text: /* Copyright (c) 2016, 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 <CCryptoBoringSSL_rand.h>
  
  #if defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE)
  
  #include <string.h>
  
  #include <CCryptoBoringSSL_chacha.h>
  
  #include "../internal.h"
  #include "../fipsmodule/rand/internal.h"
  
  
  // g_num_calls is the number of calls to |CRYPTO_sysrand| that have occurred.
  //
  // This is intentionally not thread-safe. If the fuzzer mode is ever used in a
  // multi-threaded program, replace this with a thread-local. (A mutex would not
  // be deterministic.)
  static uint64_t g_num_calls = 0;
  
  void RAND_reset_for_fuzzing(void) { g_num_calls = 0; }
  
  void CRYPTO_sysrand(uint8_t *out, size_t requested) {
    static const uint8_t kZeroKey[32];
  
    uint8_t nonce[12];
    OPENSSL_memset(nonce, 0, sizeof(nonce));
    OPENSSL_memcpy(nonce, &g_num_calls, sizeof(g_num_calls));
  
    OPENSSL_memset(out, 0, requested);
    CRYPTO_chacha_20(out, out, requested, kZeroKey, nonce, 0);
    g_num_calls++;
  }
  
  void CRYPTO_sysrand_for_seed(uint8_t *out, size_t requested) {
    CRYPTO_sysrand(out, requested);
  }
  
  void CRYPTO_sysrand_if_available(uint8_t *out, size_t requested) {
    CRYPTO_sysrand(out, requested);
  }
  
  #endif  // BORINGSSL_UNSAFE_DETERMINISTIC_MODE
  