Andrew Walbran | 9487efd | 2024-08-20 18:37:59 +0100 | [diff] [blame] | 1 | // Copyright (C) 2024 The Android Open Source Project |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | use std::{mem::forget, ptr::NonNull}; |
| 16 | |
| 17 | /// Rust wrapper around `native_handle_t`. |
| 18 | /// |
| 19 | /// This owns the `native_handle_t` and its file descriptors, and will close them and free it when |
| 20 | /// it is dropped. |
| 21 | #[derive(Debug)] |
| 22 | pub struct NativeHandle(NonNull<ffi::native_handle_t>); |
| 23 | |
| 24 | impl NativeHandle { |
| 25 | /// Wraps a raw `native_handle_t` pointer, taking ownership of it. |
| 26 | /// |
| 27 | /// # Safety |
| 28 | /// |
| 29 | /// `native_handle` must be a valid pointer to a `native_handle_t`, and must not be used |
| 30 | /// anywhere else after calling this method. |
| 31 | pub unsafe fn from_raw(native_handle: NonNull<ffi::native_handle_t>) -> Self { |
| 32 | Self(native_handle) |
| 33 | } |
| 34 | |
| 35 | /// Creates a new `NativeHandle` wrapping a clone of the given `native_handle_t` pointer. |
| 36 | /// |
| 37 | /// Unlike [`from_raw`](Self::from_raw) this doesn't take ownership of the pointer passed in, so |
| 38 | /// the caller remains responsible for closing and freeing it. |
| 39 | /// |
| 40 | /// # Safety |
| 41 | /// |
| 42 | /// `native_handle` must be a valid pointer to a `native_handle_t`. |
| 43 | pub unsafe fn clone_from_raw(native_handle: NonNull<ffi::native_handle_t>) -> Option<Self> { |
| 44 | // SAFETY: The caller promised that `native_handle` was valid. |
| 45 | let cloned = unsafe { ffi::native_handle_clone(native_handle.as_ptr()) }; |
| 46 | NonNull::new(cloned).map(Self) |
| 47 | } |
| 48 | |
| 49 | /// Returns a raw pointer to the wrapped `native_handle_t`. |
| 50 | /// |
| 51 | /// This is only valid as long as this `NativeHandle` exists, so shouldn't be stored. It mustn't |
| 52 | /// be closed or deleted. |
| 53 | pub fn as_raw(&self) -> NonNull<ffi::native_handle_t> { |
| 54 | self.0 |
| 55 | } |
| 56 | |
| 57 | /// Turns the `NativeHandle` into a raw `native_handle_t`. |
| 58 | /// |
| 59 | /// The caller takes ownership of the `native_handle_t` and its file descriptors, so is |
| 60 | /// responsible for closing and freeing it. |
| 61 | pub fn into_raw(self) -> NonNull<ffi::native_handle_t> { |
| 62 | let raw = self.0; |
| 63 | forget(self); |
| 64 | raw |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | impl Clone for NativeHandle { |
| 69 | fn clone(&self) -> Self { |
| 70 | // SAFETY: Our wrapped `native_handle_t` pointer is always valid. |
| 71 | unsafe { Self::clone_from_raw(self.0) }.expect("native_handle_clone returned null") |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | impl Drop for NativeHandle { |
| 76 | fn drop(&mut self) { |
| 77 | // SAFETY: Our wrapped `native_handle_t` pointer is always valid, and it won't be accessed |
| 78 | // after this because we own it and are being dropped. |
| 79 | unsafe { |
| 80 | assert_eq!(ffi::native_handle_close(self.0.as_ptr()), 0); |
| 81 | assert_eq!(ffi::native_handle_delete(self.0.as_ptr()), 0); |
| 82 | } |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | // SAFETY: `NativeHandle` owns the `native_handle_t`, which just contains some integers and file |
| 87 | // descriptors, which aren't tied to any particular thread. |
| 88 | unsafe impl Send for NativeHandle {} |
| 89 | |
| 90 | // SAFETY: A `NativeHandle` can be used from different threads simultaneously, as is is just |
| 91 | // integers and file descriptors. |
| 92 | unsafe impl Sync for NativeHandle {} |