Files
mfem/general/hash.cpp
T
Will Pazner 7714f8f42c Move Hasher to hash_util.hpp, add TupleHasher
Remove specializations of std::hash for non-user-defined types.
2025-08-26 15:31:14 -07:00

84 lines
2.2 KiB
C++

// Copyright (c) 2010-2025, Lawrence Livermore National Security, LLC. Produced
// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
// LICENSE and NOTICE for details. LLNL-CODE-806117.
//
// This file is part of the MFEM library. For more information and source code
// availability visit https://mfem.org.
//
// MFEM is free software; you can redistribute it and/or modify it under the
// terms of the BSD-3 license. We welcome feedback and contributions, see file
// CONTRIBUTING.md for details.
#include "hash.hpp"
#ifdef MFEM_USE_GNUTLS
#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>
#if GNUTLS_VERSION_NUMBER >= 0x020a00
#define HAVE_GNUTLS_HASH_FUNCTIONS
#endif
#endif
namespace mfem
{
#ifdef HAVE_GNUTLS_HASH_FUNCTIONS
constexpr gnutls_digest_algorithm_t HASH_ALGORITHM = GNUTLS_DIG_SHA256;
#endif
HashFunction::HashFunction()
{
#ifndef HAVE_GNUTLS_HASH_FUNCTIONS
hash_data = nullptr;
#else
gnutls_hash_init((gnutls_hash_hd_t*)(&hash_data), HASH_ALGORITHM);
#endif
}
HashFunction::~HashFunction()
{
#ifdef HAVE_GNUTLS_HASH_FUNCTIONS
gnutls_hash_deinit((gnutls_hash_hd_t)hash_data, nullptr);
#endif
}
void HashFunction::HashBuffer(const void *buffer, size_t num_bytes)
{
#ifndef HAVE_GNUTLS_HASH_FUNCTIONS
MFEM_CONTRACT_VAR(buffer);
MFEM_CONTRACT_VAR(num_bytes);
#else
gnutls_hash((gnutls_hash_hd_t)hash_data, buffer, num_bytes);
#endif
}
inline constexpr char to_hex(unsigned char u)
{
return (u < 10) ? '0' + u : (u < 16) ? 'a' + (u - 10) : '?';
}
std::string HashFunction::GetHash() const
{
std::string hash;
#ifndef MFEM_USE_GNUTLS
hash = "(GnuTLS is required for hashing)";
#elif !defined (HAVE_GNUTLS_HASH_FUNCTIONS)
hash = "(Old GnuTLS version: does not support hashing)";
#else
constexpr unsigned max_hash_len = 64;
unsigned char hash_bytes[max_hash_len];
unsigned hash_len = gnutls_hash_get_len(HASH_ALGORITHM);
MFEM_VERIFY(hash_len <= max_hash_len, "internal error");
hash.reserve(2*hash_len);
gnutls_hash_output((gnutls_hash_hd_t)hash_data, hash_bytes);
for (unsigned i = 0; i < hash_len; i++)
{
hash += to_hex(hash_bytes[i]/16);
hash += to_hex(hash_bytes[i]%16);
}
#endif
return hash;
}
} // namespace mfem