1 //===-------------------------- random.cpp --------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #if defined(_WIN32)
11 // Must be defined before including stdlib.h to enable rand_s().
12 #define _CRT_RAND_S
13 #include <stdio.h>
14 #endif
15 
16 #include "random"
17 #include "system_error"
18 
19 #ifdef __sun__
20 #define rename solaris_headers_are_broken
21 #endif
22 #if !defined(_WIN32)
23 #include <fcntl.h>
24 #include <unistd.h>
25 #endif // defined(_WIN32)
26 #include <errno.h>
27 
28 _LIBCPP_BEGIN_NAMESPACE_STD
29 
30 #if defined(_WIN32)
random_device(const string &)31 random_device::random_device(const string&)
32 {
33 }
34 
~random_device()35 random_device::~random_device()
36 {
37 }
38 
39 unsigned
operator ()()40 random_device::operator()()
41 {
42     unsigned r;
43     errno_t err = rand_s(&r);
44     if (err)
45         __throw_system_error(err, "random_device rand_s failed.");
46     return r;
47 }
48 #else
49 random_device::random_device(const string& __token)
50     : __f_(open(__token.c_str(), O_RDONLY))
51 {
52     if (__f_ < 0)
53         __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
54 }
55 
56 random_device::~random_device()
57 {
58     close(__f_);
59 }
60 
61 unsigned
62 random_device::operator()()
63 {
64     unsigned r;
65     size_t n = sizeof(r);
66     char* p = reinterpret_cast<char*>(&r);
67     while (n > 0)
68     {
69         ssize_t s = read(__f_, p, n);
70         if (s == 0)
71             __throw_system_error(ENODATA, "random_device got EOF");
72         if (s == -1)
73         {
74             if (errno != EINTR)
75                 __throw_system_error(errno, "random_device got an unexpected error");
76             continue;
77         }
78         n -= static_cast<size_t>(s);
79         p += static_cast<size_t>(s);
80     }
81     return r;
82 }
83 #endif // defined(_WIN32)
84 
85 double
entropy() const86 random_device::entropy() const _NOEXCEPT
87 {
88     return 0;
89 }
90 
91 _LIBCPP_END_NAMESPACE_STD
92