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/* Case-insensitive string comparison function for unibyte locales.
Copyright (C) 1998-1999, 2005-2007, 2009-2026 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <strings.h>
#include <ctype.h>
#include <limits.h>
/* 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;
if (p1 == p2 || n == 0)
return 0;
for (;; p1++, p2++)
{
unsigned char c1 = tolower (*p1);
unsigned char c2 = tolower (*p2);
if (--n == 0 || c1 == '\0' || 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 _GL_CMP (c1, c2);
}
}
}
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