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Don't assume u32 alignment of random() state buffer

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This commit is contained in:
Peter Limkilde Svendsen
2020-06-24 16:46:59 +00:00
committed by Jeremy Soller
parent 954f010cc1
commit 5c8393d5aa
2 changed files with 36 additions and 22 deletions
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src/header/stdlib/mod.rs
+14 -8
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@@ -388,12 +388,12 @@ pub unsafe extern "C" fn initstate(seed: c_uint, state: *mut c_char, size: size_
_ => 63,
};
random::X_PTR = (state as *mut u32).offset(1);
random::X_PTR = (state.cast::<[u8; 4]>()).offset(1);
random::seed(seed);
random::save_state();
// TODO: unlock?
old_state as _
old_state.cast::<_>()
}
}
@@ -763,12 +763,18 @@ pub unsafe extern "C" fn random() -> c_long {
random::ensure_x_ptr_init();
if random::N == 0 {
*random::X_PTR = random::lcg31_step(*random::X_PTR);
k = *random::X_PTR;
let x_old = u32::from_ne_bytes(*random::X_PTR);
let x_new = random::lcg31_step(x_old);
*random::X_PTR = x_new.to_ne_bytes();
k = x_new;
} else {
*random::X_PTR.add(usize::from(random::I)) += *random::X_PTR.add(usize::from(random::J));
// The non-u32-aligned way of saying x[i] += x[j]...
let x_i_old = u32::from_ne_bytes(*random::X_PTR.add(usize::from(random::I)));
let x_j = u32::from_ne_bytes(*random::X_PTR.add(usize::from(random::J)));
let x_i_new = x_i_old.wrapping_add(x_j);
*random::X_PTR.add(usize::from(random::I)) = x_i_new.to_ne_bytes();
k = *random::X_PTR.add(usize::from(random::I)) >> 1;
k = x_i_new >> 1;
random::I += 1;
if random::I == random::N {
@@ -916,9 +922,9 @@ pub unsafe extern "C" fn setstate(state: *mut c_char) -> *mut c_char {
// TODO: lock?
let old_state = random::save_state();
random::load_state(state as *mut u32);
random::load_state(state.cast::<_>());
// TODO: unlock?
old_state as _
old_state.cast::<_>()
}
#[no_mangle]