fidl_next_codec/wire/
ptr.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use core::mem::MaybeUninit;
6
7use munge::munge;
8
9use crate::{DecodeError, Slot, WireU64};
10
11/// A raw FIDL pointer
12#[repr(C, align(8))]
13pub union WirePointer<T> {
14    encoded: WireU64,
15    decoded: *mut T,
16}
17
18impl<T> WirePointer<T> {
19    /// Returns whether the wire pointer was encoded present.
20    pub fn is_encoded_present(slot: Slot<'_, Self>) -> Result<bool, DecodeError> {
21        munge!(let Self { encoded } = slot);
22        match **encoded {
23            0 => Ok(false),
24            u64::MAX => Ok(true),
25            x => Err(DecodeError::InvalidPointerPresence(x)),
26        }
27    }
28
29    /// Encodes that a pointer is present in an output.
30    pub fn encode_present(out: &mut MaybeUninit<Self>) {
31        munge!(let Self { encoded } = out);
32        encoded.write(WireU64(u64::MAX));
33    }
34
35    /// Encodes that a pointer is absent in a slot.
36    pub fn encode_absent(out: &mut MaybeUninit<Self>) {
37        munge!(let Self { encoded } = out);
38        encoded.write(WireU64(0));
39    }
40
41    /// Sets the decoded value of the pointer.
42    pub fn set_decoded(slot: Slot<'_, Self>, ptr: *mut T) {
43        munge!(let Self { mut decoded } = slot);
44        // SAFETY: Identical to `decoded.write(ptr.into_raw())`, but raw
45        // pointers don't currently implement `IntoBytes`.
46        unsafe {
47            *decoded.as_mut_ptr() = ptr;
48        }
49    }
50
51    /// Returns the underlying pointer.
52    pub fn as_ptr(&self) -> *mut T {
53        unsafe { self.decoded }
54    }
55}
fidl_next_codec/wire/ptr.rs

fidl_next_codec/wire/
ptr.rs
