feat: finish cdylib ffi and improve ffi C header

wfassoc-cdylib/src/ffi_types.rs

@@ -0,0 +1,66 @@
+//! The module including all FFI types used by this crate.
+
+use std::ffi::c_void;
+use num_enum::TryFromPrimitive;
+
+// region: HICON
+
+/// The type representing Win32 HICON handle.
+/// 
+/// In theory, we can fetch HICON type from "windows_sys" crate.
+/// However, I don't want to add it as this crate's dependency,
+/// because I don't use anything within it except this type.
+/// So I check Microsoft document, re-define it in there for this crate.
+/// Reference: https://learn.microsoft.com/en-us/windows/win32/winprog/windows-data-types
+pub type HICON = *mut c_void;
+
+/// The invalid value of Win32 HICON handle.
+/// 
+/// The same reason like [HICON] to re-define it in there.
+pub const INVALID_ICON: HICON = std::ptr::null_mut();
+
+// endregion
+
+// region: Scope
+
+/// The FFI wrapper for [wfassoc::Scope].
+#[repr(u32)]
+#[derive(Debug, Copy, Clone, TryFromPrimitive)]
+pub enum Scope {
+    User = 0,
+    System = 1,
+}
+
+impl From<Scope> for wfassoc::Scope {
+    fn from(value: Scope) -> Self {
+        match value {
+            Scope::User => wfassoc::Scope::User,
+            Scope::System => wfassoc::Scope::System,
+        }
+    }
+}
+
+// endregion
+
+// region: View
+
+/// The FFI wrapper for [wfassoc::View].
+#[repr(u32)]
+#[derive(Debug, Copy, Clone, TryFromPrimitive)]
+pub enum View {
+    User = 0,
+    System = 1,
+    Hybrid = 2,
+}
+
+impl From<View> for wfassoc::View {
+    fn from(value: View) -> Self {
+        match value {
+            View::User => wfassoc::View::User,
+            View::System => wfassoc::View::System,
+            View::Hybrid => wfassoc::View::Hybrid,
+        }
+    }
+}
+
+// endregion

wfassoc-cdylib/src/lib.rs

@@ -1,16 +1,13 @@
 mod cstr_ffi;
 mod last_error;
 mod object_pool;
+mod ffi_types;
 
-use num_enum::TryFromPrimitive;
 use object_pool::ObjectPool;
 use std::sync::{LazyLock, RwLock};
 use thiserror::Error as TeError;
 use wfassoc::highlevel::{Program, Schema};
 
-pub use cstr_ffi::CStyleString;
-pub use object_pool::Token;
-
 // region: Error
 
 /// Error occurs in this crate.
@@ -198,39 +195,9 @@ static EXT_STATUE_POOL: LazyLock<RwLock<ObjectPool<wfassoc::highlevel::ProgramEx
 
 // region: Exposed Types
 
-#[repr(u32)]
-#[derive(Debug, Copy, Clone, TryFromPrimitive)]
-pub enum Scope {
-    User = 0,
-    System = 1,
-}
-
-impl From<Scope> for wfassoc::Scope {
-    fn from(value: Scope) -> Self {
-        match value {
-            Scope::User => wfassoc::Scope::User,
-            Scope::System => wfassoc::Scope::System,
-        }
-    }
-}
-
-#[repr(u32)]
-#[derive(Debug, Copy, Clone, TryFromPrimitive)]
-pub enum View {
-    User = 0,
-    System = 1,
-    Hybrid = 2,
-}
-
-impl From<View> for wfassoc::View {
-    fn from(value: View) -> Self {
-        match value {
-            View::User => wfassoc::View::User,
-            View::System => wfassoc::View::System,
-            View::Hybrid => wfassoc::View::Hybrid,
-        }
-    }
-}
+pub use cstr_ffi::CStyleString;
+pub use object_pool::Token;
+pub use ffi_types::{HICON, Scope, View};
 
 // endregion
 
@@ -273,6 +240,11 @@ pub extern "C" fn WFHasPrivilege() -> bool {
     wfassoc::win32::utilities::has_privilege()
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn WFInvalidToken() -> Token {
+    object_pool::invalid_token()
+}
+
 // endregion
 
 // region: Schema
@@ -581,11 +553,16 @@ pub extern "C" fn WFProgramQueryExt(
         let pool = pull_reader!(PROGRAM_POOL)?;
         let program = pool.get(in_program)?;
         let view = resolve_enum!(View, in_view)?;
-        
+
         let ext_status = program.query_ext(view.into(), in_index)?;
-        todo!();
-        let mut pool = pull_writer!(EXT_STATUE_POOL)?;
-        Ok(pool.allocate(ext_status)?)
+        let token = match ext_status {
+            Some(ext_status) => {
+                let mut pool = pull_writer!(EXT_STATUE_POOL)?;
+                pool.allocate(ext_status)?
+            },
+            None => object_pool::invalid_token(),
+        };
+        Ok(token)
     })
 }
 
@@ -600,22 +577,33 @@ pub extern "C" fn WFExtStatusDestroy(in_ext_status: in_param_ty!(Token)) -> bool
 }
 
 #[unsafe(no_mangle)]
-pub extern "C" fn WFExtStatuGetName(in_ext_status: in_param_ty!(Token), out_name: out_param_ty!(CStyleString)) -> bool {
+pub extern "C" fn WFExtStatuGetName(
+    in_ext_status: in_param_ty!(Token),
+    out_name: out_param_ty!(CStyleString),
+) -> bool {
     cffi_wrapper!(|in_ext_status: Token| -> (out_name: CStyleString) {
         let pool = pull_reader!(EXT_STATUE_POOL)?;
         let ext_status = pool.get(in_ext_status)?;
-        
+
         cstr_ffi::set_ffi_string(ext_status.get_name())?;
         Ok(cstr_ffi::get_ffi_string())
     })
 }
 
 #[unsafe(no_mangle)]
-pub extern "C" fn WFExtStatuGetIcon(in_ext_status: in_param_ty!(Token), out_icon: out_param_ty!(HICON)) -> bool {
+pub extern "C" fn WFExtStatuGetIcon(
+    in_ext_status: in_param_ty!(Token),
+    out_icon: out_param_ty!(HICON),
+) -> bool {
     cffi_wrapper!(|in_ext_status: Token| -> (out_icon: HICON) {
         let pool = pull_reader!(EXT_STATUE_POOL)?;
         let ext_status = pool.get(in_ext_status)?;
-        Ok(ext_status.get_icon())
+
+        let icon = match ext_status.get_icon() {
+            Some(icon) => icon.get_icon(),
+            None => ffi_types::INVALID_ICON,
+        };
+        Ok(icon)
     })
 }
 

wfassoc-cdylib/src/object_pool.rs

@@ -17,6 +17,14 @@ pub enum Error {
 /// The token for fetching object in [ObjectPool].
 pub type Token = u64;
 
+/// Get the invalid token.
+/// 
+/// Invalid token is always invalid for fetching object in pool,
+/// And can be useful in FFI scenario.
+pub fn invalid_token() -> Token {
+    DefaultKey::null().data().as_ffi()
+}
+
 /// A pool for managing objects with unique tokens.
 /// 
 /// It is highly suggested to use this pool with [std::sync::RwLock] guard.