libs/nativewindow/rust/src/lib.rs - LeafOS-Project/android_frameworks_native - Gitiles

 // Copyright (C) 2023 The Android Open Source Project
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 //! Pleasant Rust bindings for libnativewindow, including AHardwareBuffer

 extern crate nativewindow_bindgen as ffi;

 pub mod surface;

 pub use ffi::{AHardwareBuffer_Format, AHardwareBuffer_UsageFlags};

 use binder::{
     binder_impl::{BorrowedParcel, UnstructuredParcelable},
     impl_deserialize_for_unstructured_parcelable, impl_serialize_for_unstructured_parcelable,
     unstable_api::{status_result, AsNative},
     StatusCode,
 };
 use ffi::{AHardwareBuffer, AHardwareBuffer_readFromParcel, AHardwareBuffer_writeToParcel};
 use std::fmt::{self, Debug, Formatter};
 use std::mem::ManuallyDrop;
 use std::ptr::{self, null_mut, NonNull};

 /// Wrapper around an opaque C `AHardwareBuffer`.
 #[derive(PartialEq, Eq)]
 pub struct HardwareBuffer(NonNull<AHardwareBuffer>);

 impl HardwareBuffer {
     /// Test whether the given format and usage flag combination is allocatable.  If this function
     /// returns true, it means that a buffer with the given description can be allocated on this
     /// implementation, unless resource exhaustion occurs. If this function returns false, it means
     /// that the allocation of the given description will never succeed.
     ///
     /// Available since API 29
     pub fn is_supported(
         width: u32,
         height: u32,
         layers: u32,
         format: AHardwareBuffer_Format::Type,
         usage: AHardwareBuffer_UsageFlags,
         stride: u32,
     ) -> bool {
         let buffer_desc = ffi::AHardwareBuffer_Desc {
             width,
             height,
             layers,
             format,
             usage: usage.0,
             stride,
             rfu0: 0,
             rfu1: 0,
         };
         // SAFETY: *buffer_desc will never be null.
         let status = unsafe { ffi::AHardwareBuffer_isSupported(&buffer_desc) };

         status == 1
     }

     /// Allocates a buffer that matches the passed AHardwareBuffer_Desc. If allocation succeeds, the
     /// buffer can be used according to the usage flags specified in its description. If a buffer is
     /// used in ways not compatible with its usage flags, the results are undefined and may include
     /// program termination.
     ///
     /// Available since API level 26.
     #[inline]
     pub fn new(
         width: u32,
         height: u32,
         layers: u32,
         format: AHardwareBuffer_Format::Type,
         usage: AHardwareBuffer_UsageFlags,
     ) -> Option<Self> {
         let buffer_desc = ffi::AHardwareBuffer_Desc {
             width,
             height,
             layers,
             format,
             usage: usage.0,
             stride: 0,
             rfu0: 0,
             rfu1: 0,
         };
         let mut ptr = ptr::null_mut();
         // SAFETY: The returned pointer is valid until we drop/deallocate it. The function may fail
         // and return a status, but we check it later.
         let status = unsafe { ffi::AHardwareBuffer_allocate(&buffer_desc, &mut ptr) };

         if status == 0 {
             Some(Self(NonNull::new(ptr).expect("Allocated AHardwareBuffer was null")))
         } else {
             None
         }
     }

     /// Adopts the given raw pointer and wraps it in a Rust HardwareBuffer.
     ///
     /// # Safety
     ///
     /// This function takes ownership of the pointer and does NOT increment the refcount on the
     /// buffer. If the caller uses the pointer after the created object is dropped it will cause
     /// undefined behaviour. If the caller wants to continue using the pointer after calling this
     /// then use [`clone_from_raw`](Self::clone_from_raw) instead.
     pub unsafe fn from_raw(buffer_ptr: NonNull<AHardwareBuffer>) -> Self {
         Self(buffer_ptr)
     }

     /// Creates a new Rust HardwareBuffer to wrap the given AHardwareBuffer without taking ownership
     /// of it.
     ///
     /// Unlike [`from_raw`](Self::from_raw) this method will increment the refcount on the buffer.
     /// This means that the caller can continue to use the raw buffer it passed in, and must call
     /// [`AHardwareBuffer_release`](ffi::AHardwareBuffer_release) when it is finished with it to
     /// avoid a memory leak.
     ///
     /// # Safety
     ///
     /// The buffer pointer must point to a valid `AHardwareBuffer`.
     pub unsafe fn clone_from_raw(buffer: NonNull<AHardwareBuffer>) -> Self {
         // SAFETY: The caller guarantees that the AHardwareBuffer pointer is valid.
         unsafe { ffi::AHardwareBuffer_acquire(buffer.as_ptr()) };
         Self(buffer)
     }

     /// Get the internal |AHardwareBuffer| pointer without decrementing the refcount. This can
     /// be used to provide a pointer to the AHB for a C/C++ API over the FFI.
     pub fn into_raw(self) -> NonNull<AHardwareBuffer> {
         let buffer = ManuallyDrop::new(self);
         buffer.0
     }

     /// Get the system wide unique id for an AHardwareBuffer. This function may panic in extreme
     /// and undocumented circumstances.
     ///
     /// Available since API level 31.
     pub fn id(&self) -> u64 {
         let mut out_id = 0;
         // SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
         // because it must have been allocated by `AHardwareBuffer_allocate`,
         // `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
         // released it. The id pointer must be valid because it comes from a reference.
         let status = unsafe { ffi::AHardwareBuffer_getId(self.0.as_ptr(), &mut out_id) };
         assert_eq!(status, 0, "id() failed for AHardwareBuffer with error code: {status}");

         out_id
     }

     /// Get the width of this buffer
     pub fn width(&self) -> u32 {
         self.description().width
     }

     /// Get the height of this buffer
     pub fn height(&self) -> u32 {
         self.description().height
     }

     /// Get the number of layers of this buffer
     pub fn layers(&self) -> u32 {
         self.description().layers
     }

     /// Get the format of this buffer
     pub fn format(&self) -> AHardwareBuffer_Format::Type {
         self.description().format
     }

     /// Get the usage bitvector of this buffer
     pub fn usage(&self) -> AHardwareBuffer_UsageFlags {
         AHardwareBuffer_UsageFlags(self.description().usage)
     }

     /// Get the stride of this buffer
     pub fn stride(&self) -> u32 {
         self.description().stride
     }

     fn description(&self) -> ffi::AHardwareBuffer_Desc {
         let mut buffer_desc = ffi::AHardwareBuffer_Desc {
             width: 0,
             height: 0,
             layers: 0,
             format: 0,
             usage: 0,
             stride: 0,
             rfu0: 0,
             rfu1: 0,
         };
         // SAFETY: neither the buffer nor AHardwareBuffer_Desc pointers will be null.
         unsafe { ffi::AHardwareBuffer_describe(self.0.as_ref(), &mut buffer_desc) };
         buffer_desc
     }
 }

 impl Drop for HardwareBuffer {
     fn drop(&mut self) {
         // SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
         // because it must have been allocated by `AHardwareBuffer_allocate`,
         // `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
         // released it.
         unsafe { ffi::AHardwareBuffer_release(self.0.as_ptr()) }
     }
 }

 impl Debug for HardwareBuffer {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         f.debug_struct("HardwareBuffer").field("id", &self.id()).finish()
     }
 }

 impl Clone for HardwareBuffer {
     fn clone(&self) -> Self {
         // SAFETY: ptr is guaranteed to be non-null and the acquire can not fail.
         unsafe { ffi::AHardwareBuffer_acquire(self.0.as_ptr()) };
         Self(self.0)
     }
 }

 impl UnstructuredParcelable for HardwareBuffer {
     fn write_to_parcel(&self, parcel: &mut BorrowedParcel) -> Result<(), StatusCode> {
         let status =
         // SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
         // because it must have been allocated by `AHardwareBuffer_allocate`,
         // `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
         // released it.
             unsafe { AHardwareBuffer_writeToParcel(self.0.as_ptr(), parcel.as_native_mut()) };
         status_result(status)
     }

     fn from_parcel(parcel: &BorrowedParcel) -> Result<Self, StatusCode> {
         let mut buffer = null_mut();

         let status =
         // SAFETY: Both pointers must be valid because they are obtained from references.
         // `AHardwareBuffer_readFromParcel` doesn't store them or do anything else special
         // with them. If it returns success then it will have allocated a new
         // `AHardwareBuffer` and incremented the reference count, so we can use it until we
         // release it.
             unsafe { AHardwareBuffer_readFromParcel(parcel.as_native(), &mut buffer) };

         status_result(status)?;

         Ok(Self(
             NonNull::new(buffer).expect(
                 "AHardwareBuffer_readFromParcel returned success but didn't allocate buffer",
             ),
         ))
     }
 }

 impl_deserialize_for_unstructured_parcelable!(HardwareBuffer);
 impl_serialize_for_unstructured_parcelable!(HardwareBuffer);

 // SAFETY: The underlying *AHardwareBuffers can be moved between threads.
 unsafe impl Send for HardwareBuffer {}

 // SAFETY: The underlying *AHardwareBuffers can be used from multiple threads.
 //
 // AHardwareBuffers are backed by C++ GraphicBuffers, which are mostly immutable. The only cases
 // where they are not immutable are:
 //
 //   - reallocation (which is never actually done across the codebase and requires special
 //     privileges/platform code access to do)
 //   - "locking" for reading/writing (which is explicitly allowed to be done across multiple threads
 //     according to the docs on the underlying gralloc calls)
 unsafe impl Sync for HardwareBuffer {}

 #[cfg(test)]
 mod test {
     use super::*;

     #[test]
     fn create_valid_buffer_returns_ok() {
         let buffer = HardwareBuffer::new(
             512,
             512,
             1,
             AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
         );
         assert!(buffer.is_some());
     }

     #[test]
     fn create_invalid_buffer_returns_err() {
         let buffer = HardwareBuffer::new(512, 512, 1, 0, AHardwareBuffer_UsageFlags(0));
         assert!(buffer.is_none());
     }

     #[test]
     fn from_raw_allows_getters() {
         let buffer_desc = ffi::AHardwareBuffer_Desc {
             width: 1024,
             height: 512,
             layers: 1,
             format: AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             usage: AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN.0,
             stride: 0,
             rfu0: 0,
             rfu1: 0,
         };
         let mut raw_buffer_ptr = ptr::null_mut();

         // SAFETY: The pointers are valid because they come from references, and
         // `AHardwareBuffer_allocate` doesn't retain them after it returns.
         let status = unsafe { ffi::AHardwareBuffer_allocate(&buffer_desc, &mut raw_buffer_ptr) };
         assert_eq!(status, 0);

         // SAFETY: The pointer must be valid because it was just allocated successfully, and we
         // don't use it after calling this.
         let buffer = unsafe { HardwareBuffer::from_raw(NonNull::new(raw_buffer_ptr).unwrap()) };
         assert_eq!(buffer.width(), 1024);
     }

     #[test]
     fn basic_getters() {
         let buffer = HardwareBuffer::new(
             1024,
             512,
             1,
             AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
         )
         .expect("Buffer with some basic parameters was not created successfully");

         assert_eq!(buffer.width(), 1024);
         assert_eq!(buffer.height(), 512);
         assert_eq!(buffer.layers(), 1);
         assert_eq!(buffer.format(), AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM);
         assert_eq!(
             buffer.usage(),
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN
         );
     }

     #[test]
     fn id_getter() {
         let buffer = HardwareBuffer::new(
             1024,
             512,
             1,
             AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
         )
         .expect("Buffer with some basic parameters was not created successfully");

         assert_ne!(0, buffer.id());
     }

     #[test]
     fn clone() {
         let buffer = HardwareBuffer::new(
             1024,
             512,
             1,
             AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
         )
         .expect("Buffer with some basic parameters was not created successfully");
         let buffer2 = buffer.clone();

         assert_eq!(buffer, buffer2);
     }

     #[test]
     fn into_raw() {
         let buffer = HardwareBuffer::new(
             1024,
             512,
             1,
             AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
             AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
         )
         .expect("Buffer with some basic parameters was not created successfully");
         let buffer2 = buffer.clone();

         let raw_buffer = buffer.into_raw();
         // SAFETY: This is the same pointer we had before.
         let remade_buffer = unsafe { HardwareBuffer::from_raw(raw_buffer) };

         assert_eq!(remade_buffer, buffer2);
     }
 }
	// Copyright (C) 2023 The Android Open Source Project
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	//! Pleasant Rust bindings for libnativewindow, including AHardwareBuffer

	extern crate nativewindow_bindgen as ffi;

	pub mod surface;

	pub use ffi::{AHardwareBuffer_Format, AHardwareBuffer_UsageFlags};

	use binder::{
	binder_impl::{BorrowedParcel, UnstructuredParcelable},
	impl_deserialize_for_unstructured_parcelable, impl_serialize_for_unstructured_parcelable,
	unstable_api::{status_result, AsNative},
	StatusCode,
	};
	use ffi::{AHardwareBuffer, AHardwareBuffer_readFromParcel, AHardwareBuffer_writeToParcel};
	use std::fmt::{self, Debug, Formatter};
	use std::mem::ManuallyDrop;
	use std::ptr::{self, null_mut, NonNull};

	/// Wrapper around an opaque C `AHardwareBuffer`.
	#[derive(PartialEq, Eq)]
	pub struct HardwareBuffer(NonNull<AHardwareBuffer>);

	impl HardwareBuffer {
	/// Test whether the given format and usage flag combination is allocatable. If this function
	/// returns true, it means that a buffer with the given description can be allocated on this
	/// implementation, unless resource exhaustion occurs. If this function returns false, it means
	/// that the allocation of the given description will never succeed.
	///
	/// Available since API 29
	pub fn is_supported(
	width: u32,
	height: u32,
	layers: u32,
	format: AHardwareBuffer_Format::Type,
	usage: AHardwareBuffer_UsageFlags,
	stride: u32,
	) -> bool {
	let buffer_desc = ffi::AHardwareBuffer_Desc {
	width,
	height,
	layers,
	format,
	usage: usage.0,
	stride,
	rfu0: 0,
	rfu1: 0,
	};
	// SAFETY: *buffer_desc will never be null.
	let status = unsafe { ffi::AHardwareBuffer_isSupported(&buffer_desc) };

	status == 1
	}

	/// Allocates a buffer that matches the passed AHardwareBuffer_Desc. If allocation succeeds, the
	/// buffer can be used according to the usage flags specified in its description. If a buffer is
	/// used in ways not compatible with its usage flags, the results are undefined and may include
	/// program termination.
	///
	/// Available since API level 26.
	#[inline]
	pub fn new(
	width: u32,
	height: u32,
	layers: u32,
	format: AHardwareBuffer_Format::Type,
	usage: AHardwareBuffer_UsageFlags,
	) -> Option<Self> {
	let buffer_desc = ffi::AHardwareBuffer_Desc {
	width,
	height,
	layers,
	format,
	usage: usage.0,
	stride: 0,
	rfu0: 0,
	rfu1: 0,
	};
	let mut ptr = ptr::null_mut();
	// SAFETY: The returned pointer is valid until we drop/deallocate it. The function may fail
	// and return a status, but we check it later.
	let status = unsafe { ffi::AHardwareBuffer_allocate(&buffer_desc, &mut ptr) };

	if status == 0 {
	Some(Self(NonNull::new(ptr).expect("Allocated AHardwareBuffer was null")))
	} else {
	None
	}
	}

	/// Adopts the given raw pointer and wraps it in a Rust HardwareBuffer.
	///
	/// # Safety
	///
	/// This function takes ownership of the pointer and does NOT increment the refcount on the
	/// buffer. If the caller uses the pointer after the created object is dropped it will cause
	/// undefined behaviour. If the caller wants to continue using the pointer after calling this
	/// then use [`clone_from_raw`](Self::clone_from_raw) instead.
	pub unsafe fn from_raw(buffer_ptr: NonNull<AHardwareBuffer>) -> Self {
	Self(buffer_ptr)
	}

	/// Creates a new Rust HardwareBuffer to wrap the given AHardwareBuffer without taking ownership
	/// of it.
	///
	/// Unlike [`from_raw`](Self::from_raw) this method will increment the refcount on the buffer.
	/// This means that the caller can continue to use the raw buffer it passed in, and must call
	/// [`AHardwareBuffer_release`](ffi::AHardwareBuffer_release) when it is finished with it to
	/// avoid a memory leak.
	///
	/// # Safety
	///
	/// The buffer pointer must point to a valid `AHardwareBuffer`.
	pub unsafe fn clone_from_raw(buffer: NonNull<AHardwareBuffer>) -> Self {
	// SAFETY: The caller guarantees that the AHardwareBuffer pointer is valid.
	unsafe { ffi::AHardwareBuffer_acquire(buffer.as_ptr()) };
	Self(buffer)
	}

	/// Get the internal \|AHardwareBuffer\| pointer without decrementing the refcount. This can
	/// be used to provide a pointer to the AHB for a C/C++ API over the FFI.
	pub fn into_raw(self) -> NonNull<AHardwareBuffer> {
	let buffer = ManuallyDrop::new(self);
	buffer.0
	}

	/// Get the system wide unique id for an AHardwareBuffer. This function may panic in extreme
	/// and undocumented circumstances.
	///
	/// Available since API level 31.
	pub fn id(&self) -> u64 {
	let mut out_id = 0;
	// SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
	// because it must have been allocated by `AHardwareBuffer_allocate`,
	// `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
	// released it. The id pointer must be valid because it comes from a reference.
	let status = unsafe { ffi::AHardwareBuffer_getId(self.0.as_ptr(), &mut out_id) };
	assert_eq!(status, 0, "id() failed for AHardwareBuffer with error code: {status}");

	out_id
	}

	/// Get the width of this buffer
	pub fn width(&self) -> u32 {
	self.description().width
	}

	/// Get the height of this buffer
	pub fn height(&self) -> u32 {
	self.description().height
	}

	/// Get the number of layers of this buffer
	pub fn layers(&self) -> u32 {
	self.description().layers
	}

	/// Get the format of this buffer
	pub fn format(&self) -> AHardwareBuffer_Format::Type {
	self.description().format
	}

	/// Get the usage bitvector of this buffer
	pub fn usage(&self) -> AHardwareBuffer_UsageFlags {
	AHardwareBuffer_UsageFlags(self.description().usage)
	}

	/// Get the stride of this buffer
	pub fn stride(&self) -> u32 {
	self.description().stride
	}

	fn description(&self) -> ffi::AHardwareBuffer_Desc {
	let mut buffer_desc = ffi::AHardwareBuffer_Desc {
	width: 0,
	height: 0,
	layers: 0,
	format: 0,
	usage: 0,
	stride: 0,
	rfu0: 0,
	rfu1: 0,
	};
	// SAFETY: neither the buffer nor AHardwareBuffer_Desc pointers will be null.
	unsafe { ffi::AHardwareBuffer_describe(self.0.as_ref(), &mut buffer_desc) };
	buffer_desc
	}
	}

	impl Drop for HardwareBuffer {
	fn drop(&mut self) {
	// SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
	// because it must have been allocated by `AHardwareBuffer_allocate`,
	// `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
	// released it.
	unsafe { ffi::AHardwareBuffer_release(self.0.as_ptr()) }
	}
	}

	impl Debug for HardwareBuffer {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
	f.debug_struct("HardwareBuffer").field("id", &self.id()).finish()
	}
	}

	impl Clone for HardwareBuffer {
	fn clone(&self) -> Self {
	// SAFETY: ptr is guaranteed to be non-null and the acquire can not fail.
	unsafe { ffi::AHardwareBuffer_acquire(self.0.as_ptr()) };
	Self(self.0)
	}
	}

	impl UnstructuredParcelable for HardwareBuffer {
	fn write_to_parcel(&self, parcel: &mut BorrowedParcel) -> Result<(), StatusCode> {
	let status =
	// SAFETY: The AHardwareBuffer pointer we pass is guaranteed to be non-null and valid
	// because it must have been allocated by `AHardwareBuffer_allocate`,
	// `AHardwareBuffer_readFromParcel` or the caller of `from_raw` and we have not yet
	// released it.
	unsafe { AHardwareBuffer_writeToParcel(self.0.as_ptr(), parcel.as_native_mut()) };
	status_result(status)
	}

	fn from_parcel(parcel: &BorrowedParcel) -> Result<Self, StatusCode> {
	let mut buffer = null_mut();

	let status =
	// SAFETY: Both pointers must be valid because they are obtained from references.
	// `AHardwareBuffer_readFromParcel` doesn't store them or do anything else special
	// with them. If it returns success then it will have allocated a new
	// `AHardwareBuffer` and incremented the reference count, so we can use it until we
	// release it.
	unsafe { AHardwareBuffer_readFromParcel(parcel.as_native(), &mut buffer) };

	status_result(status)?;

	Ok(Self(
	NonNull::new(buffer).expect(
	"AHardwareBuffer_readFromParcel returned success but didn't allocate buffer",
	),
	))
	}
	}

	impl_deserialize_for_unstructured_parcelable!(HardwareBuffer);
	impl_serialize_for_unstructured_parcelable!(HardwareBuffer);

	// SAFETY: The underlying *AHardwareBuffers can be moved between threads.
	unsafe impl Send for HardwareBuffer {}

	// SAFETY: The underlying *AHardwareBuffers can be used from multiple threads.
	//
	// AHardwareBuffers are backed by C++ GraphicBuffers, which are mostly immutable. The only cases
	// where they are not immutable are:
	//
	// - reallocation (which is never actually done across the codebase and requires special
	// privileges/platform code access to do)
	// - "locking" for reading/writing (which is explicitly allowed to be done across multiple threads
	// according to the docs on the underlying gralloc calls)
	unsafe impl Sync for HardwareBuffer {}

	#[cfg(test)]
	mod test {
	use super::*;

	#[test]
	fn create_valid_buffer_returns_ok() {
	let buffer = HardwareBuffer::new(
	512,
	512,
	1,
	AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
	);
	assert!(buffer.is_some());
	}

	#[test]
	fn create_invalid_buffer_returns_err() {
	let buffer = HardwareBuffer::new(512, 512, 1, 0, AHardwareBuffer_UsageFlags(0));
	assert!(buffer.is_none());
	}

	#[test]
	fn from_raw_allows_getters() {
	let buffer_desc = ffi::AHardwareBuffer_Desc {
	width: 1024,
	height: 512,
	layers: 1,
	format: AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	usage: AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN.0,
	stride: 0,
	rfu0: 0,
	rfu1: 0,
	};
	let mut raw_buffer_ptr = ptr::null_mut();

	// SAFETY: The pointers are valid because they come from references, and
	// `AHardwareBuffer_allocate` doesn't retain them after it returns.
	let status = unsafe { ffi::AHardwareBuffer_allocate(&buffer_desc, &mut raw_buffer_ptr) };
	assert_eq!(status, 0);

	// SAFETY: The pointer must be valid because it was just allocated successfully, and we
	// don't use it after calling this.
	let buffer = unsafe { HardwareBuffer::from_raw(NonNull::new(raw_buffer_ptr).unwrap()) };
	assert_eq!(buffer.width(), 1024);
	}

	#[test]
	fn basic_getters() {
	let buffer = HardwareBuffer::new(
	1024,
	512,
	1,
	AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
	)
	.expect("Buffer with some basic parameters was not created successfully");

	assert_eq!(buffer.width(), 1024);
	assert_eq!(buffer.height(), 512);
	assert_eq!(buffer.layers(), 1);
	assert_eq!(buffer.format(), AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM);
	assert_eq!(
	buffer.usage(),
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN
	);
	}

	#[test]
	fn id_getter() {
	let buffer = HardwareBuffer::new(
	1024,
	512,
	1,
	AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
	)
	.expect("Buffer with some basic parameters was not created successfully");

	assert_ne!(0, buffer.id());
	}

	#[test]
	fn clone() {
	let buffer = HardwareBuffer::new(
	1024,
	512,
	1,
	AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
	)
	.expect("Buffer with some basic parameters was not created successfully");
	let buffer2 = buffer.clone();

	assert_eq!(buffer, buffer2);
	}

	#[test]
	fn into_raw() {
	let buffer = HardwareBuffer::new(
	1024,
	512,
	1,
	AHardwareBuffer_Format::AHARDWAREBUFFER_FORMAT_R8G8B8A8_UNORM,
	AHardwareBuffer_UsageFlags::AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN,
	)
	.expect("Buffer with some basic parameters was not created successfully");
	let buffer2 = buffer.clone();

	let raw_buffer = buffer.into_raw();
	// SAFETY: This is the same pointer we had before.
	let remade_buffer = unsafe { HardwareBuffer::from_raw(raw_buffer) };

	assert_eq!(remade_buffer, buffer2);
	}
	}