/*      $OpenBSD: mmap_mod.c,v 1.2 2010/06/20 17:56:07 phessler Exp $   */

/*
 * Public domain. 2007, Artur Grabowski <art@openbsd.org>
 */

#include <sys/types.h>
#include <sys/mman.h>
#include <err.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

/*
 * Test a corner case where a pmap can lose mod/ref bits after unmapping
 * and remapping a page.
 */
int
main()
{
        char name[20] = "/tmp/fluff.XXXXXX";
        char *buf, *pat;
        size_t ps;
        int fd;

        ps = getpagesize();

        if ((fd = mkstemp(name)) == -1)
                err(1, "mkstemp");

        if (unlink(name) == -1)
                err(1, "unlink");

        if (ftruncate(fd, ps))
                err(1, "ftruncate");

        if ((pat = malloc(ps)) == NULL)
                err(1, "malloc");

        memset(pat, 'a', ps);

        if (pwrite(fd, pat, ps, 0) != ps)
                err(1, "write");

        buf = mmap(NULL, ps, PROT_READ|PROT_WRITE, MAP_FILE|MAP_SHARED, fd, 0);
        if (buf == MAP_FAILED)
                err(1, "mmap");

        if (*buf != 'a')
                errx(1, "mapped area - no file data ('%c' != 'a')", *buf);

        memset(buf, 'x', ps);

        if (munmap(buf, ps) == -1)
                err(1, "munmap");

        buf = mmap(NULL, ps, PROT_READ|PROT_WRITE, MAP_FILE|MAP_SHARED, fd, 0);
        if (buf == MAP_FAILED)
                err(1, "mmap 2");

        if (*buf != 'x')
                errx(1, "mapped area lost modifications ('%c' != 'x')", *buf);

        if (msync(buf, ps, MS_SYNC) == -1)
                err(1, "msync");

        if (pread(fd, pat, ps, 0) != ps)
                err(1, "pread");

        if (*pat != 'x')
                errx(1, "synced area lost modifications ('%c' != 'x')", *pat);

        return (0);
}