1 //===-------------------------- random.cpp --------------------------------===//
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 #endif
40
41
42 _LIBCPP_BEGIN_NAMESPACE_STD
43
44 #if defined(_LIBCPP_USING_GETENTROPY)
45
random_device(const string & __token)46 random_device::random_device(const string& __token)
47 {
48 if (__token != "/dev/urandom")
49 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
50 }
51
~random_device()52 random_device::~random_device()
53 {
54 }
55
56 unsigned
operator ()()57 random_device::operator()()
58 {
59 unsigned r;
60 size_t n = sizeof(r);
61 int err = getentropy(&r, n);
62 if (err)
63 __throw_system_error(errno, "random_device getentropy failed");
64 return r;
65 }
66
67 #elif defined(_LIBCPP_USING_ARC4_RANDOM)
68
69 random_device::random_device(const string& __token)
70 {
71 if (__token != "/dev/urandom")
72 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
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 #else
174 #error "Random device not implemented for this architecture"
175 #endif
176
177 double
entropy() const178 random_device::entropy() const noexcept
179 {
180 #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
181 int ent;
182 if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
183 return 0;
184
185 if (ent < 0)
186 return 0;
187
188 if (ent > std::numeric_limits<result_type>::digits)
189 return std::numeric_limits<result_type>::digits;
190
191 return ent;
192 #elif defined(__OpenBSD__)
193 return std::numeric_limits<result_type>::digits;
194 #else
195 return 0;
196 #endif
197 }
198
199 _LIBCPP_END_NAMESPACE_STD
200