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/* $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);
}
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