xref: /freebsd/contrib/llvm-project/libcxx/src/random.cpp (revision 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)
1349cc55cSDimitry Andric //===----------------------------------------------------------------------===//
20b57cec5SDimitry Andric //
30b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
40b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
50b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
60b57cec5SDimitry Andric //
70b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
80b57cec5SDimitry Andric 
90b57cec5SDimitry Andric #include <__config>
100b57cec5SDimitry Andric 
110b57cec5SDimitry Andric #if defined(_LIBCPP_USING_WIN32_RANDOM)
120b57cec5SDimitry Andric     // Must be defined before including stdlib.h to enable rand_s().
130b57cec5SDimitry Andric #   define _CRT_RAND_S
140b57cec5SDimitry Andric #endif // defined(_LIBCPP_USING_WIN32_RANDOM)
150b57cec5SDimitry Andric 
16*06c3fb27SDimitry Andric #include <__system_error/system_error.h>
1781ad6265SDimitry Andric #include <limits>
1881ad6265SDimitry Andric #include <random>
190b57cec5SDimitry Andric 
200b57cec5SDimitry Andric #include <errno.h>
210b57cec5SDimitry Andric #include <stdio.h>
220b57cec5SDimitry Andric #include <stdlib.h>
230b57cec5SDimitry Andric 
240b57cec5SDimitry Andric #if defined(_LIBCPP_USING_GETENTROPY)
250b57cec5SDimitry Andric #   include <sys/random.h>
260b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_DEV_RANDOM)
270b57cec5SDimitry Andric #   include <fcntl.h>
280b57cec5SDimitry Andric #   include <unistd.h>
29e8d8bef9SDimitry Andric #   if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>)
30e8d8bef9SDimitry Andric #       include <sys/ioctl.h>
31e8d8bef9SDimitry Andric #       include <linux/random.h>
32e8d8bef9SDimitry Andric #   endif
330b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_NACL_RANDOM)
340b57cec5SDimitry Andric #   include <nacl/nacl_random.h>
3504eeddc0SDimitry Andric #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
3604eeddc0SDimitry Andric #  include <zircon/syscalls.h>
370b57cec5SDimitry Andric #endif
380b57cec5SDimitry Andric 
390b57cec5SDimitry Andric 
400b57cec5SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD
410b57cec5SDimitry Andric 
420b57cec5SDimitry Andric #if defined(_LIBCPP_USING_GETENTROPY)
430b57cec5SDimitry Andric 
440b57cec5SDimitry Andric random_device::random_device(const string& __token)
450b57cec5SDimitry Andric {
460b57cec5SDimitry Andric     if (__token != "/dev/urandom")
470b57cec5SDimitry Andric         __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
480b57cec5SDimitry Andric }
490b57cec5SDimitry Andric 
500b57cec5SDimitry Andric random_device::~random_device()
510b57cec5SDimitry Andric {
520b57cec5SDimitry Andric }
530b57cec5SDimitry Andric 
540b57cec5SDimitry Andric unsigned
550b57cec5SDimitry Andric random_device::operator()()
560b57cec5SDimitry Andric {
570b57cec5SDimitry Andric     unsigned r;
580b57cec5SDimitry Andric     size_t n = sizeof(r);
590b57cec5SDimitry Andric     int err = getentropy(&r, n);
600b57cec5SDimitry Andric     if (err)
610b57cec5SDimitry Andric         __throw_system_error(errno, "random_device getentropy failed");
620b57cec5SDimitry Andric     return r;
630b57cec5SDimitry Andric }
640b57cec5SDimitry Andric 
650b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_ARC4_RANDOM)
660b57cec5SDimitry Andric 
6704eeddc0SDimitry Andric random_device::random_device(const string&)
680b57cec5SDimitry Andric {
690b57cec5SDimitry Andric }
700b57cec5SDimitry Andric 
710b57cec5SDimitry Andric random_device::~random_device()
720b57cec5SDimitry Andric {
730b57cec5SDimitry Andric }
740b57cec5SDimitry Andric 
750b57cec5SDimitry Andric unsigned
760b57cec5SDimitry Andric random_device::operator()()
770b57cec5SDimitry Andric {
780b57cec5SDimitry Andric     return arc4random();
790b57cec5SDimitry Andric }
800b57cec5SDimitry Andric 
810b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_DEV_RANDOM)
820b57cec5SDimitry Andric 
830b57cec5SDimitry Andric random_device::random_device(const string& __token)
840b57cec5SDimitry Andric     : __f_(open(__token.c_str(), O_RDONLY))
850b57cec5SDimitry Andric {
860b57cec5SDimitry Andric     if (__f_ < 0)
870b57cec5SDimitry Andric         __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
880b57cec5SDimitry Andric }
890b57cec5SDimitry Andric 
900b57cec5SDimitry Andric random_device::~random_device()
910b57cec5SDimitry Andric {
920b57cec5SDimitry Andric     close(__f_);
930b57cec5SDimitry Andric }
940b57cec5SDimitry Andric 
950b57cec5SDimitry Andric unsigned
960b57cec5SDimitry Andric random_device::operator()()
970b57cec5SDimitry Andric {
980b57cec5SDimitry Andric     unsigned r;
990b57cec5SDimitry Andric     size_t n = sizeof(r);
1000b57cec5SDimitry Andric     char* p = reinterpret_cast<char*>(&r);
1010b57cec5SDimitry Andric     while (n > 0)
1020b57cec5SDimitry Andric     {
1030b57cec5SDimitry Andric         ssize_t s = read(__f_, p, n);
1040b57cec5SDimitry Andric         if (s == 0)
1050b57cec5SDimitry Andric             __throw_system_error(ENODATA, "random_device got EOF");
1060b57cec5SDimitry Andric         if (s == -1)
1070b57cec5SDimitry Andric         {
1080b57cec5SDimitry Andric             if (errno != EINTR)
1090b57cec5SDimitry Andric                 __throw_system_error(errno, "random_device got an unexpected error");
1100b57cec5SDimitry Andric             continue;
1110b57cec5SDimitry Andric         }
1120b57cec5SDimitry Andric         n -= static_cast<size_t>(s);
1130b57cec5SDimitry Andric         p += static_cast<size_t>(s);
1140b57cec5SDimitry Andric     }
1150b57cec5SDimitry Andric     return r;
1160b57cec5SDimitry Andric }
1170b57cec5SDimitry Andric 
1180b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_NACL_RANDOM)
1190b57cec5SDimitry Andric 
1200b57cec5SDimitry Andric random_device::random_device(const string& __token)
1210b57cec5SDimitry Andric {
1220b57cec5SDimitry Andric     if (__token != "/dev/urandom")
1230b57cec5SDimitry Andric         __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
1240b57cec5SDimitry Andric     int error = nacl_secure_random_init();
1250b57cec5SDimitry Andric     if (error)
1260b57cec5SDimitry Andric         __throw_system_error(error, ("random device failed to open " + __token).c_str());
1270b57cec5SDimitry Andric }
1280b57cec5SDimitry Andric 
1290b57cec5SDimitry Andric random_device::~random_device()
1300b57cec5SDimitry Andric {
1310b57cec5SDimitry Andric }
1320b57cec5SDimitry Andric 
1330b57cec5SDimitry Andric unsigned
1340b57cec5SDimitry Andric random_device::operator()()
1350b57cec5SDimitry Andric {
1360b57cec5SDimitry Andric     unsigned r;
1370b57cec5SDimitry Andric     size_t n = sizeof(r);
1380b57cec5SDimitry Andric     size_t bytes_written;
1390b57cec5SDimitry Andric     int error = nacl_secure_random(&r, n, &bytes_written);
1400b57cec5SDimitry Andric     if (error != 0)
1410b57cec5SDimitry Andric         __throw_system_error(error, "random_device failed getting bytes");
1420b57cec5SDimitry Andric     else if (bytes_written != n)
1430b57cec5SDimitry Andric         __throw_runtime_error("random_device failed to obtain enough bytes");
1440b57cec5SDimitry Andric     return r;
1450b57cec5SDimitry Andric }
1460b57cec5SDimitry Andric 
1470b57cec5SDimitry Andric #elif defined(_LIBCPP_USING_WIN32_RANDOM)
1480b57cec5SDimitry Andric 
1490b57cec5SDimitry Andric random_device::random_device(const string& __token)
1500b57cec5SDimitry Andric {
1510b57cec5SDimitry Andric     if (__token != "/dev/urandom")
1520b57cec5SDimitry Andric         __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
1530b57cec5SDimitry Andric }
1540b57cec5SDimitry Andric 
1550b57cec5SDimitry Andric random_device::~random_device()
1560b57cec5SDimitry Andric {
1570b57cec5SDimitry Andric }
1580b57cec5SDimitry Andric 
1590b57cec5SDimitry Andric unsigned
1600b57cec5SDimitry Andric random_device::operator()()
1610b57cec5SDimitry Andric {
1620b57cec5SDimitry Andric     unsigned r;
1630b57cec5SDimitry Andric     errno_t err = rand_s(&r);
1640b57cec5SDimitry Andric     if (err)
1650b57cec5SDimitry Andric         __throw_system_error(err, "random_device rand_s failed.");
1660b57cec5SDimitry Andric     return r;
1670b57cec5SDimitry Andric }
1680b57cec5SDimitry Andric 
16904eeddc0SDimitry Andric #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
17004eeddc0SDimitry Andric 
17104eeddc0SDimitry Andric random_device::random_device(const string& __token) {
17204eeddc0SDimitry Andric   if (__token != "/dev/urandom")
17304eeddc0SDimitry Andric     __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
17404eeddc0SDimitry Andric }
17504eeddc0SDimitry Andric 
17604eeddc0SDimitry Andric random_device::~random_device() {}
17704eeddc0SDimitry Andric 
17804eeddc0SDimitry Andric unsigned random_device::operator()() {
17904eeddc0SDimitry Andric   // Implicitly link against the vDSO system call ABI without
18004eeddc0SDimitry Andric   // requiring the final link to specify -lzircon explicitly when
18104eeddc0SDimitry Andric   // statically linking libc++.
18204eeddc0SDimitry Andric #  pragma comment(lib, "zircon")
18304eeddc0SDimitry Andric 
18404eeddc0SDimitry Andric   // The system call cannot fail.  It returns only when the bits are ready.
18504eeddc0SDimitry Andric   unsigned r;
18604eeddc0SDimitry Andric   _zx_cprng_draw(&r, sizeof(r));
18704eeddc0SDimitry Andric   return r;
18804eeddc0SDimitry Andric }
18904eeddc0SDimitry Andric 
1900b57cec5SDimitry Andric #else
1910b57cec5SDimitry Andric #error "Random device not implemented for this architecture"
1920b57cec5SDimitry Andric #endif
1930b57cec5SDimitry Andric 
1940b57cec5SDimitry Andric double
195fe6060f1SDimitry Andric random_device::entropy() const noexcept
1960b57cec5SDimitry Andric {
197e8d8bef9SDimitry Andric #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
198e8d8bef9SDimitry Andric   int ent;
199e8d8bef9SDimitry Andric   if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
2000b57cec5SDimitry Andric     return 0;
201e8d8bef9SDimitry Andric 
202e8d8bef9SDimitry Andric   if (ent < 0)
203e8d8bef9SDimitry Andric     return 0;
204e8d8bef9SDimitry Andric 
205e8d8bef9SDimitry Andric   if (ent > std::numeric_limits<result_type>::digits)
206e8d8bef9SDimitry Andric     return std::numeric_limits<result_type>::digits;
207e8d8bef9SDimitry Andric 
208e8d8bef9SDimitry Andric   return ent;
2093a9a9c0cSDimitry Andric #elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)
210e8d8bef9SDimitry Andric   return std::numeric_limits<result_type>::digits;
211e8d8bef9SDimitry Andric #else
212e8d8bef9SDimitry Andric   return 0;
213e8d8bef9SDimitry Andric #endif
2140b57cec5SDimitry Andric }
2150b57cec5SDimitry Andric 
2160b57cec5SDimitry Andric _LIBCPP_END_NAMESPACE_STD
217