Add a libbinder_rs wrapper around the new ARpc APIs
This allows rust clients to set up client connections to binder RPC
services underneath the libbinder_rs service manager APIs.
Test: atest binderRpcTest vm_accessor_test
Bug: 358427181
Change-Id: I05f1c5ff4e3447262eaf9df8250c9d99e3414559
diff --git a/libs/binder/rust/src/lib.rs b/libs/binder/rust/src/lib.rs
index e70f4f0..9d4ed33 100644
--- a/libs/binder/rust/src/lib.rs
+++ b/libs/binder/rust/src/lib.rs
@@ -104,6 +104,8 @@
mod service;
#[cfg(not(trusty))]
mod state;
+#[cfg(not(any(android_vendor, android_vndk)))]
+mod system_only;
use binder_ndk_sys as sys;
@@ -120,6 +122,8 @@
};
#[cfg(not(trusty))]
pub use state::{ProcessState, ThreadState};
+#[cfg(not(any(android_vendor, android_vndk)))]
+pub use system_only::{Accessor, ConnectionInfo};
/// Binder result containing a [`Status`] on error.
pub type Result<T> = std::result::Result<T, Status>;
diff --git a/libs/binder/rust/src/system_only.rs b/libs/binder/rust/src/system_only.rs
new file mode 100644
index 0000000..a91d84d
--- /dev/null
+++ b/libs/binder/rust/src/system_only.rs
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2024 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.
+ */
+
+use crate::proxy::SpIBinder;
+use crate::sys;
+
+use std::ffi::{c_void, CStr, CString};
+use std::os::raw::c_char;
+
+use libc::sockaddr;
+use nix::sys::socket::{SockaddrLike, UnixAddr, VsockAddr};
+use std::sync::Arc;
+use std::{fmt, ptr};
+
+/// Rust wrapper around ABinderRpc_Accessor objects for RPC binder service management.
+///
+/// Dropping the `Accessor` will drop the underlying object and the binder it owns.
+pub struct Accessor {
+ accessor: *mut sys::ABinderRpc_Accessor,
+}
+
+impl fmt::Debug for Accessor {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(f, "ABinderRpc_Accessor({:p})", self.accessor)
+ }
+}
+
+/// Socket connection info required for libbinder to connect to a service.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ConnectionInfo {
+ /// For vsock connection
+ Vsock(VsockAddr),
+ /// For unix domain socket connection
+ Unix(UnixAddr),
+}
+
+/// Safety: A `Accessor` is a wrapper around `ABinderRpc_Accessor` which is
+/// `Sync` and `Send`. As
+/// `ABinderRpc_Accessor` is threadsafe, this structure is too.
+/// The Fn owned the Accessor has `Sync` and `Send` properties
+unsafe impl Send for Accessor {}
+
+/// Safety: A `Accessor` is a wrapper around `ABinderRpc_Accessor` which is
+/// `Sync` and `Send`. As `ABinderRpc_Accessor` is threadsafe, this structure is too.
+/// The Fn owned the Accessor has `Sync` and `Send` properties
+unsafe impl Sync for Accessor {}
+
+impl Accessor {
+ /// Create a new accessor that will call the given callback when its
+ /// connection info is required.
+ /// The callback object and all objects it captures are owned by the Accessor
+ /// and will be deleted some time after the Accessor is Dropped. If the callback
+ /// is being called when the Accessor is Dropped, the callback will not be deleted
+ /// immediately.
+ pub fn new<F>(instance: &str, callback: F) -> Accessor
+ where
+ F: Fn(&str) -> Option<ConnectionInfo> + Send + Sync + 'static,
+ {
+ let callback: *mut c_void = Arc::into_raw(Arc::new(callback)) as *mut c_void;
+ let inst = CString::new(instance).unwrap();
+
+ // Safety: The function pointer is a valid connection_info callback.
+ // This call returns an owned `ABinderRpc_Accessor` pointer which
+ // must be destroyed via `ABinderRpc_Accessor_delete` when no longer
+ // needed.
+ // When the underlying ABinderRpc_Accessor is deleted, it will call
+ // the cookie_decr_refcount callback to release its strong ref.
+ let accessor = unsafe {
+ sys::ABinderRpc_Accessor_new(
+ inst.as_ptr(),
+ Some(Self::connection_info::<F>),
+ callback,
+ Some(Self::cookie_decr_refcount::<F>),
+ )
+ };
+
+ Accessor { accessor }
+ }
+
+ /// Get the underlying binder for this Accessor for when it needs to be either
+ /// registered with service manager or sent to another process.
+ pub fn as_binder(&self) -> Option<SpIBinder> {
+ // Safety: `ABinderRpc_Accessor_asBinder` returns either a null pointer or a
+ // valid pointer to an owned `AIBinder`. Either of these values is safe to
+ // pass to `SpIBinder::from_raw`.
+ unsafe { SpIBinder::from_raw(sys::ABinderRpc_Accessor_asBinder(self.accessor)) }
+ }
+
+ /// Callback invoked from C++ when the connection info is needed.
+ ///
+ /// # Safety
+ ///
+ /// The `instance` parameter must be a non-null pointer to a valid C string for
+ /// CStr::from_ptr. The memory must contain a valid null terminator at the end of
+ /// the string within isize::MAX from the pointer. The memory must not be mutated for
+ /// the duration of this function call and must be valid for reads from the pointer
+ /// to the null terminator.
+ /// The `cookie` parameter must be the cookie for an `Arc<F>` and
+ /// the caller must hold a ref-count to it.
+ unsafe extern "C" fn connection_info<F>(
+ instance: *const c_char,
+ cookie: *mut c_void,
+ ) -> *mut binder_ndk_sys::ABinderRpc_ConnectionInfo
+ where
+ F: Fn(&str) -> Option<ConnectionInfo> + Send + Sync + 'static,
+ {
+ if cookie.is_null() || instance.is_null() {
+ log::error!("Cookie({cookie:p}) or instance({instance:p}) is null!");
+ return ptr::null_mut();
+ }
+ // Safety: The caller promises that `cookie` is for an Arc<F>.
+ let callback = unsafe { (cookie as *const F).as_ref().unwrap() };
+
+ // Safety: The caller in libbinder_ndk will have already verified this is a valid
+ // C string
+ let inst = unsafe {
+ match CStr::from_ptr(instance).to_str() {
+ Ok(s) => s,
+ Err(err) => {
+ log::error!("Failed to get a valid C string! {err:?}");
+ return ptr::null_mut();
+ }
+ }
+ };
+
+ let connection = match callback(inst) {
+ Some(con) => con,
+ None => {
+ return ptr::null_mut();
+ }
+ };
+
+ match connection {
+ ConnectionInfo::Vsock(addr) => {
+ // Safety: The sockaddr is being copied in the NDK API
+ unsafe { sys::ABinderRpc_ConnectionInfo_new(addr.as_ptr(), addr.len()) }
+ }
+ ConnectionInfo::Unix(addr) => {
+ // Safety: The sockaddr is being copied in the NDK API
+ // The cast is from sockaddr_un* to sockaddr*.
+ unsafe {
+ sys::ABinderRpc_ConnectionInfo_new(addr.as_ptr() as *const sockaddr, addr.len())
+ }
+ }
+ }
+ }
+
+ /// Callback that decrements the ref-count.
+ /// This is invoked from C++ when a binder is unlinked.
+ ///
+ /// # Safety
+ ///
+ /// The `cookie` parameter must be the cookie for an `Arc<F>` and
+ /// the owner must give up a ref-count to it.
+ unsafe extern "C" fn cookie_decr_refcount<F>(cookie: *mut c_void)
+ where
+ F: Fn(&str) -> Option<ConnectionInfo> + Send + Sync + 'static,
+ {
+ // Safety: The caller promises that `cookie` is for an Arc<F>.
+ unsafe { Arc::decrement_strong_count(cookie as *const F) };
+ }
+}
+
+impl Drop for Accessor {
+ fn drop(&mut self) {
+ // Safety: `self.accessor` is always a valid, owned
+ // `ABinderRpc_Accessor` pointer returned by
+ // `ABinderRpc_Accessor_new` when `self` was created. This delete
+ // method can only be called once when `self` is dropped.
+ unsafe {
+ sys::ABinderRpc_Accessor_delete(self.accessor);
+ }
+ }
+}