rust: split Parcel enum into two types

Test: m
Bug: 200676345
Change-Id: I351ea0500035dafe0c8444cbb96074725c1c8630
diff --git a/libs/binder/rust/src/binder.rs b/libs/binder/rust/src/binder.rs
index 4e048d7..bd2e695 100644
--- a/libs/binder/rust/src/binder.rs
+++ b/libs/binder/rust/src/binder.rs
@@ -17,7 +17,7 @@
 //! Trait definitions for binder objects
 
 use crate::error::{status_t, Result, StatusCode};
-use crate::parcel::{OwnedParcel, Parcel};
+use crate::parcel::{Parcel, BorrowedParcel};
 use crate::proxy::{DeathRecipient, SpIBinder, WpIBinder};
 use crate::sys;
 
@@ -129,7 +129,7 @@
     /// Handle and reply to a request to invoke a transaction on this object.
     ///
     /// `reply` may be [`None`] if the sender does not expect a reply.
-    fn on_transact(&self, code: TransactionCode, data: &Parcel, reply: &mut Parcel) -> Result<()>;
+    fn on_transact(&self, code: TransactionCode, data: &BorrowedParcel<'_>, reply: &mut BorrowedParcel<'_>) -> Result<()>;
 
     /// Handle a request to invoke the dump transaction on this
     /// object.
@@ -177,25 +177,25 @@
     fn get_extension(&mut self) -> Result<Option<SpIBinder>>;
 
     /// Create a Parcel that can be used with `submit_transact`.
-    fn prepare_transact(&self) -> Result<OwnedParcel>;
+    fn prepare_transact(&self) -> Result<Parcel>;
 
     /// Perform a generic operation with the object.
     ///
-    /// The provided [`OwnedParcel`] must have been created by a call to
+    /// The provided [`Parcel`] must have been created by a call to
     /// `prepare_transact` on the same binder.
     ///
     /// # Arguments
     ///
     /// * `code` - Transaction code for the operation.
-    /// * `data` - [`OwnedParcel`] with input data.
+    /// * `data` - [`Parcel`] with input data.
     /// * `flags` - Transaction flags, e.g. marking the transaction as
     ///   asynchronous ([`FLAG_ONEWAY`](FLAG_ONEWAY)).
     fn submit_transact(
         &self,
         code: TransactionCode,
-        data: OwnedParcel,
+        data: Parcel,
         flags: TransactionFlags,
-    ) -> Result<OwnedParcel>;
+    ) -> Result<Parcel>;
 
     /// Perform a generic operation with the object. This is a convenience
     /// method that internally calls `prepare_transact` followed by
@@ -206,15 +206,15 @@
     /// * `flags` - Transaction flags, e.g. marking the transaction as
     ///   asynchronous ([`FLAG_ONEWAY`](FLAG_ONEWAY))
     /// * `input_callback` A callback for building the `Parcel`.
-    fn transact<F: FnOnce(&mut Parcel) -> Result<()>>(
+    fn transact<F: FnOnce(BorrowedParcel<'_>) -> Result<()>>(
         &self,
         code: TransactionCode,
         flags: TransactionFlags,
         input_callback: F,
     ) -> Result<Parcel> {
         let mut parcel = self.prepare_transact()?;
-        input_callback(&mut parcel.borrowed())?;
-        self.submit_transact(code, parcel, flags).map(OwnedParcel::into_parcel)
+        input_callback(parcel.borrowed())?;
+        self.submit_transact(code, parcel, flags)
     }
 }
 
@@ -475,8 +475,8 @@
 ///     fn on_transact(
 ///         &self,
 ///         code: TransactionCode,
-///         data: &Parcel,
-///         reply: &mut Parcel,
+///         data: &BorrowedParcel,
+///         reply: &mut BorrowedParcel,
 ///     ) -> Result<()> {
 ///         // ...
 ///     }
@@ -655,13 +655,13 @@
 /// have the following type:
 ///
 /// ```
-/// # use binder::{Interface, TransactionCode, Parcel};
+/// # use binder::{Interface, TransactionCode, BorrowedParcel};
 /// # trait Placeholder {
 /// fn on_transact(
 ///     service: &dyn Interface,
 ///     code: TransactionCode,
-///     data: &Parcel,
-///     reply: &mut Parcel,
+///     data: &BorrowedParcel,
+///     reply: &mut BorrowedParcel,
 /// ) -> binder::Result<()>;
 /// # }
 /// ```
@@ -676,7 +676,7 @@
 /// using the provided function, `on_transact`.
 ///
 /// ```
-/// use binder::{declare_binder_interface, Binder, Interface, TransactionCode, Parcel};
+/// use binder::{declare_binder_interface, Binder, Interface, TransactionCode, BorrowedParcel};
 ///
 /// pub trait IServiceManager: Interface {
 ///     // remote methods...
@@ -692,8 +692,8 @@
 /// fn on_transact(
 ///     service: &dyn IServiceManager,
 ///     code: TransactionCode,
-///     data: &Parcel,
-///     reply: &mut Parcel,
+///     data: &BorrowedParcel,
+///     reply: &mut BorrowedParcel,
 /// ) -> binder::Result<()> {
 ///     // ...
 ///     Ok(())
@@ -847,7 +847,7 @@
                 $descriptor
             }
 
-            fn on_transact(&self, code: $crate::TransactionCode, data: &$crate::Parcel, reply: &mut $crate::Parcel) -> $crate::Result<()> {
+            fn on_transact(&self, code: $crate::TransactionCode, data: &$crate::BorrowedParcel<'_>, reply: &mut $crate::BorrowedParcel<'_>) -> $crate::Result<()> {
                 match $on_transact(&*self.0, code, data, reply) {
                     // The C++ backend converts UNEXPECTED_NULL into an exception
                     Err($crate::StatusCode::UNEXPECTED_NULL) => {
@@ -922,14 +922,14 @@
         where
             dyn $interface: $crate::Interface
         {
-            fn serialize(&self, parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize(&self, parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 let binder = $crate::Interface::as_binder(self);
                 parcel.write(&binder)
             }
         }
 
         impl $crate::parcel::SerializeOption for dyn $interface + '_ {
-            fn serialize_option(this: Option<&Self>, parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize_option(this: Option<&Self>, parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 parcel.write(&this.map($crate::Interface::as_binder))
             }
         }
@@ -988,14 +988,14 @@
         }
 
         impl<P: $crate::BinderAsyncPool> $crate::parcel::Serialize for dyn $async_interface<P> + '_ {
-            fn serialize(&self, parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize(&self, parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 let binder = $crate::Interface::as_binder(self);
                 parcel.write(&binder)
             }
         }
 
         impl<P: $crate::BinderAsyncPool> $crate::parcel::SerializeOption for dyn $async_interface<P> + '_ {
-            fn serialize_option(this: Option<&Self>, parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize_option(this: Option<&Self>, parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 parcel.write(&this.map($crate::Interface::as_binder))
             }
         }
@@ -1040,26 +1040,26 @@
         }
 
         impl $crate::parcel::Serialize for $enum {
-            fn serialize(&self, parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize(&self, parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 parcel.write(&self.0)
             }
         }
 
         impl $crate::parcel::SerializeArray for $enum {
-            fn serialize_array(slice: &[Self], parcel: &mut $crate::parcel::Parcel) -> $crate::Result<()> {
+            fn serialize_array(slice: &[Self], parcel: &mut $crate::parcel::BorrowedParcel<'_>) -> $crate::Result<()> {
                 let v: Vec<$backing> = slice.iter().map(|x| x.0).collect();
                 <$backing as binder::parcel::SerializeArray>::serialize_array(&v[..], parcel)
             }
         }
 
         impl $crate::parcel::Deserialize for $enum {
-            fn deserialize(parcel: &$crate::parcel::Parcel) -> $crate::Result<Self> {
+            fn deserialize(parcel: &$crate::parcel::BorrowedParcel<'_>) -> $crate::Result<Self> {
                 parcel.read().map(Self)
             }
         }
 
         impl $crate::parcel::DeserializeArray for $enum {
-            fn deserialize_array(parcel: &$crate::parcel::Parcel) -> $crate::Result<Option<Vec<Self>>> {
+            fn deserialize_array(parcel: &$crate::parcel::BorrowedParcel<'_>) -> $crate::Result<Option<Vec<Self>>> {
                 let v: Option<Vec<$backing>> =
                     <$backing as binder::parcel::DeserializeArray>::deserialize_array(parcel)?;
                 Ok(v.map(|v| v.into_iter().map(Self).collect()))
diff --git a/libs/binder/rust/src/lib.rs b/libs/binder/rust/src/lib.rs
index 2ac2d2f..cce55c0 100644
--- a/libs/binder/rust/src/lib.rs
+++ b/libs/binder/rust/src/lib.rs
@@ -50,8 +50,8 @@
 //! fn on_transact(
 //!     service: &dyn ITest,
 //!     code: TransactionCode,
-//!     _data: &Parcel,
-//!     reply: &mut Parcel,
+//!     _data: &BorrowedParcel,
+//!     reply: &mut BorrowedParcel,
 //! ) -> binder::Result<()> {
 //!     match code {
 //!         SpIBinder::FIRST_CALL_TRANSACTION => {
@@ -115,7 +115,7 @@
 pub use crate::binder_async::{BoxFuture, BinderAsyncPool};
 pub use error::{status_t, ExceptionCode, Result, Status, StatusCode};
 pub use native::{add_service, force_lazy_services_persist, register_lazy_service, Binder};
-pub use parcel::{OwnedParcel, Parcel};
+pub use parcel::{BorrowedParcel, Parcel};
 pub use proxy::{get_interface, get_service, wait_for_interface, wait_for_service};
 pub use proxy::{AssociateClass, DeathRecipient, Proxy, SpIBinder, WpIBinder};
 pub use state::{ProcessState, ThreadState};
diff --git a/libs/binder/rust/src/native.rs b/libs/binder/rust/src/native.rs
index a91092e..f5d7187 100644
--- a/libs/binder/rust/src/native.rs
+++ b/libs/binder/rust/src/native.rs
@@ -18,7 +18,7 @@
     AsNative, Interface, InterfaceClassMethods, Remotable, Stability, TransactionCode,
 };
 use crate::error::{status_result, status_t, Result, StatusCode};
-use crate::parcel::{Parcel, Serialize};
+use crate::parcel::{BorrowedParcel, Serialize};
 use crate::proxy::SpIBinder;
 use crate::sys;
 
@@ -161,8 +161,8 @@
     ///        # fn on_transact(
     ///        #     service: &dyn IBar,
     ///        #     code: TransactionCode,
-    ///        #     data: &Parcel,
-    ///        #     reply: &mut Parcel,
+    ///        #     data: &BorrowedParcel,
+    ///        #     reply: &mut BorrowedParcel,
     ///        # ) -> binder::Result<()> {
     ///        #     Ok(())
     ///        # }
@@ -277,8 +277,8 @@
         reply: *mut sys::AParcel,
     ) -> status_t {
         let res = {
-            let mut reply = Parcel::borrowed(reply).unwrap();
-            let data = Parcel::borrowed(data as *mut sys::AParcel).unwrap();
+            let mut reply = BorrowedParcel::from_raw(reply).unwrap();
+            let data = BorrowedParcel::from_raw(data as *mut sys::AParcel).unwrap();
             let object = sys::AIBinder_getUserData(binder);
             let binder: &T = &*(object as *const T);
             binder.on_transact(code, &data, &mut reply)
@@ -384,7 +384,7 @@
 }
 
 impl<B: Remotable> Serialize for Binder<B> {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         parcel.write_binder(Some(&self.as_binder()))
     }
 }
@@ -503,8 +503,8 @@
     fn on_transact(
         &self,
         _code: TransactionCode,
-        _data: &Parcel,
-        _reply: &mut Parcel,
+        _data: &BorrowedParcel<'_>,
+        _reply: &mut BorrowedParcel<'_>,
     ) -> Result<()> {
         Ok(())
     }
diff --git a/libs/binder/rust/src/parcel.rs b/libs/binder/rust/src/parcel.rs
index a0e1478..206b90c 100644
--- a/libs/binder/rust/src/parcel.rs
+++ b/libs/binder/rust/src/parcel.rs
@@ -21,11 +21,10 @@
 use crate::proxy::SpIBinder;
 use crate::sys;
 
-use std::cell::RefCell;
 use std::convert::TryInto;
 use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
-use std::ptr;
+use std::ptr::{self, NonNull};
 use std::fmt;
 
 mod file_descriptor;
@@ -46,53 +45,41 @@
 /// other side of the IPC, and references to live Binder objects that will
 /// result in the other side receiving a proxy Binder connected with the
 /// original Binder in the Parcel.
-pub enum Parcel {
-    /// Owned parcel pointer
-    Owned(*mut sys::AParcel),
-    /// Borrowed parcel pointer (will not be destroyed on drop)
-    Borrowed(*mut sys::AParcel),
-}
-
-/// A variant of Parcel that is known to be owned.
-pub struct OwnedParcel {
-    ptr: *mut sys::AParcel,
+///
+/// This type represents a parcel that is owned by Rust code.
+#[repr(transparent)]
+pub struct Parcel {
+    ptr: NonNull<sys::AParcel>,
 }
 
 /// # Safety
 ///
 /// This type guarantees that it owns the AParcel and that all access to
-/// the AParcel happens through the OwnedParcel, so it is ok to send across
+/// the AParcel happens through the Parcel, so it is ok to send across
 /// threads.
-unsafe impl Send for OwnedParcel {}
+unsafe impl Send for Parcel {}
 
-/// A variant of Parcel that is known to be borrowed.
+/// Container for a message (data and object references) that can be sent
+/// through Binder.
+///
+/// This object is a borrowed variant of [`Parcel`]. It is a separate type from
+/// `&mut Parcel` because it is not valid to `mem::swap` two parcels.
+#[repr(transparent)]
 pub struct BorrowedParcel<'a> {
-    inner: Parcel,
+    ptr: NonNull<sys::AParcel>,
     _lifetime: PhantomData<&'a mut Parcel>,
 }
 
-impl OwnedParcel {
-    /// Create a new empty `OwnedParcel`.
-    pub fn new() -> OwnedParcel {
+impl Parcel {
+    /// Create a new empty `Parcel`.
+    pub fn new() -> Parcel {
         let ptr = unsafe {
             // Safety: If `AParcel_create` succeeds, it always returns
             // a valid pointer. If it fails, the process will crash.
             sys::AParcel_create()
         };
-        assert!(!ptr.is_null());
-        Self { ptr }
-    }
-
-    /// Convert the provided parcel to an owned parcel, or return `None` if it
-    /// is borrowed.
-    pub fn try_from(parcel: Parcel) -> Option<OwnedParcel> {
-        match &parcel {
-            Parcel::Owned(ptr) => {
-                let ptr = *ptr;
-                std::mem::forget(parcel);
-                Some(OwnedParcel { ptr })
-            }
-            Parcel::Borrowed(_) => None,
+        Self {
+            ptr: NonNull::new(ptr).expect("AParcel_create returned null pointer")
         }
     }
 
@@ -107,108 +94,43 @@
     ///
     /// Additionally, the caller must guarantee that it is valid to take
     /// ownership of the AParcel object. All future access to the AParcel
-    /// must happen through this `OwnedParcel`.
+    /// must happen through this `Parcel`.
     ///
-    /// Because `OwnedParcel` implements `Send`, the pointer must never point
-    /// to any thread-local data, e.g., a variable on the stack, either directly
-    /// or indirectly.
-    pub unsafe fn from_raw(ptr: *mut sys::AParcel) -> Option<OwnedParcel> {
-        ptr.as_mut().map(|ptr| Self { ptr })
+    /// Because `Parcel` implements `Send`, the pointer must never point to any
+    /// thread-local data, e.g., a variable on the stack, either directly or
+    /// indirectly.
+    pub unsafe fn from_raw(ptr: *mut sys::AParcel) -> Option<Parcel> {
+        NonNull::new(ptr).map(|ptr| Self { ptr })
     }
 
     /// Consume the parcel, transferring ownership to the caller.
     pub(crate) fn into_raw(self) -> *mut sys::AParcel {
-        let ptr = self.ptr;
+        let ptr = self.ptr.as_ptr();
         let _ = ManuallyDrop::new(self);
         ptr
     }
 
-    /// Convert this `OwnedParcel` into an owned `Parcel`.
-    pub fn into_parcel(self) -> Parcel {
-        Parcel::Owned(self.into_raw())
-    }
-
     /// Get a borrowed view into the contents of this `Parcel`.
     pub fn borrowed(&mut self) -> BorrowedParcel<'_> {
+        // Safety: The raw pointer is a valid pointer to an AParcel, and the
+        // lifetime of the returned `BorrowedParcel` is tied to `self`, so the
+        // borrow checker will ensure that the `AParcel` can only be accessed
+        // via the `BorrowParcel` until it goes out of scope.
         BorrowedParcel {
-            inner: Parcel::Borrowed(self.ptr),
+            ptr: self.ptr,
             _lifetime: PhantomData,
         }
     }
-}
 
-impl Default for OwnedParcel {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-impl Clone for OwnedParcel {
-    fn clone(&self) -> Self {
-        let mut new_parcel = Self::new();
-        new_parcel
-            .borrowed()
-            .append_all_from(&Parcel::Borrowed(self.ptr))
-            .expect("Failed to append from Parcel");
-        new_parcel
-    }
-}
-
-impl<'a> std::ops::Deref for BorrowedParcel<'a> {
-    type Target = Parcel;
-    fn deref(&self) -> &Parcel {
-        &self.inner
-    }
-}
-impl<'a> std::ops::DerefMut for BorrowedParcel<'a> {
-    fn deref_mut(&mut self) -> &mut Parcel {
-        &mut self.inner
-    }
-}
-
-/// # Safety
-///
-/// The `Parcel` constructors guarantee that a `Parcel` object will always
-/// contain a valid pointer to an `AParcel`.
-unsafe impl AsNative<sys::AParcel> for Parcel {
-    fn as_native(&self) -> *const sys::AParcel {
-        match *self {
-            Self::Owned(x) | Self::Borrowed(x) => x,
+    /// Get an immutable borrowed view into the contents of this `Parcel`.
+    pub fn borrowed_ref(&self) -> &BorrowedParcel<'_> {
+        // Safety: Parcel and BorrowedParcel are both represented in the same
+        // way as a NonNull<sys::AParcel> due to their use of repr(transparent),
+        // so casting references as done here is valid.
+        unsafe {
+            &*(self as *const Parcel as *const BorrowedParcel<'_>)
         }
     }
-
-    fn as_native_mut(&mut self) -> *mut sys::AParcel {
-        match *self {
-            Self::Owned(x) | Self::Borrowed(x) => x,
-        }
-    }
-}
-
-impl Parcel {
-    /// Create a new empty `Parcel`.
-    ///
-    /// Creates a new owned empty parcel that can be written to
-    /// using the serialization methods and appended to and
-    /// from using `append_from` and `append_from_all`.
-    pub fn new() -> Parcel {
-        let parcel = unsafe {
-            // Safety: If `AParcel_create` succeeds, it always returns
-            // a valid pointer. If it fails, the process will crash.
-            sys::AParcel_create()
-        };
-        assert!(!parcel.is_null());
-        Self::Owned(parcel)
-    }
-
-    /// Create a borrowed reference to a parcel object from a raw pointer.
-    ///
-    /// # Safety
-    ///
-    /// This constructor is safe if the raw pointer parameter is either null
-    /// (resulting in `None`), or a valid pointer to an `AParcel` object.
-    pub(crate) unsafe fn borrowed(ptr: *mut sys::AParcel) -> Option<Parcel> {
-        ptr.as_mut().map(|ptr| Self::Borrowed(ptr))
-    }
 }
 
 impl Default for Parcel {
@@ -221,14 +143,77 @@
     fn clone(&self) -> Self {
         let mut new_parcel = Self::new();
         new_parcel
-            .append_all_from(self)
+            .borrowed()
+            .append_all_from(self.borrowed_ref())
             .expect("Failed to append from Parcel");
         new_parcel
     }
 }
 
+impl<'a> BorrowedParcel<'a> {
+    /// Create a borrowed reference to a parcel object from a raw pointer.
+    ///
+    /// # Safety
+    ///
+    /// This constructor is safe if the raw pointer parameter is either null
+    /// (resulting in `None`), or a valid pointer to an `AParcel` object.
+    ///
+    /// Since the raw pointer is not restricted by any lifetime, the lifetime on
+    /// the returned `BorrowedParcel` object can be chosen arbitrarily by the
+    /// caller. The caller must ensure it is valid to mutably borrow the AParcel
+    /// for the duration of the lifetime that the caller chooses. Note that
+    /// since this is a mutable borrow, it must have exclusive access to the
+    /// AParcel for the duration of the borrow.
+    pub unsafe fn from_raw(ptr: *mut sys::AParcel) -> Option<BorrowedParcel<'a>> {
+        Some(Self {
+            ptr: NonNull::new(ptr)?,
+            _lifetime: PhantomData,
+        })
+    }
+
+    /// Get a sub-reference to this reference to the parcel.
+    pub fn reborrow(&mut self) -> BorrowedParcel<'_> {
+        // Safety: The raw pointer is a valid pointer to an AParcel, and the
+        // lifetime of the returned `BorrowedParcel` is tied to `self`, so the
+        // borrow checker will ensure that the `AParcel` can only be accessed
+        // via the `BorrowParcel` until it goes out of scope.
+        BorrowedParcel {
+            ptr: self.ptr,
+            _lifetime: PhantomData,
+        }
+    }
+}
+
+/// # Safety
+///
+/// The `Parcel` constructors guarantee that a `Parcel` object will always
+/// contain a valid pointer to an `AParcel`.
+unsafe impl AsNative<sys::AParcel> for Parcel {
+    fn as_native(&self) -> *const sys::AParcel {
+        self.ptr.as_ptr()
+    }
+
+    fn as_native_mut(&mut self) -> *mut sys::AParcel {
+        self.ptr.as_ptr()
+    }
+}
+
+/// # Safety
+///
+/// The `BorrowedParcel` constructors guarantee that a `BorrowedParcel` object
+/// will always contain a valid pointer to an `AParcel`.
+unsafe impl<'a> AsNative<sys::AParcel> for BorrowedParcel<'a> {
+    fn as_native(&self) -> *const sys::AParcel {
+        self.ptr.as_ptr()
+    }
+
+    fn as_native_mut(&mut self) -> *mut sys::AParcel {
+        self.ptr.as_ptr()
+    }
+}
+
 // Data serialization methods
-impl Parcel {
+impl<'a> BorrowedParcel<'a> {
     /// Data written to parcelable is zero'd before being deleted or reallocated.
     pub fn mark_sensitive(&mut self) {
         unsafe {
@@ -237,12 +222,12 @@
         }
     }
 
-    /// Write a type that implements [`Serialize`] to the `Parcel`.
+    /// Write a type that implements [`Serialize`] to the parcel.
     pub fn write<S: Serialize + ?Sized>(&mut self, parcelable: &S) -> Result<()> {
         parcelable.serialize(self)
     }
 
-    /// Writes the length of a slice to the `Parcel`.
+    /// Writes the length of a slice to the parcel.
     ///
     /// This is used in AIDL-generated client side code to indicate the
     /// allocated space for an output array parameter.
@@ -255,7 +240,7 @@
         }
     }
 
-    /// Perform a series of writes to the `Parcel`, prepended with the length
+    /// Perform a series of writes to the parcel, prepended with the length
     /// (in bytes) of the written data.
     ///
     /// The length `0i32` will be written to the parcel first, followed by the
@@ -269,7 +254,7 @@
     ///
     /// ```
     /// # use binder::{Binder, Interface, Parcel};
-    /// # let mut parcel = Parcel::Owned(std::ptr::null_mut());
+    /// # let mut parcel = Parcel::new();
     /// parcel.sized_write(|subparcel| {
     ///     subparcel.write(&1u32)?;
     ///     subparcel.write(&2u32)?;
@@ -283,14 +268,14 @@
     /// [16i32, 1u32, 2u32, 3u32]
     /// ```
     pub fn sized_write<F>(&mut self, f: F) -> Result<()>
-    where for<'a>
-        F: Fn(&'a WritableSubParcel<'a>) -> Result<()>
+    where
+        for<'b> F: FnOnce(&'b mut WritableSubParcel<'b>) -> Result<()>
     {
         let start = self.get_data_position();
         self.write(&0i32)?;
         {
-            let subparcel = WritableSubParcel(RefCell::new(self));
-            f(&subparcel)?;
+            let mut subparcel = WritableSubParcel(self.reborrow());
+            f(&mut subparcel)?;
         }
         let end = self.get_data_position();
         unsafe {
@@ -307,8 +292,8 @@
     /// Returns the current position in the parcel data.
     pub fn get_data_position(&self) -> i32 {
         unsafe {
-            // Safety: `Parcel` always contains a valid pointer to an `AParcel`,
-            // and this call is otherwise safe.
+            // Safety: `BorrowedParcel` always contains a valid pointer to an
+            // `AParcel`, and this call is otherwise safe.
             sys::AParcel_getDataPosition(self.as_native())
         }
     }
@@ -316,8 +301,8 @@
     /// Returns the total size of the parcel.
     pub fn get_data_size(&self) -> i32 {
         unsafe {
-            // Safety: `Parcel` always contains a valid pointer to an `AParcel`,
-            // and this call is otherwise safe.
+            // Safety: `BorrowedParcel` always contains a valid pointer to an
+            // `AParcel`, and this call is otherwise safe.
             sys::AParcel_getDataSize(self.as_native())
         }
     }
@@ -335,11 +320,11 @@
         status_result(sys::AParcel_setDataPosition(self.as_native(), pos))
     }
 
-    /// Append a subset of another `Parcel`.
+    /// Append a subset of another parcel.
     ///
     /// This appends `size` bytes of data from `other` starting at offset
-    /// `start` to the current `Parcel`, or returns an error if not possible.
-    pub fn append_from(&mut self, other: &Self, start: i32, size: i32) -> Result<()> {
+    /// `start` to the current parcel, or returns an error if not possible.
+    pub fn append_from(&mut self, other: &impl AsNative<sys::AParcel>, start: i32, size: i32) -> Result<()> {
         let status = unsafe {
             // Safety: `Parcel::appendFrom` from C++ checks that `start`
             // and `size` are in bounds, and returns an error otherwise.
@@ -354,33 +339,125 @@
         status_result(status)
     }
 
-    /// Append the contents of another `Parcel`.
-    pub fn append_all_from(&mut self, other: &Self) -> Result<()> {
-        self.append_from(other, 0, other.get_data_size())
+    /// Append the contents of another parcel.
+    pub fn append_all_from(&mut self, other: &impl AsNative<sys::AParcel>) -> Result<()> {
+        // Safety: `BorrowedParcel` always contains a valid pointer to an
+        // `AParcel`, and this call is otherwise safe.
+        let size = unsafe { sys::AParcel_getDataSize(other.as_native()) };
+        self.append_from(other, 0, size)
     }
 }
 
-/// A segment of a writable parcel, used for [`Parcel::sized_write`].
-pub struct WritableSubParcel<'a>(RefCell<&'a mut Parcel>);
+/// A segment of a writable parcel, used for [`BorrowedParcel::sized_write`].
+pub struct WritableSubParcel<'a>(BorrowedParcel<'a>);
 
 impl<'a> WritableSubParcel<'a> {
     /// Write a type that implements [`Serialize`] to the sub-parcel.
-    pub fn write<S: Serialize + ?Sized>(&self, parcelable: &S) -> Result<()> {
-        parcelable.serialize(&mut *self.0.borrow_mut())
+    pub fn write<S: Serialize + ?Sized>(&mut self, parcelable: &S) -> Result<()> {
+        parcelable.serialize(&mut self.0)
+    }
+}
+
+impl Parcel {
+    /// Data written to parcelable is zero'd before being deleted or reallocated.
+    pub fn mark_sensitive(&mut self) {
+        self.borrowed().mark_sensitive()
+    }
+
+    /// Write a type that implements [`Serialize`] to the parcel.
+    pub fn write<S: Serialize + ?Sized>(&mut self, parcelable: &S) -> Result<()> {
+        self.borrowed().write(parcelable)
+    }
+
+    /// Writes the length of a slice to the parcel.
+    ///
+    /// This is used in AIDL-generated client side code to indicate the
+    /// allocated space for an output array parameter.
+    pub fn write_slice_size<T>(&mut self, slice: Option<&[T]>) -> Result<()> {
+        self.borrowed().write_slice_size(slice)
+    }
+
+    /// Perform a series of writes to the parcel, prepended with the length
+    /// (in bytes) of the written data.
+    ///
+    /// The length `0i32` will be written to the parcel first, followed by the
+    /// writes performed by the callback. The initial length will then be
+    /// updated to the length of all data written by the callback, plus the
+    /// size of the length elemement itself (4 bytes).
+    ///
+    /// # Examples
+    ///
+    /// After the following call:
+    ///
+    /// ```
+    /// # use binder::{Binder, Interface, Parcel};
+    /// # let mut parcel = Parcel::new();
+    /// parcel.sized_write(|subparcel| {
+    ///     subparcel.write(&1u32)?;
+    ///     subparcel.write(&2u32)?;
+    ///     subparcel.write(&3u32)
+    /// });
+    /// ```
+    ///
+    /// `parcel` will contain the following:
+    ///
+    /// ```ignore
+    /// [16i32, 1u32, 2u32, 3u32]
+    /// ```
+    pub fn sized_write<F>(&mut self, f: F) -> Result<()>
+    where
+        for<'b> F: FnOnce(&'b mut WritableSubParcel<'b>) -> Result<()>
+    {
+        self.borrowed().sized_write(f)
+    }
+
+    /// Returns the current position in the parcel data.
+    pub fn get_data_position(&self) -> i32 {
+        self.borrowed_ref().get_data_position()
+    }
+
+    /// Returns the total size of the parcel.
+    pub fn get_data_size(&self) -> i32 {
+        self.borrowed_ref().get_data_size()
+    }
+
+    /// Move the current read/write position in the parcel.
+    ///
+    /// # Safety
+    ///
+    /// This method is safe if `pos` is less than the current size of the parcel
+    /// data buffer. Otherwise, we are relying on correct bounds checking in the
+    /// Parcel C++ code on every subsequent read or write to this parcel. If all
+    /// accesses are bounds checked, this call is still safe, but we can't rely
+    /// on that.
+    pub unsafe fn set_data_position(&self, pos: i32) -> Result<()> {
+        self.borrowed_ref().set_data_position(pos)
+    }
+
+    /// Append a subset of another parcel.
+    ///
+    /// This appends `size` bytes of data from `other` starting at offset
+    /// `start` to the current parcel, or returns an error if not possible.
+    pub fn append_from(&mut self, other: &impl AsNative<sys::AParcel>, start: i32, size: i32) -> Result<()> {
+        self.borrowed().append_from(other, start, size)
+    }
+
+    /// Append the contents of another parcel.
+    pub fn append_all_from(&mut self, other: &impl AsNative<sys::AParcel>) -> Result<()> {
+        self.borrowed().append_all_from(other)
     }
 }
 
 // Data deserialization methods
-impl Parcel {
-    /// Attempt to read a type that implements [`Deserialize`] from this
-    /// `Parcel`.
+impl<'a> BorrowedParcel<'a> {
+    /// Attempt to read a type that implements [`Deserialize`] from this parcel.
     pub fn read<D: Deserialize>(&self) -> Result<D> {
         D::deserialize(self)
     }
 
-    /// Attempt to read a type that implements [`Deserialize`] from this
-    /// `Parcel` onto an existing value. This operation will overwrite the old
-    /// value partially or completely, depending on how much data is available.
+    /// Attempt to read a type that implements [`Deserialize`] from this parcel
+    /// onto an existing value. This operation will overwrite the old value
+    /// partially or completely, depending on how much data is available.
     pub fn read_onto<D: Deserialize>(&self, x: &mut D) -> Result<()> {
         x.deserialize_from(self)
     }
@@ -413,9 +490,9 @@
     /// });
     /// ```
     ///
-    pub fn sized_read<F>(&self, mut f: F) -> Result<()>
+    pub fn sized_read<F>(&self, f: F) -> Result<()>
     where
-        for<'a> F: FnMut(ReadableSubParcel<'a>) -> Result<()>
+        for<'b> F: FnOnce(ReadableSubParcel<'b>) -> Result<()>
     {
         let start = self.get_data_position();
         let parcelable_size: i32 = self.read()?;
@@ -430,7 +507,10 @@
         }
 
         let subparcel = ReadableSubParcel {
-            parcel: self,
+            parcel: BorrowedParcel {
+                ptr: self.ptr,
+                _lifetime: PhantomData,
+            },
             end_position: end,
         };
         f(subparcel)?;
@@ -444,8 +524,8 @@
         Ok(())
     }
 
-    /// Read a vector size from the `Parcel` and resize the given output vector
-    /// to be correctly sized for that amount of data.
+    /// Read a vector size from the parcel and resize the given output vector to
+    /// be correctly sized for that amount of data.
     ///
     /// This method is used in AIDL-generated server side code for methods that
     /// take a mutable slice reference parameter.
@@ -463,7 +543,7 @@
         Ok(())
     }
 
-    /// Read a vector size from the `Parcel` and either create a correctly sized
+    /// Read a vector size from the parcel and either create a correctly sized
     /// vector for that amount of data or set the output parameter to None if
     /// the vector should be null.
     ///
@@ -491,7 +571,7 @@
 
 /// A segment of a readable parcel, used for [`Parcel::sized_read`].
 pub struct ReadableSubParcel<'a> {
-    parcel: &'a Parcel,
+    parcel: BorrowedParcel<'a>,
     end_position: i32,
 }
 
@@ -501,7 +581,7 @@
         // The caller should have checked this,
         // but it can't hurt to double-check
         assert!(self.has_more_data());
-        D::deserialize(self.parcel)
+        D::deserialize(&self.parcel)
     }
 
     /// Check if the sub-parcel has more data to read
@@ -510,11 +590,82 @@
     }
 }
 
-// Internal APIs
 impl Parcel {
+    /// Attempt to read a type that implements [`Deserialize`] from this parcel.
+    pub fn read<D: Deserialize>(&self) -> Result<D> {
+        self.borrowed_ref().read()
+    }
+
+    /// Attempt to read a type that implements [`Deserialize`] from this parcel
+    /// onto an existing value. This operation will overwrite the old value
+    /// partially or completely, depending on how much data is available.
+    pub fn read_onto<D: Deserialize>(&self, x: &mut D) -> Result<()> {
+        self.borrowed_ref().read_onto(x)
+    }
+
+    /// Safely read a sized parcelable.
+    ///
+    /// Read the size of a parcelable, compute the end position
+    /// of that parcelable, then build a sized readable sub-parcel
+    /// and call a closure with the sub-parcel as its parameter.
+    /// The closure can keep reading data from the sub-parcel
+    /// until it runs out of input data. The closure is responsible
+    /// for calling [`ReadableSubParcel::has_more_data`] to check for
+    /// more data before every read, at least until Rust generators
+    /// are stabilized.
+    /// After the closure returns, skip to the end of the current
+    /// parcelable regardless of how much the closure has read.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// let mut parcelable = Default::default();
+    /// parcel.sized_read(|subparcel| {
+    ///     if subparcel.has_more_data() {
+    ///         parcelable.a = subparcel.read()?;
+    ///     }
+    ///     if subparcel.has_more_data() {
+    ///         parcelable.b = subparcel.read()?;
+    ///     }
+    ///     Ok(())
+    /// });
+    /// ```
+    ///
+    pub fn sized_read<F>(&self, f: F) -> Result<()>
+    where
+        for<'b> F: FnOnce(ReadableSubParcel<'b>) -> Result<()>
+    {
+        self.borrowed_ref().sized_read(f)
+    }
+
+    /// Read a vector size from the parcel and resize the given output vector to
+    /// be correctly sized for that amount of data.
+    ///
+    /// This method is used in AIDL-generated server side code for methods that
+    /// take a mutable slice reference parameter.
+    pub fn resize_out_vec<D: Default + Deserialize>(&self, out_vec: &mut Vec<D>) -> Result<()> {
+        self.borrowed_ref().resize_out_vec(out_vec)
+    }
+
+    /// Read a vector size from the parcel and either create a correctly sized
+    /// vector for that amount of data or set the output parameter to None if
+    /// the vector should be null.
+    ///
+    /// This method is used in AIDL-generated server side code for methods that
+    /// take a mutable slice reference parameter.
+    pub fn resize_nullable_out_vec<D: Default + Deserialize>(
+        &self,
+        out_vec: &mut Option<Vec<D>>,
+    ) -> Result<()> {
+        self.borrowed_ref().resize_nullable_out_vec(out_vec)
+    }
+}
+
+// Internal APIs
+impl<'a> BorrowedParcel<'a> {
     pub(crate) fn write_binder(&mut self, binder: Option<&SpIBinder>) -> Result<()> {
         unsafe {
-            // Safety: `Parcel` always contains a valid pointer to an
+            // Safety: `BorrowedParcel` always contains a valid pointer to an
             // `AParcel`. `AsNative` for `Option<SpIBinder`> will either return
             // null or a valid pointer to an `AIBinder`, both of which are
             // valid, safe inputs to `AParcel_writeStrongBinder`.
@@ -534,7 +685,7 @@
     pub(crate) fn read_binder(&self) -> Result<Option<SpIBinder>> {
         let mut binder = ptr::null_mut();
         let status = unsafe {
-            // Safety: `Parcel` always contains a valid pointer to an
+            // Safety: `BorrowedParcel` always contains a valid pointer to an
             // `AParcel`. We pass a valid, mutable out pointer to the `binder`
             // parameter. After this call, `binder` will be either null or a
             // valid pointer to an `AIBinder` owned by the caller.
@@ -554,25 +705,11 @@
 impl Drop for Parcel {
     fn drop(&mut self) {
         // Run the C++ Parcel complete object destructor
-        if let Self::Owned(ptr) = *self {
-            unsafe {
-                // Safety: `Parcel` always contains a valid pointer to an
-                // `AParcel`. If we own the parcel, we can safely delete it
-                // here.
-                sys::AParcel_delete(ptr)
-            }
-        }
-    }
-}
-
-impl Drop for OwnedParcel {
-    fn drop(&mut self) {
-        // Run the C++ Parcel complete object destructor
         unsafe {
-            // Safety: `OwnedParcel` always contains a valid pointer to an
+            // Safety: `Parcel` always contains a valid pointer to an
             // `AParcel`. Since we own the parcel, we can safely delete it
             // here.
-            sys::AParcel_delete(self.ptr)
+            sys::AParcel_delete(self.ptr.as_ptr())
         }
     }
 }
@@ -584,9 +721,9 @@
     }
 }
 
-impl fmt::Debug for OwnedParcel {
+impl<'a> fmt::Debug for BorrowedParcel<'a> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("OwnedParcel")
+        f.debug_struct("BorrowedParcel")
             .finish()
     }
 }
@@ -608,7 +745,7 @@
     assert_eq!(parcel.read::<Option<String>>(), Ok(None));
     assert_eq!(parcel.read::<String>(), Err(StatusCode::UNEXPECTED_NULL));
 
-    assert_eq!(parcel.read_binder().err(), Some(StatusCode::BAD_TYPE));
+    assert_eq!(parcel.borrowed_ref().read_binder().err(), Some(StatusCode::BAD_TYPE));
 
     parcel.write(&1i32).unwrap();
 
diff --git a/libs/binder/rust/src/parcel/file_descriptor.rs b/libs/binder/rust/src/parcel/file_descriptor.rs
index 8bcc5d0..b0dea94 100644
--- a/libs/binder/rust/src/parcel/file_descriptor.rs
+++ b/libs/binder/rust/src/parcel/file_descriptor.rs
@@ -15,7 +15,7 @@
  */
 
 use super::{
-    Deserialize, DeserializeArray, DeserializeOption, Parcel, Serialize, SerializeArray,
+    Deserialize, DeserializeArray, DeserializeOption, BorrowedParcel, Serialize, SerializeArray,
     SerializeOption,
 };
 use crate::binder::AsNative;
@@ -61,7 +61,7 @@
 }
 
 impl Serialize for ParcelFileDescriptor {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         let fd = self.0.as_raw_fd();
         let status = unsafe {
             // Safety: `Parcel` always contains a valid pointer to an
@@ -78,7 +78,7 @@
 impl SerializeArray for ParcelFileDescriptor {}
 
 impl SerializeOption for ParcelFileDescriptor {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         if let Some(f) = this {
             f.serialize(parcel)
         } else {
@@ -95,7 +95,7 @@
 }
 
 impl DeserializeOption for ParcelFileDescriptor {
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<Self>> {
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
         let mut fd = -1i32;
         unsafe {
             // Safety: `Parcel` always contains a valid pointer to an
@@ -125,7 +125,7 @@
 }
 
 impl Deserialize for ParcelFileDescriptor {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         Deserialize::deserialize(parcel)
             .transpose()
             .unwrap_or(Err(StatusCode::UNEXPECTED_NULL))
diff --git a/libs/binder/rust/src/parcel/parcelable.rs b/libs/binder/rust/src/parcel/parcelable.rs
index db9d8b0..9007cba 100644
--- a/libs/binder/rust/src/parcel/parcelable.rs
+++ b/libs/binder/rust/src/parcel/parcelable.rs
@@ -16,14 +16,14 @@
 
 use crate::binder::{AsNative, FromIBinder, Stability, Strong};
 use crate::error::{status_result, status_t, Result, Status, StatusCode};
-use crate::parcel::Parcel;
+use crate::parcel::BorrowedParcel;
 use crate::proxy::SpIBinder;
 use crate::sys;
 
 use std::convert::{TryFrom, TryInto};
 use std::ffi::c_void;
 use std::os::raw::{c_char, c_ulong};
-use std::mem::{self, MaybeUninit};
+use std::mem::{self, MaybeUninit, ManuallyDrop};
 use std::ptr;
 use std::slice;
 
@@ -39,7 +39,7 @@
     /// `Serialize::serialize` and its variants are generally
     /// preferred over this function, since the former also
     /// prepend a header.
-    fn write_to_parcel(&self, parcel: &mut Parcel) -> Result<()>;
+    fn write_to_parcel(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()>;
 
     /// Internal deserialization function for parcelables.
     ///
@@ -47,26 +47,26 @@
     /// `Deserialize::deserialize` and its variants are generally
     /// preferred over this function, since the former also
     /// parse the additional header.
-    fn read_from_parcel(&mut self, parcel: &Parcel) -> Result<()>;
+    fn read_from_parcel(&mut self, parcel: &BorrowedParcel<'_>) -> Result<()>;
 }
 
 /// A struct whose instances can be written to a [`Parcel`].
 // Might be able to hook this up as a serde backend in the future?
 pub trait Serialize {
     /// Serialize this instance into the given [`Parcel`].
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()>;
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()>;
 }
 
 /// A struct whose instances can be restored from a [`Parcel`].
 // Might be able to hook this up as a serde backend in the future?
 pub trait Deserialize: Sized {
     /// Deserialize an instance from the given [`Parcel`].
-    fn deserialize(parcel: &Parcel) -> Result<Self>;
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self>;
 
     /// Deserialize an instance from the given [`Parcel`] onto the
     /// current object. This operation will overwrite the old value
     /// partially or completely, depending on how much data is available.
-    fn deserialize_from(&mut self, parcel: &Parcel) -> Result<()> {
+    fn deserialize_from(&mut self, parcel: &BorrowedParcel<'_>) -> Result<()> {
         *self = Self::deserialize(parcel)?;
         Ok(())
     }
@@ -80,8 +80,8 @@
 // We want the default implementation for most types, but an override for
 // a few special ones like `readByteArray` for `u8`.
 pub trait SerializeArray: Serialize + Sized {
-    /// Serialize an array of this type into the given [`Parcel`].
-    fn serialize_array(slice: &[Self], parcel: &mut Parcel) -> Result<()> {
+    /// Serialize an array of this type into the given parcel.
+    fn serialize_array(slice: &[Self], parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         let res = unsafe {
             // Safety: Safe FFI, slice will always be a safe pointer to pass.
             sys::AParcel_writeParcelableArray(
@@ -111,7 +111,7 @@
 
     let slice: &[T] = slice::from_raw_parts(array.cast(), index+1);
 
-    let mut parcel = match Parcel::borrowed(parcel) {
+    let mut parcel = match BorrowedParcel::from_raw(parcel) {
         None => return StatusCode::UNEXPECTED_NULL as status_t,
         Some(p) => p,
     };
@@ -126,8 +126,8 @@
 /// Defaults to calling Deserialize::deserialize() manually for every element,
 /// but can be overridden for custom implementations like `readByteArray`.
 pub trait DeserializeArray: Deserialize {
-    /// Deserialize an array of type from the given [`Parcel`].
-    fn deserialize_array(parcel: &Parcel) -> Result<Option<Vec<Self>>> {
+    /// Deserialize an array of type from the given parcel.
+    fn deserialize_array(parcel: &BorrowedParcel<'_>) -> Result<Option<Vec<Self>>> {
         let mut vec: Option<Vec<MaybeUninit<Self>>> = None;
         let res = unsafe {
             // Safety: Safe FFI, vec is the correct opaque type expected by
@@ -173,7 +173,7 @@
         None => return StatusCode::BAD_INDEX as status_t,
     };
 
-    let parcel = match Parcel::borrowed(parcel as *mut _) {
+    let parcel = match BorrowedParcel::from_raw(parcel as *mut _) {
         None => return StatusCode::UNEXPECTED_NULL as status_t,
         Some(p) => p,
     };
@@ -205,8 +205,8 @@
 // We also use it to provide a default implementation for AIDL-generated
 // parcelables.
 pub trait SerializeOption: Serialize {
-    /// Serialize an Option of this type into the given [`Parcel`].
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    /// Serialize an Option of this type into the given parcel.
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         if let Some(inner) = this {
             parcel.write(&NON_NULL_PARCELABLE_FLAG)?;
             parcel.write(inner)
@@ -218,8 +218,8 @@
 
 /// Helper trait for types that can be nullable when deserialized.
 pub trait DeserializeOption: Deserialize {
-    /// Deserialize an Option of this type from the given [`Parcel`].
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<Self>> {
+    /// Deserialize an Option of this type from the given parcel.
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
         let null: i32 = parcel.read()?;
         if null == NULL_PARCELABLE_FLAG {
             Ok(None)
@@ -228,10 +228,10 @@
         }
     }
 
-    /// Deserialize an Option of this type from the given [`Parcel`] onto the
+    /// Deserialize an Option of this type from the given parcel onto the
     /// current object. This operation will overwrite the current value
     /// partially or completely, depending on how much data is available.
-    fn deserialize_option_from(this: &mut Option<Self>, parcel: &Parcel) -> Result<()> {
+    fn deserialize_option_from(this: &mut Option<Self>, parcel: &BorrowedParcel<'_>) -> Result<()> {
         *this = Self::deserialize_option(parcel)?;
         Ok(())
     }
@@ -297,10 +297,23 @@
     };
 }
 
+/// Safety: All elements in the vector must be properly initialized.
+unsafe fn vec_assume_init<T>(vec: Vec<MaybeUninit<T>>) -> Vec<T> {
+    // We can convert from Vec<MaybeUninit<T>> to Vec<T> because MaybeUninit<T>
+    // has the same alignment and size as T, so the pointer to the vector
+    // allocation will be compatible.
+    let mut vec = ManuallyDrop::new(vec);
+    Vec::from_raw_parts(
+        vec.as_mut_ptr().cast(),
+        vec.len(),
+        vec.capacity(),
+    )
+}
+
 macro_rules! impl_parcelable {
     {Serialize, $ty:ty, $write_fn:path} => {
         impl Serialize for $ty {
-            fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+            fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
                 unsafe {
                     // Safety: `Parcel` always contains a valid pointer to an
                     // `AParcel`, and any `$ty` literal value is safe to pass to
@@ -313,7 +326,7 @@
 
     {Deserialize, $ty:ty, $read_fn:path} => {
         impl Deserialize for $ty {
-            fn deserialize(parcel: &Parcel) -> Result<Self> {
+            fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
                 let mut val = Self::default();
                 unsafe {
                     // Safety: `Parcel` always contains a valid pointer to an
@@ -329,7 +342,7 @@
 
     {SerializeArray, $ty:ty, $write_array_fn:path} => {
         impl SerializeArray for $ty {
-            fn serialize_array(slice: &[Self], parcel: &mut Parcel) -> Result<()> {
+            fn serialize_array(slice: &[Self], parcel: &mut BorrowedParcel<'_>) -> Result<()> {
                 let status = unsafe {
                     // Safety: `Parcel` always contains a valid pointer to an
                     // `AParcel`. If the slice is > 0 length, `slice.as_ptr()`
@@ -353,7 +366,7 @@
 
     {DeserializeArray, $ty:ty, $read_array_fn:path} => {
         impl DeserializeArray for $ty {
-            fn deserialize_array(parcel: &Parcel) -> Result<Option<Vec<Self>>> {
+            fn deserialize_array(parcel: &BorrowedParcel<'_>) -> Result<Option<Vec<Self>>> {
                 let mut vec: Option<Vec<MaybeUninit<Self>>> = None;
                 let status = unsafe {
                     // Safety: `Parcel` always contains a valid pointer to an
@@ -371,11 +384,8 @@
                     // Safety: We are assuming that the NDK correctly
                     // initialized every element of the vector by now, so we
                     // know that all the MaybeUninits are now properly
-                    // initialized. We can transmute from Vec<MaybeUninit<T>> to
-                    // Vec<T> because MaybeUninit<T> has the same alignment and
-                    // size as T, so the pointer to the vector allocation will
-                    // be compatible.
-                    mem::transmute(vec)
+                    // initialized.
+                    vec.map(|vec| vec_assume_init(vec))
                 };
                 Ok(vec)
             }
@@ -443,19 +453,19 @@
 impl DeserializeArray for bool {}
 
 impl Serialize for u8 {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         (*self as i8).serialize(parcel)
     }
 }
 
 impl Deserialize for u8 {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         i8::deserialize(parcel).map(|v| v as u8)
     }
 }
 
 impl SerializeArray for u8 {
-    fn serialize_array(slice: &[Self], parcel: &mut Parcel) -> Result<()> {
+    fn serialize_array(slice: &[Self], parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         let status = unsafe {
             // Safety: `Parcel` always contains a valid pointer to an
             // `AParcel`. If the slice is > 0 length, `slice.as_ptr()` will be a
@@ -474,19 +484,19 @@
 }
 
 impl Serialize for i16 {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         (*self as u16).serialize(parcel)
     }
 }
 
 impl Deserialize for i16 {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         u16::deserialize(parcel).map(|v| v as i16)
     }
 }
 
 impl SerializeArray for i16 {
-    fn serialize_array(slice: &[Self], parcel: &mut Parcel) -> Result<()> {
+    fn serialize_array(slice: &[Self], parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         let status = unsafe {
             // Safety: `Parcel` always contains a valid pointer to an
             // `AParcel`. If the slice is > 0 length, `slice.as_ptr()` will be a
@@ -505,7 +515,7 @@
 }
 
 impl SerializeOption for str {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         match this {
             None => unsafe {
                 // Safety: `Parcel` always contains a valid pointer to an
@@ -541,7 +551,7 @@
 }
 
 impl Serialize for str {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         Some(self).serialize(parcel)
     }
 }
@@ -549,7 +559,7 @@
 impl SerializeArray for &str {}
 
 impl Serialize for String {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         Some(self.as_str()).serialize(parcel)
     }
 }
@@ -557,13 +567,13 @@
 impl SerializeArray for String {}
 
 impl SerializeOption for String {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(this.map(String::as_str), parcel)
     }
 }
 
 impl Deserialize for Option<String> {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         let mut vec: Option<Vec<u8>> = None;
         let status = unsafe {
             // Safety: `Parcel` always contains a valid pointer to an `AParcel`.
@@ -591,7 +601,7 @@
 impl DeserializeArray for Option<String> {}
 
 impl Deserialize for String {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         Deserialize::deserialize(parcel)
             .transpose()
             .unwrap_or(Err(StatusCode::UNEXPECTED_NULL))
@@ -601,19 +611,19 @@
 impl DeserializeArray for String {}
 
 impl<T: SerializeArray> Serialize for [T] {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeArray::serialize_array(self, parcel)
     }
 }
 
 impl<T: SerializeArray> Serialize for Vec<T> {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeArray::serialize_array(&self[..], parcel)
     }
 }
 
 impl<T: SerializeArray> SerializeOption for [T] {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         if let Some(v) = this {
             SerializeArray::serialize_array(v, parcel)
         } else {
@@ -623,13 +633,13 @@
 }
 
 impl<T: SerializeArray> SerializeOption for Vec<T> {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(this.map(Vec::as_slice), parcel)
     }
 }
 
 impl<T: DeserializeArray> Deserialize for Vec<T> {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         DeserializeArray::deserialize_array(parcel)
             .transpose()
             .unwrap_or(Err(StatusCode::UNEXPECTED_NULL))
@@ -637,25 +647,25 @@
 }
 
 impl<T: DeserializeArray> DeserializeOption for Vec<T> {
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<Self>> {
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
         DeserializeArray::deserialize_array(parcel)
     }
 }
 
 impl Serialize for Stability {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         i32::from(*self).serialize(parcel)
     }
 }
 
 impl Deserialize for Stability {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         i32::deserialize(parcel).and_then(Stability::try_from)
     }
 }
 
 impl Serialize for Status {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         unsafe {
             // Safety: `Parcel` always contains a valid pointer to an `AParcel`
             // and `Status` always contains a valid pointer to an `AStatus`, so
@@ -670,7 +680,7 @@
 }
 
 impl Deserialize for Status {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         let mut status_ptr = ptr::null_mut();
         let ret_status = unsafe {
             // Safety: `Parcel` always contains a valid pointer to an
@@ -691,13 +701,13 @@
 }
 
 impl<T: Serialize + FromIBinder + ?Sized> Serialize for Strong<T> {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         Serialize::serialize(&**self, parcel)
     }
 }
 
 impl<T: SerializeOption + FromIBinder + ?Sized> SerializeOption for Strong<T> {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(this.map(|b| &**b), parcel)
     }
 }
@@ -705,14 +715,14 @@
 impl<T: Serialize + FromIBinder + ?Sized> SerializeArray for Strong<T> {}
 
 impl<T: FromIBinder + ?Sized> Deserialize for Strong<T> {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         let ibinder: SpIBinder = parcel.read()?;
         FromIBinder::try_from(ibinder)
     }
 }
 
 impl<T: FromIBinder + ?Sized> DeserializeOption for Strong<T> {
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<Self>> {
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
         let ibinder: Option<SpIBinder> = parcel.read()?;
         ibinder.map(FromIBinder::try_from).transpose()
     }
@@ -722,29 +732,29 @@
 
 // We need these to support Option<&T> for all T
 impl<T: Serialize + ?Sized> Serialize for &T {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         Serialize::serialize(*self, parcel)
     }
 }
 
 impl<T: SerializeOption + ?Sized> SerializeOption for &T {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(this.copied(), parcel)
     }
 }
 
 impl<T: SerializeOption> Serialize for Option<T> {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(self.as_ref(), parcel)
     }
 }
 
 impl<T: DeserializeOption> Deserialize for Option<T> {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         DeserializeOption::deserialize_option(parcel)
     }
 
-    fn deserialize_from(&mut self, parcel: &Parcel) -> Result<()> {
+    fn deserialize_from(&mut self, parcel: &BorrowedParcel<'_>) -> Result<()> {
         DeserializeOption::deserialize_option_from(self, parcel)
     }
 }
@@ -762,7 +772,7 @@
         impl $crate::parcel::Serialize for $parcelable {
             fn serialize(
                 &self,
-                parcel: &mut $crate::parcel::Parcel,
+                parcel: &mut $crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<()> {
                 <Self as $crate::parcel::SerializeOption>::serialize_option(
                     Some(self),
@@ -776,7 +786,7 @@
         impl $crate::parcel::SerializeOption for $parcelable {
             fn serialize_option(
                 this: Option<&Self>,
-                parcel: &mut $crate::parcel::Parcel,
+                parcel: &mut $crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<()> {
                 if let Some(this) = this {
                     use $crate::parcel::Parcelable;
@@ -796,13 +806,12 @@
 /// `Deserialize`, `DeserializeArray` and `DeserializeOption` for
 /// structured parcelables. The target type must implement the
 /// `Parcelable` trait.
-/// ```
 #[macro_export]
 macro_rules! impl_deserialize_for_parcelable {
     ($parcelable:ident) => {
         impl $crate::parcel::Deserialize for $parcelable {
             fn deserialize(
-                parcel: &$crate::parcel::Parcel,
+                parcel: &$crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<Self> {
                 $crate::parcel::DeserializeOption::deserialize_option(parcel)
                     .transpose()
@@ -810,7 +819,7 @@
             }
             fn deserialize_from(
                 &mut self,
-                parcel: &$crate::parcel::Parcel,
+                parcel: &$crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<()> {
                 let status: i32 = parcel.read()?;
                 if status == $crate::parcel::NULL_PARCELABLE_FLAG {
@@ -826,7 +835,7 @@
 
         impl $crate::parcel::DeserializeOption for $parcelable {
             fn deserialize_option(
-                parcel: &$crate::parcel::Parcel,
+                parcel: &$crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<Option<Self>> {
                 let mut result = None;
                 Self::deserialize_option_from(&mut result, parcel)?;
@@ -834,7 +843,7 @@
             }
             fn deserialize_option_from(
                 this: &mut Option<Self>,
-                parcel: &$crate::parcel::Parcel,
+                parcel: &$crate::parcel::BorrowedParcel<'_>,
             ) -> $crate::Result<()> {
                 let status: i32 = parcel.read()?;
                 if status == $crate::parcel::NULL_PARCELABLE_FLAG {
@@ -851,326 +860,332 @@
 }
 
 impl<T: Serialize> Serialize for Box<T> {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         Serialize::serialize(&**self, parcel)
     }
 }
 
 impl<T: Deserialize> Deserialize for Box<T> {
-    fn deserialize(parcel: &Parcel) -> Result<Self> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
         Deserialize::deserialize(parcel).map(Box::new)
     }
 }
 
 impl<T: SerializeOption> SerializeOption for Box<T> {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         SerializeOption::serialize_option(this.map(|inner| &**inner), parcel)
     }
 }
 
 impl<T: DeserializeOption> DeserializeOption for Box<T> {
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<Self>> {
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<Self>> {
         DeserializeOption::deserialize_option(parcel).map(|t| t.map(Box::new))
     }
 }
 
-#[test]
-fn test_custom_parcelable() {
-    struct Custom(u32, bool, String, Vec<String>);
+#[cfg(test)]
+mod tests {
+    use crate::Parcel;
+    use super::*;
 
-    impl Serialize for Custom {
-        fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
-            self.0.serialize(parcel)?;
-            self.1.serialize(parcel)?;
-            self.2.serialize(parcel)?;
-            self.3.serialize(parcel)
+    #[test]
+    fn test_custom_parcelable() {
+        struct Custom(u32, bool, String, Vec<String>);
+
+        impl Serialize for Custom {
+            fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
+                self.0.serialize(parcel)?;
+                self.1.serialize(parcel)?;
+                self.2.serialize(parcel)?;
+                self.3.serialize(parcel)
+            }
         }
-    }
 
-    impl Deserialize for Custom {
-        fn deserialize(parcel: &Parcel) -> Result<Self> {
-            Ok(Custom(
-                parcel.read()?,
-                parcel.read()?,
-                parcel.read()?,
-                parcel.read::<Option<Vec<String>>>()?.unwrap(),
-            ))
+        impl Deserialize for Custom {
+            fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<Self> {
+                Ok(Custom(
+                        parcel.read()?,
+                        parcel.read()?,
+                        parcel.read()?,
+                        parcel.read::<Option<Vec<String>>>()?.unwrap(),
+                        ))
+            }
         }
+
+        let string8 = "Custom Parcelable".to_string();
+
+        let s1 = "str1".to_string();
+        let s2 = "str2".to_string();
+        let s3 = "str3".to_string();
+
+        let strs = vec![s1, s2, s3];
+
+        let custom = Custom(123_456_789, true, string8, strs);
+
+        let mut parcel = Parcel::new();
+        let start = parcel.get_data_position();
+
+        assert!(custom.serialize(&mut parcel.borrowed()).is_ok());
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let custom2 = Custom::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(custom2.0, 123_456_789);
+        assert!(custom2.1);
+        assert_eq!(custom2.2, custom.2);
+        assert_eq!(custom2.3, custom.3);
     }
 
-    let string8 = "Custom Parcelable".to_string();
+    #[test]
+    #[allow(clippy::excessive_precision)]
+    fn test_slice_parcelables() {
+        let bools = [true, false, false, true];
 
-    let s1 = "str1".to_string();
-    let s2 = "str2".to_string();
-    let s3 = "str3".to_string();
+        let mut parcel = Parcel::new();
+        let start = parcel.get_data_position();
 
-    let strs = vec![s1, s2, s3];
+        assert!(bools.serialize(&mut parcel.borrowed()).is_ok());
 
-    let custom = Custom(123_456_789, true, string8, strs);
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
 
-    let mut parcel = Parcel::new();
-    let start = parcel.get_data_position();
+        assert_eq!(parcel.read::<u32>().unwrap(), 4);
+        assert_eq!(parcel.read::<u32>().unwrap(), 1);
+        assert_eq!(parcel.read::<u32>().unwrap(), 0);
+        assert_eq!(parcel.read::<u32>().unwrap(), 0);
+        assert_eq!(parcel.read::<u32>().unwrap(), 1);
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
 
-    assert!(custom.serialize(&mut parcel).is_ok());
+        let vec = Vec::<bool>::deserialize(parcel.borrowed_ref()).unwrap();
 
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
+        assert_eq!(vec, [true, false, false, true]);
+
+        let u8s = [101u8, 255, 42, 117];
+
+        let mut parcel = Parcel::new();
+        let start = parcel.get_data_position();
+
+        assert!(parcel.write(&u8s[..]).is_ok());
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x752aff65); // bytes
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<u8>::deserialize(parcel.borrowed_ref()).unwrap();
+        assert_eq!(vec, [101, 255, 42, 117]);
+
+        let i8s = [-128i8, 127, 42, -117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert!(parcel.write(&i8s[..]).is_ok());
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x8b2a7f80); // bytes
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<u8>::deserialize(parcel.borrowed_ref()).unwrap();
+        assert_eq!(vec, [-128i8 as u8, 127, 42, -117i8 as u8]);
+
+        let u16s = [u16::max_value(), 12_345, 42, 117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(u16s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0xffff); // u16::max_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 12345); // 12,345
+        assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
+        assert_eq!(parcel.read::<u32>().unwrap(), 117); // 117
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<u16>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [u16::max_value(), 12_345, 42, 117]);
+
+        let i16s = [i16::max_value(), i16::min_value(), 42, -117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(i16s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x7fff); // i16::max_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x8000); // i16::min_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
+        assert_eq!(parcel.read::<u32>().unwrap(), 0xff8b); // -117
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<i16>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [i16::max_value(), i16::min_value(), 42, -117]);
+
+        let u32s = [u32::max_value(), 12_345, 42, 117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(u32s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0xffffffff); // u32::max_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 12345); // 12,345
+        assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
+        assert_eq!(parcel.read::<u32>().unwrap(), 117); // 117
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<u32>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [u32::max_value(), 12_345, 42, 117]);
+
+        let i32s = [i32::max_value(), i32::min_value(), 42, -117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(i32s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x7fffffff); // i32::max_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 0x80000000); // i32::min_value()
+        assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
+        assert_eq!(parcel.read::<u32>().unwrap(), 0xffffff8b); // -117
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<i32>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [i32::max_value(), i32::min_value(), 42, -117]);
+
+        let u64s = [u64::max_value(), 12_345, 42, 117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(u64s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<u64>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [u64::max_value(), 12_345, 42, 117]);
+
+        let i64s = [i64::max_value(), i64::min_value(), 42, -117];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(i64s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<i64>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, [i64::max_value(), i64::min_value(), 42, -117]);
+
+        let f32s = [
+            std::f32::NAN,
+            std::f32::INFINITY,
+            1.23456789,
+            std::f32::EPSILON,
+        ];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(f32s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<f32>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        // NAN != NAN so we can't use it in the assert_eq:
+        assert!(vec[0].is_nan());
+        assert_eq!(vec[1..], f32s[1..]);
+
+        let f64s = [
+            std::f64::NAN,
+            std::f64::INFINITY,
+            1.234567890123456789,
+            std::f64::EPSILON,
+        ];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(f64s.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<f64>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        // NAN != NAN so we can't use it in the assert_eq:
+        assert!(vec[0].is_nan());
+        assert_eq!(vec[1..], f64s[1..]);
+
+        let s1 = "Hello, Binder!";
+        let s2 = "This is a utf8 string.";
+        let s3 = "Some more text here.";
+        let s4 = "Embedded nulls \0 \0";
+
+        let strs = [s1, s2, s3, s4];
+
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+        assert!(strs.serialize(&mut parcel.borrowed()).is_ok());
+        unsafe {
+            assert!(parcel.set_data_position(start).is_ok());
+        }
+
+        let vec = Vec::<String>::deserialize(parcel.borrowed_ref()).unwrap();
+
+        assert_eq!(vec, strs);
     }
-
-    let custom2 = Custom::deserialize(&parcel).unwrap();
-
-    assert_eq!(custom2.0, 123_456_789);
-    assert!(custom2.1);
-    assert_eq!(custom2.2, custom.2);
-    assert_eq!(custom2.3, custom.3);
-}
-
-#[test]
-#[allow(clippy::excessive_precision)]
-fn test_slice_parcelables() {
-    let bools = [true, false, false, true];
-
-    let mut parcel = Parcel::new();
-    let start = parcel.get_data_position();
-
-    assert!(bools.serialize(&mut parcel).is_ok());
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4);
-    assert_eq!(parcel.read::<u32>().unwrap(), 1);
-    assert_eq!(parcel.read::<u32>().unwrap(), 0);
-    assert_eq!(parcel.read::<u32>().unwrap(), 0);
-    assert_eq!(parcel.read::<u32>().unwrap(), 1);
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<bool>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [true, false, false, true]);
-
-    let u8s = [101u8, 255, 42, 117];
-
-    let mut parcel = Parcel::new();
-    let start = parcel.get_data_position();
-
-    assert!(parcel.write(&u8s[..]).is_ok());
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x752aff65); // bytes
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<u8>::deserialize(&parcel).unwrap();
-    assert_eq!(vec, [101, 255, 42, 117]);
-
-    let i8s = [-128i8, 127, 42, -117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert!(parcel.write(&i8s[..]).is_ok());
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x8b2a7f80); // bytes
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<u8>::deserialize(&parcel).unwrap();
-    assert_eq!(vec, [-128i8 as u8, 127, 42, -117i8 as u8]);
-
-    let u16s = [u16::max_value(), 12_345, 42, 117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(u16s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0xffff); // u16::max_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 12345); // 12,345
-    assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
-    assert_eq!(parcel.read::<u32>().unwrap(), 117); // 117
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<u16>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [u16::max_value(), 12_345, 42, 117]);
-
-    let i16s = [i16::max_value(), i16::min_value(), 42, -117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(i16s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x7fff); // i16::max_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x8000); // i16::min_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
-    assert_eq!(parcel.read::<u32>().unwrap(), 0xff8b); // -117
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<i16>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [i16::max_value(), i16::min_value(), 42, -117]);
-
-    let u32s = [u32::max_value(), 12_345, 42, 117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(u32s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0xffffffff); // u32::max_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 12345); // 12,345
-    assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
-    assert_eq!(parcel.read::<u32>().unwrap(), 117); // 117
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<u32>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [u32::max_value(), 12_345, 42, 117]);
-
-    let i32s = [i32::max_value(), i32::min_value(), 42, -117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(i32s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    assert_eq!(parcel.read::<u32>().unwrap(), 4); // 4 items
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x7fffffff); // i32::max_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 0x80000000); // i32::min_value()
-    assert_eq!(parcel.read::<u32>().unwrap(), 42); // 42
-    assert_eq!(parcel.read::<u32>().unwrap(), 0xffffff8b); // -117
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<i32>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [i32::max_value(), i32::min_value(), 42, -117]);
-
-    let u64s = [u64::max_value(), 12_345, 42, 117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(u64s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<u64>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [u64::max_value(), 12_345, 42, 117]);
-
-    let i64s = [i64::max_value(), i64::min_value(), 42, -117];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(i64s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<i64>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, [i64::max_value(), i64::min_value(), 42, -117]);
-
-    let f32s = [
-        std::f32::NAN,
-        std::f32::INFINITY,
-        1.23456789,
-        std::f32::EPSILON,
-    ];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(f32s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<f32>::deserialize(&parcel).unwrap();
-
-    // NAN != NAN so we can't use it in the assert_eq:
-    assert!(vec[0].is_nan());
-    assert_eq!(vec[1..], f32s[1..]);
-
-    let f64s = [
-        std::f64::NAN,
-        std::f64::INFINITY,
-        1.234567890123456789,
-        std::f64::EPSILON,
-    ];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(f64s.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<f64>::deserialize(&parcel).unwrap();
-
-    // NAN != NAN so we can't use it in the assert_eq:
-    assert!(vec[0].is_nan());
-    assert_eq!(vec[1..], f64s[1..]);
-
-    let s1 = "Hello, Binder!";
-    let s2 = "This is a utf8 string.";
-    let s3 = "Some more text here.";
-    let s4 = "Embedded nulls \0 \0";
-
-    let strs = [s1, s2, s3, s4];
-
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-    assert!(strs.serialize(&mut parcel).is_ok());
-    unsafe {
-        assert!(parcel.set_data_position(start).is_ok());
-    }
-
-    let vec = Vec::<String>::deserialize(&parcel).unwrap();
-
-    assert_eq!(vec, strs);
 }
diff --git a/libs/binder/rust/src/parcel/parcelable_holder.rs b/libs/binder/rust/src/parcel/parcelable_holder.rs
index bccfd2d..b4282b2 100644
--- a/libs/binder/rust/src/parcel/parcelable_holder.rs
+++ b/libs/binder/rust/src/parcel/parcelable_holder.rs
@@ -16,7 +16,7 @@
 
 use crate::binder::Stability;
 use crate::error::{Result, StatusCode};
-use crate::parcel::{OwnedParcel, Parcel, Parcelable};
+use crate::parcel::{Parcel, BorrowedParcel, Parcelable};
 use crate::{impl_deserialize_for_parcelable, impl_serialize_for_parcelable};
 
 use downcast_rs::{impl_downcast, DowncastSync};
@@ -50,7 +50,7 @@
         parcelable: Arc<dyn AnyParcelable>,
         name: String,
     },
-    Parcel(OwnedParcel),
+    Parcel(Parcel),
 }
 
 impl Default for ParcelableHolderData {
@@ -148,7 +148,6 @@
                 }
             }
             ParcelableHolderData::Parcel(ref mut parcel) => {
-                let parcel = parcel.borrowed();
                 unsafe {
                     // Safety: 0 should always be a valid position.
                     parcel.set_data_position(0)?;
@@ -160,7 +159,7 @@
                 }
 
                 let mut parcelable = T::default();
-                parcelable.read_from_parcel(&parcel)?;
+                parcelable.read_from_parcel(parcel.borrowed_ref())?;
 
                 let parcelable = Arc::new(parcelable);
                 let result = Arc::clone(&parcelable);
@@ -181,7 +180,7 @@
 impl_deserialize_for_parcelable!(ParcelableHolder);
 
 impl Parcelable for ParcelableHolder {
-    fn write_to_parcel(&self, parcel: &mut Parcel) -> Result<()> {
+    fn write_to_parcel(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         parcel.write(&self.stability)?;
 
         let mut data = self.data.lock().unwrap();
@@ -214,14 +213,13 @@
                 Ok(())
             }
             ParcelableHolderData::Parcel(ref mut p) => {
-                let p = p.borrowed();
                 parcel.write(&p.get_data_size())?;
-                parcel.append_all_from(&p)
+                parcel.append_all_from(&*p)
             }
         }
     }
 
-    fn read_from_parcel(&mut self, parcel: &Parcel) -> Result<()> {
+    fn read_from_parcel(&mut self, parcel: &BorrowedParcel<'_>) -> Result<()> {
         self.stability = parcel.read()?;
 
         let data_size: i32 = parcel.read()?;
@@ -242,10 +240,8 @@
             .checked_add(data_size)
             .ok_or(StatusCode::BAD_VALUE)?;
 
-        let mut new_parcel = OwnedParcel::new();
-        new_parcel
-            .borrowed()
-            .append_from(parcel, data_start, data_size)?;
+        let mut new_parcel = Parcel::new();
+        new_parcel.append_from(parcel, data_start, data_size)?;
         *self.data.get_mut().unwrap() = ParcelableHolderData::Parcel(new_parcel);
 
         unsafe {
diff --git a/libs/binder/rust/src/proxy.rs b/libs/binder/rust/src/proxy.rs
index a8d0c33..83553d7 100644
--- a/libs/binder/rust/src/proxy.rs
+++ b/libs/binder/rust/src/proxy.rs
@@ -22,8 +22,7 @@
 };
 use crate::error::{status_result, Result, StatusCode};
 use crate::parcel::{
-    Deserialize, DeserializeArray, DeserializeOption, OwnedParcel, Parcel, Serialize, SerializeArray,
-    SerializeOption,
+    Parcel, BorrowedParcel, Deserialize, DeserializeArray, DeserializeOption, Serialize, SerializeArray, SerializeOption,
 };
 use crate::sys;
 
@@ -235,7 +234,7 @@
 }
 
 impl<T: AsNative<sys::AIBinder>> IBinderInternal for T {
-    fn prepare_transact(&self) -> Result<OwnedParcel> {
+    fn prepare_transact(&self) -> Result<Parcel> {
         let mut input = ptr::null_mut();
         let status = unsafe {
             // Safety: `SpIBinder` guarantees that `self` always contains a
@@ -255,16 +254,16 @@
             // Safety: At this point, `input` is either a valid, owned `AParcel`
             // pointer, or null. `OwnedParcel::from_raw` safely handles both cases,
             // taking ownership of the parcel.
-            OwnedParcel::from_raw(input).ok_or(StatusCode::UNEXPECTED_NULL)
+            Parcel::from_raw(input).ok_or(StatusCode::UNEXPECTED_NULL)
         }
     }
 
     fn submit_transact(
         &self,
         code: TransactionCode,
-        data: OwnedParcel,
+        data: Parcel,
         flags: TransactionFlags,
-    ) -> Result<OwnedParcel> {
+    ) -> Result<Parcel> {
         let mut reply = ptr::null_mut();
         let status = unsafe {
             // Safety: `SpIBinder` guarantees that `self` always contains a
@@ -299,7 +298,7 @@
             // construct a `Parcel` out of it. `AIBinder_transact` passes
             // ownership of the `reply` parcel to Rust, so we need to
             // construct an owned variant.
-            OwnedParcel::from_raw(reply).ok_or(StatusCode::UNEXPECTED_NULL)
+            Parcel::from_raw(reply).ok_or(StatusCode::UNEXPECTED_NULL)
         }
     }
 
@@ -415,13 +414,13 @@
 }
 
 impl Serialize for SpIBinder {
-    fn serialize(&self, parcel: &mut Parcel) -> Result<()> {
+    fn serialize(&self, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         parcel.write_binder(Some(self))
     }
 }
 
 impl SerializeOption for SpIBinder {
-    fn serialize_option(this: Option<&Self>, parcel: &mut Parcel) -> Result<()> {
+    fn serialize_option(this: Option<&Self>, parcel: &mut BorrowedParcel<'_>) -> Result<()> {
         parcel.write_binder(this)
     }
 }
@@ -429,7 +428,7 @@
 impl SerializeArray for SpIBinder {}
 
 impl Deserialize for SpIBinder {
-    fn deserialize(parcel: &Parcel) -> Result<SpIBinder> {
+    fn deserialize(parcel: &BorrowedParcel<'_>) -> Result<SpIBinder> {
         parcel
             .read_binder()
             .transpose()
@@ -438,7 +437,7 @@
 }
 
 impl DeserializeOption for SpIBinder {
-    fn deserialize_option(parcel: &Parcel) -> Result<Option<SpIBinder>> {
+    fn deserialize_option(parcel: &BorrowedParcel<'_>) -> Result<Option<SpIBinder>> {
         parcel.read_binder()
     }
 }