ladybird/Libraries/LibC/strings.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <assert.h>
#include <ctype.h>
#include <strings.h>

extern "C" {

static char foldcase(char ch)
{
    if (isalpha(ch))
        return tolower(ch);
    return ch;
}

int strcasecmp(const char* s1, const char* s2)
{
    for (; foldcase(*s1) == foldcase(*s2); ++s1, ++s2) {
        if (*s1 == 0)
            return 0;
    }
    return foldcase(*(const unsigned char*)s1) < foldcase(*(const unsigned char*)s2) ? -1 : 1;
}

int strncasecmp(const char* s1, const char* s2, size_t n)
{
    if (!n)
        return 0;
    do {
        if (foldcase(*s1) != foldcase(*s2++))
            return foldcase(*(const unsigned char*)s1) - foldcase(*(const unsigned char*)--s2);
        if (*s1++ == 0)
            break;
    } while (--n);
    return 0;
}
}