1#define _DEFAULT_SOURCE
2#include <unistd.h>
3#include <sys/random.h>
4#include <pthread.h>
5#include <errno.h>
6
7int getentropy(void *buffer, size_t len)
8{
9 int cs, ret = 0;
10 char *pos = buffer;
11
12 if (len > 256) {
13 errno = EIO;
14 return -1;
15 }
16
17 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
18
19 while (len) {
20 ret = getrandom(pos, len, 0);
21 if (ret < 0) {
22 if (errno == EINTR) continue;
23 else break;
24 }
25 pos += ret;
26 len -= ret;
27 ret = 0;
28 }
29
30 pthread_setcancelstate(cs, 0);
31
32 return ret;
33}
34