arc4random.h revision 6209c81d40e2b4e129a28bda3259150d79d507e8 
1/*	$OpenBSD: arc4random_linux.h,v 1.7 2014/07/20 20:51:13 bcook Exp $	*/
2
3/*
4 * Copyright (c) 1996, David Mazieres <dm@uun.org>
5 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
6 * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>
7 *
8 * Permission to use, copy, modify, and distribute this software for any
9 * purpose with or without fee is hereby granted, provided that the above
10 * copyright notice and this permission notice appear in all copies.
11 *
12 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 */
20
21/*
22 * Stub functions for portability.
23 */
24
25#include <sys/mman.h>
26
27#include <pthread.h>
28#include <signal.h>
29
30// Android gets these from "thread_private.h".
31#include "thread_private.h"
32//static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;
33//#define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)
34//#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)
35
36#ifdef __GLIBC__
37extern void *__dso_handle;
38extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);
39#define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)
40#else
41#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
42#endif
43
44static inline void
45_getentropy_fail(void)
46{
47	raise(SIGKILL);
48}
49
50static volatile sig_atomic_t _rs_forked;
51
52static inline void
53_rs_forkhandler(void)
54{
55	_rs_forked = 1;
56}
57
58static inline void
59_rs_forkdetect(void)
60{
61	static pid_t _rs_pid = 0;
62	pid_t pid = getpid();
63
64	if (_rs_pid == 0 || _rs_pid != pid || _rs_forked) {
65		_rs_pid = pid;
66		_rs_forked = 0;
67		if (rs)
68			memset(rs, 0, sizeof(*rs));
69	}
70}
71
72static inline int
73_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
74{
75	if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,
76	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)
77		return (-1);
78
79	if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,
80	    MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {
81		munmap(*rsxp, sizeof(**rsxp));
82		return (-1);
83	}
84
85	_ARC4_ATFORK(_rs_forkhandler);
86	return (0);
87}
88