45 lines
1.1 KiB
V
45 lines
1.1 KiB
V
// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
|
|
// Use of this source code is governed by an MIT license
|
|
// that can be found in the LICENSE file.
|
|
|
|
module rand
|
|
|
|
#include <sys/random.h>
|
|
|
|
fn C.getrandom(p byteptr, n size_t, flags u32) int
|
|
|
|
const (
|
|
read_batch_size = 256
|
|
)
|
|
|
|
pub fn read(bytes_needed int) ?[]byte {
|
|
mut buffer := &byte(0)
|
|
unsafe {
|
|
buffer = malloc(bytes_needed)
|
|
}
|
|
mut bstart := buffer
|
|
mut bytes_read := 0
|
|
mut remaining_bytes := bytes_needed
|
|
// getrandom syscall wont block if requesting <= 256 bytes
|
|
for bytes_read < bytes_needed {
|
|
batch_size := if remaining_bytes > read_batch_size { read_batch_size } else { remaining_bytes }
|
|
unsafe {
|
|
bstart = buffer + bytes_read
|
|
}
|
|
rbytes := getrandom(batch_size, bstart)
|
|
if rbytes == -1 {
|
|
free(buffer)
|
|
return read_error
|
|
}
|
|
bytes_read += rbytes
|
|
}
|
|
return c_array_to_bytes_tmp(bytes_needed, buffer)
|
|
}
|
|
|
|
fn v_getrandom(bytes_needed int, buffer voidptr) int {
|
|
if bytes_needed > read_batch_size {
|
|
panic('getrandom() dont request more than $read_batch_size bytes at once.')
|
|
}
|
|
return C.getrandom(buffer, bytes_needed, 0)
|
|
}
|