jazz up Rust bindings, document some

src/hzclient.rs

@@ -1,79 +1,121 @@
-use std::{ffi, path::Path};
+use std::ffi;
 
-#[repr(u32)]
+pub(crate) mod sys {
-pub enum ResultCode {
+    use std::ffi;
+
+    #[repr(u32)]
+    #[allow(unused)] // it IS used, just not by Rust
+    pub enum ResultCode {
         Unchanged,
         Changed,
         Fail,
+    }
+
+    extern "C" {
+        pub(crate) fn rust_new_hazelnut_client() -> *mut ffi::c_void;
+        pub(crate) fn rust_destroy_hazelnut_client(client: *mut ffi::c_void);
+
+        pub(crate) fn rust_hazelnut_client_open(
+            client: *mut ffi::c_void,
+            url: *const ffi::c_char,
+        ) -> bool;
+
+        pub(crate) fn rust_hazelnut_client_tick(client: *mut ffi::c_void) -> ResultCode;
+
+        // Explicitly lock/unlock.
+        pub(crate) fn rust_hazelnut_client_lock(client: *mut ffi::c_void);
+        pub(crate) fn rust_hazelnut_client_unlock(client: *mut ffi::c_void);
+
+        // Use only when locked
+        pub(crate) fn rust_hazelnut_client_get_framebuffer(client: *mut ffi::c_void) -> *mut u32;
+        pub(crate) fn rust_hazelnut_client_get_width(client: *mut ffi::c_void) -> u32;
+        pub(crate) fn rust_hazelnut_client_get_height(client: *mut ffi::c_void) -> u32;
+    }
 }
 
-extern "C" {
+pub type ResultCode = sys::ResultCode;
-    fn rust_new_hazelnut_client() -> *mut ffi::c_void;
-    fn rust_destroy_hazelnut_client(client: *mut ffi::c_void);
-
-    fn rust_hazelnut_client_open(client: *mut ffi::c_void, url: *const ffi::c_char) -> bool;
-
-    fn rust_hazelnut_client_tick(client: *mut ffi::c_void) -> ResultCode;
-
-    fn rust_hazelnut_client_lock(client: *mut ffi::c_void);
-    fn rust_hazelnut_client_unlock(client: *mut ffi::c_void);
-
-    fn rust_hazelnut_client_get_framebuffer(client: *mut ffi::c_void) -> *mut u32;
-    fn rust_hazelnut_client_get_width(client: *mut ffi::c_void) -> u32;
-    fn rust_hazelnut_client_get_height(client: *mut ffi::c_void) -> u32;
-}
 
+/// A Hazelnut IVSHMEM client. Wraps the C++ code (see ./rust_wrapper.cpp and the shared sources)
+/// so that we can use it in Rust, semi-safely. (Note that I really do not like the current
+/// state of these bindings, and they were written JUST to get working.
+/// I am aware they are not very idiomatic and of other problems with them.)
 pub struct HazelnutClient(*mut std::ffi::c_void);
 
 impl HazelnutClient {
+    /// Creates a new client.
     pub fn new() -> HazelnutClient {
-        unsafe { Self(rust_new_hazelnut_client()) }
-    }
-
-    pub fn open(&mut self, path: String) -> bool {
-        let cstr = ffi::CString::new(path).expect("dumbass");
-
         unsafe {
-            return rust_hazelnut_client_open(self.0, cstr.as_ptr());
+            let client = sys::rust_new_hazelnut_client();
+            assert!(
+                !client.is_null(),
+                "C++ code failed to allocate a client object"
+            );
+
+            Self(client)
+        }
     }
 
+    /// Opens the given IVSHMEM shmem file.
+    pub fn open(&mut self, path: &String) -> bool {
+        let cstr = ffi::CString::new(path.clone()).expect("dumbass");
+
+        // FIXME: this really should work by FD so we can just return io::Result<> or something, but bleh
+        // for now it's "fine", also it's a path in the shared sources currently.
+        unsafe {
+            return sys::rust_hazelnut_client_open(self.0, cstr.as_ptr());
+        }
     }
 
+    /// Ticks this client.
+    ///
+    /// # Notes
+    /// If this returns [ResultCode::Changed], then the Hazelnut lock (see [HazelnutClient::lock] and [HazelnutClient::unlock]) is still held,
+    /// so you will need to unlock after your processing and let the guest VM continue processing.
     pub fn tick_one(&mut self) -> ResultCode {
         unsafe {
-            return rust_hazelnut_client_tick(self.0);
+            return sys::rust_hazelnut_client_tick(self.0);
         }
     }
 
+    /// Explicitly lock the Hazelnut IVSHMEM memory.
+    /// During this, the guest VM will wait for us to release the lock, and we can read from the memory without
+    /// risk of it being changed.
     pub fn lock(&mut self) {
         unsafe {
-            return rust_hazelnut_client_lock(self.0);
+            return sys::rust_hazelnut_client_lock(self.0);
         }
     }
 
+    /// Unlock the Hazelnut IVSHMEM memory.
     pub fn unlock(&mut self) {
         unsafe {
-            return rust_hazelnut_client_unlock(self.0);
+            return sys::rust_hazelnut_client_unlock(self.0);
         }
     }
 
-    /// only use while lock is held!
+    /// Obtains the framebuffer dimensions.
+    ///
+    /// # Safety
+    /// Only use while the Hazelnut atomic lock is held!
     pub fn dimensions(&mut self) -> (u32, u32) {
         let tup = unsafe {
-            let width = rust_hazelnut_client_get_width(self.0);
+            let width = sys::rust_hazelnut_client_get_width(self.0);
-            let height = rust_hazelnut_client_get_height(self.0);
+            let height = sys::rust_hazelnut_client_get_height(self.0);
             (width, height)
         };
         tup
     }
 
-    /// only use while lock is held!
+    /// Obtains a mutable slice containing the framebuffer.
+    ///
+    /// # Safety
+    /// Only use while the Hazelnut atomic lock is held!
     pub fn framebuffer(&mut self) -> &mut [u32] {
         let sl = unsafe {
-            let fb_ptr = rust_hazelnut_client_get_framebuffer(self.0);
+            let fb_ptr = sys::rust_hazelnut_client_get_framebuffer(self.0);
             let dim = self.dimensions();
 
-            std::slice::from_raw_parts_mut(fb_ptr, ((dim.0 * dim.1) as usize * 4))
+            std::slice::from_raw_parts_mut(fb_ptr, (dim.0 * dim.1) as usize * 4)
         };
         sl
     }
@@ -82,7 +124,7 @@ impl HazelnutClient {
 impl Drop for HazelnutClient {
     fn drop(&mut self) {
         unsafe {
-            rust_destroy_hazelnut_client(self.0);
+            sys::rust_destroy_hazelnut_client(self.0);
         }
         self.0 = std::ptr::null_mut();
     }

src/main.rs

@@ -5,21 +5,29 @@ mod hzclient;
 fn main() {
     let mut screen_width: u32 = 320;
     let mut screen_height: u32 = 200;
-
+    let mut window: Option<Window> = None;
-    let mut window = Window::new("FbcServer", 320, 200, WindowOptions::default())
-        .expect("you banned forever: rules do not");
 
     let mut client = hzclient::HazelnutClient::new();
 
-    if !client.open("/dev/shm/lg-win7".into()) {
+    let socket_path: String = "/dev/shm/lg-win7".into();
-        println!("FUCK");
+
+    if !client.open(&socket_path) {
+        println!("Could not open IVSHMEM.");
+        return ();
     } else {
-        println!("Opened ivshmem!!!");
+        println!("Opened IVSHMEM device.");
     }
 
-    //let mut argb_buffer: Vec<u32> = Vec::new();
-
     loop {
+        match window.as_mut() {
+            Some(window) => {
+                if !window.is_open() {
+                    break;
+                }
+            }
+            None => {}
+        }
+
         match client.tick_one() {
             hzclient::ResultCode::Fail => break,
             hzclient::ResultCode::Changed => {
@@ -29,30 +37,35 @@ fn main() {
                     screen_width = dims.0;
                     screen_height = dims.1;
 
-                    window = Window::new(
+                    window = Some(
-                        "FbcServer",
+                        Window::new(
+                            &format!("Hazelnut client \"{socket_path}\" ({screen_width}x{screen_height})"),
                             screen_width as usize,
                             screen_height as usize,
                             WindowOptions::default(),
                         )
-                    .expect("you banned forever: rules do not");
+                        .expect("Could not create window"),
+                    );
                 }
 
-                window.update_with_buffer(
+                window
+                    .as_mut()
+                    .unwrap()
+                    .update_with_buffer(
                         &client.framebuffer(),
                         screen_width as usize,
                         screen_height as usize,
-                ).expect("well its done anyways");
+                    )
+                    .expect("Failed to update");
 
                 client.unlock();
             }
-            hzclient::ResultCode::Unchanged => {
+            hzclient::ResultCode::Unchanged => match window.as_mut() {
+                Some(window) => {
                     window.update();
-                // Not needed, C++ unlocks us
+                }
-                //client.unlock();
+                _ => {}
+            },
         }
     }
-    }
-
-    println!("Hello, world!");
 }