lib/libc/stdlib/lsearch.c

   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 1.7 2012/06/25 22:32:45 abs 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(const void *key, void *base, size_t *nelp, size_t width,
  55     cmp_fn_t compar)
  56 {
  57
  58         _DIAGASSERT(key != NULL);
  59         _DIAGASSERT(base != NULL);
  60         _DIAGASSERT(compar != NULL);
  61
  62         return(linear_base(key, base, nelp, width, compar, 1));
  63 }
  64
  65 void *
  66 lfind(const void *key, const void *base, size_t *nelp, size_t width,
  67     cmp_fn_t compar)
  68 {
  69
  70         _DIAGASSERT(key != NULL);
  71         _DIAGASSERT(base != NULL);
  72         _DIAGASSERT(compar != NULL);
  73
  74         return(linear_base(key, __UNCONST(base), nelp, width, compar, 0));
  75 }
  76
  77 static void *
  78 linear_base(const void *key, void *base, size_t *nelp, size_t width,
  79         cmp_fn_t compar, int add_flag)
  80 {
  81         char *element, *end;
  82
  83         _DIAGASSERT(key != NULL);
  84         _DIAGASSERT(base != NULL);
  85         _DIAGASSERT(compar != NULL);
  86
  87         end = (char *)base + *nelp * width;
  88         for (element = (char *)base; element < end; element += width)
  89                 if (!compar(element, key))              /* key found */
  90                         return element;
  91
  92         if (!add_flag)                                  /* key not found */
  93                 return(NULL);
  94
  95         /*
  96          * The UNIX System User's Manual, 1986 edition claims that
  97          * a NULL pointer is returned by lsearch with errno set
  98          * appropriately, if there is not enough room in the table
  99          * to add a new item.  This can't be done as none of these
 100          * routines have any method of determining the size of the
 101          * table.  This comment isn't in the 1986-87 System V
 102          * manual.
 103          */
 104         ++*nelp;
 105         memcpy(end, key, width);
 106         return end;
 107 }