[rpc_binder] Add ARpcServer_newBoundSocket API

This cl is part of the change to replace the init-dependent binder
API ARpcServer_newInitUnixDomain with a more generic version
ARpcServer_newBoundSocket.

Test: atest microdroid_manager_test
Bug: 275729094

Change-Id: I5b8688fb5964e775845a3b878466f8a3cfee2e25

5 files changed, 15 insertions, 31 deletions

diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 34331381db..deff76b3a5 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -525,7 +525,6 @@ cc_library {
         "libbase",
         "libbinder",
         "libbinder_ndk",
-        "libcutils_sockets",
         "liblog",
         "libutils",
     ],
diff --git a/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp b/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
index a157792156..7d0acd1843 100644
--- a/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
+++ b/libs/binder/include_rpc_unstable/binder_rpc_unstable.hpp
@@ -40,12 +40,13 @@ enum class ARpcSession_FileDescriptorTransportMode {
 [[nodiscard]] ARpcServer* ARpcServer_newVsock(AIBinder* service, unsigned int cid,
                                               unsigned int port);
 
-// Starts a Unix domain RPC server with a given init-managed Unix domain `name`
+// Starts a Unix domain RPC server with an open raw socket file descriptor
 // and a given root IBinder object.
-// The socket should be created in init.rc with the same `name`.
+// The socket should be created and bound to an address.
 // Returns an opaque handle to the running server instance, or null if the server
 // could not be started.
-[[nodiscard]] ARpcServer* ARpcServer_newInitUnixDomain(AIBinder* service, const char* name);
+// The socket will be closed by the server once the server goes out of scope.
+[[nodiscard]] ARpcServer* ARpcServer_newBoundSocket(AIBinder* service, int socketFd);
 
 // Starts an RPC server that bootstraps sessions using an existing Unix domain
 // socket pair, with a given root IBinder object.
diff --git a/libs/binder/libbinder_rpc_unstable.cpp b/libs/binder/libbinder_rpc_unstable.cpp
index a167f235d5..f51cd9bc99 100644
--- a/libs/binder/libbinder_rpc_unstable.cpp
+++ b/libs/binder/libbinder_rpc_unstable.cpp
@@ -105,22 +105,15 @@ ARpcServer* ARpcServer_newVsock(AIBinder* service, unsigned int cid, unsigned in
     return createObjectHandle<ARpcServer>(server);
 }
 
-ARpcServer* ARpcServer_newInitUnixDomain(AIBinder* service, const char* name) {
+ARpcServer* ARpcServer_newBoundSocket(AIBinder* service, int socketFd) {
     auto server = RpcServer::make();
-    auto fd = unique_fd(android_get_control_socket(name));
+    auto fd = unique_fd(socketFd);
     if (!fd.ok()) {
-        LOG(ERROR) << "Failed to get fd for the socket:" << name;
+        LOG(ERROR) << "Invalid socket fd " << socketFd;
         return nullptr;
     }
-    // Control socket fds are inherited from init, so they don't have O_CLOEXEC set.
-    // But we don't want any child processes to inherit the socket we are running
-    // the server on, so attempt to set the flag now.
-    if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
-        LOG(WARNING) << "Failed to set CLOEXEC on control socket with name " << name
-                     << " error: " << errno;
-    }
     if (status_t status = server->setupRawSocketServer(std::move(fd)); status != OK) {
-        LOG(ERROR) << "Failed to set up Unix Domain RPC server with name " << name
+        LOG(ERROR) << "Failed to set up RPC server with fd " << socketFd
                    << " error: " << statusToString(status).c_str();
         return nullptr;
     }
diff --git a/libs/binder/libbinder_rpc_unstable.map.txt b/libs/binder/libbinder_rpc_unstable.map.txt
index 63679c28d0..50f7deb7d9 100644
--- a/libs/binder/libbinder_rpc_unstable.map.txt
+++ b/libs/binder/libbinder_rpc_unstable.map.txt
@@ -3,7 +3,7 @@ LIBBINDER_RPC_UNSTABLE_SHIM { # platform-only
     ARpcServer_free;
     ARpcServer_join;
     ARpcServer_newInet;
-    ARpcServer_newInitUnixDomain;
+    ARpcServer_newBoundSocket;
     ARpcServer_newVsock;
     ARpcServer_shutdown;
     ARpcServer_start;
diff --git a/libs/binder/rust/rpcbinder/src/server.rs b/libs/binder/rust/rpcbinder/src/server.rs
index c87876ac15..81f68f5a29 100644
--- a/libs/binder/rust/rpcbinder/src/server.rs
+++ b/libs/binder/rust/rpcbinder/src/server.rs
@@ -57,26 +57,17 @@ impl RpcServer {
     }
 
     /// Creates a binder RPC server, serving the supplied binder service implementation on the given
-    /// socket file name. The socket should be initialized in init.rc with the same name.
-    pub fn new_init_unix_domain(
-        mut service: SpIBinder,
-        socket_name: &str,
-    ) -> Result<RpcServer, Error> {
-        let socket_name = match CString::new(socket_name) {
-            Ok(s) => s,
-            Err(e) => {
-                log::error!("Cannot convert {} to CString. Error: {:?}", socket_name, e);
-                return Err(Error::from(ErrorKind::InvalidInput));
-            }
-        };
+    /// socket file descriptor. The socket should be bound to an address before calling this
+    /// function.
+    pub fn new_bound_socket(mut service: SpIBinder, socket_fd: OwnedFd) -> Result<RpcServer, Error> {
         let service = service.as_native_mut();
 
         // SAFETY: Service ownership is transferring to the server and won't be valid afterward.
         // Plus the binder objects are threadsafe.
+        // The server takes ownership of the socket FD.
         unsafe {
-            Self::checked_from_ptr(binder_rpc_unstable_bindgen::ARpcServer_newInitUnixDomain(
-                service,
-                socket_name.as_ptr(),
+            Self::checked_from_ptr(binder_rpc_unstable_bindgen::ARpcServer_newBoundSocket(
+                service, socket_fd.into_raw_fd(),
             ))
         }
     }