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meli/melib/src/utils/random.rs

79 lines
2.1 KiB
Rust

/*
* meli - melib crate.
*
* Copyright 2017-2020 Manos Pitsidianakis
*
* This file is part of meli.
*
* meli is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* meli is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with meli. If not, see <http://www.gnu.org/licenses/>.
*/
use std::{fs::File, io::prelude::*, time::SystemTime};
const EXPECT: &str = "Could not open/read /dev/urandom";
pub fn random_u64() -> u64 {
let mut f = File::open("/dev/urandom").expect(EXPECT);
let mut buffer = [0; 8];
// read exactly 8 bytes
f.read_exact(&mut buffer).expect(EXPECT);
u64::from(buffer[0])
| (u64::from(buffer[1]) << 8)
| (u64::from(buffer[2]) << 16)
| (u64::from(buffer[3]) << 24)
| (u64::from(buffer[4]) << 32)
| (u64::from(buffer[5]) << 40)
| (u64::from(buffer[6]) << 48)
| (u64::from(buffer[7]) << 56)
}
pub fn random_u32() -> u32 {
let mut f = File::open("/dev/urandom").expect(EXPECT);
let mut buffer = [0; 4];
// read exactly 4 bytes
f.read_exact(&mut buffer).expect(EXPECT);
u32::from(buffer[0])
| (u32::from(buffer[1]) << 8)
| (u32::from(buffer[2]) << 16)
| (u32::from(buffer[3]) << 24)
}
pub fn random_u8() -> u8 {
let mut f = File::open("/dev/urandom").expect(EXPECT);
let mut buffer = [0; 1];
// read exactly 1 byte
f.read_exact(&mut buffer).expect(EXPECT);
buffer[0]
}
pub fn clock() -> u64 {
SystemTime::now()
.duration_since(SystemTime::UNIX_EPOCH)
.unwrap()
.as_secs()
}
pub fn clock_millis() -> u128 {
SystemTime::now()
.duration_since(SystemTime::UNIX_EPOCH)
.unwrap()
.as_millis()
}