Use pipe instead of eventfd for unix compatibility

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "x11-clipboard"
-version = "0.9.1"
+version = "0.9.2"
 authors = ["quininer kel <[email protected]>"]
 description = "x11 clipboard support for Rust."
 repository = "https://github.com/quininer/x11-clipboard"

src/error.rs

@@ -17,6 +17,7 @@ pub enum Error {
     Timeout,
     Owner,
     UnexpectedType(Atom),
+    // Could change name on next major, since this uses pipes now.
     EventFdCreate,
 }
 

src/lib.rs

@@ -12,14 +12,14 @@ use std::time::{ Duration, Instant };
 use std::sync::{ Arc, RwLock };
 use std::sync::mpsc::{ Sender, channel };
 use std::collections::HashMap;
-use std::os::fd::AsRawFd;
+use std::os::fd::OwnedFd;
 use x11rb::connection::{Connection, RequestConnection};
 use x11rb::{COPY_DEPTH_FROM_PARENT, CURRENT_TIME};
 use x11rb::errors::ConnectError;
 use x11rb::protocol::{Event, xfixes};
 use x11rb::protocol::xproto::{AtomEnum, ConnectionExt, CreateWindowAux, EventMask, Property, WindowClass};
 use error::Error;
-use run::{create_eventfd, EventFd};
+use run::{create_pipe_drop_fd, PipeDropFds};
 
 pub const INCR_CHUNK_SIZE: usize = 4000;
 const POLL_DURATION: u64 = 50;
@@ -76,20 +76,10 @@ pub struct Clipboard {
     pub setter: Arc<Context>,
     setmap: SetMap,
     send: Sender<Atom>,
-    efd: EventFd,
+    // Relying on the Drop in OwnedFd to close the fd
+    _drop_fd: OwnedFd,
 }
 
-impl Drop for Clipboard {
-    fn drop(&mut self) {
-        // Need to write any 8 bytes that are not 0 to trigger a read-ready
-        const ANY: &[u8; 8] = &[1, 1, 1, 1, 1, 1, 1, 1];
-        unsafe {
-            // Safety: The FD is valid and owned, the buffer has a static lifetime and is not mutated
-            // Best attempt close stream on thread
-            let _ = libc::write(self.efd.0.as_raw_fd(), ANY.as_ptr() as *const libc::c_void, ANY.len());
-        }
-    }
-}
 pub struct Context {
     pub connection: RustConnection,
     pub screen: usize,
@@ -153,13 +143,14 @@ impl Clipboard {
         let setmap = Arc::new(RwLock::new(HashMap::new()));
         let setmap2 = Arc::clone(&setmap);
 
-        let efd = create_eventfd()?;
-        let efd_c = efd.clone();
+        let PipeDropFds {
+            read_pipe, write_pipe
+        } = create_pipe_drop_fd()?;
         let (sender, receiver) = channel();
         let max_length = setter.connection.maximum_request_bytes();
-        thread::spawn(move || run::run(setter2, setmap2, max_length, receiver, efd_c));
+        thread::spawn(move || run::run(setter2, setmap2, max_length, receiver, read_pipe));
 
-        Ok(Clipboard { getter, setter, setmap, send: sender, efd })
+        Ok(Clipboard { getter, setter, setmap, send: sender, _drop_fd: write_pipe })
     }
 
     fn process_event<T>(&self, buff: &mut Vec<u8>, selection: Atom, target: Atom, property: Atom, timeout: T, use_xfixes: bool, sequence_number: u64)

src/run.rs

@@ -26,46 +26,55 @@ struct IncrState {
     pos: usize
 }
 
+pub(crate) struct PipeDropFds {
+    pub(crate) read_pipe: OwnedFd,
+    pub(crate) write_pipe: OwnedFd,
+}
 
-#[derive(Clone)]
-pub(crate) struct EventFd(pub(crate) Arc<OwnedFd>);
-
-pub(crate) fn create_eventfd() -> Result<EventFd, Error>{
-    let event_fd_owned = unsafe {
-        // Docs: https://man7.org/linux/man-pages/man2/eventfd.2.html
-        // Safety: No pointer passing or other spookiness, used correctly according to the above docs
-        let event_fd_res = libc::eventfd(0, libc::EFD_CLOEXEC);
-        // Could check that it's bigger than STDOUT, STDERR, STDIN
-        if event_fd_res < 0 {
+pub(crate) fn create_pipe_drop_fd() -> Result<PipeDropFds, Error>{
+    let pipe_drop_fds = unsafe {
+        // Docs Linux: https://man7.org/linux/man-pages/man2/pipe.2.html
+        // Posix: https://pubs.opengroup.org/onlinepubs/9699919799/
+        // Safety: See above docs, api expects a 2-long array of file descriptors, and flags
+        let mut pipes: [libc::c_int; 2] = [0, 0];
+        let pipe_create_res = libc::pipe(pipes.as_mut_ptr());
+        if pipe_create_res < 0 {
             // Don't want to have to read from errno_location, just skip propagating errno.
             return Err(Error::EventFdCreate);
         }
-        // Safety: Trusting the OS to give a correct FD
-        OwnedFd::from_raw_fd(event_fd_res)
+        // Safety: Trusting the OS to give correct FDs
+        let read_pipe = OwnedFd::from_raw_fd(pipes[0]);
+        let write_pipe = OwnedFd::from_raw_fd(pipes[1]);
+        PipeDropFds {
+            read_pipe,
+            write_pipe,
+        }
     };
-    Ok(EventFd(Arc::new(event_fd_owned)))
+    Ok(pipe_drop_fds)
 }
 
-pub(crate) fn run(context: Arc<Context>, setmap: SetMap, max_length: usize, receiver: Receiver<Atom>, evt_fd: EventFd) {
+pub(crate) fn run(context: Arc<Context>, setmap: SetMap, max_length: usize, receiver: Receiver<Atom>, read_pipe: OwnedFd) {
     let mut incr_map = HashMap::<Atom, Atom>::new();
     let mut state_map = HashMap::<Atom, IncrState>::new();
 
     let stream_fd = context.connection.stream().as_fd();
-    let borrowed_fd = evt_fd.0.as_fd();
-    // Poll both stream and eventfd for new Read-ready events
+    let borrowed_fd = read_pipe.as_fd();
+    // Poll stream for new Read-ready events, check if the other side of the pipe has been dropped
     let mut pollfds: [libc::pollfd; 2] = [libc::pollfd {
         fd: stream_fd.as_raw_fd(),
         events: libc::POLLIN,
         revents: 0,
     }, libc::pollfd {
         fd: borrowed_fd.as_raw_fd(),
-        events: libc::POLLIN,
+        // If the other end is dropped, this pipe will get a HUP on poll
+        events: libc::POLLHUP,
         revents: 0,
     }];
     let len = pollfds.len();
     loop {
         unsafe {
-            // Docs: https://man7.org/linux/man-pages/man2/poll.2.html
+            // Docs Linux: https://man7.org/linux/man-pages/man2/poll.2.html
+            // Posix: https://pubs.opengroup.org/onlinepubs/9699919799/
             // Safety: Passing in a mutable pointer that lives for the duration of the call, the length is
             // set to the length of that pointer.
             // Any negative value (-1 for example) means infinite timeout.
@@ -75,8 +84,8 @@ pub(crate) fn run(context: Arc<Context>, setmap: SetMap, max_length: usize, rece
                 return;
             }
         }
-        if pollfds[1].revents & libc::POLLIN != 0 {
-            // kill-signal on eventfd
+        if pollfds[1].revents & libc::POLLHUP != 0 {
+            // kill-signal on pollfd
             return;
         }
         loop {