text: // Copyright (c) 2009-2014 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #if defined(HAVE_CONFIG_H)
  #include "config/futurexco-config.h"
  #endif
  
  #include <cstddef>
  
  #if defined(HAVE_SYS_SELECT_H)
  #include <sys/select.h>
  #endif
  
  extern "C" void* memcpy(void* a, const void* b, size_t c);
  void* memcpy_int(void* a, const void* b, size_t c)
  {
      return memcpy(a, b, c);
  }
  
  namespace
  {
  // trigger: Use the memcpy_int wrapper which calls our internal memcpy.
  //   A direct call to memcpy may be optimized away by the compiler.
  // test: Fill an array with a sequence of integers. memcpy to a new empty array.
  //   Verify that the arrays are equal. Use an odd size to decrease the odds of
  //   the call being optimized away.
  template <unsigned int T>
  bool sanity_test_memcpy()
  {
      unsigned int memcpy_test[T];
      unsigned int memcpy_verify[T] = {};
      for (unsigned int i = 0; i != T; ++i)
          memcpy_test[i] = i;
  
      memcpy_int(memcpy_verify, memcpy_test, sizeof(memcpy_test));
  
      for (unsigned int i = 0; i != T; ++i) {
          if (memcpy_verify[i] != i)
              return false;
      }
      return true;
  }
  
  #if defined(HAVE_SYS_SELECT_H)
  // trigger: Call FD_SET to trigger __fdelt_chk. FORTIFY_SOURCE must be defined
  //   as >0 and optimizations must be set to at least -O2.
  // test: Add a file descriptor to an empty fd_set. Verify that it has been
  //   correctly added.
  bool sanity_test_fdelt()
  {
      fd_set fds;
      FD_ZERO(&fds);
      FD_SET(0, &fds);
      return FD_ISSET(0, &fds);
  }
  #endif
  
  } // anon namespace
  
  bool glibc_sanity_test()
  {
  #if defined(HAVE_SYS_SELECT_H)
      if (!sanity_test_fdelt())
          return false;
  #endif
      return sanity_test_memcpy<1025>();
  }
  