1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
/* Written in 2018 by David Blackman and Sebastiano Vigna (vigna@acm.org)
To the extent possible under law, the author has dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.
See <http://creativecommons.org/publicdomain/zero/1.0/>. */
#include "git2_util.h"
#include "rand.h"
#include "runtime.h"
#if defined(GIT_RAND_GETENTROPY)
# include <sys/random.h>
#endif
#if defined(GIT_WIN32)
# include <wincrypt.h>
#endif
static uint64_t state[4];
static git_mutex state_lock;
typedef union {
double f;
uint64_t d;
} bits;
#if defined(GIT_WIN32)
GIT_INLINE(int) getseed(uint64_t *seed)
{
HCRYPTPROV provider;
SYSTEMTIME systemtime;
FILETIME filetime, idletime, kerneltime, usertime;
bits convert;
if (CryptAcquireContext(&provider, 0, 0, PROV_RSA_FULL,
CRYPT_VERIFYCONTEXT|CRYPT_SILENT)) {
BOOL success = CryptGenRandom(provider, sizeof(uint64_t), (void *)seed);
CryptReleaseContext(provider, 0);
if (success)
return 0;
}
GetSystemTime(&systemtime);
if (!SystemTimeToFileTime(&systemtime, &filetime)) {
git_error_set(GIT_ERROR_OS, "could not get time for random seed");
return -1;
}
/* Fall-through: generate a seed from the time and system state */
*seed = 0;
*seed |= ((uint64_t)filetime.dwLowDateTime << 32);
*seed |= ((uint64_t)filetime.dwHighDateTime);
GetSystemTimes(&idletime, &kerneltime, &usertime);
*seed ^= ((uint64_t)idletime.dwLowDateTime << 32);
*seed ^= ((uint64_t)kerneltime.dwLowDateTime);
*seed ^= ((uint64_t)usertime.dwLowDateTime << 32);
*seed ^= ((uint64_t)idletime.dwHighDateTime);
*seed ^= ((uint64_t)kerneltime.dwHighDateTime << 12);
*seed ^= ((uint64_t)usertime.dwHighDateTime << 24);
*seed ^= ((uint64_t)GetCurrentProcessId() << 32);
*seed ^= ((uint64_t)GetCurrentThreadId() << 48);
convert.f = git__timer(); *seed ^= (convert.d);
/* Mix in the addresses of some functions and variables */
*seed ^= (((uint64_t)((uintptr_t)seed) << 32));
*seed ^= (((uint64_t)((uintptr_t)&errno)));
return 0;
}
#else
GIT_INLINE(int) getseed(uint64_t *seed)
{
struct timeval tv;
double loadavg[3];
bits convert;
int fd;
# if defined(GIT_RAND_GETENTROPY)
GIT_UNUSED((fd = 0));
if (getentropy(seed, sizeof(uint64_t)) == 0)
return 0;
# else
/*
* Try to read from /dev/urandom; most modern systems will have
* this, but we may be chrooted, etc, so it's not a fatal error
*/
if ((fd = open("/dev/urandom", O_RDONLY)) >= 0) {
ssize_t ret = read(fd, seed, sizeof(uint64_t));
close(fd);
if (ret == (ssize_t)sizeof(uint64_t))
return 0;
}
# endif
/* Fall-through: generate a seed from the time and system state */
if (gettimeofday(&tv, NULL) < 0) {
git_error_set(GIT_ERROR_OS, "could get time for random seed");
return -1;
}
*seed = 0;
*seed |= ((uint64_t)tv.tv_usec << 40);
*seed |= ((uint64_t)tv.tv_sec);
*seed ^= ((uint64_t)getpid() << 48);
*seed ^= ((uint64_t)getppid() << 32);
*seed ^= ((uint64_t)getpgid(0) << 28);
*seed ^= ((uint64_t)getsid(0) << 16);
*seed ^= ((uint64_t)getuid() << 8);
*seed ^= ((uint64_t)getgid());
# if defined(GIT_RAND_GETLOADAVG)
getloadavg(loadavg, 3);
convert.f = loadavg[0]; *seed ^= (convert.d >> 36);
convert.f = loadavg[1]; *seed ^= (convert.d);
convert.f = loadavg[2]; *seed ^= (convert.d >> 16);
# else
GIT_UNUSED(loadavg[0]);
# endif
convert.f = git__timer(); *seed ^= (convert.d);
/* Mix in the addresses of some variables */
*seed ^= ((uint64_t)((size_t)((void *)seed)) << 32);
*seed ^= ((uint64_t)((size_t)((void *)&errno)));
return 0;
}
#endif
static void git_rand_global_shutdown(void)
{
git_mutex_free(&state_lock);
}
int git_rand_global_init(void)
{
uint64_t seed = 0;
if (git_mutex_init(&state_lock) < 0 || getseed(&seed) < 0)
return -1;
if (!seed) {
git_error_set(GIT_ERROR_INTERNAL, "failed to generate random seed");
return -1;
}
git_rand_seed(seed);
git_runtime_shutdown_register(git_rand_global_shutdown);
return 0;
}
/*
* This is splitmix64. xoroshiro256** uses 256 bit seed; this is used
* to generate 256 bits of seed from the given 64, per the author's
* recommendation.
*/
GIT_INLINE(uint64_t) splitmix64(uint64_t *in)
{
uint64_t z;
*in += 0x9e3779b97f4a7c15;
z = *in;
z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
return z ^ (z >> 31);
}
void git_rand_seed(uint64_t seed)
{
uint64_t mixer;
mixer = seed;
git_mutex_lock(&state_lock);
state[0] = splitmix64(&mixer);
state[1] = splitmix64(&mixer);
state[2] = splitmix64(&mixer);
state[3] = splitmix64(&mixer);
git_mutex_unlock(&state_lock);
}
/* This is xoshiro256** 1.0, one of our all-purpose, rock-solid
generators. It has excellent (sub-ns) speed, a state (256 bits) that is
large enough for any parallel application, and it passes all tests we
are aware of.
For generating just floating-point numbers, xoshiro256+ is even faster.
The state must be seeded so that it is not everywhere zero. If you have
a 64-bit seed, we suggest to seed a splitmix64 generator and use its
output to fill s. */
GIT_INLINE(uint64_t) rotl(const uint64_t x, int k) {
return (x << k) | (x >> (64 - k));
}
uint64_t git_rand_next(void) {
uint64_t t, result;
git_mutex_lock(&state_lock);
result = rotl(state[1] * 5, 7) * 9;
t = state[1] << 17;
state[2] ^= state[0];
state[3] ^= state[1];
state[1] ^= state[2];
state[0] ^= state[3];
state[2] ^= t;
state[3] = rotl(state[3], 45);
git_mutex_unlock(&state_lock);
return result;
}
|
