//===----------------------------------------------------------------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#include <__config>

#if defined(_LIBCPP_USING_WIN32_RANDOM)

    // Must be defined before including stdlib.h to enable rand_s().

#   define _CRT_RAND_S

#endif // defined(_LIBCPP_USING_WIN32_RANDOM)

#include <limits>

#include <random>

#include <system_error>

#if defined(__sun__)

#   define rename solaris_headers_are_broken

#endif // defined(__sun__)

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#if defined(_LIBCPP_USING_GETENTROPY)

#   include <sys/random.h>

#elif defined(_LIBCPP_USING_DEV_RANDOM)

#   include <fcntl.h>

#   include <unistd.h>

#   if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>)

#       include <sys/ioctl.h>

#       include <linux/random.h>

#   endif

#elif defined(_LIBCPP_USING_NACL_RANDOM)

#   include <nacl/nacl_random.h>

#elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)

#  include <zircon/syscalls.h>

#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if defined(_LIBCPP_USING_GETENTROPY)

random_device::random_device(const string& __token)

{

    if (__token != "/dev/urandom")

        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());

}

random_device::~random_device()

{

}

unsigned

random_device::operator()()

{

    unsigned r;

    size_t n = sizeof(r);

    int err = getentropy(&r, n);

    if (err)

        __throw_system_error(errno, "random_device getentropy failed");

    return r;

}

#elif defined(_LIBCPP_USING_ARC4_RANDOM)

random_device::random_device(const string&)

{

}

random_device::~random_device()

{

}

unsigned

random_device::operator()()

{

    return arc4random();

}

#elif defined(_LIBCPP_USING_DEV_RANDOM)

random_device::random_device(const string& __token)

    : __f_(open(__token.c_str(), O_RDONLY))

{

    if (__f_ < 0)

        __throw_system_error(errno, ("random_device failed to open " + __token).c_str());

}

random_device::~random_device()

{

    close(__f_);

}

unsigned

random_device::operator()()

{

    unsigned r;

    size_t n = sizeof(r);

    char* p = reinterpret_cast<char*>(&r);

    while (n > 0)

    {

        ssize_t s = read(__f_, p, n);

        if (s == 0)

            __throw_system_error(ENODATA, "random_device got EOF");

        if (s == -1)

        {

            if (errno != EINTR)

                __throw_system_error(errno, "random_device got an unexpected error");

            continue;

        }

        n -= static_cast<size_t>(s);

        p += static_cast<size_t>(s);

    }

    return r;

}

#elif defined(_LIBCPP_USING_NACL_RANDOM)

random_device::random_device(const string& __token)

{

    if (__token != "/dev/urandom")

        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());

    int error = nacl_secure_random_init();

    if (error)

        __throw_system_error(error, ("random device failed to open " + __token).c_str());

}

random_device::~random_device()

{

}

unsigned

random_device::operator()()

{

    unsigned r;

    size_t n = sizeof(r);

    size_t bytes_written;

    int error = nacl_secure_random(&r, n, &bytes_written);

    if (error != 0)

        __throw_system_error(error, "random_device failed getting bytes");

    else if (bytes_written != n)

        __throw_runtime_error("random_device failed to obtain enough bytes");

    return r;

}

#elif defined(_LIBCPP_USING_WIN32_RANDOM)

random_device::random_device(const string& __token)

{

    if (__token != "/dev/urandom")

        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());

}

random_device::~random_device()

{

}

unsigned

random_device::operator()()

{

    unsigned r;

    errno_t err = rand_s(&r);

    if (err)

        __throw_system_error(err, "random_device rand_s failed.");

    return r;

}

#elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)

random_device::random_device(const string& __token) {

  if (__token != "/dev/urandom")

    __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());

}

random_device::~random_device() {}

unsigned random_device::operator()() {

  // Implicitly link against the vDSO system call ABI without

  // requiring the final link to specify -lzircon explicitly when

  // statically linking libc++.

#  pragma comment(lib, "zircon")

  // The system call cannot fail.  It returns only when the bits are ready.

  unsigned r;

  _zx_cprng_draw(&r, sizeof(r));

  return r;

}

#else

#error "Random device not implemented for this architecture"

#endif

double

random_device::entropy() const noexcept

{

#if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)

  int ent;

  if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)

    return 0;

  if (ent < 0)

    return 0;

  if (ent > std::numeric_limits<result_type>::digits)

    return std::numeric_limits<result_type>::digits;

  return ent;

#elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)

  return std::numeric_limits<result_type>::digits;

#else

  return 0;

#endif

}

_LIBCPP_END_NAMESPACE_STD