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/*
* libexplain - Explain errno values returned by libc functions
* Copyright (C) 2009, 2012 Peter Miller
* Written by Peter Miller <pmiller@opensource.org.au>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libexplain/ac/stdlib.h>
#include <libexplain/ac/string.h>
#include <libexplain/ac/sys/mman.h>
#include <libexplain/ac/unistd.h>
static int
mincore_says_is_in_core(void *data, size_t data_size)
{
size_t page_size;
size_t lo_pages;
size_t hi_pages;
void *lo;
void *hi;
size_t bsize;
size_t vec_bytes;
unsigned char vec[100];
page_size = getpagesize();
lo_pages = (size_t)data / page_size;
hi_pages = ((size_t)data + data_size + page_size - 1) / page_size;
lo = (void *)(lo_pages * page_size);
hi = (void *)(hi_pages * page_size);
bsize = (char *)hi - (char *)lo;
vec_bytes = hi_pages - lo_pages;
if (vec_bytes > sizeof(vec))
return 0;
return (mincore(lo, bsize, (void *)vec) >= 0);
}
static int
mincore_detects_stack_ok(void)
{
char dummy[1000];
/* set memory to force copy-on-write, of necessary */
memset(dummy, 0xAA, sizeof(dummy));
return mincore_says_is_in_core(dummy, sizeof(dummy));
}
static int
mincore_detects_heap_ok(void)
{
size_t dummy_size;
char *dummy;
int result;
dummy_size = 1000;
dummy = malloc(dummy_size);
/* set memory to force copy-on-write, of necessary */
memset(dummy, 0xAA, dummy_size);
result = mincore_says_is_in_core(dummy, dummy_size);
free(dummy);
return result;
}
int
main(int argc, char **argv)
{
int ok;
(void)argc;
(void)argv;
/*
* The mincore function is highly variable in implementation between
* Unix implementations, and even from one release to another of a
* single brand of Unix. So we have to check.
*
* "[The mincore function] is probably still more os-specific and, in
* fact, architecture specific, than you think. This deep in the VM live
* daemons." -- Daniel Pittman <daniel@rimspace.net>
*/
ok = mincore_detects_stack_ok() && mincore_detects_heap_ok();
return (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}
/* vim: set ts=8 sw=4 et : */
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