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