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The `PinnedDrop` trait that facilitates destruction of pinned types. It has to be implemented via the `#[pinned_drop]` macro, since the `drop` function should not be called by normal code, only by other destructors. It also only works on structs that are annotated with `#[pin_data(PinnedDrop)]`. Co-developed-by: Gary Guo <gary@garyguo.net> Signed-off-by: Gary Guo <gary@garyguo.net> Signed-off-by: Benno Lossin <benno.lossin@proton.me> Reviewed-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Andreas Hindborg <a.hindborg@samsung.com> Link: https://lore.kernel.org/r/20230408122429.1103522-10-y86-dev@protonmail.com Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
49 lines
1.8 KiB
Rust
49 lines
1.8 KiB
Rust
// SPDX-License-Identifier: Apache-2.0 OR MIT
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use proc_macro::{TokenStream, TokenTree};
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pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> TokenStream {
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let mut toks = input.into_iter().collect::<Vec<_>>();
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assert!(!toks.is_empty());
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// Ensure that we have an `impl` item.
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assert!(matches!(&toks[0], TokenTree::Ident(i) if i.to_string() == "impl"));
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// Ensure that we are implementing `PinnedDrop`.
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let mut nesting: usize = 0;
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let mut pinned_drop_idx = None;
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for (i, tt) in toks.iter().enumerate() {
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match tt {
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TokenTree::Punct(p) if p.as_char() == '<' => {
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nesting += 1;
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}
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TokenTree::Punct(p) if p.as_char() == '>' => {
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nesting = nesting.checked_sub(1).unwrap();
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continue;
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}
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_ => {}
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}
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if i >= 1 && nesting == 0 {
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// Found the end of the generics, this should be `PinnedDrop`.
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assert!(
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matches!(tt, TokenTree::Ident(i) if i.to_string() == "PinnedDrop"),
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"expected 'PinnedDrop', found: '{:?}'",
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tt
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);
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pinned_drop_idx = Some(i);
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break;
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}
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}
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let idx = pinned_drop_idx
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.unwrap_or_else(|| panic!("Expected an `impl` block implementing `PinnedDrop`."));
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// Fully qualify the `PinnedDrop`, as to avoid any tampering.
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toks.splice(idx..idx, quote!(::kernel::init::));
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// Take the `{}` body and call the declarative macro.
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if let Some(TokenTree::Group(last)) = toks.pop() {
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let last = last.stream();
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quote!(::kernel::__pinned_drop! {
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@impl_sig(#(#toks)*),
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@impl_body(#last),
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})
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} else {
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TokenStream::from_iter(toks)
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}
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}
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