/*-
 * Copyright (c) 2023 The FreeBSD Foundation
 *
 * This software was developed by Robert Clausecker <fuz@FreeBSD.org>
 * under sponsorship from the FreeBSD Foundation.
 *
 * 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 AUTHOR 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 AUTHOR 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 <sys/cdefs.h>

#include <atf-c.h>
#include <dlfcn.h>
#include <string.h>

int (*volatile strncmp_fn)(const char *, const char *, size_t);

static void
alignment_testcase(char *a, char *b, int want, size_t len)
{
        int res;

        res = strncmp_fn(a, b, len);
        ATF_CHECK_MSG(want == (res > 0) - (res < 0),
            "strcmp(%p \"%s\", %p \"%s\", %zu) = %d != %d",
            (void *)a, a, (void *)b, b, len, res, want);
}

static void
check_strncmp_alignments(char a[], char b[],
    size_t a_off, size_t b_off, size_t len, size_t pos)
{
        char *a_str, *b_str, a_orig, b_orig;

        a[a_off] = '\0';
        b[b_off] = '\0';

        a_str = a + a_off + 1;
        b_str = b + b_off + 1;

        a_str[len] = '\0';
        b_str[len] = '\0';
        a_str[len+1] = 'A';
        b_str[len+1] = 'B';

        a_orig = a_str[pos];
        b_orig = b_str[pos];

        alignment_testcase(a_str, b_str, 0, len + 16);
        alignment_testcase(a_str, b_str, 0, len + 1);
        alignment_testcase(a_str, b_str, 0, len);

        if (pos < len) {
                a_str[pos] = '\0';
                alignment_testcase(a_str, b_str, -1, len + 16);
                alignment_testcase(a_str, b_str, -1, len + 1);
                alignment_testcase(a_str, b_str, -1, len);
                alignment_testcase(a_str, b_str, -1, pos + 1);
                alignment_testcase(a_str, b_str, 0, pos);
                a_str[pos] = a_orig;

                b_str[pos] = '\0';
                alignment_testcase(a_str, b_str, 1, len + 16);
                alignment_testcase(a_str, b_str, 1, len + 1);
                alignment_testcase(a_str, b_str, 1, len);
                alignment_testcase(a_str, b_str, 1, pos + 1);
                alignment_testcase(a_str, b_str, 0, pos);
                b_str[pos] = b_orig;
        }

        a_str[pos] = 'X';
        alignment_testcase(a_str, b_str, 1, len + 16);
        alignment_testcase(a_str, b_str, 0, pos);
        alignment_testcase(a_str, b_str, 1, pos + 1);
        if (pos < len) {
                alignment_testcase(a_str, b_str, 1, len);
                alignment_testcase(a_str, b_str, 1, len + 1);
        }
        a_str[pos] = a_orig;

        b_str[pos] = 'X';
        alignment_testcase(a_str, b_str, -1, len + 16);
        alignment_testcase(a_str, b_str, 0, pos);
        alignment_testcase(a_str, b_str, -1, pos + 1);
        if (pos < len) {
                alignment_testcase(a_str, b_str, -1, len);
                alignment_testcase(a_str, b_str, -1, len + 1);
        }
        b_str[pos] = b_orig;

        a[a_off] = '-';
        b[b_off] = '-';
        a_str[len] = '-';
        b_str[len] = '-';
        a_str[len+1] = '-';
        b_str[len+1] = '-';
}

ATF_TC(strncmp_alignments);
ATF_TC_HEAD(strncmp_alignments, tc)
{
        atf_tc_set_md_var(tc, "descr", "Test strncmp(3) with various alignments");
}

ATF_TC_BODY(strncmp_alignments, tc)
{
        size_t a_off, b_off, len, pos;
        char a[64+16+16+3], b[64+16+16+3];

        memset(a, '-', sizeof(a));
        memset(b, '-', sizeof(b));
        a[sizeof(a) - 1] = '\0';
        b[sizeof(b) - 1] = '\0';

        for (a_off = 0; a_off < 16; a_off++)
                for (b_off = 0; b_off < 16; b_off++)
                        for (len = 1; len <= 64; len++)
                                for (pos = 0; pos <= len; pos++)
                                        check_strncmp_alignments(a, b, a_off, b_off, len, pos);
}

ATF_TC(strncmp_null);
ATF_TC_HEAD(strncmp_null, tc)
{
        atf_tc_set_md_var(tc, "descr", "Test strncmp(3) with null pointers");
}

ATF_TC_BODY(strncmp_null, tc)
{
        alignment_testcase(NULL, NULL, 0, 0);
}

ATF_TP_ADD_TCS(tp)
{
        void *dl_handle;

        dl_handle = dlopen(NULL, RTLD_LAZY);
        strncmp_fn = dlsym(dl_handle, "test_strncmp");
        if (strncmp_fn == NULL)
                strncmp_fn = strncmp;

        ATF_TP_ADD_TC(tp, strncmp_alignments);
        ATF_TP_ADD_TC(tp, strncmp_null);

        return atf_no_error();
}