endorse or promote
products
.\"    derived from this software without specific prior written
permission.
.\"
.\" THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
.\"
.\"	$OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp $
.\"
.Dd June 15, 1997
.Dt TSEARCH 3
.Os
.Sh NAME
.Nm tsearch, tfind, tdelete, twalk
.Nd manipulate binary search trees
.Sh SYNOPSIS
.Fd #include <search.h>
.Ft void *
.Fn tdelete "const void *key" "void **rootp", "int (*compar) (const void
*, const void *)"
.Ft void *
.Fn tfind "const void *key" "void * const *rootp", "int (*compar) (const
void *, const void *)"
.Ft void *
.Fn tsearch "const void *key" "void **rootp", "int (*compar) (const void
*, const void *)"
.Ft void
.Fn twalk "const void *root" "void (*compar) (const void *, VISIT, int)"
.Sh DESCRIPTION
The
.Fn tdelete ,
.Fn tfind ,
.Fn tsearch ,
and
.Fn twalk
functions manage binary search trees based on algorithms T and D
from Knuth (6.2.2).  The comparison function passed in by
the user has the same style of return values as
.Xr strcmp 3 .
.Pp
.Fn Tfind
searches for the datum matched by the argument
.Fa key
in the binary tree rooted at
.Fa rootp ,
returning a pointer to the datum if it is found and NULL
if it is not.
.Pp
.Fn Tsearch
is identical to
.Fn tfind
except that if no match is found,
.Fa key
is inserted into the tree and a pointer to it is returned.  If
.Fa rootp
points to a NULL value a new binary search tree is created.
.Pp
.Fn Tdelete
deletes a node from the specified binary search tree and returns
a pointer to the parent of the node to be deleted.
It takes the same arguments as
.Fn tfind
and
.Fn tsearch .
If the node to be deleted is the root of the binary search tree,
.Fa rootp
will be adjusted.
.Pp
.Fn Twalk
walks the binary search tree rooted in
.fa root
and calls the function
.Fa action
on each node.
.Fa Action
is called with three arguments: a pointer to the current node,
a value from the enum 
.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
specifying the traversal type, and a node level (where level
zero is the root of the tree).
.Sh SEE ALSO
.Xr bsearch 3 ,
.Xr hsearch 3 ,
.Xr lsearch 3
.Sh RETURN VALUES
The
.Fn tsearch
function returns NULL if allocation of a new node fails (usually
due to a lack of free memory).
.Pp
.Fn Tfind ,
.Fn tsearch ,
and
.Fn tdelete
return NULL if
.Fa rootp
is NULL or the datum cannot be found.
.Pp
The
.Fn twalk
function returns no value.