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
|
/* See LICENSE file for copyright and license details. */
#include "common.h"
static char reservoir[128U << 10];
static size_t reservoir_off = sizeof(reservoir);
static int random_fd;
static const char *random_fname;
size_t
max_blksize(void)
{
size_t ret = sizeof(reservoir);
while (ret & (ret - 1U))
ret &= ret - 1U;
return ret;
}
void
init_random(int fd, const char *fname)
{
struct stat st;
random_fname = fname;
random_fd = fd;
errno = 0;
if (isatty(random_fd) || errno == EBADF) {
use_builtin_generator:
random_fd = -1;
libsimple_srand();
} else if (fstat(random_fd, &st)) {
if (errno == EBADF)
goto use_builtin_generator;
eprintf("fstat %s:", random_fname);
} else if (S_ISFIFO(st.st_mode) || S_ISCHR(st.st_mode) || S_ISSOCK(st.st_mode)) {
eprintf("%s is of a unsupported inode type (must be TTY, character device, FIFO, or socket)", fname);
}
}
const char *
get_random(size_t needed)
{
size_t off;
ssize_t r;
if (sizeof(reservoir) - reservoir_off >= needed)
return &reservoir[reservoir_off];
if (random_fd < 0) {
libsimple_random_bytes(&libsimple_random_bits, NULL, reservoir, reservoir_off);
reservoir_off = 0;
return reservoir;
}
for (off = 0; off < reservoir_off;) {
r = read(random_fd, &reservoir[off], reservoir_off - off);
if (r <= 0) {
if (!r)
eprintf("random source depleted");
if (errno == EINTR)
continue;
eprintf("read %s:", random_fname);
}
off += (size_t)r;
}
reservoir_off = 0;
return reservoir;
}
void
used_random(ssize_t amount)
{
reservoir_off += (size_t)amount;
}
|
