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lsearch.c revision 1.6 
      1 /*
      2  * Copyright (c) 1989, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * This code is derived from software contributed to Berkeley by
      6  * Roger L. Snyder.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in the
     15  *    documentation and/or other materials provided with the distribution.
     16  * 3. Neither the name of the University nor the names of its contributors
     17  *    may be used to endorse or promote products derived from this software
     18  *    without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     30  * SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 #if 0
     36 static char sccsid[] = "@(#)lsearch.c	8.1 (Berkeley) 6/4/93";
     37 #else
     38 __RCSID("$NetBSD: lsearch.c,v 1.6 2012/03/20 16:38:44 matt Exp $");
     39 #endif
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <sys/types.h>
     43 
     44 #include <assert.h>
     45 #include <errno.h>
     46 #include <string.h>
     47 #include <search.h>
     48 
     49 typedef int (*cmp_fn_t)(const void *, const void *);
     50 static void *linear_base(const void *, void *, size_t *, size_t,
     51 			     cmp_fn_t, int);
     52 
     53 void *
     54 lsearch(key, base, nelp, width, compar)
     55 	const void *key;
     56 	void *base;
     57 	size_t *nelp, width;
     58 	cmp_fn_t compar;
     59 {
     60 
     61 	_DIAGASSERT(key != NULL);
     62 	_DIAGASSERT(base != NULL);
     63 	_DIAGASSERT(compar != NULL);
     64 
     65 	return(linear_base(key, base, nelp, width, compar, 1));
     66 }
     67 
     68 void *
     69 lfind(key, base, nelp, width, compar)
     70 	const void *key, *base;
     71 	size_t *nelp, width;
     72 	cmp_fn_t compar;
     73 {
     74 
     75 	_DIAGASSERT(key != NULL);
     76 	_DIAGASSERT(base != NULL);
     77 	_DIAGASSERT(compar != NULL);
     78 
     79 	return(linear_base(key, __UNCONST(base), nelp, width, compar, 0));
     80 }
     81 
     82 static void *
     83 linear_base(const void *key, void *base, size_t *nelp, size_t width,
     84 	cmp_fn_t compar, int add_flag)
     85 {
     86 	char *element, *end;
     87 
     88 	_DIAGASSERT(key != NULL);
     89 	_DIAGASSERT(base != NULL);
     90 	_DIAGASSERT(compar != NULL);
     91 
     92 	end = (char *)base + *nelp * width;
     93 	for (element = (char *)base; element < end; element += width)
     94 		if (!compar(element, key))		/* key found */
     95 			return element;
     96 
     97 	if (!add_flag)					/* key not found */
     98 		return(NULL);
     99 
    100 	/*
    101 	 * The UNIX System User's Manual, 1986 edition claims that
    102 	 * a NULL pointer is returned by lsearch with errno set
    103 	 * appropriately, if there is not enough room in the table
    104 	 * to add a new item.  This can't be done as none of these
    105 	 * routines have any method of determining the size of the
    106 	 * table.  This comment isn't in the 1986-87 System V
    107 	 * manual.
    108 	 */
    109 	++*nelp;
    110 	memcpy(end, key, width);
    111 	return end;
    112 }
    113