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std::rand: seed ISAAC with no transmutes. 

Slice transmutes are now (and, really, always were) dangerous, so we
avoid them and do the (only?) non-(undefined behaviour in C) pointer
cast: casting to *u8.
This commit is contained in:
Huon Wilson 2013-10-22 23:11:17 +11:00
parent b8932c6304
commit 6e7bbdacb9
1 changed files with 16 additions and 7 deletions
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23
src/libstd/rand/isaac.rs
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@ -10,10 +10,11 @@
//! The ISAAC random number generator.
use cast;
use rand::{Rng, SeedableRng, OSRng};
use iter::{Iterator, range, range_step, Repeat};
use option::{None, Some};
use vec::raw;
use mem;
static RAND_SIZE_LEN: u32 = 8;
static RAND_SIZE: u32 = 1 << RAND_SIZE_LEN;
@ -42,9 +43,12 @@ impl IsaacRng {
pub fn new() -> IsaacRng {
let mut rng = EMPTY;
{
let bytes = unsafe {cast::transmute::<&mut [u32], &mut [u8]>(rng.rsl)};
OSRng::new().fill_bytes(bytes);
unsafe {
let ptr = raw::to_mut_ptr(rng.rsl);
do raw::mut_buf_as_slice(ptr as *mut u8, mem::size_of_val(&rng.rsl)) |slice| {
OSRng::new().fill_bytes(slice);
}
}
rng.init(true);
@ -238,10 +242,15 @@ impl Isaac64Rng {
/// seed.
pub fn new() -> Isaac64Rng {
let mut rng = EMPTY_64;
{
let bytes = unsafe {cast::transmute::<&mut [u64], &mut [u8]>(rng.rsl)};
OSRng::new().fill_bytes(bytes);
unsafe {
let ptr = raw::to_mut_ptr(rng.rsl);
do raw::mut_buf_as_slice(ptr as *mut u8, mem::size_of_val(&rng.rsl)) |slice| {
OSRng::new().fill_bytes(slice);
}
}
rng.init(true);
rng
}