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 <linux/random.h>
31 # include <sys/ioctl.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 _LIBCPP_BEGIN_NAMESPACE_STD
40
41 #if defined(_LIBCPP_USING_GETENTROPY)
42
random_device(const string & __token)43 random_device::random_device(const string& __token) {
44 if (__token != "/dev/urandom")
45 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
46 }
47
~random_device()48 random_device::~random_device() {}
49
operator ()()50 unsigned random_device::operator()() {
51 unsigned r;
52 size_t n = sizeof(r);
53 int err = getentropy(&r, n);
54 if (err)
55 __throw_system_error(errno, "random_device getentropy failed");
56 return r;
57 }
58
59 #elif defined(_LIBCPP_USING_ARC4_RANDOM)
60
61 random_device::random_device(const string&) {}
62
63 random_device::~random_device() {}
64
65 unsigned random_device::operator()() { return arc4random(); }
66
67 #elif defined(_LIBCPP_USING_DEV_RANDOM)
68
69 random_device::random_device(const string& __token) : __f_(open(__token.c_str(), O_RDONLY)) {
70 if (__f_ < 0)
71 __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
72 }
73
74 random_device::~random_device() { close(__f_); }
75
76 unsigned random_device::operator()() {
77 unsigned r;
78 size_t n = sizeof(r);
79 char* p = reinterpret_cast<char*>(&r);
80 while (n > 0) {
81 ssize_t s = read(__f_, p, n);
82 if (s == 0)
83 __throw_system_error(ENOMSG, "random_device got EOF");
84 if (s == -1) {
85 if (errno != EINTR)
86 __throw_system_error(errno, "random_device got an unexpected error");
87 continue;
88 }
89 n -= static_cast<size_t>(s);
90 p += static_cast<size_t>(s);
91 }
92 return r;
93 }
94
95 #elif defined(_LIBCPP_USING_NACL_RANDOM)
96
97 random_device::random_device(const string& __token) {
98 if (__token != "/dev/urandom")
99 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
100 int error = nacl_secure_random_init();
101 if (error)
102 __throw_system_error(error, ("random device failed to open " + __token).c_str());
103 }
104
105 random_device::~random_device() {}
106
107 unsigned random_device::operator()() {
108 unsigned r;
109 size_t n = sizeof(r);
110 size_t bytes_written;
111 int error = nacl_secure_random(&r, n, &bytes_written);
112 if (error != 0)
113 __throw_system_error(error, "random_device failed getting bytes");
114 else if (bytes_written != n)
115 __throw_runtime_error("random_device failed to obtain enough bytes");
116 return r;
117 }
118
119 #elif defined(_LIBCPP_USING_WIN32_RANDOM)
120
121 random_device::random_device(const string& __token) {
122 if (__token != "/dev/urandom")
123 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
124 }
125
126 random_device::~random_device() {}
127
128 unsigned random_device::operator()() {
129 unsigned r;
130 errno_t err = rand_s(&r);
131 if (err)
132 __throw_system_error(err, "random_device rand_s failed.");
133 return r;
134 }
135
136 #elif defined(_LIBCPP_USING_FUCHSIA_CPRNG)
137
138 random_device::random_device(const string& __token) {
139 if (__token != "/dev/urandom")
140 __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
141 }
142
143 random_device::~random_device() {}
144
145 unsigned random_device::operator()() {
146 // Implicitly link against the vDSO system call ABI without
147 // requiring the final link to specify -lzircon explicitly when
148 // statically linking libc++.
149 # pragma comment(lib, "zircon")
150
151 // The system call cannot fail. It returns only when the bits are ready.
152 unsigned r;
153 _zx_cprng_draw(&r, sizeof(r));
154 return r;
155 }
156
157 #else
158 # error "Random device not implemented for this architecture"
159 #endif
160
entropy() const161 double random_device::entropy() const noexcept {
162 #if defined(_LIBCPP_USING_DEV_RANDOM) && defined(RNDGETENTCNT)
163 int ent;
164 if (::ioctl(__f_, RNDGETENTCNT, &ent) < 0)
165 return 0;
166
167 if (ent < 0)
168 return 0;
169
170 if (ent > std::numeric_limits<result_type>::digits)
171 return std::numeric_limits<result_type>::digits;
172
173 return ent;
174 #elif defined(_LIBCPP_USING_ARC4_RANDOM) || defined(_LIBCPP_USING_FUCHSIA_CPRNG)
175 return std::numeric_limits<result_type>::digits;
176 #else
177 return 0;
178 #endif
179 }
180
181 _LIBCPP_END_NAMESPACE_STD
182