/*  $OpenBSD: arc4random_linux.h,v 1.12 2019/07/11 10:37:28 inoguchi Exp $  */

/*

 * Copyright (c) 1996, David Mazieres <dm@uun.org>

 * Copyright (c) 2008, Damien Miller <djm@openbsd.org>

 * Copyright (c) 2013, Markus Friedl <markus@openbsd.org>

 * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org>

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 */

/*

 * Stub functions for portability.

 */

#include <sys/mman.h>

#include <pthread.h>

#include <signal.h>

static pthread_mutex_t arc4random_mtx = PTHREAD_MUTEX_INITIALIZER;

#define _ARC4_LOCK()   pthread_mutex_lock(&arc4random_mtx)

#define _ARC4_UNLOCK() pthread_mutex_unlock(&arc4random_mtx)

#if defined(__GLIBC__) && !(defined(__UCLIBC__) && !defined(__ARCH_USE_MMU__))

extern void *__dso_handle;

extern int __register_atfork(void (*)(void), void(*)(void), void (*)(void), void *);

#define _ARC4_ATFORK(f) __register_atfork(NULL, NULL, (f), __dso_handle)

#else

#define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))

#endif

static inline void

_getentropy_fail(void)

{

  raise(SIGKILL);

}

static volatile sig_atomic_t _rs_forked;

static inline void

_rs_forkhandler(void)

{

  _rs_forked = 1;

}

static inline void

_rs_forkdetect(void)

{

  static pid_t _rs_pid = 0;

  pid_t pid = getpid();

        /* XXX unusual calls to clone() can bypass checks */

  if (_rs_pid == 0 || _rs_pid == 1 || _rs_pid != pid || _rs_forked) {

    _rs_pid = pid;

    _rs_forked = 0;

    if (rs)

      memset(rs, 0, sizeof(*rs));

  }

}

static inline int

_rs_allocate(struct _rs **rsp, struct _rsx **rsxp)

{

  if ((*rsp = mmap(NULL, sizeof(**rsp), PROT_READ|PROT_WRITE,

      MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED)

    return (-1);

  if ((*rsxp = mmap(NULL, sizeof(**rsxp), PROT_READ|PROT_WRITE,

      MAP_ANON|MAP_PRIVATE, -1, 0)) == MAP_FAILED) {

    munmap(*rsp, sizeof(**rsp));

    *rsp = NULL;

    return (-1);

  }

  _ARC4_ATFORK(_rs_forkhandler);

  return (0);

}