Adding FFI functions for Hyperlight Guest CAPI

src/hyperlight_guest_capi/src/flatbuffer.rs

@@ -15,6 +15,9 @@ limitations under the License.
 */
 
 use alloc::boxed::Box;
+use alloc::ffi::CString;
+use alloc::string::String;
+use alloc::vec::Vec;
 use core::ffi::{CStr, c_char};
 
 use hyperlight_common::flatbuffer_wrappers::util::get_flatbuffer_result;
@@ -92,6 +95,13 @@ pub extern "C" fn hl_flatbuffer_result_from_Bytes(data: *const u8, len: usize) -
     Box::new(unsafe { FfiVec::from_vec(vec) })
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_flatbuffer_result_from_Bool(value: bool) -> Box<FfiVec> {
+    let vec = get_flatbuffer_result(value);
+
+    Box::new(unsafe { FfiVec::from_vec(vec) })
+}
+
 //--- Functions for getting values returned by host functions calls
 
 #[unsafe(no_mangle)]
@@ -115,4 +125,34 @@ pub extern "C" fn hl_get_host_return_value_as_ULong() -> u64 {
     get_host_return_value().expect("Unable to get host return value as ulong")
 }
 
-// TODO add bool, float, double, string, vecbytes
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_get_host_return_value_as_Bool() -> bool {
+    get_host_return_value().expect("Unable to get host return value as bool")
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_get_host_return_value_as_Float() -> f32 {
+    get_host_return_value().expect("Unable to get host return value as f32")
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_get_host_return_value_as_Double() -> f64 {
+    get_host_return_value().expect("Unable to get host return value as f64")
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_get_host_return_value_as_String() -> *const c_char {
+    let string_value: String =
+        get_host_return_value().expect("Unable to get host return value as string");
+
+    let c_string = CString::new(string_value).expect("Failed to create CString");
+    c_string.into_raw()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn hl_get_host_return_value_as_VecBytes() -> Box<FfiVec> {
+    let vec_value: Vec<u8> =
+        get_host_return_value().expect("Unable to get host return value as vec bytes");
+
+    Box::new(unsafe { FfiVec::from_vec(vec_value) })
+}

src/hyperlight_host/tests/common/mod.rs

@@ -35,6 +35,14 @@ pub fn new_uninit_rust() -> Result<UninitializedSandbox> {
     )
 }
 
+/// Returns a c-language simpleguest.
+pub fn new_uninit_c() -> Result<UninitializedSandbox> {
+    UninitializedSandbox::new(
+        GuestBinary::FilePath(c_simple_guest_as_string().unwrap()),
+        None,
+    )
+}
+
 pub fn get_simpleguest_sandboxes(
     writer: Option<HostFunction<i32, (String,)>>, // An optional writer to make sure correct info is passed to the host printer
 ) -> Vec<MultiUseSandbox> {

src/hyperlight_host/tests/integration_test.rs

@@ -765,3 +765,89 @@ fn log_test_messages(levelfilter: Option<log::LevelFilter>) {
             .unwrap();
     }
 }
+
+/// Tests whether host is able to return Bool as return type
+/// or not
+#[test]
+fn test_if_guest_is_able_to_get_bool_return_values_from_host() {
+    let mut sbox1 = new_uninit_c().unwrap();
+
+    sbox1
+        .register("HostBool", |a: i32, b: i32| a + b > 10)
+        .unwrap();
+    let mut sbox3 = sbox1.evolve().unwrap();
+
+    for i in 1..10 {
+        if i < 6 {
+            let res = sbox3
+                .call::<bool>("GuestRetrievesBoolValue", (i, i))
+                .unwrap();
+            println!("{:?}", res);
+            assert!(matches!(res, false));
+        } else {
+            let res = sbox3
+                .call::<bool>("GuestRetrievesBoolValue", (i, i))
+                .unwrap();
+            println!("{:?}", res);
+            assert!(matches!(res, true));
+        }
+    }
+}
+
+/// Tests whether host is able to return Float/f32 as return type
+/// or not
+#[ignore]
+#[test]
+fn test_if_guest_is_able_to_get_float_return_values_from_host() {
+    let mut sbox1 = new_uninit_c().unwrap();
+
+    sbox1
+        .register("HostAddFloat", |a: f32, b: f32| a + b)
+        .unwrap();
+    let mut sbox3 = sbox1.evolve().unwrap();
+    let res = sbox3
+        .call::<f32>("GuestRetrievesFloatValue", (1.34_f32, 1.34_f32))
+        .unwrap();
+    println!("{:?}", res);
+    assert_eq!(res, 2.68_f32);
+}
+
+/// Tests whether host is able to return Double/f64 as return type
+/// or not
+#[ignore]
+#[test]
+fn test_if_guest_is_able_to_get_double_return_values_from_host() {
+    let mut sbox1 = new_uninit_c().unwrap();
+
+    sbox1
+        .register("HostAddDouble", |a: f64, b: f64| a + b)
+        .unwrap();
+    let mut sbox3 = sbox1.evolve().unwrap();
+    let res = sbox3
+        .call::<f64>("GuestRetrievesDoubleValue", (1.34_f64, 1.34_f64))
+        .unwrap();
+    println!("{:?}", res);
+    assert_eq!(res, 2.68_f64);
+}
+
+/// Tests whether host is able to return String as return type
+/// or not
+#[test]
+fn test_if_guest_is_able_to_get_string_return_values_from_host() {
+    let mut sbox1 = new_uninit_c().unwrap();
+
+    sbox1
+        .register("HostAddStrings", |a: String| {
+            a + ", string added by Host Function"
+        })
+        .unwrap();
+    let mut sbox3 = sbox1.evolve().unwrap();
+    let res = sbox3
+        .call::<String>("GuestRetrievesStringValue", ())
+        .unwrap();
+    println!("{:?}", res);
+    assert_eq!(
+        res,
+        "Guest Function, string added by Host Function".to_string()
+    );
+}

src/tests/c_guests/c_simpleguest/main.c

@@ -256,6 +256,80 @@ int guest_function(const char *from_host) {
   return 0;
 }
 
+bool guest_fn_checks_if_host_returns_bool_value(int32_t a, int32_t b) {
+  hl_Parameter params[2];
+
+  params[0].tag = hl_ParameterType_Int;
+  params[0].value.Int = a;
+
+  params[1].tag = hl_ParameterType_Int;
+  params[1].value.Int = b;
+
+  const hl_FunctionCall host_call = {.function_name = "HostBool",
+                                     .parameters = params,
+                                     .parameters_len = 2,
+                                     .return_type = hl_ReturnType_Bool
+                                    };
+  hl_call_host_function(&host_call);                                 
+  return hl_get_host_return_value_as_Bool();
+}
+
+float guest_fn_checks_if_host_returns_float_value(float a, float b) {
+  hl_Parameter params[2];
+
+  params[0].tag = hl_ParameterType_Float;
+  params[0].value.Float = a;
+
+  params[1].tag = hl_ParameterType_Float;
+  params[1].value.Float = b;
+
+  const hl_FunctionCall host_call = {.function_name = "HostAddFloat",
+                                     .parameters = params,
+                                     .parameters_len = 2,
+                                     .return_type = hl_ReturnType_Float
+                                    };
+  hl_call_host_function(&host_call); 
+  return hl_get_host_return_value_as_Float();
+}
+
+double guest_fn_checks_if_host_returns_double_value(double a, double b) {
+  hl_Parameter params[2];
+
+  params[0].tag = hl_ParameterType_Double;
+  params[0].value.Double = a;
+
+  params[1].tag = hl_ParameterType_Double;
+  params[1].value.Double = b;
+
+  const hl_FunctionCall host_call = {.function_name = "HostAddDouble",
+                                     .parameters = params,
+                                     .parameters_len = 2,
+                                     .return_type = hl_ReturnType_Double
+                                    };
+  hl_call_host_function(&host_call); 
+  return hl_get_host_return_value_as_Double();
+}
+
+const char* guest_fn_checks_if_host_returns_string_value() {
+  char guest_message[256] = "Guest Function";
+  hl_Parameter params;
+
+  params.tag = hl_ParameterType_String;
+  params.value.String = guest_message;
+
+  const hl_FunctionCall host_call = {.function_name = "HostAddStrings",
+                                     .parameters = &params,
+                                     .parameters_len = 1,
+                                     .return_type = hl_ReturnType_String
+                                    };
+  hl_call_host_function(&host_call); 
+  return hl_get_host_return_value_as_String();
+}
+
+HYPERLIGHT_WRAP_FUNCTION(guest_fn_checks_if_host_returns_float_value, Float, 2, Float, Float)
+HYPERLIGHT_WRAP_FUNCTION(guest_fn_checks_if_host_returns_double_value, Double, 2, Double, Double)
+HYPERLIGHT_WRAP_FUNCTION(guest_fn_checks_if_host_returns_string_value, String, 0)
+HYPERLIGHT_WRAP_FUNCTION(guest_fn_checks_if_host_returns_bool_value, Bool, 2, Int, Int)
 HYPERLIGHT_WRAP_FUNCTION(echo, String, 1, String)
 // HYPERLIGHT_WRAP_FUNCTION(set_byte_array_to_zero, 1, VecBytes) is not valid for functions that return VecBytes
 HYPERLIGHT_WRAP_FUNCTION(guest_function, Int, 1, String)
@@ -289,6 +363,10 @@ HYPERLIGHT_WRAP_FUNCTION(log_message, Int, 2, String, Long)
 
 void hyperlight_main(void)
 {
+    HYPERLIGHT_REGISTER_FUNCTION("GuestRetrievesFloatValue", guest_fn_checks_if_host_returns_float_value);
+    HYPERLIGHT_REGISTER_FUNCTION("GuestRetrievesDoubleValue", guest_fn_checks_if_host_returns_double_value);
+    HYPERLIGHT_REGISTER_FUNCTION("GuestRetrievesStringValue", guest_fn_checks_if_host_returns_string_value);
+    HYPERLIGHT_REGISTER_FUNCTION("GuestRetrievesBoolValue", guest_fn_checks_if_host_returns_bool_value);
     HYPERLIGHT_REGISTER_FUNCTION("Echo", echo);
     // HYPERLIGHT_REGISTER_FUNCTION macro does not work for functions that return VecBytes,
     // so we use hl_register_function_definition directly
@@ -338,4 +416,4 @@ hl_Vec *c_guest_dispatch_function(const hl_FunctionCall *function_call) {
   }
 
   return NULL;
-}
+}