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/* strncasecmp.c -- case insensitive string comparator
Copyright (C) 1998-1999, 2005-2007, 2009-2020 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <string.h>
#include <ctype.h>
#include <limits.h>
#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
/* Compare no more than N bytes of strings S1 and S2, ignoring case,
returning less than, equal to or greater than zero if S1 is
lexicographically less than, equal to or greater than S2.
Note: This function cannot work correctly in multibyte locales. */
int
strncasecmp (const char *s1, const char *s2, size_t n)
{
register const unsigned char *p1 = (const unsigned char *) s1;
register const unsigned char *p2 = (const unsigned char *) s2;
unsigned char c1, c2;
if (p1 == p2 || n == 0)
return 0;
do
{
c1 = TOLOWER (*p1);
c2 = TOLOWER (*p2);
if (--n == 0 || c1 == '\0')
break;
++p1;
++p2;
}
while (c1 == c2);
if (UCHAR_MAX <= INT_MAX)
return c1 - c2;
else
/* On machines where 'char' and 'int' are types of the same size, the
difference of two 'unsigned char' values - including the sign bit -
doesn't fit in an 'int'. */
return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
}
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