blob: 14b286175cac7cbcc0c9770c635f305b97c937bd (
plain)
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
|
#ifndef RAND_BYTES_H
#define RAND_BYTES_H
#include <stddef.h> // size_t
#include <sys/random.h> // getentropy()
#include <err.h> // errx()
// Fill `buf` with `len` random bytes using `getentropy()`.
//
// Prints an error message to standard error and exits with a non-zero
// error code if `len` random bytes could not be read.
static void rand_bytes(void * const buf, size_t len) {
uint8_t *u8 = (uint8_t*) buf;
// the maximum length for getentropy() is 256 bytes, so split requests
// for more than 256 bytes into multiple calls to `getentropy()`.
while (len > 256) {
// read 256 bytes, check for error
if (getentropy(u8, 256) == -1) {
// print error message, exit with error
errx(-1, "getentropy() failed");
}
// increment pointer, decrement length
u8 += 256;
len -= 256;
}
// read remaining bytes, check for error
if (getentropy(u8, len) == -1) {
// print error message, exit with error
errx(-1, "getentropy() failed");
}
}
#endif /* RAND_BYTES_H */
|
