Commit 1fa51679 authored by Benno Lossin's avatar Benno Lossin
Browse files

rust: pin-init: add code blocks to `[try_][pin_]init!` macros 



Allow writing `_: { /* any number of statements */ }` in initializers to
run arbitrary code during initialization.

    try_init!(MyStruct {
        _: {
            if check_something() {
                return Err(MyError);
            }
        },
        foo: Foo::new(val),
        _: {
            println!("successfully initialized `MyStruct`");
        },
    })

Tested-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Reviewed-by: default avatarGary Guo <gary@garyguo.net>
Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Tested-by: default avatarDanilo Krummrich <dakr@kernel.org>
Reviewed-by: default avatarDanilo Krummrich <dakr@kernel.org>
Signed-off-by: default avatarBenno Lossin <lossin@kernel.org>
parent 619db96d

rust/pin-init/src/lib.rs

+2 −0
Original line number Diff line number Diff line
@@ -740,6 +740,8 @@ macro_rules! stack_try_pin_init { 
/// As already mentioned in the examples above, inside of `pin_init!` a `struct` initializer with

/// the following modifications is expected:

/// - Fields that you want to initialize in-place have to use `<-` instead of `:`.

/// - You can use `_: { /* run any user-code here */ },` anywhere where you can place fields in

///   order to run arbitrary code.

/// - In front of the initializer you can write `&this in` to have access to a [`NonNull<Self>`]

///   pointer named `this` inside of the initializer.

/// - Using struct update syntax one can place `..Zeroable::init_zeroed()` at the very end of the

rust/pin-init/src/macros.rs

+29 −0
Original line number Diff line number Diff line
@@ -1263,6 +1263,21 @@ fn assert_zeroable<T: $crate::Zeroable>(_: *mut T) {} 
        // have been initialized. Therefore we can now dismiss the guards by forgetting them.

        $(::core::mem::forget($guards);)*

    };

    (init_slot($($use_data:ident)?):

        @data($data:ident),

        @slot($slot:ident),

        @guards($($guards:ident,)*),

        // arbitrary code block

        @munch_fields(_: { $($code:tt)* }, $($rest:tt)*),

    ) => {

        { $($code)* }

        $crate::__init_internal!(init_slot($($use_data)?):

            @data($data),

            @slot($slot),

            @guards($($guards,)*),

            @munch_fields($($rest)*),

        );

    };

    (init_slot($use_data:ident): // `use_data` is present, so we use the `data` to init fields.

        @data($data:ident),

        @slot($slot:ident),
@@ -1358,6 +1373,20 @@ fn assert_zeroable<T: $crate::Zeroable>(_: *mut T) {} 
            );

        }

    };

    (make_initializer:

        @slot($slot:ident),

        @type_name($t:path),

        @munch_fields(_: { $($code:tt)* }, $($rest:tt)*),

        @acc($($acc:tt)*),

    ) => {

        // code blocks are ignored for the initializer check

        $crate::__init_internal!(make_initializer:

            @slot($slot),

            @type_name($t),

            @munch_fields($($rest)*),

            @acc($($acc)*),

        );

    };

    (make_initializer:

        @slot($slot:ident),

        @type_name($t:path),