crypto/rand_extra/forkunsafe.c

/* Copyright (c) 2017, Google Inc.
 *
 * Permission to use, copy, modify, and/or 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. */

#include <openssl/rand.h>

#include <stdlib.h>

#include "../fipsmodule/rand/internal.h"


// g_buffering_enabled is true if fork-unsafe buffering has been enabled.
static int g_buffering_enabled = 0;

// g_lock protects |g_buffering_enabled|.
static struct CRYPTO_STATIC_MUTEX g_lock = CRYPTO_STATIC_MUTEX_INIT;

#if !defined(OPENSSL_WINDOWS)
void RAND_enable_fork_unsafe_buffering(int fd) {
  // We no longer support setting the file-descriptor with this function.
  if (fd != -1) {
    abort();
  }

  CRYPTO_STATIC_MUTEX_lock_write(&g_lock);
  g_buffering_enabled = 1;
  CRYPTO_STATIC_MUTEX_unlock_write(&g_lock);
}
#endif

int rand_fork_unsafe_buffering_enabled(void) {
  CRYPTO_STATIC_MUTEX_lock_read(&g_lock);
  const int ret = g_buffering_enabled;
  CRYPTO_STATIC_MUTEX_unlock_read(&g_lock);
  return ret;
}