Add safe wrapper for RpcPreconnectedClient.
Test: atest compos_key_tests MicrodroidHostTestCases MicrodroidTestApp
Change-Id: I8dcc6c9b0465950bfaced03699fa3167dc3dc641
diff --git a/libs/binder_common/rpc_client.rs b/libs/binder_common/rpc_client.rs
index 1aabe84..33fd732 100644
--- a/libs/binder_common/rpc_client.rs
+++ b/libs/binder_common/rpc_client.rs
@@ -17,10 +17,11 @@
//! Helpers for implementing an RPC Binder client.
use binder::unstable_api::{new_spibinder, AIBinder};
-use binder::{StatusCode, Strong};
+use binder::{FromIBinder, StatusCode, Strong};
+use std::os::{raw, unix::io::RawFd};
/// Connects to a binder RPC server.
-pub fn connect_rpc_binder<T: binder::FromIBinder + ?Sized>(
+pub fn connect_rpc_binder<T: FromIBinder + ?Sized>(
cid: u32,
port: u32,
) -> Result<Strong<T>, StatusCode> {
@@ -35,3 +36,40 @@
Err(StatusCode::BAD_VALUE)
}
}
+
+type RequestFd<'a> = &'a mut dyn FnMut() -> Option<RawFd>;
+
+/// Connects to a Binder RPC server, using the given callback to get (and take ownership of) file
+/// descriptors already connected to it.
+pub fn connect_preconnected_rpc_binder<T: FromIBinder + ?Sized>(
+ mut request_fd: impl FnMut() -> Option<RawFd>,
+) -> Result<Strong<T>, StatusCode> {
+ // Double reference the factory because trait objects aren't FFI safe.
+ let mut request_fd_ref: RequestFd = &mut request_fd;
+ let param = &mut request_fd_ref as *mut RequestFd as *mut raw::c_void;
+
+ // SAFETY: AIBinder returned by RpcPreconnectedClient has correct reference count, and the
+ // ownership can be safely taken by new_spibinder. RpcPreconnectedClient does not take ownership
+ // of param, only passing it to request_fd_wrapper.
+ let ibinder = unsafe {
+ new_spibinder(binder_rpc_unstable_bindgen::RpcPreconnectedClient(
+ Some(request_fd_wrapper),
+ param,
+ ) as *mut AIBinder)
+ };
+
+ if let Some(ibinder) = ibinder {
+ <T>::try_from(ibinder)
+ } else {
+ Err(StatusCode::BAD_VALUE)
+ }
+}
+
+unsafe extern "C" fn request_fd_wrapper(param: *mut raw::c_void) -> raw::c_int {
+ // SAFETY: This is only ever called by RpcPreconnectedClient, within the lifetime of the
+ // BinderFdFactory reference, with param being a properly aligned non-null pointer to an
+ // initialized instance.
+ let request_fd_ptr = param as *mut RequestFd;
+ let request_fd = request_fd_ptr.as_mut().unwrap();
+ request_fd().unwrap_or(-1)
+}