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zeroize: Relax Zeroize trait bounds for Vec #276

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Merged
merged 1 commit into from
Oct 13, 2019
Merged

zeroize: Relax Zeroize trait bounds for Vec #276

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34 changes: 2 additions & 32 deletions zeroize/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -312,14 +312,13 @@ where
#[cfg(feature = "alloc")]
impl<Z> Zeroize for Vec<Z>
where
Z: Clone + Default + Zeroize,
Z: Zeroize,
{
/// "Best effort" zeroization for `Vec`.
///
/// Ensures the entire capacity of the `Vec` is zeroed. Cannot ensure that
/// previous reallocations did not leave values on the heap.
fn zeroize(&mut self) {
self.resize(self.capacity(), Default::default());
self.iter_mut().zeroize();
self.clear();
}
Expand Down Expand Up @@ -378,9 +377,6 @@ where
}
}

// We could `derive(Zeroize)` for this, but doing it by hand allows `Zeroizing`
// to function regardless of whether the `zeroize_derive` feature is enabled
// or not.
impl<Z> Drop for Zeroizing<Z>
where
Z: Zeroize,
Expand All @@ -407,7 +403,7 @@ fn volatile_write<T: Copy + Sized>(dst: &mut T, src: T) {
/// Perform a volatile `memset` operation which fills a slice with a value
#[inline]
fn volatile_set<T: Copy + Sized>(dst: &mut [T], src: T) {
// TODO(tarcieri): use `volatile_set_memory` on nightly?
// TODO(tarcieri): use `volatile_set_memory` when stabilized
for elem in dst {
volatile_write(elem, src);
}
Expand All @@ -434,32 +430,6 @@ mod tests {
assert!(vec.is_empty());
}

#[cfg(feature = "alloc")]
#[test]
fn zeroize_vec_past_len() {
let mut vec = Vec::with_capacity(5);
for i in 0..4 {
vec.push(10 + i);
}
vec.clear();

// safe if: new_len <= capacity AND elements "were initialised"
unsafe {
vec.set_len(1);
}
assert_eq!(10, vec[0], "clear() hasn't erased our push()es");

vec.clear();
vec.zeroize();

unsafe {
vec.set_len(4);
}
for i in 0..4 {
assert_eq!(0, vec[i], "it's been zero'd");
}
}

#[cfg(feature = "alloc")]
#[test]
fn zeroize_string() {
Expand Down