usr/src/lib/libmail/common/casncmp.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*
  33  *  NAME
  34  *      casncmp - compare strings ignoring case
  35  *
  36  *  SYNOPSIS
  37  *      int casncmp(char *s1, char *s2, ssize_t n)
  38  *
  39  *  DESCRIPTION
  40  *      Compare two strings ignoring case differences.
  41  *      Stop after n bytes or the trailing NUL.
  42  */
  43
  44 #include "libmail.h"
  45 #include <ctype.h>
  46 #include <sys/types.h>
  47
  48 int
  49 casncmp(char *s1, char *s2, ssize_t n)
  50 {
  51         if (s1 == s2)
  52                 return (0);
  53         while ((--n >= 0) && (tolower(*s1) == tolower(*s2))) {
  54                 s2++;
  55                 if (*s1++ == '\0')
  56                         return (0);
  57         }
  58         return ((n < 0)? 0: (*s1 - *s2));
  59 }