blocxx
RandomNumber.cpp
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32
33
39#include "blocxx/BLOCXX_config.h"
41#include "blocxx/Assertion.hpp"
42#include "blocxx/ThreadOnce.hpp"
43#include "blocxx/Mutex.hpp"
44#include "blocxx/MutexLock.hpp"
46#include <fstream>
47#include <sys/types.h>
48
49#ifdef BLOCXX_HAVE_UNISTD_H
50#include <unistd.h>
51#endif
52
53#ifdef BLOCXX_HAVE_SYS_TIME_H
54#include <sys/time.h>
55#endif
56
57#include <stdlib.h>
58#include <time.h>
59
60namespace BLOCXX_NAMESPACE
61{
62
64namespace
65{
66OnceFlag guard = BLOCXX_ONCE_INIT;
67unsigned int seed = 0;
68}
69
71RandomNumber::RandomNumber(Int32 lowVal, Int32 highVal)
72: m_lowVal(lowVal), m_highVal(highVal)
73{
74 if (lowVal > highVal)
75 {
76 m_lowVal = highVal;
77 m_highVal = lowVal;
78 }
79 callOnce(guard, &initRandomness);
80}
81
83void
85{
86#ifdef BLOCXX_WIN32
87 time_t timeval = ::time(NULL);
88 seed = timeval;
89#else
90 // use the time as part of the seed
91 struct timeval tv;
92 gettimeofday(&tv, 0);
93 // try to get something from the kernel
94 std::ifstream infile("/dev/urandom", std::ios::in);
95 if (!infile)
96 {
97 infile.open("/dev/random", std::ios::in);
98 }
99 // don't initialize this, we may get random stack
100 // junk in case infile isn't usable.
101 unsigned int dev_rand_input;
102 if (infile)
103 {
104 infile.read(reinterpret_cast<char*>(&dev_rand_input), sizeof(dev_rand_input));
105 infile.close();
106 }
107 // Build the seed. Take into account our pid and uid.
108 seed = dev_rand_input ^ (getpid() << 16) ^ getuid() ^ tv.tv_sec ^ tv.tv_usec;
109#endif
110#ifdef BLOCXX_HAVE_SRANDOM
111 srandom(seed);
112#else
113 srand(seed);
114#endif
115}
116
118void
120{
121 // Do nothing. This function is so that RandomNumber has the same interface as CryptographicRandomNumber
122}
123
124namespace
125{
127}
129Int32
131{
132 MutexLock lock(g_guard);
133#ifdef BLOCXX_HAVE_RANDOM
134 return m_lowVal + (random() % (m_highVal - m_lowVal + 1));
135#else
136 return m_lowVal + (rand() % (m_highVal - m_lowVal + 1));
137#endif
138}
139
140} // end namespace BLOCXX_NAMESPACE
141
#define BLOCXX_GLOBAL_MUTEX_INIT()
This class can be used to store a global variable that is lazily initialized in a thread safe manner.
RandomNumber(Int32 lowVal=0, Int32 highVal=RAND_MAX)
Taken from RFC 1321.
void BLOCXX_COMMON_API callOnce(OnceFlag &flag, FuncT F)
The first time callOnce is called with a given onceFlag argument, it calls func with no argument and ...