1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include <__config> 10 11 #if defined(_LIBCPP_USING_WIN32_RANDOM) 12 // Must be defined before including stdlib.h to enable rand_s(). 13 # define _CRT_RAND_S 14 #endif // defined(_LIBCPP_USING_WIN32_RANDOM) 15 16 #include <__system_error/system_error.h> 17 #include <limits> 18 #include <random> 19 20 #include <errno.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 24 #if defined(_LIBCPP_USING_GETENTROPY) 25 # include <sys/random.h> 26 #elif defined(_LIBCPP_USING_DEV_RANDOM) 27 # include <fcntl.h> 28 # include <unistd.h> 29 # if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>) 30 # include <sys/ioctl.h> 31 # include <linux/random.h> 32 # endif 33 #elif defined(_LIBCPP_USING_NACL_RANDOM) 34 # include <nacl/nacl_random.h> 35 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG) 36 # include <zircon/syscalls.h> 37 #endif 38 39 40 _LIBCPP_BEGIN_NAMESPACE_STD 41 42 #if defined(_LIBCPP_USING_GETENTROPY) 43 44 random_device::random_device(const string& __token) 45 { 46 if (__token != "/dev/urandom") 47 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); 48 } 49 50 random_device::~random_device() 51 { 52 } 53 54 unsigned 55 random_device::operator()() 56 { 57 unsigned r; 58 size_t n = sizeof(r); 59 int err = getentropy(&r, n); 60 if (err) 61 __throw_system_error(errno, "random_device getentropy failed"); 62 return r; 63 } 64 65 #elif defined(_LIBCPP_USING_ARC4_RANDOM) 66 67 random_device::random_device(const string&) 68 { 69 } 70 71 random_device::~random_device() 72 { 73 } 74 75 unsigned 76 random_device::operator()() 77 { 78 return arc4random(); 79 } 80 81 #elif defined(_LIBCPP_USING_DEV_RANDOM) 82 83 random_device::random_device(const string& __token) 84 : __f_(open(__token.c_str(), O_RDONLY)) 85 { 86 if (__f_ < 0) 87 __throw_system_error(errno, ("random_device failed to open " + __token).c_str()); 88 } 89 90 random_device::~random_device() 91 { 92 close(__f_); 93 } 94 95 unsigned 96 random_device::operator()() 97 { 98 unsigned r; 99 size_t n = sizeof(r); 100 char* p = reinterpret_cast<char*>(&r); 101 while (n > 0) 102 { 103 ssize_t s = read(__f_, p, n); 104 if (s == 0) 105 __throw_system_error(ENODATA, "random_device got EOF"); 106 if (s == -1) 107 { 108 if (errno != EINTR) 109 __throw_system_error(errno, "random_device got an unexpected error"); 110 continue; 111 } 112 n -= static_cast<size_t>(s); 113 p += static_cast<size_t>(s); 114 } 115 return r; 116 } 117 118 #elif defined(_LIBCPP_USING_NACL_RANDOM) 119 120 random_device::random_device(const string& __token) 121 { 122 if (__token != "/dev/urandom") 123 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); 124 int error = nacl_secure_random_init(); 125 if (error) 126 __throw_system_error(error, ("random device failed to open " + __token).c_str()); 127 } 128 129 random_device::~random_device() 130 { 131 } 132 133 unsigned 134 random_device::operator()() 135 { 136 unsigned r; 137 size_t n = sizeof(r); 138 size_t bytes_written; 139 int error = nacl_secure_random(&r, n, &bytes_written); 140 if (error != 0) 141 __throw_system_error(error, "random_device failed getting bytes"); 142 else if (bytes_written != n) 143 __throw_runtime_error("random_device failed to obtain enough bytes"); 144 return r; 145 } 146 147 #elif defined(_LIBCPP_USING_WIN32_RANDOM) 148 149 random_device::random_device(const string& __token) 150 { 151 if (__token != "/dev/urandom") 152 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); 153 } 154 155 random_device::~random_device() 156 { 157 } 158 159 unsigned 160 random_device::operator()() 161 { 162 unsigned r; 163 errno_t err = rand_s(&r); 164 if (err) 165 __throw_system_error(err, "random_device rand_s failed."); 166 return r; 167 } 168 169 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG) 170 171 random_device::random_device(const string& __token) { 172 if (__token != "/dev/urandom") 173 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str()); 174 } 175 176 random_device::~random_device() {} 177 178 unsigned random_device::operator()() { 179 // Implicitly link against the vDSO system call ABI without 180 // requiring the final link to specify -lzircon explicitly when 181 // statically linking libc++. 182 # pragma comment(lib, "zircon") 183 184 // The system call cannot fail. It returns only when the bits are ready. 185 unsigned r; 186 _zx_cprng_draw(&r, sizeof(r)); 187 return r; 188 } 189 190 #else 191 #error "Random device not implemented for this architecture" 192 #endif 193 194 double 195 random_device::entropy() const noexcept 196 { 197 #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT) 198 int ent; 199 if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0) 200 return 0; 201 202 if (ent < 0) 203 return 0; 204 205 if (ent > std::numeric_limits<result_type>::digits) 206 return std::numeric_limits<result_type>::digits; 207 208 return ent; 209 #elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG) 210 return std::numeric_limits<result_type>::digits; 211 #else 212 return 0; 213 #endif 214 } 215 216 _LIBCPP_END_NAMESPACE_STD 217