diff --git a/keystore2/test_utils/run_as.rs b/keystore2/test_utils/run_as.rs
index d42303d..2485ab5 100644
--- a/keystore2/test_utils/run_as.rs
+++ b/keystore2/test_utils/run_as.rs
@@ -30,9 +30,11 @@
 use nix::sys::wait::{waitpid, WaitStatus};
 use nix::unistd::{
     close, fork, pipe as nix_pipe, read as nix_read, setgid, setuid, write as nix_write,
-    ForkResult, Gid, Uid,
+    ForkResult, Gid, Pid, Uid,
 };
 use serde::{de::DeserializeOwned, Serialize};
+use std::io::{Read, Write};
+use std::marker::PhantomData;
 use std::os::unix::io::RawFd;
 
 fn transition(se_context: selinux::Context, uid: Uid, gid: Gid) {
@@ -48,17 +50,10 @@
 /// reads from the pipe into an expending vector, until no more data can be read.
 struct PipeReader(RawFd);
 
-impl PipeReader {
-    pub fn read_all(&self) -> Result<Vec<u8>, nix::Error> {
-        let mut buffer = [0u8; 128];
-        let mut result = Vec::<u8>::new();
-        loop {
-            let bytes = nix_read(self.0, &mut buffer)?;
-            if bytes == 0 {
-                return Ok(result);
-            }
-            result.extend_from_slice(&buffer[0..bytes]);
-        }
+impl Read for PipeReader {
+    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
+        let bytes = nix_read(self.0, buf)?;
+        Ok(bytes)
     }
 }
 
@@ -73,46 +68,264 @@
 /// writes the given buffer into the pipe, returning the number of bytes written.
 struct PipeWriter(RawFd);
 
-impl PipeWriter {
-    pub fn write(&self, data: &[u8]) -> Result<usize, nix::Error> {
-        nix_write(self.0, data)
-    }
-}
-
 impl Drop for PipeWriter {
     fn drop(&mut self) {
         close(self.0).expect("Failed to close writer pipe fd.");
     }
 }
 
+impl Write for PipeWriter {
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        let written = nix_write(self.0, buf)?;
+        Ok(written)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        // Flush is a NO-OP.
+        Ok(())
+    }
+}
+
+/// Denotes the sender side of a serializing channel.
+pub struct ChannelWriter<T: Serialize + DeserializeOwned>(PipeWriter, PhantomData<T>);
+
+impl<T: Serialize + DeserializeOwned> ChannelWriter<T> {
+    /// Sends a serializable object to a the corresponding ChannelReader.
+    /// Sending is always non blocking. Panics if any error occurs during io or serialization.
+    pub fn send(&mut self, value: &T) {
+        let serialized = serde_cbor::to_vec(value)
+            .expect("In ChannelWriter::send: Failed to serialize to vector.");
+        let size = serialized.len().to_be_bytes();
+        match self.0.write(&size).expect("In ChannelWriter::send: Failed to write serialized size.")
+        {
+            w if w != std::mem::size_of::<usize>() => {
+                panic!(
+                    "In ChannelWriter::send: Failed to write serialized size. (written: {}).",
+                    w
+                );
+            }
+            _ => {}
+        };
+        match self
+            .0
+            .write(&serialized)
+            .expect("In ChannelWriter::send: Failed to write serialized data.")
+        {
+            w if w != serialized.len() => {
+                panic!(
+                    "In ChannelWriter::send: Failed to write serialized data. (written: {}).",
+                    w
+                );
+            }
+            _ => {}
+        };
+    }
+}
+
+/// Represents the receiving and of a serializing channel.
+pub struct ChannelReader<T>(PipeReader, PhantomData<T>);
+
+impl<T: Serialize + DeserializeOwned> ChannelReader<T> {
+    /// Receives a serializable object from the corresponding ChannelWriter.
+    /// Receiving blocks until an object of type T has been read from the channel.
+    /// Panics if an error occurs during io or deserialization.
+    pub fn recv(&mut self) -> T {
+        let mut size_buffer = [0u8; std::mem::size_of::<usize>()];
+        match self.0.read(&mut size_buffer).expect("In ChannelReader::recv: Failed to read size.") {
+            r if r != size_buffer.len() => {
+                panic!("In ChannelReader::recv: Failed to read size. Insufficient data: {}", r);
+            }
+            _ => {}
+        };
+        let size = usize::from_be_bytes(size_buffer);
+        let mut data_buffer = vec![0u8; size];
+        match self
+            .0
+            .read(&mut data_buffer)
+            .expect("In ChannelReader::recv: Failed to read serialized data.")
+        {
+            r if r != data_buffer.len() => {
+                panic!(
+                    "In ChannelReader::recv: Failed to read serialized data. Insufficient data: {}",
+                    r
+                );
+            }
+            _ => {}
+        };
+
+        serde_cbor::from_slice(&data_buffer)
+            .expect("In ChannelReader::recv: Failed to deserialize data.")
+    }
+}
+
 fn pipe() -> Result<(PipeReader, PipeWriter), nix::Error> {
     let (read_fd, write_fd) = nix_pipe()?;
     Ok((PipeReader(read_fd), PipeWriter(write_fd)))
 }
 
+fn pipe_channel<T>() -> Result<(ChannelReader<T>, ChannelWriter<T>), nix::Error>
+where
+    T: Serialize + DeserializeOwned,
+{
+    let (reader, writer) = pipe()?;
+    Ok((
+        ChannelReader::<T>(reader, Default::default()),
+        ChannelWriter::<T>(writer, Default::default()),
+    ))
+}
+
+/// Handle for handling child processes.
+pub struct ChildHandle<R: Serialize + DeserializeOwned, M: Serialize + DeserializeOwned> {
+    pid: Pid,
+    result_reader: ChannelReader<R>,
+    cmd_writer: ChannelWriter<M>,
+    response_reader: ChannelReader<M>,
+    exit_status: Option<WaitStatus>,
+}
+
+impl<R: Serialize + DeserializeOwned, M: Serialize + DeserializeOwned> ChildHandle<R, M> {
+    /// Send a command message to the child.
+    pub fn send(&mut self, data: &M) {
+        self.cmd_writer.send(data)
+    }
+
+    /// Receive a response from the child.
+    pub fn recv(&mut self) -> M {
+        self.response_reader.recv()
+    }
+
+    /// Get child result. Panics if the child did not exit with status 0 or if a serialization
+    /// error occurred.
+    pub fn get_result(mut self) -> R {
+        let status =
+            waitpid(self.pid, None).expect("ChildHandle::wait: Failed while waiting for child.");
+        match status {
+            WaitStatus::Exited(pid, 0) => {
+                // Child exited successfully.
+                // Read the result from the pipe.
+                self.exit_status = Some(WaitStatus::Exited(pid, 0));
+                self.result_reader.recv()
+            }
+            WaitStatus::Exited(pid, c) => {
+                panic!("Child did not exit as expected: {:?}", WaitStatus::Exited(pid, c));
+            }
+            status => {
+                panic!("Child did not exit at all: {:?}", status);
+            }
+        }
+    }
+}
+
+impl<R: Serialize + DeserializeOwned, M: Serialize + DeserializeOwned> Drop for ChildHandle<R, M> {
+    fn drop(&mut self) {
+        if self.exit_status.is_none() {
+            panic!("Child result not checked.")
+        }
+    }
+}
+
+/// Run the given closure in a new process running with the new identity given as
+/// `uid`, `gid`, and `se_context`. Parent process will run without waiting for child status.
+///
+/// # Safety
+/// run_as_child runs the given closure in the client branch of fork. And it uses non
+/// async signal safe API. This means that calling this function in a multi threaded program
+/// yields undefined behavior in the child. As of this writing, it is safe to call this function
+/// from a Rust device test, because every test itself is spawned as a separate process.
+///
+/// # Safety Binder
+/// It is okay for the closure to use binder services, however, this does not work
+/// if the parent initialized libbinder already. So do not use binder outside of the closure
+/// in your test.
+pub unsafe fn run_as_child<F, R, M>(
+    se_context: &str,
+    uid: Uid,
+    gid: Gid,
+    f: F,
+) -> Result<ChildHandle<R, M>, nix::Error>
+where
+    R: Serialize + DeserializeOwned,
+    M: Serialize + DeserializeOwned,
+    F: 'static + Send + FnOnce(&mut ChannelReader<M>, &mut ChannelWriter<M>) -> R,
+{
+    let se_context =
+        selinux::Context::new(se_context).expect("Unable to construct selinux::Context.");
+    let (result_reader, mut result_writer) = pipe_channel().expect("Failed to create pipe.");
+    let (mut cmd_reader, cmd_writer) = pipe_channel().expect("Failed to create cmd pipe.");
+    let (response_reader, mut response_writer) =
+        pipe_channel().expect("Failed to create cmd pipe.");
+
+    match fork() {
+        Ok(ForkResult::Parent { child, .. }) => {
+            drop(response_writer);
+            drop(cmd_reader);
+            drop(result_writer);
+
+            Ok(ChildHandle::<R, M> {
+                pid: child,
+                result_reader,
+                response_reader,
+                cmd_writer,
+                exit_status: None,
+            })
+        }
+        Ok(ForkResult::Child) => {
+            drop(cmd_writer);
+            drop(response_reader);
+            drop(result_reader);
+
+            // This will panic on error or insufficient privileges.
+            transition(se_context, uid, gid);
+
+            // Run the closure.
+            let result = f(&mut cmd_reader, &mut response_writer);
+
+            // Serialize the result of the closure.
+            result_writer.send(&result);
+
+            // Set exit status to `0`.
+            std::process::exit(0);
+        }
+        Err(errno) => {
+            panic!("Failed to fork: {:?}", errno);
+        }
+    }
+}
+
 /// Run the given closure in a new process running with the new identity given as
 /// `uid`, `gid`, and `se_context`.
-pub fn run_as<F, R>(se_context: &str, uid: Uid, gid: Gid, f: F) -> R
+///
+/// # Safety
+/// run_as runs the given closure in the client branch of fork. And it uses non
+/// async signal safe API. This means that calling this function in a multi threaded program
+/// yields undefined behavior in the child. As of this writing, it is safe to call this function
+/// from a Rust device test, because every test itself is spawned as a separate process.
+///
+/// # Safety Binder
+/// It is okay for the closure to use binder services, however, this does not work
+/// if the parent initialized libbinder already. So do not use binder outside of the closure
+/// in your test.
+pub unsafe fn run_as<F, R>(se_context: &str, uid: Uid, gid: Gid, f: F) -> R
 where
     R: Serialize + DeserializeOwned,
     F: 'static + Send + FnOnce() -> R,
 {
     let se_context =
         selinux::Context::new(se_context).expect("Unable to construct selinux::Context.");
-    let (reader, writer) = pipe().expect("Failed to create pipe.");
+    let (mut reader, mut writer) = pipe_channel::<R>().expect("Failed to create pipe.");
 
-    match unsafe { fork() } {
+    match fork() {
         Ok(ForkResult::Parent { child, .. }) => {
             drop(writer);
             let status = waitpid(child, None).expect("Failed while waiting for child.");
             if let WaitStatus::Exited(_, 0) = status {
                 // Child exited successfully.
                 // Read the result from the pipe.
-                let serialized_result =
-                    reader.read_all().expect("Failed to read result from child.");
+                // let serialized_result =
+                //     reader.read_all().expect("Failed to read result from child.");
 
                 // Deserialize the result and return it.
-                serde_cbor::from_slice(&serialized_result).expect("Failed to deserialize result.")
+                reader.recv()
             } else {
                 panic!("Child did not exit as expected {:?}", status);
             }
@@ -125,10 +338,7 @@
             let result = f();
 
             // Serialize the result of the closure.
-            let vec = serde_cbor::to_vec(&result).expect("Result serialization failed");
-
-            // Send the result to the parent using the pipe.
-            writer.write(&vec).expect("Failed to send serialized result to parent.");
+            writer.send(&result);
 
             // Set exit status to `0`.
             std::process::exit(0);
@@ -151,9 +361,13 @@
     #[test]
     #[should_panic]
     fn test_run_as_panics_on_closure_panic() {
-        run_as(selinux::getcon().unwrap().to_str().unwrap(), getuid(), getgid(), || {
-            panic!("Closure must panic.")
-        });
+        // Safety: run_as must be called from a single threaded process.
+        // This device test is run as a separate single threaded process.
+        unsafe {
+            run_as(selinux::getcon().unwrap().to_str().unwrap(), getuid(), getgid(), || {
+                panic!("Closure must panic.")
+            })
+        };
     }
 
     static TARGET_UID: Uid = Uid::from_raw(10020);
@@ -163,11 +377,15 @@
     /// Tests that the closure is running as the target identity.
     #[test]
     fn test_transition_to_untrusted_app() {
-        run_as(TARGET_CTX, TARGET_UID, TARGET_GID, || {
-            assert_eq!(TARGET_UID, getuid());
-            assert_eq!(TARGET_GID, getgid());
-            assert_eq!(TARGET_CTX, selinux::getcon().unwrap().to_str().unwrap());
-        });
+        // Safety: run_as must be called from a single threaded process.
+        // This device test is run as a separate single threaded process.
+        unsafe {
+            run_as(TARGET_CTX, TARGET_UID, TARGET_GID, || {
+                assert_eq!(TARGET_UID, getuid());
+                assert_eq!(TARGET_GID, getgid());
+                assert_eq!(TARGET_CTX, selinux::getcon().unwrap().to_str().unwrap());
+            })
+        };
     }
 
     #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
@@ -185,7 +403,72 @@
             c: "supercalifragilisticexpialidocious".to_owned(),
         };
         let test_result_clone = test_result.clone();
-        let result = run_as(TARGET_CTX, TARGET_UID, TARGET_GID, || test_result_clone);
+        // Safety: run_as must be called from a single threaded process.
+        // This device test is run as a separate single threaded process.
+        let result = unsafe { run_as(TARGET_CTX, TARGET_UID, TARGET_GID, || test_result_clone) };
         assert_eq!(test_result, result);
     }
+
+    #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+    enum PingPong {
+        Ping,
+        Pong,
+    }
+
+    /// Tests that closure is running under given user identity and communicates with calling
+    /// process using pipe.
+    #[test]
+    fn test_run_as_child() {
+        let test_result = SomeResult {
+            a: 5,
+            b: 0xffffffffffffffff,
+            c: "supercalifragilisticexpialidocious".to_owned(),
+        };
+        let test_result_clone = test_result.clone();
+
+        // Safety: run_as_child must be called from a single threaded process.
+        // This device test is run as a separate single threaded process.
+        let mut child_handle: ChildHandle<SomeResult, PingPong> = unsafe {
+            run_as_child(TARGET_CTX, TARGET_UID, TARGET_GID, |cmd_reader, response_writer| {
+                assert_eq!(TARGET_UID, getuid());
+                assert_eq!(TARGET_GID, getgid());
+                assert_eq!(TARGET_CTX, selinux::getcon().unwrap().to_str().unwrap());
+
+                let ping: PingPong = cmd_reader.recv();
+                assert_eq!(ping, PingPong::Ping);
+
+                response_writer.send(&PingPong::Pong);
+
+                let ping: PingPong = cmd_reader.recv();
+                assert_eq!(ping, PingPong::Ping);
+                let pong: PingPong = cmd_reader.recv();
+                assert_eq!(pong, PingPong::Pong);
+
+                response_writer.send(&PingPong::Pong);
+                response_writer.send(&PingPong::Ping);
+
+                test_result_clone
+            })
+            .unwrap()
+        };
+
+        // Send one ping.
+        child_handle.send(&PingPong::Ping);
+
+        // Expect one pong.
+        let pong = child_handle.recv();
+        assert_eq!(pong, PingPong::Pong);
+
+        // Send ping and pong.
+        child_handle.send(&PingPong::Ping);
+        child_handle.send(&PingPong::Pong);
+
+        // Expect pong and ping.
+        let pong = child_handle.recv();
+        assert_eq!(pong, PingPong::Pong);
+        let ping = child_handle.recv();
+        assert_eq!(ping, PingPong::Ping);
+
+        assert_eq!(child_handle.get_result(), test_result);
+    }
 }