/*-
 * Copyright (c) 2009 David Schultz <das@FreeBSD.org>
 * Copyright (c) 2023, 2024 The FreeBSD Foundation
 * All rights reserved.
 *
 * Portions of this software were 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 <sys/param.h>
#include <sys/mman.h>
#include <assert.h>
#include <dlfcn.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <atf-c.h>

void *(*memccpy_fn)(void *restrict, const void *restrict, int, size_t);

static char *
makebuf(size_t len, int guard_at_end)
{
        char *buf;
        size_t alloc_size, page_size;

        page_size = getpagesize();
        alloc_size = roundup2(len, page_size) + page_size;

        buf = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
        assert(buf);
        if (guard_at_end) {
                assert(mprotect(buf + alloc_size - page_size, page_size, PROT_NONE) == 0);
                return (buf + alloc_size - page_size - len);
        } else {
                assert(mprotect(buf, page_size, PROT_NONE) == 0);
                return (buf + page_size);
        }
}

static void
freebuf(char * buf, size_t len, int guard_at_end)
{
        size_t alloc_size, page_size;

        page_size = getpagesize();
        alloc_size = roundup2(len, page_size) + page_size;

        if (guard_at_end)
                munmap(buf + len + page_size - alloc_size, alloc_size);
        else
                munmap(buf - page_size, alloc_size);
}

static void
test_memccpy(const char *s, size_t size)
{
        char *src, *dst, *expected;
        size_t bufsize, x;
        int i, j;

        for (i = 0; i <= 1; i++) {
                for (j = 0; j <= 1; j++) {
                        for (bufsize = 0; bufsize <= size + 32; bufsize++) {
                                dst = makebuf(bufsize, j);
                                if (bufsize < size) {
                                        src = makebuf(bufsize, i);
                                        memcpy(src, s, bufsize);
                                        expected = NULL;
                                } else {
                                        src = makebuf(size, i);
                                        memcpy(src, s, size);
                                        expected = dst + size;
                                }

                                memset(dst, 'X', bufsize);
                                assert(memccpy_fn(dst, src, s[size-1], bufsize) == expected);
                                assert(memcmp(src, dst, MIN(bufsize, size)) == 0);
                                for (x = size; x < bufsize; x++)
                                        assert(dst[x] == 'X');

                                freebuf(dst, bufsize, j);
                                freebuf(src, bufsize < size ? bufsize : size, i);
                        }
                }
        }
}

static void
test_sentinel(char *dest, char *src, size_t destlen, size_t srclen)
{
        size_t i, effective_len;
        void *res, *wantres;
        const char *fail = NULL;
        char terminator;

        for (i = 0; i < srclen; i++)
                /* src will never include (){} */
                src[i] = '0' + i;

        /* source sentinels: not to be copied */
        src[-1] = '(';
        src[srclen] = ')';

        memset(dest, '\xee', destlen);

        /* destination sentinels: not to be touched */
        dest[-1] = '{';
        dest[destlen] = '}';

        effective_len = srclen < destlen ? srclen : destlen;
        wantres = srclen <= destlen ? dest + srclen : NULL;
        terminator = src[srclen-1];
        res = memccpy_fn(dest, src, terminator, destlen);

        if (dest[-1] != '{')
                fail = "start sentinel overwritten";
        else if (dest[destlen] != '}')
                fail = "end sentinel overwritten";
        else if (res != wantres)
                fail = "incorrect return value";
        else if (destlen > 0 && memcmp(src, dest, effective_len) != 0)
                fail = "string not copied correctly";
        else for (i = srclen; i < destlen; i++)
                if (dest[i] != '\xee') {
                        fail = "buffer mutilated behind string";
                        break;
                }

        if (fail)
                atf_tc_fail_nonfatal("%s\n"
                    "memccpy(%p \"%s\", %p \"%s\", %u '%c', %zu) = %p (want %p)\n",
                    fail, dest, dest, src, src, terminator, terminator, destlen, res, wantres);
}

ATF_TC_WITHOUT_HEAD(null);
ATF_TC_BODY(null, tc)
{
        ATF_CHECK_EQ(memccpy_fn(NULL, "foo", 42, 0), NULL);
}

ATF_TC(zero_extension);
ATF_TC_HEAD(zero_extension, tc)
{
        atf_tc_set_md_var(tc, "descr",
            "Ensure the upper bits of the terminator are ignored");
}
ATF_TC_BODY(zero_extension, tc)
{
        int mask = -1 & ~UCHAR_MAX;
        char buf[16];

        memset(buf, 0xcc, sizeof(buf));
        ATF_CHECK_EQ(memccpy(buf, "foobar", 'r', sizeof(buf)), buf + sizeof("foobar") - 1);
        ATF_CHECK_EQ(memcmp(buf, "foobar", sizeof("foobar") - 1), 0);

        memset(buf, 0xcc, sizeof(buf));
        ATF_CHECK_EQ(memccpy(buf, "foobar", mask | 'r', sizeof(buf)), buf + sizeof("foobar") - 1);
        ATF_CHECK_EQ(memcmp(buf, "foobar", sizeof("foobar") - 1), 0);
}

ATF_TC_WITHOUT_HEAD(bounds);
ATF_TC_BODY(bounds, tc)
{
        size_t i;
        char buf[64];

        for (i = 0; i < sizeof(buf) - 1; i++) {
                buf[i] = ' ' + i;
                buf[i+1] = '\0';
                test_memccpy(buf, i + 1);
        }
}

ATF_TC_WITHOUT_HEAD(alignments);
ATF_TC_BODY(alignments, tc)
{
        size_t srcalign, destalign, srclen, destlen;
        char src[15+2+64]; /* 15 offsets + 64 max length + sentinels */
        char dest[15+2+64]; /* 15 offsets + 64 max length + sentinels */

        for (srcalign = 0; srcalign < 16; srcalign++)
                for (destalign = 0; destalign < 16; destalign++)
                        for (srclen = 1; srclen < 64; srclen++)
                                for (destlen = 0; destlen < 64; destlen++)
                                        test_sentinel(dest+destalign+1,
                                            src+srcalign+1, destlen, srclen);
}

ATF_TP_ADD_TCS(tp)
{
        void *dl_handle;

        dl_handle = dlopen(NULL, RTLD_LAZY);
        memccpy_fn = dlsym(dl_handle, "test_memccpy");
        if (memccpy_fn == NULL)
                memccpy_fn = memccpy;

        ATF_TP_ADD_TC(tp, null);
        ATF_TP_ADD_TC(tp, zero_extension);
        ATF_TP_ADD_TC(tp, bounds);
        ATF_TP_ADD_TC(tp, alignments);

        return (atf_no_error());
}