Initial commit
diff --git a/src/utils.rs b/src/utils.rs
new file mode 100644
index 0000000..441ead1
--- /dev/null
+++ b/src/utils.rs
@@ -0,0 +1,48 @@
+use std::alloc::Layout;
+use std::mem;
+
+/// Calls a function and aborts if it panics.
+///
+/// This is useful in unsafe code where we can't recover from panics.
+#[inline]
+pub(crate) fn abort_on_panic<T>(f: impl FnOnce() -> T) -> T {
+ struct Bomb;
+
+ impl Drop for Bomb {
+ fn drop(&mut self) {
+ std::process::abort();
+ }
+ }
+
+ let bomb = Bomb;
+ let t = f();
+ mem::forget(bomb);
+ t
+}
+
+/// Returns the layout for `a` followed by `b` and the offset of `b`.
+///
+/// This function was adapted from the currently unstable `Layout::extend()`:
+/// https://doc.rust-lang.org/nightly/std/alloc/struct.Layout.html#method.extend
+#[inline]
+pub(crate) fn extend(a: Layout, b: Layout) -> (Layout, usize) {
+ let new_align = a.align().max(b.align());
+ let pad = padding_needed_for(a, b.align());
+
+ let offset = a.size().checked_add(pad).unwrap();
+ let new_size = offset.checked_add(b.size()).unwrap();
+
+ let layout = Layout::from_size_align(new_size, new_align).unwrap();
+ (layout, offset)
+}
+
+/// Returns the padding after `layout` that aligns the following address to `align`.
+///
+/// This function was adapted from the currently unstable `Layout::padding_needed_for()`:
+/// https://doc.rust-lang.org/nightly/std/alloc/struct.Layout.html#method.padding_needed_for
+#[inline]
+pub(crate) fn padding_needed_for(layout: Layout, align: usize) -> usize {
+ let len = layout.size();
+ let len_rounded_up = len.wrapping_add(align).wrapping_sub(1) & !align.wrapping_sub(1);
+ len_rounded_up.wrapping_sub(len)
+}