libavf: Add callback support

Test: atest vts_libavf_test
Bug: 381195543
Change-Id: I5f3920b7fd223ad50088cdbc429aca19e3717121
diff --git a/libs/libavf/include/android/virtualization.h b/libs/libavf/include/android/virtualization.h
index ef57325..03d04a9 100644
--- a/libs/libavf/include/android/virtualization.h
+++ b/libs/libavf/include/android/virtualization.h
@@ -337,17 +337,30 @@
 int AVirtualMachine_createRaw(const AVirtualizationService* _Nonnull service,
                               AVirtualMachineRawConfig* _Nonnull config, int consoleOutFd,
                               int consoleInFd, int logFd,
-                              AVirtualMachine* _Null_unspecified* _Nonnull vm) __INTRODUCED_IN(36);
+                              const AVirtualMachine* _Null_unspecified* _Nonnull vm)
+        __INTRODUCED_IN(36);
+
+/**
+ * A callback to be called when virtual machine stops.
+ *
+ * \param vm stopped vm
+ * \param reason stop reason
+ */
+typedef void (*AVirtualMachine_stopCallback)(const AVirtualMachine* _Nonnull vm,
+                                             enum AVirtualMachineStopReason reason);
 
 /**
  * Start a virtual machine. `AVirtualMachine_start` is synchronous and blocks until the virtual
  * machine is initialized and free to start executing code, or until an error happens.
  *
  * \param vm a handle on a virtual machine.
+ * \param callback an optional callback to be called when VM stops.
  *
  * \return If successful, it returns 0. Otherwise, it returns `-EIO`.
  */
-int AVirtualMachine_start(AVirtualMachine* _Nonnull vm) __INTRODUCED_IN(36);
+int AVirtualMachine_start(const AVirtualMachine* _Nonnull vm,
+                          const AVirtualMachine_stopCallback _Nullable callback)
+        __INTRODUCED_IN(36);
 
 /**
  * Stop a virtual machine. Stopping a virtual machine is like pulling the plug on a real computer;
@@ -366,7 +379,7 @@
  *
  * \return If successful, it returns 0. Otherwise, it returns `-EIO`.
  */
-int AVirtualMachine_stop(AVirtualMachine* _Nonnull vm) __INTRODUCED_IN(36);
+int AVirtualMachine_stop(const AVirtualMachine* _Nonnull vm) __INTRODUCED_IN(36);
 
 /**
  * Open a vsock connection to the VM on the given port. The caller takes ownership of the returned
@@ -379,7 +392,8 @@
  *
  * \return If successful, it returns a valid file descriptor. Otherwise, it returns `-EIO`.
  */
-int AVirtualMachine_connectVsock(AVirtualMachine* _Nonnull vm, uint32_t port) __INTRODUCED_IN(36);
+int AVirtualMachine_connectVsock(const AVirtualMachine* _Nonnull vm, uint32_t port)
+        __INTRODUCED_IN(36);
 
 /**
  * Wait until a virtual machine stops or the given timeout elapses.
@@ -393,7 +407,7 @@
  *     sets `reason` and returns true.
  *   - If the timeout expired, it returns `false`.
  */
-bool AVirtualMachine_waitForStop(AVirtualMachine* _Nonnull vm,
+bool AVirtualMachine_waitForStop(const AVirtualMachine* _Nonnull vm,
                                  const struct timespec* _Nullable timeout,
                                  enum AVirtualMachineStopReason* _Nonnull reason)
         __INTRODUCED_IN(36);
@@ -408,6 +422,6 @@
  *
  * \param vm a handle on a virtual machine.
  */
-void AVirtualMachine_destroy(AVirtualMachine* _Nullable vm) __INTRODUCED_IN(36);
+void AVirtualMachine_destroy(const AVirtualMachine* _Nullable vm) __INTRODUCED_IN(36);
 
 __END_DECLS
diff --git a/libs/libavf/src/lib.rs b/libs/libavf/src/lib.rs
index 50c5e2e..256803f 100644
--- a/libs/libavf/src/lib.rs
+++ b/libs/libavf/src/lib.rs
@@ -19,6 +19,7 @@
 use std::os::fd::{FromRawFd, IntoRawFd};
 use std::os::raw::{c_char, c_int};
 use std::ptr;
+use std::sync::Arc;
 use std::time::Duration;
 
 use android_system_virtualizationservice::{
@@ -29,10 +30,10 @@
     },
     binder::{ParcelFileDescriptor, Strong},
 };
-use avf_bindgen::AVirtualMachineStopReason;
+use avf_bindgen::{AVirtualMachineStopReason, AVirtualMachine_stopCallback};
 use libc::timespec;
 use log::error;
-use vmclient::{DeathReason, VirtualizationService, VmInstance};
+use vmclient::{DeathReason, ErrorCode, VirtualizationService, VmCallback, VmInstance};
 
 /// Create a new virtual machine config object with no properties.
 #[no_mangle]
@@ -342,6 +343,49 @@
     }
 }
 
+struct LocalVmInstance {
+    vm: Arc<VmInstance>,
+    callback: AVirtualMachine_stopCallback,
+}
+
+impl VmCallback for LocalVmInstance {
+    fn on_payload_started(&self, _cid: i32) {
+        // Microdroid only. no-op.
+    }
+
+    fn on_payload_ready(&self, _cid: i32) {
+        // Microdroid only. no-op.
+    }
+
+    fn on_payload_finished(&self, _cid: i32, _exit_code: i32) {
+        // Microdroid only. no-op.
+    }
+
+    fn on_error(&self, _cid: i32, _error_code: ErrorCode, _message: &str) {
+        // Microdroid only. no-op.
+    }
+
+    fn on_died(&self, _cid: i32, death_reason: DeathReason) {
+        let Some(callback) = self.callback else {
+            return;
+        };
+        let stop_reason = death_reason_to_stop_reason(death_reason);
+        let vm_ptr: *const VmInstance = Arc::into_raw(Arc::clone(&self.vm));
+
+        // SAFETY: `callback` is assumed to be a valid, non-null function pointer passed by
+        // `AVirtualMachine_start`.
+        unsafe {
+            callback(vm_ptr.cast(), stop_reason);
+        }
+
+        // drop ptr after use.
+        // SAFETY: `vm_ptr` is a valid, non-null pointer casted above.
+        unsafe {
+            let _ = Arc::from_raw(vm_ptr);
+        }
+    }
+}
+
 /// Create a virtual machine with given `config`.
 ///
 /// # Safety
@@ -357,7 +401,7 @@
     console_out_fd: c_int,
     console_in_fd: c_int,
     log_fd: c_int,
-    vm_ptr: *mut *mut VmInstance,
+    vm_ptr: *mut *const VmInstance,
 ) -> c_int {
     // SAFETY: `service` is assumed to be a valid, non-null pointer returned by
     // `AVirtualizationService_create` or `AVirtualizationService_create_early`. It's the only
@@ -376,9 +420,8 @@
     match VmInstance::create(service.as_ref(), &config, console_out, console_in, log, None) {
         Ok(vm) => {
             // SAFETY: `vm_ptr` is assumed to be a valid, non-null pointer to a mutable raw pointer.
-            // `vm` is the only reference here and `vm_ptr` takes ownership.
             unsafe {
-                *vm_ptr = Box::into_raw(Box::new(vm));
+                *vm_ptr = Arc::into_raw(Arc::new(vm));
             }
             0
         }
@@ -394,11 +437,20 @@
 /// # Safety
 /// `vm` must be a pointer returned by `AVirtualMachine_createRaw`.
 #[no_mangle]
-pub unsafe extern "C" fn AVirtualMachine_start(vm: *const VmInstance) -> c_int {
+pub unsafe extern "C" fn AVirtualMachine_start(
+    vm: *const VmInstance,
+    callback: AVirtualMachine_stopCallback,
+) -> c_int {
     // SAFETY: `vm` is assumed to be a valid, non-null pointer returned by
     // `AVirtualMachine_createRaw`. It's the only reference to the object.
-    let vm = unsafe { &*vm };
-    match vm.start(None) {
+    let vm = unsafe { Arc::from_raw(vm) };
+    let callback = callback.map(|_| {
+        let cb: Box<dyn VmCallback + Send + Sync> =
+            Box::new(LocalVmInstance { vm: Arc::clone(&vm), callback });
+        cb
+    });
+
+    match vm.start(callback) {
         Ok(_) => 0,
         Err(e) => {
             error!("AVirtualMachine_start failed: {e:?}");
@@ -509,12 +561,12 @@
 /// `vm` must be a pointer returned by `AVirtualMachine_createRaw`. `vm` must not be reused after
 /// deletion.
 #[no_mangle]
-pub unsafe extern "C" fn AVirtualMachine_destroy(vm: *mut VmInstance) {
+pub unsafe extern "C" fn AVirtualMachine_destroy(vm: *const VmInstance) {
     if !vm.is_null() {
         // SAFETY: `vm` is assumed to be a valid, non-null pointer returned by
         // AVirtualMachine_create. It's the only reference to the object.
         unsafe {
-            let _ = Box::from_raw(vm);
+            let _ = Arc::from_raw(vm);
         }
     }
 }
diff --git a/tests/old_images_avf_test/src/main.rs b/tests/old_images_avf_test/src/main.rs
index 018a80e..d3ab5eb 100644
--- a/tests/old_images_avf_test/src/main.rs
+++ b/tests/old_images_avf_test/src/main.rs
@@ -92,7 +92,7 @@
         AVirtualMachineRawConfig_setMemoryMiB(config, VM_MEMORY_MB);
     }
 
-    let mut vm = std::ptr::null_mut();
+    let mut vm = std::ptr::null();
     let mut service = std::ptr::null_mut();
 
     ensure!(
@@ -132,7 +132,7 @@
 
     // SAFETY: vm is the only reference to a valid object
     unsafe {
-        AVirtualMachine_start(vm);
+        AVirtualMachine_start(vm, None /* callback */);
     }
 
     info!("VM started");
diff --git a/tests/vts/src/vts_libavf_test.rs b/tests/vts/src/vts_libavf_test.rs
index e30c175..8e3c5b5 100644
--- a/tests/vts/src/vts_libavf_test.rs
+++ b/tests/vts/src/vts_libavf_test.rs
@@ -20,6 +20,8 @@
 use std::fs::File;
 use std::io::{self, BufWriter, Write};
 use std::os::fd::IntoRawFd;
+use std::sync::mpsc::{self, Sender};
+use std::sync::{LazyLock, Mutex};
 use std::time::{Duration, Instant};
 use vsock::{VsockListener, VsockStream, VMADDR_CID_HOST};
 
@@ -34,6 +36,13 @@
 const WRITE_TIMEOUT: Duration = Duration::from_secs(10);
 const STOP_TIMEOUT: timespec = timespec { tv_sec: 10, tv_nsec: 0 };
 
+static ON_STOPPED_EVENT: LazyLock<Mutex<Sender<(usize, AVirtualMachineStopReason)>>> =
+    LazyLock::new(|| {
+        // Returning stub here because `Receiver` isn't `Send`.
+        let (tx, _) = mpsc::channel();
+        Mutex::new(tx)
+    });
+
 /// Processes the request in the service VM.
 fn process_request(vsock_stream: &mut VsockStream, request: Request) -> Result<Response> {
     write_request(vsock_stream, &ServiceVmRequest::Process(request))?;
@@ -74,11 +83,23 @@
     }
 }
 
+unsafe extern "C" fn on_stopped(vm: *const AVirtualMachine, reason: AVirtualMachineStopReason) {
+    ON_STOPPED_EVENT.lock().unwrap().send((vm as usize, reason)).unwrap();
+
+    // SAFETY: `vm` is a valid pointer created by AVirtualMachine_create().
+    unsafe {
+        AVirtualMachine_destroy(vm);
+    }
+}
+
 fn run_rialto(protected_vm: bool) -> Result<()> {
     let kernel_file =
         File::open("/data/local/tmp/rialto.bin").context("Failed to open kernel file")?;
     let kernel_fd = kernel_file.into_raw_fd();
 
+    let (tx, rx) = mpsc::channel();
+    (*ON_STOPPED_EVENT.lock().unwrap()) = tx;
+
     // SAFETY: AVirtualMachineRawConfig_create() isn't unsafe but rust_bindgen forces it to be seen
     // as unsafe
     let config = unsafe { AVirtualMachineRawConfig_create() };
@@ -96,7 +117,7 @@
         AVirtualMachineRawConfig_setMemoryMiB(config, VM_MEMORY_MB);
     }
 
-    let mut vm = std::ptr::null_mut();
+    let mut vm = std::ptr::null();
     let mut service = std::ptr::null_mut();
 
     ensure!(
@@ -105,11 +126,6 @@
         "AVirtualizationService_create failed"
     );
 
-    scopeguard::defer! {
-        // SAFETY: service is a valid pointer to AVirtualizationService
-        unsafe { AVirtualizationService_destroy(service); }
-    }
-
     ensure!(
         // SAFETY: &mut vm is a valid pointer to *AVirtualMachine
         unsafe {
@@ -136,9 +152,11 @@
 
     // SAFETY: vm is the only reference to a valid object
     unsafe {
-        AVirtualMachine_start(vm);
+        AVirtualMachine_start(vm, Some(on_stopped));
     }
 
+    let vm_ptr = vm as usize;
+
     info!("VM started");
 
     let mut vsock_stream = listener_thread.join().unwrap()?;
@@ -170,6 +188,14 @@
         "AVirtualMachine_waitForStop failed"
     );
 
+    assert_eq!(AVirtualMachineStopReason::AVIRTUAL_MACHINE_SHUTDOWN, stop_reason);
+
+    let timeout = Duration::from_secs(STOP_TIMEOUT.tv_sec.try_into().unwrap());
+    let (stopped_vm_ptr, stopped_reason) =
+        rx.recv_timeout(timeout).expect("Callback should have been called");
+    assert_eq!(stopped_vm_ptr, vm_ptr);
+    assert_eq!(stopped_reason, stop_reason);
+
     info!("stopped");
 
     Ok(())