mojo/public/rust/system/ffi.rs

//Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

chromium::import! {
  pub "//mojo/public/rust:mojo_c_system_bindings" as raw_ffi;
}

pub mod types {
    //! Defines some C-compatible types for the ffi layer of
    //! the bindings.
    use super::raw_ffi;

    pub use raw_ffi::MojoAddTriggerFlags;
    pub use raw_ffi::MojoAppendMessageDataFlags;
    pub use raw_ffi::MojoArmTrapFlags;
    pub use raw_ffi::MojoBeginReadDataFlags;
    pub use raw_ffi::MojoBeginWriteDataFlags;
    pub use raw_ffi::MojoCreateDataPipeFlags;
    pub use raw_ffi::MojoCreateMessageFlags;
    pub use raw_ffi::MojoCreateMessagePipeFlags;
    pub use raw_ffi::MojoCreateSharedBufferFlags;
    pub use raw_ffi::MojoCreateTrapFlags;
    pub use raw_ffi::MojoDuplicateBufferHandleFlags;
    pub use raw_ffi::MojoEndReadDataFlags;
    pub use raw_ffi::MojoEndWriteDataFlags;
    pub use raw_ffi::MojoGetBufferInfoFlags;
    pub use raw_ffi::MojoGetMessageDataFlags;
    pub use raw_ffi::MojoHandle;
    pub use raw_ffi::MojoHandleSignals;
    pub use raw_ffi::MojoHandleSignalsState;
    pub use raw_ffi::MojoMapBufferFlags;
    pub use raw_ffi::MojoMessageHandle;
    pub use raw_ffi::MojoReadDataFlags;
    pub use raw_ffi::MojoReadMessageFlags;
    pub use raw_ffi::MojoRemoveTriggerFlags;
    pub use raw_ffi::MojoTimeTicks;
    pub use raw_ffi::MojoTrapEventFlags;
    pub use raw_ffi::MojoTrapEventHandler;
    pub use raw_ffi::MojoTriggerCondition;
    pub use raw_ffi::MojoWriteDataFlags;
    pub use raw_ffi::MojoWriteMessageFlags;
    pub type MojoResultCode = raw_ffi::MojoResult;
}

pub use raw_ffi::MojoAppendMessageData;
pub use raw_ffi::MojoClose;
pub use raw_ffi::MojoCreateMessage;
pub use raw_ffi::MojoCreateMessagePipe;
pub use raw_ffi::MojoDestroyMessage;
pub use raw_ffi::MojoGetMessageData;
pub use raw_ffi::MojoGetTimeTicksNow;
pub use raw_ffi::MojoHandleSignalsState as SignalsState;
pub use raw_ffi::MojoQueryHandleSignalsState;
pub use raw_ffi::MojoReadMessage;
pub use raw_ffi::MojoWriteMessage;
pub use types::MojoResultCode;

// Most FFI functions take an options struct as input which we get from bindgen.
// Each one contains a `struct_size` member for versioning. We want to make a
// 'newtype' wrapper for each that manages the struct_size as well as adds a
// `new()` function for construction.
//
// To reduce boilerplate we use a macro.
//
// The generated structs contain methods to get raw pointers for passing to FFI
// functions. Note the FFI functions don't require the structs to live beyond
// each call.
macro_rules! declare_mojo_options {
    ($struct_name:ident, $( $field_name:ident : $field_type:ty ),*) => {
        #[repr(transparent)]
        pub struct $struct_name(raw_ffi::$struct_name);

        impl $struct_name {
            pub fn new($($field_name : $field_type),*) -> $struct_name {
                $struct_name(raw_ffi::$struct_name {
                    struct_size: ::std::mem::size_of::<$struct_name>() as u32,
                    $($field_name),*
                })
            }

            // Get an immutable pointer to the wrapped FFI struct to pass to
            // C functions.
            pub fn as_ptr(&self) -> *const raw_ffi::$struct_name {
              // $struct_name is a repr(transparent) wrapper around raw_ffi::$struct_name
              self as *const _ as *const _
            }

            // Get a mutable pointer to the wrapped FFI struct to pass to
            // C functions.
            pub fn as_mut_ptr(&mut self) -> *mut raw_ffi::$struct_name {
              // $struct_name is a repr(transparent) wrapper around raw_ffi::$struct_name
              self as *mut _  as *mut _
            }
        }

        impl std::ops::Deref for $struct_name {
          type Target = raw_ffi::$struct_name;

          fn deref(&self) -> &Self::Target {
            &self.0
          }
        }

        impl std::ops::DerefMut for $struct_name {
          fn deref_mut(&mut self) -> &mut Self::Target {
            &mut self.0
          }
        }
    }
}

declare_mojo_options!(MojoAppendMessageDataOptions, flags: types::MojoAppendMessageDataFlags);
declare_mojo_options!(MojoCreateMessagePipeOptions, flags: types::MojoCreateMessagePipeFlags);
declare_mojo_options!(MojoWriteMessageOptions, flags: types::MojoWriteMessageFlags);