v/vlib/crypto/rand/rand_linux.c.v

40 lines
1.1 KiB
V
Raw Normal View History

2022-01-04 10:21:08 +01:00
// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
2019-07-31 03:24:12 +02:00
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module rand
#include <sys/syscall.h>
2019-07-31 03:24:12 +02:00
const (
2019-10-24 13:48:20 +02:00
read_batch_size = 256
2019-07-31 03:24:12 +02:00
)
// read returns an array of `bytes_needed` random bytes read from the OS.
2022-04-15 14:35:35 +02:00
pub fn read(bytes_needed int) ?[]u8 {
mut buffer := unsafe { vcalloc_noscan(bytes_needed) }
2019-07-31 03:24:12 +02:00
mut bytes_read := 0
mut remaining_bytes := bytes_needed
2019-07-31 03:24:12 +02:00
// getrandom syscall wont block if requesting <= 256 bytes
for bytes_read < bytes_needed {
batch_size := if remaining_bytes > rand.read_batch_size {
rand.read_batch_size
} else {
remaining_bytes
}
rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
if rbytes == -1 {
unsafe { free(buffer) }
return IError(&ReadError{})
}
bytes_read += rbytes
2019-07-31 03:24:12 +02:00
}
return unsafe { buffer.vbytes(bytes_needed) }
2019-07-31 03:24:12 +02:00
}
fn getrandom(bytes_needed int, buffer voidptr) int {
if bytes_needed > rand.read_batch_size {
panic('getrandom() dont request more than $rand.read_batch_size bytes at once.')
2019-07-31 03:24:12 +02:00
}
return unsafe { C.syscall(C.SYS_getrandom, buffer, bytes_needed, 0) }
2019-07-31 03:24:12 +02:00
}