/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2020 Peter Holm <pho@FreeBSD.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 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/types.h>
#include <sys/resource.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/wait.h>

#include <vm/vm_param.h>

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define INCARNATIONS 32

static unsigned long size, original;
static int runtime, utime;

void
usage(void)
{
        fprintf(stderr, "Usage: %s [-d delay] [-p pct] [-t runtime] "
            "[-v]\n",
            getprogname());
        exit(1);
}

static unsigned long
usermem(void)
{
        unsigned long mem;
        size_t nlen = sizeof(mem);

        if (sysctlbyname("hw.usermem", &mem, &nlen, NULL, 0) == -1)
                err(1, "sysctlbyname() %s:%d", __FILE__, __LINE__);

#if defined(DEBUG)
        printf("Total free user memory %lu Mb\n",
                mem / 1024 / 1024);
#endif

        return (mem);
}
static int64_t
swap(void)
{
        struct xswdev xsw;
        size_t mibsize, size;
        int mib[16], n;
        int64_t sz;

        mibsize = sizeof mib / sizeof mib[0];
        sz = 0;

        if (sysctlnametomib("vm.swap_info", mib, &mibsize) == -1)
                err(1, "sysctlnametomib()");

        for (n = 0; ; ++n) {
                mib[mibsize] = n;
                size = sizeof xsw;
                if (sysctl(mib, mibsize + 1, &xsw, &size, NULL, 0) == -1)
                        break;
                if (xsw.xsw_version != XSWDEV_VERSION)
                        errx(1, "xswdev version mismatch");
                sz = sz + xsw.xsw_nblks - xsw.xsw_used;
        }
        if (errno != ENOENT)
                err(1, "sysctl()");

#if defined(DEBUG)
        printf("Total free swap space %jd Mb\n",
                sz * getpagesize() / 1024 / 1024);
#endif

        return (sz * getpagesize());
}

static void
setup(void)
{
        struct rlimit rlp;

        size = size / INCARNATIONS;
        original = size;
        if (size == 0)
                errx(1, "Argument too small");

        if (getrlimit(RLIMIT_DATA, &rlp) < 0)
                err(1,"getrlimit");
        rlp.rlim_cur -= 1024 * 1024;

        if (size > (unsigned long)rlp.rlim_cur)
                size = rlp.rlim_cur;

#if 0
        printf("setup: pid %d. Total %luMb\n",
                getpid(), size / 1024 / 1024 * INCARNATIONS);
#endif

        if (size == 0)
                errx(1, "Argument too small");

        return;
}

static int
test(void)
{
        volatile char *c;
        int page;
        unsigned long i, j;
        time_t start;

        c = malloc(size);
        while (c == NULL) {
                size -=  1024 * 1024;
                c = malloc(size);
        }
        if (size != original)
                printf("Malloc size changed from %ld Mb to %ld Mb\n",
                    original / 1024 / 1024, size / 1024 / 1024);
        page = getpagesize();
        start = time(NULL);
        while ((time(NULL) - start) < runtime) {
                i = j = 0;
                while (i < size) {
                        c[i] = 1;
                        i += page;
                        if ((time(NULL) - start) >= runtime)
                                break;
                        usleep(utime);
                }
        }
        free((void *)c);

        _exit(0);
}

int
main(int argc, char **argv)
{
        int64_t s;
        pid_t pids[INCARNATIONS];
        unsigned long u;
        int ch, i, pct, verbose;

        s = swap();
        u = usermem();

        runtime = 120;  /* 2 minutes */
        utime = 1000;   /* 0.001 sec */
        verbose = 0;
        if (s == 0)
                pct = 80;
        else
                pct = 101;
        while ((ch = getopt(argc, argv, "d:p:t:v")) != -1) {
                switch(ch) {
                case 'd':       /* delay in usec */
                        if (sscanf(optarg, "%d", &utime) != 1)
                                usage();
                        break;
                case 'p':       /* % of usermem */
                        if (sscanf(optarg, "%d", &pct) != 1)
                                usage();
                        break;
                case 't':       /* runtime in sec*/
                        if (sscanf(optarg, "%d", &runtime) != 1)
                                usage();
                        break;
                case 'v':       /* verbose*/
                        verbose = 1;
                        break;
                default:
                        usage();
                }
        }

        if (s == 0 &&  pct > 80)
                errx(1, "pct range with no swap is 0-80");
        size = u / 100 * pct;
        if (verbose == 1)
                fprintf(stderr, "pct = %d, sleep = %d usec, size = %lumb\n",
                    pct, utime, size / 1024 / 1024);
        setup();

        for (i = 0; i < INCARNATIONS; i++)
                if ((pids[i] = fork()) == 0)
                        test();

        for (i = 0; i < INCARNATIONS; i++)
                if (waitpid(pids[i], NULL, 0) != pids[i])
                        err(1, "paitpid(%d)", pids[i]);

        return (0);
}