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      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 (at) uun.org>
      5  * Copyright (c) 2008, Damien Miller <djm (at) openbsd.org>
      6  * Copyright (c) 2013, Markus Friedl <markus (at) 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__
     37 extern void *__dso_handle;
     38 extern 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 
     44 static inline void
     45 _getentropy_fail(void)
     46 {
     47 	raise(SIGKILL);
     48 }
     49 
     50 static volatile sig_atomic_t _rs_forked;
     51 
     52 static inline void
     53 _rs_forkhandler(void)
     54 {
     55 	_rs_forked = 1;
     56 }
     57 
     58 static 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 
     72 static 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