validate: Make use of rust more complex error types in action types

For sync action failures, instead of requiring users to report the error
through the Reporter interface, let it pass the detail of the failure into
the ActionError::Error directly and report it in the validate reporting
system automatically.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1265>

gstreamer-validate/src/action_type.rs

@@ -1,7 +1,7 @@
 use std::{ffi::c_int, ptr};
 
 use crate::ffi;
-use glib::translate::*;
+use glib::{object::Cast, translate::*};
 
 #[derive(Debug)]
 #[repr(transparent)]
@@ -325,14 +325,29 @@ impl<'a> ActionTypeBuilder<'a> {
         ) -> c_int {
             let action_type = ffi::gst_validate_get_action_type((*action).type_);
             let scenario = from_glib_borrow(scenario);
-            let action = crate::Action::from_glib_borrow(action);
+            let raction = from_glib_borrow(action);
 
             let func: &ActionFunction = &*(gst::ffi::gst_mini_object_get_qdata(
                 action_type as *mut gst::ffi::GstMiniObject,
                 QUARK_ACTION_TYPE_FUNC.get().unwrap().into_glib(),
             ) as *const Box<ActionFunction>);
 
-            (*func)(&scenario, action).into_glib()
+            let res = (*func)(&scenario, raction);
+
+            if let Err(crate::ActionError::Error(ref err)) = res {
+                scenario
+                    .dynamic_cast_ref::<crate::Reporter>()
+                    .unwrap()
+                    .report_action(
+                        &crate::Action::from_glib_none(action),
+                        glib::Quark::from_str("scenario::execution-error"),
+                        err,
+                    );
+
+                return ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR_REPORTED;
+            }
+
+            res.into_glib()
         }
 
         unsafe {
@@ -391,6 +406,7 @@ impl ActionTypeExtManual for crate::ActionType {
 #[cfg(test)]
 mod tests {
     use std::{
+        env,
         io::Write,
         sync::{Arc, Condvar, Mutex},
     };
@@ -399,6 +415,8 @@ mod tests {
     fn test_action_types() {
         gst::init().unwrap();
         use crate::prelude::*;
+        // Validate should not exit process on criticals
+        env::set_var("GST_VALIDATE", "");
         crate::init();
 
         let fails_called = Arc::new(Mutex::new(false));
@@ -410,7 +428,9 @@ mod tests {
                 move |_, _action| {
                     *fails_called.lock().unwrap() = true;
 
-                    Err(crate::ActionError::Error)
+                    Err(crate::ActionError::Error(
+                        "the `fails` action seems to fail".into(),
+                    ))
                 }
             ),
         )
@@ -509,7 +529,7 @@ mod tests {
         scenario.connect_action_done(glib::clone!(
             #[strong]
             async_called,
-            move |_, action| {
+            move |_, _| {
                 async_called.1.notify_one();
             }
         ));

gstreamer-validate/src/enums.rs

@@ -35,11 +35,10 @@ impl IntoGlib for ActionSuccess {
     }
 }
 
-#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
+#[derive(Clone, Debug, Eq, PartialEq, Hash)]
 #[repr(i32)]
 pub enum ActionError {
-    Error = ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR,
-    ErrorReported = ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR_REPORTED,
+    Error(String),
     None = ffi::GST_VALIDATE_EXECUTE_ACTION_NONE,
 }
 
@@ -47,10 +46,11 @@ impl ActionError {
     pub fn from_value(value: impl Into<i32>) -> Self {
         skip_assert_initialized!();
         match value.into() {
-            ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR => ActionError::Error,
-            ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR_REPORTED => ActionError::ErrorReported,
+            ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR => {
+                ActionError::Error("Execution failed".to_string())
+            }
             ffi::GST_VALIDATE_EXECUTE_ACTION_NONE => ActionError::None,
-            _ => ActionError::Error,
+            _ => ActionError::Error("Unknown error".to_string()),
         }
     }
 }
@@ -60,7 +60,10 @@ impl IntoGlib for ActionError {
 
     #[inline]
     fn into_glib(self) -> ffi::GstValidateActionReturn {
-        self as ffi::GstValidateActionReturn
+        match self {
+            ActionError::Error(_) => ffi::GST_VALIDATE_EXECUTE_ACTION_ERROR,
+            ActionError::None => ffi::GST_VALIDATE_EXECUTE_ACTION_NONE,
+        }
     }
 }
 
@@ -129,9 +132,10 @@ impl ActionReturn {
     #[inline]
     pub fn into_result(self) -> Result<ActionSuccess, ActionError> {
         match self {
-            Self::Error | Self::ErrorReported | Self::None => {
-                Err(unsafe { std::mem::transmute::<ActionReturn, ActionError>(self) })
+            Self::Error | Self::ErrorReported => {
+                Err(ActionError::Error("Execution failed".to_string()))
             }
+            Self::None => Err(ActionError::None),
             _ => Ok(unsafe { std::mem::transmute::<ActionReturn, ActionSuccess>(self) }),
         }
     }
@@ -139,7 +143,11 @@ impl ActionReturn {
     #[inline]
     pub fn from_error(v: ActionError) -> Self {
         skip_assert_initialized!();
-        unsafe { std::mem::transmute::<ActionError, ActionReturn>(v) }
+
+        match v {
+            ActionError::Error(_) => Self::Error,
+            ActionError::None => Self::None,
+        }
     }
 
     #[inline]