WIP use BorrowedFd in arguments

Implementation of #592.

This is required for IO safety. Or perhaps `AsFd` generics would be
useful.

This will be a breaking API change, and require Rust 1.65.

Currently `wayland-client` compiles here, but server-side needs the same
changes, and things need to be cleaned up a bit.

wayland-client/src/conn.rs

@@ -199,10 +199,11 @@ impl Connection {
     pub fn send_request<I: Proxy>(
         &self,
         proxy: &I,
-        request: I::Request,
+        request: I::Request<'_>,
         data: Option<Arc<dyn ObjectData>>,
     ) -> Result<ObjectId, InvalidId> {
         let (msg, child_spec) = proxy.write_request(self, request)?;
+        let msg = msg.map_fd(|fd| fd.as_raw_fd());
         self.backend.send_request(msg, data, child_spec)
     }
 

wayland-client/src/lib.rs

@@ -169,12 +169,11 @@
 use std::{
     fmt,
     hash::{Hash, Hasher},
-    os::unix::io::RawFd,
     sync::Arc,
 };
 use wayland_backend::{
     client::{InvalidId, ObjectData, ObjectId, WaylandError, WeakBackend},
-    io_lifetimes::OwnedFd,
+    io_lifetimes::{BorrowedFd, OwnedFd},
     protocol::{Interface, Message},
 };
 
@@ -227,7 +226,7 @@ pub trait Proxy: Clone + std::fmt::Debug + Sized {
     /// The event enum for this interface
     type Event;
     /// The request enum for this interface
-    type Request;
+    type Request<'a>;
 
     /// The interface description
     fn interface() -> &'static Interface;
@@ -278,15 +277,15 @@ pub trait Proxy: Clone + std::fmt::Debug + Sized {
     ///
     /// It is an error to use this function on requests that create objects; use
     /// [Proxy::send_constructor] for such requests.
-    fn send_request(&self, req: Self::Request) -> Result<(), InvalidId>;
+    fn send_request(&self, req: Self::Request<'_>) -> Result<(), InvalidId>;
 
     /// Send a request for this object that creates another object.
     ///
     /// It is an error to use this function on requests that do not create objects; use
     /// [Proxy::send_request] for such requests.
     fn send_constructor<I: Proxy>(
         &self,
-        req: Self::Request,
+        req: Self::Request<'_>,
         data: Arc<dyn ObjectData>,
     ) -> Result<I, InvalidId>;
 
@@ -304,11 +303,11 @@ pub trait Proxy: Clone + std::fmt::Debug + Sized {
     /// **Note:** This method is mostly meant as an implementation detail to be
     /// used by code generated by wayland-scanner.
     #[allow(clippy::type_complexity)]
-    fn write_request(
+    fn write_request<'a>(
         &self,
         conn: &Connection,
-        req: Self::Request,
-    ) -> Result<(Message<ObjectId, RawFd>, Option<(&'static Interface, u32)>), InvalidId>;
+        req: Self::Request<'a>,
+    ) -> Result<(Message<ObjectId, BorrowedFd<'a>>, Option<(&'static Interface, u32)>), InvalidId>;
 
     /// Creates a weak handle to this object
     ///

wayland-scanner/src/client_gen.rs

@@ -21,13 +21,13 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
     let enums = crate::common::generate_enums_for(interface);
     let sinces = crate::common::gen_msg_constants(&interface.requests, &interface.events);
 
-    let requests = crate::common::gen_message_enum(
+    let (requests, requests_is_generic) = crate::common::gen_message_enum(
         &format_ident!("Request"),
         Side::Client,
         false,
         &interface.requests,
     );
-    let events = crate::common::gen_message_enum(
+    let (events, _) = crate::common::gen_message_enum(
         &format_ident!("Event"),
         Side::Client,
         true,
@@ -49,6 +49,12 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
     };
     let doc_attr = to_doc_attr(&docs);
 
+    let request_generic = if requests_is_generic {
+        quote! { 'request }
+    } else {
+        quote! {}
+    };
+
     quote! {
         #mod_doc
         pub mod #mod_name {
@@ -103,7 +109,7 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
             }
 
             impl super::wayland_client::Proxy for #iface_name {
-                type Request = Request;
+                type Request<'request> = Request<#request_generic>;
                 type Event = Event;
 
                 #[inline]
@@ -134,14 +140,14 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
                     &self.backend
                 }
 
-                fn send_request(&self, req: Self::Request) -> Result<(), InvalidId> {
+                fn send_request(&self, req: Self::Request<'_>) -> Result<(), InvalidId> {
                     let conn = Connection::from_backend(self.backend.upgrade().ok_or(InvalidId)?);
                     let id = conn.send_request(self, req, None)?;
                     debug_assert!(id.is_null());
                     Ok(())
                 }
 
-                fn send_constructor<I: Proxy>(&self, req: Self::Request, data: Arc<dyn ObjectData>) -> Result<I, InvalidId> {
+                fn send_constructor<I: Proxy>(&self, req: Self::Request<'_>, data: Arc<dyn ObjectData>) -> Result<I, InvalidId> {
                     let conn = Connection::from_backend(self.backend.upgrade().ok_or(InvalidId)?);
                     let id = conn.send_request(self, req, Some(data))?;
                     Proxy::from_id(&conn, id)
@@ -167,7 +173,7 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
                     #parse_body
                 }
 
-                fn write_request(&self, conn: &Connection, msg: Self::Request) -> Result<(Message<ObjectId, std::os::unix::io::RawFd>, Option<(&'static Interface, u32)>), InvalidId> {
+                fn write_request<'a>(&self, conn: &Connection, msg: Self::Request<'a>) -> Result<(Message<ObjectId, io_lifetimes::BorrowedFd<'a>>, Option<(&'static Interface, u32)>), InvalidId> {
                     #write_body
                 }
             }
@@ -211,7 +217,7 @@ fn gen_methods(interface: &Interface) -> TokenStream {
                     Type::Fixed => quote! { f64 },
                     Type::String => if arg.allow_null { quote!{ Option<String> } } else { quote!{ String } },
                     Type::Array => if arg.allow_null { quote!{ Option<Vec<u8>> } } else { quote!{ Vec<u8> } },
-                    Type::Fd => quote! { ::std::os::unix::io::RawFd },
+                    Type::Fd => quote! { ::std::os::unix::io::BorrowedFd<'_> },
                     Type::Object => {
                         let iface = arg.interface.as_ref().unwrap();
                         let iface_mod = Ident::new(iface, Span::call_site());

wayland-scanner/src/common.rs

@@ -159,7 +159,9 @@ pub(crate) fn gen_message_enum(
     side: Side,
     receiver: bool,
     messages: &[Message],
-) -> TokenStream {
+) -> (TokenStream, bool) {
+    let mut needs_generic = false;
+
     let variants = messages.iter().map(|msg| {
         let mut docs = String::new();
         if let Some((ref short, ref long)) = msg.description {
@@ -199,7 +201,8 @@ pub(crate) fn gen_message_enum(
                             if receiver {
                                 quote! { io_lifetimes::OwnedFd }
                             } else {
-                                quote! { std::os::unix::io::RawFd }
+                                needs_generic = true;
+                                quote! { io_lifetimes::BorrowedFd<'a> }
                             }
                         }
                         Type::Object => {
@@ -275,7 +278,7 @@ pub(crate) fn gen_message_enum(
             #doc_attr
             #msg_variant_decl
         }
-    });
+    }).collect::<Vec<_>>();
 
     let opcodes = messages.iter().enumerate().map(|(opcode, msg)| {
         let msg_name = Ident::new(&snake_to_camel(&msg.name), Span::call_site());
@@ -291,22 +294,28 @@ pub(crate) fn gen_message_enum(
         }
     });
 
-    quote! {
+    let generic = if needs_generic {
+        quote! { 'a }
+    } else {
+        quote! {}
+    };
+
+    (quote! {
         #[derive(Debug)]
         #[non_exhaustive]
-        pub enum #name {
+        pub enum #name<#generic> {
             #(#variants,)*
         }
 
-        impl #name {
+        impl<#generic> #name<#generic> {
             #[doc="Get the opcode number of this message"]
             pub fn opcode(&self) -> u16 {
                 match *self {
                     #(#opcodes,)*
                 }
             }
         }
-    }
+    }, needs_generic)
 }
 
 pub(crate) fn gen_parse_body(interface: &Interface, side: Side) -> TokenStream {

wayland-scanner/src/server_gen.rs

@@ -26,13 +26,13 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
     let enums = crate::common::generate_enums_for(interface);
     let msg_constants = crate::common::gen_msg_constants(&interface.requests, &interface.events);
 
-    let requests = crate::common::gen_message_enum(
+    let (requests, _) = crate::common::gen_message_enum(
         &format_ident!("Request"),
         Side::Server,
         true,
         &interface.requests,
     );
-    let events = crate::common::gen_message_enum(
+    let (events, events_is_generic) = crate::common::gen_message_enum(
         &format_ident!("Event"),
         Side::Server,
         false,
@@ -54,6 +54,12 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
     };
     let doc_attr = to_doc_attr(&docs);
 
+    let event_generic = if events_is_generic {
+        quote! { 'event }
+    } else {
+        quote! {}
+    };
+
     quote! {
         #mod_doc
         pub mod #mod_name {
@@ -109,7 +115,7 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
 
             impl super::wayland_server::Resource for #iface_name {
                 type Request = Request;
-                type Event = Event;
+                type Event<'event> = Event<#event_generic>;
 
                 #[inline]
                 fn interface() -> &'static Interface{
@@ -150,7 +156,7 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
                     Ok(#iface_name { id, data, version, handle: conn.backend_handle().downgrade() })
                 }
 
-                fn send_event(&self, evt: Self::Event) -> Result<(), InvalidId> {
+                fn send_event(&self, evt: Self::Event<'_>) -> Result<(), InvalidId> {
                     let handle = DisplayHandle::from(self.handle.upgrade().ok_or(InvalidId)?);
                     handle.send_event(self, evt)
                 }
@@ -159,7 +165,7 @@ fn generate_objects_for(interface: &Interface) -> TokenStream {
                     #parse_body
                 }
 
-                fn write_event(&self, conn: &DisplayHandle, msg: Self::Event) -> Result<Message<ObjectId, std::os::unix::io::RawFd>, InvalidId> {
+                fn write_event<'a>(&self, conn: &DisplayHandle, msg: Self::Event<'a>) -> Result<Message<ObjectId, std::os::unix::io::BorrowedFd<'a>>, InvalidId> {
                     #write_body
                 }
 
@@ -213,7 +219,7 @@ fn gen_methods(interface: &Interface) -> TokenStream {
                                 quote! { Vec<u8> }
                             }
                         }
-                        Type::Fd => quote! { ::std::os::unix::io::RawFd },
+                        Type::Fd => quote! { ::std::os::unix::io::BorrowedFd<'_> },
                         Type::Object | Type::NewId => {
                             let iface = arg.interface.as_ref().unwrap();
                             let iface_mod = Ident::new(iface, Span::call_site());

wayland-server/src/display.rs

@@ -1,4 +1,4 @@
-use std::{os::unix::net::UnixStream, sync::Arc};
+use std::{os::unix::{io::AsRawFd, net::UnixStream}, sync::Arc};
 
 use wayland_backend::{
     protocol::ObjectInfo,
@@ -161,8 +161,9 @@ impl DisplayHandle {
     ///
     /// This is intended to be a low-level method. You can alternatively use the methods on the
     /// type representing your object, or [`Resource::send_event()`], which may be more convenient.
-    pub fn send_event<I: Resource>(&self, resource: &I, event: I::Event) -> Result<(), InvalidId> {
+    pub fn send_event<I: Resource>(&self, resource: &I, event: I::Event<'_>) -> Result<(), InvalidId> {
         let msg = resource.write_event(self, event)?;
+        let msg = msg.map_fd(|fd| fd.as_raw_fd());
         self.handle.send_event(msg)
     }
 

wayland-server/src/lib.rs

@@ -137,7 +137,7 @@ use std::{
 /// Trait representing a Wayland interface
 pub trait Resource: Clone + std::fmt::Debug + Sized {
     /// The event enum for this interface
-    type Event;
+    type Event<'a>;
     /// The request enum for this interface
     type Request;
 
@@ -192,7 +192,7 @@ pub trait Resource: Clone + std::fmt::Debug + Sized {
     fn from_id(dh: &DisplayHandle, id: ObjectId) -> Result<Self, InvalidId>;
 
     /// Send an event to this object
-    fn send_event(&self, evt: Self::Event) -> Result<(), InvalidId>;
+    fn send_event(&self, evt: Self::Event<'_>) -> Result<(), InvalidId>;
 
     /// Trigger a protocol error on this object
     ///
@@ -219,11 +219,11 @@ pub trait Resource: Clone + std::fmt::Debug + Sized {
     ///
     /// **Note:** This method is mostly meant as an implementation detail to be used by code generated by
     /// wayland-scanner.
-    fn write_event(
+    fn write_event<'a>(
         &self,
         dh: &DisplayHandle,
-        req: Self::Event,
-    ) -> Result<Message<ObjectId, std::os::unix::io::RawFd>, InvalidId>;
+        req: Self::Event<'a>,
+    ) -> Result<Message<ObjectId, std::os::unix::io::BorrowedFd<'a>>, InvalidId>;
 
     /// Creates a weak handle to this object
     ///