arc4random_test.c revision 227522 
1/*-
2 * Copyright (c) 2011 David Schultz
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/tools/regression/lib/libc/gen/test-arc4random.c 227522 2011-11-15 05:55:15Z das $");
29
30#include <sys/mman.h>
31#include <sys/types.h>
32#include <sys/wait.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#include <unistd.h>
37
38/*
39 * BUFSIZE is the number of bytes of rc4 output to compare.  The probability
40 * that this test fails spuriously is 2**(-BUFSIZE * 8).
41 */
42#define	BUFSIZE		8
43
44/*
45 * Test whether arc4random_buf() returns the same sequence of bytes in both
46 * parent and child processes.  (Hint: It shouldn't.)
47 */
48int main(int argc, char *argv[]) {
49	struct shared_page {
50		char parentbuf[BUFSIZE];
51		char childbuf[BUFSIZE];
52	} *page;
53	pid_t pid;
54	char c;
55
56	printf("1..1\n");
57
58	page = mmap(NULL, sizeof(struct shared_page), PROT_READ | PROT_WRITE,
59		    MAP_ANON | MAP_SHARED, -1, 0);
60	if (page == MAP_FAILED) {
61		printf("fail 1 - mmap\n");
62		exit(1);
63	}
64
65	arc4random_buf(&c, 1);
66
67	pid = fork();
68	if (pid < 0) {
69		printf("fail 1 - fork\n");
70		exit(1);
71	}
72	if (pid == 0) {
73		/* child */
74		arc4random_buf(page->childbuf, BUFSIZE);
75		exit(0);
76	} else {
77		/* parent */
78		int status;
79		arc4random_buf(page->parentbuf, BUFSIZE);
80		wait(&status);
81	}
82	if (memcmp(page->parentbuf, page->childbuf, BUFSIZE) == 0) {
83		printf("fail 1 - sequences are the same\n");
84		exit(1);
85	}
86
87	printf("ok 1 - sequences are different\n");
88	exit(0);
89}
90