c3-lang/libbsd/src/arc4random_linux.h

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• Hash : b0ebb0d4
  Author :
  Date : 2019-08-06T23:16:42
  

  build: Use __register_atfork() only if really available
  
  This is a glibc-specific symbol that has no public declaration. But is
  being used by the OpenBSD and this implementation as a hack to avoid
  having to link against the pthread library. This interface is at least
  included in LSB 5.0 [L], and using pthread_atfork() is otherwise
  problematic anyway [P].
  
   [L] <https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/baselib---register-atfork.html>
   [P] <http://austingroupbugs.net/view.php?id=851>
  
  One problem is that we were using it whenever __GLIBC__ is defined,
  which is supposed to be defined only on an actual glibc, but uClibc
  defines that macro, but it does not provide the symbol on its noMMU
  variant.
  
  We add a new configure check that will try to link a program that uses
  that symbol to make sure it is present.
  
  Closes: !2
  Reported-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
  

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• src/arc4random_linux.h

• /*	$OpenBSD: arc4random_linux.h,v 1.11 2016/06/30 12:19:51 bcook 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)
  
  #ifdef HAVE___REGISTER_ATFORK
  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);
  }
  

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