diff options
| -rw-r--r-- | src/liballoc/rc.rs | 14 | ||||
| -rw-r--r-- | src/liballoc/sync.rs | 14 |
2 files changed, 24 insertions, 4 deletions
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs index 3080a8bf459..b176e0f6e2a 100644 --- a/src/liballoc/rc.rs +++ b/src/liballoc/rc.rs @@ -565,9 +565,19 @@ impl<T: ?Sized> Rc<T> { /// ``` #[stable(feature = "rc_raw", since = "1.17.0")] pub fn into_raw(this: Self) -> *const T { - let ptr: *const T = &*this; + let ptr: *mut RcBox<T> = NonNull::as_ptr(this.ptr); + let fake_ptr = ptr as *mut T; mem::forget(this); - ptr + + // SAFETY: This cannot go through Deref::deref. + // Instead, we manually offset the pointer rather than manifesting a reference. + // This is so that the returned pointer retains the same provenance as our pointer. + // This is required so that e.g. `get_mut` can write through the pointer + // after the Rc is recovered through `from_raw`. + unsafe { + let offset = data_offset(&(*ptr).value); + set_data_ptr(fake_ptr, (ptr as *mut u8).offset(offset)) + } } /// Constructs an `Rc` from a raw pointer. diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs index dc53ad28407..4aa0190b149 100644 --- a/src/liballoc/sync.rs +++ b/src/liballoc/sync.rs @@ -545,9 +545,19 @@ impl<T: ?Sized> Arc<T> { /// ``` #[stable(feature = "rc_raw", since = "1.17.0")] pub fn into_raw(this: Self) -> *const T { - let ptr: *const T = &*this; + let ptr: *mut ArcInner<T> = NonNull::as_ptr(this.ptr); + let fake_ptr = ptr as *mut T; mem::forget(this); - ptr + + // SAFETY: This cannot go through Deref::deref. + // Instead, we manually offset the pointer rather than manifesting a reference. + // This is so that the returned pointer retains the same provenance as our pointer. + // This is required so that e.g. `get_mut` can write through the pointer + // after the Arc is recovered through `from_raw`. + unsafe { + let offset = data_offset(&(*ptr).data); + set_data_ptr(fake_ptr, (ptr as *mut u8).offset(offset)) + } } /// Constructs an `Arc` from a raw pointer. |