xstate: refactor clipboard selections

Before, every time the clipboard selection changed, satellite would copy
everything on it and force itself to be the clipboard owner, regardless
of X11 or Wayland. Now, satellite is only the owner when the clipboard
owner comes from Wayland, and uses the XFixes extension to watch for
changes in clipboard ownership X11 side. Satellite also now avoids
copying all of the clipboard contents into memory every time, instead
copying directly on request. This is a pretty big change, but should
hopefully help make the clipboard more stable.

Also added some misc test cleanup/using helper functions where possible.
Using the XFixes extension may also end up being necessary for
implementing drag and drop, so it's good the infrastructure is there
now.

src/server/tests.rs

@@ -3,6 +3,7 @@ use crate::xstate::{SetState, WmName};
 use paste::paste;
 use rustix::event::{poll, PollFd, PollFlags};
 use std::collections::HashMap;
+use std::io::Write;
 use std::os::fd::{AsRawFd, BorrowedFd};
 use std::os::unix::net::UnixStream;
 use std::sync::{Arc, Mutex};
@@ -182,19 +183,30 @@ impl super::FromServerState<FakeXConnection> for () {
     fn create(_: &FakeServerState) -> Self {}
 }
 
-impl crate::MimeTypeData for testwl::PasteData {
-    fn name(&self) -> &str {
-        &self.mime_type
+impl crate::X11Selection for Vec<testwl::PasteData> {
+    fn mime_types(&self) -> Vec<&str> {
+        self.iter().map(|data| data.mime_type.as_str()).collect()
     }
 
-    fn data(&self) -> &[u8] {
-        &self.data
+    fn write_to(
+        &self,
+        mime: &str,
+        mut pipe: smithay_client_toolkit::data_device_manager::WritePipe,
+    ) {
+        println!("writing");
+        let data = self
+            .iter()
+            .find(|data| data.mime_type == mime)
+            .unwrap_or_else(|| panic!("Couldn't find mime type {mime}"));
+        pipe.write_all(&data.data)
+            .expect("Couldn't write paste data");
+        println!("goodbye pipe {mime}");
     }
 }
 
 impl super::XConnection for FakeXConnection {
     type ExtraData = ();
-    type MimeTypeData = testwl::PasteData;
+    type X11Selection = Vec<testwl::PasteData>;
     fn root_window(&self) -> Window {
         self.root
     }
@@ -1162,7 +1174,7 @@ fn copy_from_x11() {
         },
     ]);
 
-    f.satellite.set_copy_paste_source(mimes.clone());
+    f.satellite.set_copy_paste_source(&mimes);
     f.run();
 
     let server_mimes = f.testwl.data_source_mimes();
@@ -1170,9 +1182,10 @@ fn copy_from_x11() {
         assert!(server_mimes.contains(&mime.mime_type));
     }
 
-    let data = f.testwl.paste_data();
-    f.run();
-    let data = data.resolve();
+    let data = f.testwl.paste_data(|_, _| {
+        f.satellite.run();
+        true
+    });
     assert_eq!(*mimes, data);
 }
 
@@ -1236,7 +1249,7 @@ fn clipboard_x11_then_wayland() {
         },
     ]);
 
-    f.satellite.set_copy_paste_source(x11data.clone());
+    f.satellite.set_copy_paste_source(&x11data);
     f.run();
 
     let waylanddata = vec![