// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018 Dmitry Safonov, Arista Networks
 *
 * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
 */

#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "kselftest.h"

#include "vm_util.h"

#define MMAP_SZ         4096

#define BUG_ON(condition, description)                                          \
        do {                                                                    \
                if (condition)                                                  \
                        ksft_exit_fail_msg("[FAIL]\t%s:%d\t%s:%s\n",            \
                                           __func__, __LINE__, (description),   \
                                           strerror(errno));                    \
        } while (0)

#define TESTS_IN_CHILD 2

static void parent_f(int sock, unsigned long *smap, int child)
{
        int status, ret;

        ret = read(sock, &status, sizeof(int));
        BUG_ON(ret <= 0, "read(sock)");

        *smap = 0x22222BAD;
        ret = msync(smap, MMAP_SZ, MS_SYNC);
        BUG_ON(ret, "msync()");

        ret = write(sock, &status, sizeof(int));
        BUG_ON(ret <= 0, "write(sock)");

        waitpid(child, &status, 0);

        /* The ksft macros don't keep counters between processes */
        ksft_cnt.ksft_pass = WEXITSTATUS(status);
        ksft_cnt.ksft_fail = TESTS_IN_CHILD - WEXITSTATUS(status);
}

static int child_f(int sock, unsigned long *smap, int fd)
{
        int ret, buf = 0;

        smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
                        MAP_PRIVATE | MAP_POPULATE, fd, 0);
        BUG_ON(smap == MAP_FAILED, "mmap()");

        BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file");

        ret = write(sock, &buf, sizeof(int));
        BUG_ON(ret <= 0, "write(sock)");

        ret = read(sock, &buf, sizeof(int));
        BUG_ON(ret <= 0, "read(sock)");

        ksft_test_result(*smap != 0x22222BAD, "MAP_POPULATE COW private page\n");
        ksft_test_result(*smap == 0xdeadbabe, "The mapping state\n");

        /* The ksft macros don't keep counters between processes */
        return ksft_cnt.ksft_pass;
}

int main(int argc, char **argv)
{
        int sock[2], child, ret;
        FILE *ftmp;
        unsigned long *smap;

        ksft_print_header();
        ksft_set_plan(TESTS_IN_CHILD);

        ftmp = tmpfile();
        BUG_ON(!ftmp, "tmpfile()");

        ret = ftruncate(fileno(ftmp), MMAP_SZ);
        if (ret < 0 && errno == ENOENT) {
                skip_test_dodgy_fs("ftruncate()");
        }
        BUG_ON(ret, "ftruncate()");

        smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
                        MAP_SHARED, fileno(ftmp), 0);
        BUG_ON(smap == MAP_FAILED, "mmap()");

        *smap = 0xdeadbabe;
        /* Probably unnecessary, but let it be. */
        ret = msync(smap, MMAP_SZ, MS_SYNC);
        BUG_ON(ret, "msync()");

        ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock);
        BUG_ON(ret, "socketpair()");

        child = fork();
        BUG_ON(child == -1, "fork()");

        if (child) {
                ret = close(sock[0]);
                BUG_ON(ret, "close()");

                parent_f(sock[1], smap, child);

                ksft_finished();
        }

        ret = close(sock[1]);
        BUG_ON(ret, "close()");

        return child_f(sock[0], smap, fileno(ftmp));
}