43 lines
1.2 KiB
V
43 lines
1.2 KiB
V
// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
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// that can be found in the LICENSE file.
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module rand
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#include <sys/random.h>
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fn C.getrandom(p &byte, n usize, flags u32) int
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const (
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read_batch_size = 256
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)
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// read returns an array of `bytes_needed` random bytes read from the OS.
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pub fn read(bytes_needed int) ?[]u8 {
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mut buffer := unsafe { malloc_noscan(bytes_needed) }
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mut bytes_read := 0
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mut remaining_bytes := bytes_needed
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// getrandom syscall wont block if requesting <= 256 bytes
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for bytes_read < bytes_needed {
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batch_size := if remaining_bytes > rand.read_batch_size {
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rand.read_batch_size
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} else {
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remaining_bytes
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}
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rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
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if rbytes == -1 {
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unsafe { free(buffer) }
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return IError(&ReadError{})
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}
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bytes_read += rbytes
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}
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return unsafe { buffer.vbytes(bytes_needed) }
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}
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fn v_getrandom(bytes_needed int, buffer voidptr) int {
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if bytes_needed > rand.read_batch_size {
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panic('getrandom() dont request more than $rand.read_batch_size bytes at once.')
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}
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return C.getrandom(buffer, bytes_needed, 0)
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}
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