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 <limits>
17 #include <random>
18 #include <system_error>
19
20 #if defined(__sun__)
21 # define rename solaris_headers_are_broken
22 #endif // defined(__sun__)
23
24 #include <errno.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27
28 #if defined(_LIBCPP_USING_GETENTROPY)
29 # include <sys/random.h>
30 #elif defined(_LIBCPP_USING_DEV_RANDOM)
31 # include <fcntl.h>
32 # include <unistd.h>
33 # if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>)
34 # include <sys/ioctl.h>
35 # include <linux/random.h>
36 # endif
37 #elif defined(_LIBCPP_USING_NACL_RANDOM)
38 # include <nacl/nacl_random.h>
39 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
40 # include <zircon/syscalls.h>
41 #endif
42
43
44 _LIBCPP_BEGIN_NAMESPACE_STD
45
46 #if defined(_LIBCPP_USING_GETENTROPY)
47
random_device(const string & __token)48 random_device::random_device(const string& __token)
49 {
50 if (__token != "/dev/urandom")
51 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
52 }
53
~random_device()54 random_device::~random_device()
55 {
56 }
57
58 unsigned
operator ()()59 random_device::operator()()
60 {
61 unsigned r;
62 size_t n = sizeof(r);
63 int err = getentropy(&r, n);
64 if (err)
65 __throw_system_error(errno, "random_device getentropy failed");
66 return r;
67 }
68
69 #elif defined(_LIBCPP_USING_ARC4_RANDOM)
70
71 random_device::random_device(const string&)
72 {
73 }
74
75 random_device::~random_device()
76 {
77 }
78
79 unsigned
80 random_device::operator()()
81 {
82 return arc4random();
83 }
84
85 #elif defined(_LIBCPP_USING_DEV_RANDOM)
86
87 random_device::random_device(const string& __token)
88 : __f_(open(__token.c_str(), O_RDONLY))
89 {
90 if (__f_ < 0)
91 __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
92 }
93
94 random_device::~random_device()
95 {
96 close(__f_);
97 }
98
99 unsigned
100 random_device::operator()()
101 {
102 unsigned r;
103 size_t n = sizeof(r);
104 char* p = reinterpret_cast<char*>(&r);
105 while (n > 0)
106 {
107 ssize_t s = read(__f_, p, n);
108 if (s == 0)
109 __throw_system_error(ENODATA, "random_device got EOF");
110 if (s == -1)
111 {
112 if (errno != EINTR)
113 __throw_system_error(errno, "random_device got an unexpected error");
114 continue;
115 }
116 n -= static_cast<size_t>(s);
117 p += static_cast<size_t>(s);
118 }
119 return r;
120 }
121
122 #elif defined(_LIBCPP_USING_NACL_RANDOM)
123
124 random_device::random_device(const string& __token)
125 {
126 if (__token != "/dev/urandom")
127 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
128 int error = nacl_secure_random_init();
129 if (error)
130 __throw_system_error(error, ("random device failed to open " + __token).c_str());
131 }
132
133 random_device::~random_device()
134 {
135 }
136
137 unsigned
138 random_device::operator()()
139 {
140 unsigned r;
141 size_t n = sizeof(r);
142 size_t bytes_written;
143 int error = nacl_secure_random(&r, n, &bytes_written);
144 if (error != 0)
145 __throw_system_error(error, "random_device failed getting bytes");
146 else if (bytes_written != n)
147 __throw_runtime_error("random_device failed to obtain enough bytes");
148 return r;
149 }
150
151 #elif defined(_LIBCPP_USING_WIN32_RANDOM)
152
153 random_device::random_device(const string& __token)
154 {
155 if (__token != "/dev/urandom")
156 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
157 }
158
159 random_device::~random_device()
160 {
161 }
162
163 unsigned
164 random_device::operator()()
165 {
166 unsigned r;
167 errno_t err = rand_s(&r);
168 if (err)
169 __throw_system_error(err, "random_device rand_s failed.");
170 return r;
171 }
172
173 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
174
175 random_device::random_device(const string& __token) {
176 if (__token != "/dev/urandom")
177 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
178 }
179
180 random_device::~random_device() {}
181
182 unsigned random_device::operator()() {
183 // Implicitly link against the vDSO system call ABI without
184 // requiring the final link to specify -lzircon explicitly when
185 // statically linking libc++.
186 # pragma comment(lib, "zircon")
187
188 // The system call cannot fail. It returns only when the bits are ready.
189 unsigned r;
190 _zx_cprng_draw(&r, sizeof(r));
191 return r;
192 }
193
194 #else
195 #error "Random device not implemented for this architecture"
196 #endif
197
198 double
entropy() const199 random_device::entropy() const noexcept
200 {
201 #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
202 int ent;
203 if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
204 return 0;
205
206 if (ent < 0)
207 return 0;
208
209 if (ent > std::numeric_limits<result_type>::digits)
210 return std::numeric_limits<result_type>::digits;
211
212 return ent;
213 #elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)
214 return std::numeric_limits<result_type>::digits;
215 #else
216 return 0;
217 #endif
218 }
219
220 _LIBCPP_END_NAMESPACE_STD
221