v
Зеркало из https://github.com/vlang/v
1// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
2// Use of this source code is governed by an MIT license
3// that can be found in the LICENSE file.
4
5module rand
6
7#include <sys/random.h>
8
9fn C.getrandom(p &u8, n usize, flags u32) int
10
11const read_batch_size = 256
12
13// read returns an array of `bytes_needed` random bytes read from the OS.
14pub fn read(bytes_needed int) ![]u8 {
15mut buffer := unsafe { malloc_noscan(bytes_needed) }
16mut bytes_read := 0
17mut remaining_bytes := bytes_needed
18// getrandom syscall wont block if requesting <= 256 bytes
19for bytes_read < bytes_needed {
20batch_size := if remaining_bytes > read_batch_size {
21read_batch_size
22} else {
23remaining_bytes
24}
25rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
26if rbytes == -1 {
27unsafe { free(buffer) }
28return &ReadError{}
29}
30bytes_read += rbytes
31}
32return unsafe { buffer.vbytes(bytes_needed) }
33}
34
35fn v_getrandom(bytes_needed int, buffer voidptr) int {
36if bytes_needed > read_batch_size {
37panic('getrandom() dont request more than ${read_batch_size} bytes at once.')
38}
39return C.getrandom(buffer, bytes_needed, 0)
40}
41