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/throw_system_error.h>
17 #include <limits>
18 #include <random>
19 #include <string>
20
21 #include <errno.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24
25 #if defined(_LIBCPP_USING_GETENTROPY)
26 # include <sys/random.h>
27 #elif defined(_LIBCPP_USING_DEV_RANDOM)
28 # include <fcntl.h>
29 # include <unistd.h>
30 # if __has_include(<sys/ioctl.h>) && __has_include(<linux/random.h>)
31 # include <linux/random.h>
32 # include <sys/ioctl.h>
33 # endif
34 #elif defined(_LIBCPP_USING_NACL_RANDOM)
35 # include <nacl/nacl_random.h>
36 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
37 # include <zircon/syscalls.h>
38 #endif
39
40 _LIBCPP_BEGIN_NAMESPACE_STD
41
42 #if defined(_LIBCPP_USING_GETENTROPY)
43
random_device(const string & __token)44 random_device::random_device(const string& __token) {
45 if (__token != "/dev/urandom")
46 std::__throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
47 }
48
~random_device()49 random_device::~random_device() {}
50
operator ()()51 unsigned random_device::operator()() {
52 unsigned r;
53 size_t n = sizeof(r);
54 int err = getentropy(&r, n);
55 if (err)
56 std::__throw_system_error(errno, "random_device getentropy failed");
57 return r;
58 }
59
60 #elif defined(_LIBCPP_USING_ARC4_RANDOM)
61
62 random_device::random_device(const string&) {}
63
64 random_device::~random_device() {}
65
66 unsigned random_device::operator()() { return arc4random(); }
67
68 #elif defined(_LIBCPP_USING_DEV_RANDOM)
69
70 random_device::random_device(const string& __token) : __f_(open(__token.c_str(), O_RDONLY)) {
71 if (__f_ < 0)
72 std::__throw_system_error(errno, ("random_device failed to open " + __token).c_str());
73 }
74
75 random_device::~random_device() { close(__f_); }
76
77 unsigned random_device::operator()() {
78 unsigned r;
79 size_t n = sizeof(r);
80 char* p = reinterpret_cast<char*>(&r);
81 while (n > 0) {
82 ssize_t s = read(__f_, p, n);
83 if (s == 0)
84 std::__throw_system_error(ENOMSG, "random_device got EOF");
85 if (s == -1) {
86 if (errno != EINTR)
87 std::__throw_system_error(errno, "random_device got an unexpected error");
88 continue;
89 }
90 n -= static_cast<size_t>(s);
91 p += static_cast<size_t>(s);
92 }
93 return r;
94 }
95
96 #elif defined(_LIBCPP_USING_NACL_RANDOM)
97
98 random_device::random_device(const string& __token) {
99 if (__token != "/dev/urandom")
100 std::__throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
101 int error = nacl_secure_random_init();
102 if (error)
103 std::__throw_system_error(error, ("random device failed to open " + __token).c_str());
104 }
105
106 random_device::~random_device() {}
107
108 unsigned random_device::operator()() {
109 unsigned r;
110 size_t n = sizeof(r);
111 size_t bytes_written;
112 int error = nacl_secure_random(&r, n, &bytes_written);
113 if (error != 0)
114 std::__throw_system_error(error, "random_device failed getting bytes");
115 else if (bytes_written != n)
116 std::__throw_runtime_error("random_device failed to obtain enough bytes");
117 return r;
118 }
119
120 #elif defined(_LIBCPP_USING_WIN32_RANDOM)
121
122 random_device::random_device(const string& __token) {
123 if (__token != "/dev/urandom")
124 std::__throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
125 }
126
127 random_device::~random_device() {}
128
129 unsigned random_device::operator()() {
130 unsigned r;
131 errno_t err = rand_s(&r);
132 if (err)
133 std::__throw_system_error(err, "random_device rand_s failed.");
134 return r;
135 }
136
137 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
138
139 random_device::random_device(const string& __token) {
140 if (__token != "/dev/urandom")
141 std::__throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
142 }
143
144 random_device::~random_device() {}
145
146 unsigned random_device::operator()() {
147 // Implicitly link against the vDSO system call ABI without
148 // requiring the final link to specify -lzircon explicitly when
149 // statically linking libc++.
150 # pragma comment(lib, "zircon")
151
152 // The system call cannot fail. It returns only when the bits are ready.
153 unsigned r;
154 _zx_cprng_draw(&r, sizeof(r));
155 return r;
156 }
157
158 #else
159 # error "Random device not implemented for this architecture"
160 #endif
161
entropy() const162 double random_device::entropy() const noexcept {
163 #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
164 int ent;
165 if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
166 return 0;
167
168 if (ent < 0)
169 return 0;
170
171 if (ent > std::numeric_limits<result_type>::digits)
172 return std::numeric_limits<result_type>::digits;
173
174 return ent;
175 #elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)
176 return std::numeric_limits<result_type>::digits;
177 #else
178 return 0;
179 #endif
180 }
181
182 _LIBCPP_END_NAMESPACE_STD
183