1  /* Compare at most N characters of two strings without taking care for
       2     the case.
       3     Copyright (C) 1992-2023 Free Software Foundation, Inc.
       4     This file is part of the GNU C Library.
       5  
       6     The GNU C Library is free software; you can redistribute it and/or
       7     modify it under the terms of the GNU Lesser General Public
       8     License as published by the Free Software Foundation; either
       9     version 2.1 of the License, or (at your option) any later version.
      10  
      11     The GNU C Library 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 GNU
      14     Lesser General Public License for more details.
      15  
      16     You should have received a copy of the GNU Lesser General Public
      17     License along with the GNU C Library; if not, see
      18     <https://www.gnu.org/licenses/>.  */
      19  
      20  #ifdef HAVE_CONFIG_H
      21  # include <config.h>
      22  #endif
      23  
      24  #include <string.h>
      25  #include <ctype.h>
      26  
      27  #ifndef weak_alias
      28  # define __strncasecmp strncasecmp
      29  # define TOLOWER(Ch) tolower (Ch)
      30  #else
      31  # include <locale/localeinfo.h>
      32  # ifdef USE_IN_EXTENDED_LOCALE_MODEL
      33  #  define __strncasecmp __strncasecmp_l
      34  # endif
      35  # define TOLOWER(Ch) __tolower_l ((Ch), loc)
      36  #endif
      37  
      38  #ifdef USE_IN_EXTENDED_LOCALE_MODEL
      39  # define LOCALE_PARAM , locale_t loc
      40  #else
      41  # define LOCALE_PARAM
      42  #endif
      43  
      44  /* Compare no more than N characters of S1 and S2,
      45     ignoring case, returning less than, equal to or
      46     greater than zero if S1 is lexicographically less
      47     than, equal to or greater than S2.  */
      48  int
      49  __strncasecmp (const char *s1, const char *s2, size_t n LOCALE_PARAM)
      50  {
      51  #if defined _LIBC && !defined USE_IN_EXTENDED_LOCALE_MODEL
      52    locale_t loc = _NL_CURRENT_LOCALE;
      53  #endif
      54    const unsigned char *p1 = (const unsigned char *) s1;
      55    const unsigned char *p2 = (const unsigned char *) s2;
      56    int result;
      57  
      58    if (p1 == p2 || n == 0)
      59      return 0;
      60  
      61    while ((result = TOLOWER (*p1) - TOLOWER (*p2++)) == 0)
      62      if (*p1++ == '\0' || --n == 0)
      63        break;
      64  
      65    return result;
      66  }
      67  #ifndef __strncasecmp
      68  weak_alias (__strncasecmp, strncasecmp)
      69  #endif