1
0
mirror of https://github.com/vlang/v.git synced 2023-08-10 21:13:21 +03:00
v/vlib/crypto/rand/rand_lin.v

41 lines
1.0 KiB
V
Raw Normal View History

2019-07-31 04:24:12 +03:00
// Copyright (c) 2019 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
import math
#include <sys/syscall.h>
const (
2019-10-24 14:48:20 +03:00
read_batch_size = 256
2019-07-31 04:24:12 +03:00
)
pub fn read(bytes_needed int) ?[]byte {
mut buffer := malloc(bytes_needed)
mut bytes_read := 0
// getrandom syscall wont block if requesting <= 256 bytes
2019-10-24 14:48:20 +03:00
if bytes_needed > read_batch_size {
no_batches := int(math.floor(f64(bytes_needed/read_batch_size)))
2019-07-31 04:24:12 +03:00
for i:=0; i<no_batches; i++ {
2019-10-24 14:48:20 +03:00
if getrandom(read_batch_size, buffer+bytes_read) == -1 {
return read_error
2019-07-31 04:24:12 +03:00
}
2019-10-24 14:48:20 +03:00
bytes_read += read_batch_size
2019-07-31 04:24:12 +03:00
}
}
if getrandom(bytes_needed-bytes_read, buffer+bytes_read) == -1 {
2019-10-24 14:48:20 +03:00
return read_error
2019-07-31 04:24:12 +03:00
}
return c_array_to_bytes_tmp(bytes_needed, buffer)
}
fn getrandom(bytes_needed int, buffer voidptr) int {
2019-10-24 14:48:20 +03:00
if bytes_needed > read_batch_size {
panic('getrandom() dont request more thane $read_batch_size bytes at once.')
2019-07-31 04:24:12 +03:00
}
2019-08-23 00:00:31 +03:00
return C.syscall(C.SYS_getrandom, buffer, bytes_needed, 0)
2019-07-31 04:24:12 +03:00
}