gnu/dist/diffutils/lib/strcasecmp.c

   1 /*      $NetBSD$        */
   2
   3 /* strcasecmp.c -- case insensitive string comparator
   4    Copyright (C) 1998, 1999 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #ifdef LENGTH_LIMIT
  25 # define STRXCASECMP_FUNCTION strncasecmp
  26 # define STRXCASECMP_DECLARE_N , size_t n
  27 # define LENGTH_LIMIT_EXPR(Expr) Expr
  28 #else
  29 # define STRXCASECMP_FUNCTION strcasecmp
  30 # define STRXCASECMP_DECLARE_N /* empty */
  31 # define LENGTH_LIMIT_EXPR(Expr) 0
  32 #endif
  33
  34 #include <sys/types.h>
  35 #include <ctype.h>
  36
  37 #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
  38
  39 /* Compare {{no more than N characters of }}strings S1 and S2,
  40    ignoring case, returning less than, equal to or
  41    greater than zero if S1 is lexicographically less
  42    than, equal to or greater than S2.  */
  43
  44 int
  45 STRXCASECMP_FUNCTION (const char *s1, const char *s2 STRXCASECMP_DECLARE_N)
  46 {
  47   register const unsigned char *p1 = (const unsigned char *) s1;
  48   register const unsigned char *p2 = (const unsigned char *) s2;
  49   unsigned char c1, c2;
  50
  51   if (p1 == p2 || LENGTH_LIMIT_EXPR (n == 0))
  52     return 0;
  53
  54   do
  55     {
  56       c1 = TOLOWER (*p1);
  57       c2 = TOLOWER (*p2);
  58
  59       if (LENGTH_LIMIT_EXPR (--n == 0) || c1 == '\0')
  60         break;
  61
  62       ++p1;
  63       ++p2;
  64     }
  65   while (c1 == c2);
  66
  67   return c1 - c2;
  68 }