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/* $OpenBSD: dtors.c,v 1.5 2003/09/02 23:52:16 david Exp $ */
/*
* Written by Artur Grabowski <art@openbsd.org>, 2002 Public Domain.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
#include <unistd.h>
void zap(void) __attribute__((destructor));
void *destarea;
#define MAGIC "destructed"
void
zap(void)
{
memcpy(destarea, MAGIC, sizeof(MAGIC));
}
/*
* XXX - horrible abuse of exit(3), minherit(2) and fork(2).
*/
int
main(int argc, char **argv)
{
int status, ch;
int fallthru = 0;
while ((ch = getopt(argc, argv, "f")) != -1) {
switch(ch) {
case 'f':
fallthru = 1;
break;
default:
fprintf(stderr, "Usage: dtors [-f]\n");
exit(1);
}
}
destarea = mmap(NULL, getpagesize(), PROT_READ|PROT_WRITE, MAP_ANON,
-1, 0);
if (destarea == MAP_FAILED)
err(1, "mmap");
if (minherit(destarea, getpagesize(), MAP_INHERIT_SHARE) != 0)
err(1, "minherit");
memset(destarea, 0, sizeof(MAGIC));
switch(fork()) {
case -1:
err(1, "fork");
case 0:
/*
* Yes, it's exit(), not _exit(). We _want_ to run the
* destructors in the child.
*/
if (fallthru)
return (0);
else
exit(0);
}
if (wait(&status) < 0)
err(1, "wait"); /* XXX uses exit() */
if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
err(1, "child error"); /* XXX uses exit() */
_exit(memcmp(destarea, MAGIC, sizeof(MAGIC)) != 0);
}
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