fix: standardize usage of /dev/tty where possible

src/cursor/sys/unix.rs

@@ -1,11 +1,14 @@
 use std::{
-    io::{self, Error, ErrorKind, Write},
+    io::{self, Error, ErrorKind},
     time::Duration,
 };
 
 use crate::{
     event::{filter::CursorPositionFilter, poll_internal, read_internal, InternalEvent},
-    terminal::{disable_raw_mode, enable_raw_mode, sys::is_raw_mode_enabled},
+    terminal::{
+        disable_raw_mode, enable_raw_mode,
+        sys::{file_descriptor::tty_fd_out, is_raw_mode_enabled},
+    },
 };
 
 /// Returns the cursor position (column, row).
@@ -31,10 +34,8 @@ fn read_position() -> io::Result<(u16, u16)> {
 
 fn read_position_raw() -> io::Result<(u16, u16)> {
     // Use `ESC [ 6 n` to and retrieve the cursor position.
-    let mut stdout = io::stdout();
-    stdout.write_all(b"\x1B[6n")?;
-    stdout.flush()?;
-
+    let stdout = tty_fd_out()?;
+    stdout.write(b"\x1B[6n")?;
     loop {
         match poll_internal(Some(Duration::from_millis(2000)), &CursorPositionFilter) {
             Ok(true) => {

src/event/read.rs

@@ -11,7 +11,7 @@ use crate::event::{filter::Filter, source::EventSource, timeout::PollTimeout, In
 /// Can be used to read `InternalEvent`s.
 pub(crate) struct InternalEventReader {
     events: VecDeque<InternalEvent>,
-    source: Option<Box<dyn EventSource>>,
+    source: io::Result<Box<dyn EventSource>>,
     skipped_events: Vec<InternalEvent>,
 }
 
@@ -22,7 +22,7 @@ impl Default for InternalEventReader {
         #[cfg(unix)]
         let source = UnixInternalEventSource::new();
 
-        let source = source.ok().map(|x| Box::new(x) as Box<dyn EventSource>);
+        let source = source.map(|x| Box::new(x) as Box<dyn EventSource>);
 
         InternalEventReader {
             source,
@@ -50,11 +50,11 @@ impl InternalEventReader {
         }
 
         let event_source = match self.source.as_mut() {
-            Some(source) => source,
-            None => {
+            Ok(source) => source,
+            Err(e) => {
                 return Err(std::io::Error::new(
-                    std::io::ErrorKind::Other,
-                    "Failed to initialize input reader",
+                    e.kind(),
+                    format!("Failed to initialize input reader: {e:?}"),
                 ))
             }
         };
@@ -147,7 +147,7 @@ mod tests {
     fn test_poll_fails_without_event_source() {
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -164,7 +164,7 @@ mod tests {
     fn test_poll_returns_true_for_matching_event_in_queue_at_front() {
         let mut reader = InternalEventReader {
             events: vec![InternalEvent::Event(Event::Resize(10, 10))].into(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -180,7 +180,7 @@ mod tests {
                 InternalEvent::CursorPosition(10, 20),
             ]
             .into(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -193,7 +193,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: vec![EVENT].into(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -207,7 +207,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: vec![InternalEvent::Event(Event::Resize(10, 10)), CURSOR_EVENT].into(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -222,7 +222,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: vec![SKIPPED_EVENT, CURSOR_EVENT].into(),
-            source: None,
+            source: Err(io::Error::new(io::ErrorKind::Other, "not initialized")),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -236,7 +236,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -251,7 +251,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -269,7 +269,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -284,7 +284,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -301,7 +301,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -317,7 +317,7 @@ mod tests {
     fn test_poll_propagates_error() {
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(FakeSource::new(&[]))),
+            source: Ok(Box::new(FakeSource::new(&[]))),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -334,7 +334,7 @@ mod tests {
     fn test_read_propagates_error() {
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(FakeSource::new(&[]))),
+            source: Ok(Box::new(FakeSource::new(&[]))),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -355,7 +355,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 
@@ -374,7 +374,7 @@ mod tests {
 
         let mut reader = InternalEventReader {
             events: VecDeque::new(),
-            source: Some(Box::new(source)),
+            source: Ok(Box::new(source)),
             skipped_events: Vec::with_capacity(32),
         };
 

src/event/source/unix/mio.rs

@@ -8,7 +8,7 @@ use crate::event::sys::Waker;
 use crate::event::{
     source::EventSource, sys::unix::parse::parse_event, timeout::PollTimeout, Event, InternalEvent,
 };
-use crate::terminal::sys::file_descriptor::{tty_fd, FileDesc};
+use crate::terminal::sys::file_descriptor::FileDesc;
 
 // Tokens to identify file descriptor
 const TTY_TOKEN: Token = Token(0);
@@ -33,8 +33,30 @@ pub(crate) struct UnixInternalEventSource {
 }
 
 impl UnixInternalEventSource {
+    #[cfg(target_os = "macos")]
     pub fn new() -> io::Result<Self> {
-        UnixInternalEventSource::from_file_descriptor(tty_fd()?)
+        // Polling /dev/tty with mio is unsupported on MacOS so we must explicitly use stdin
+        use crate::tty::IsTty;
+        #[cfg(feature = "libc")]
+        let fd = FileDesc::new(libc::STDIN_FILENO, false);
+        #[cfg(not(feature = "libc"))]
+        let fd = FileDesc::Borrowed(rustix::stdio::stdin());
+
+        if !fd.is_tty() {
+            return Err(io::Error::new(
+                    io::ErrorKind::Unsupported,
+                    "The 'use-dev-tty' feature must be enabled to read terminal events on MacOS when stdin is not a tty.",
+                ));
+        }
+
+        UnixInternalEventSource::from_file_descriptor(fd)
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    pub fn new() -> io::Result<Self> {
+        UnixInternalEventSource::from_file_descriptor(
+            crate::terminal::sys::file_descriptor::tty_fd_in()?,
+        )
     }
 
     pub(crate) fn from_file_descriptor(input_fd: FileDesc<'static>) -> io::Result<Self> {

src/event/source/unix/tty.rs

@@ -14,7 +14,7 @@ use filedescriptor::{poll, pollfd, POLLIN};
 #[cfg(feature = "event-stream")]
 use crate::event::sys::Waker;
 use crate::event::{source::EventSource, sys::unix::parse::parse_event, InternalEvent};
-use crate::terminal::sys::file_descriptor::{tty_fd, FileDesc};
+use crate::terminal::sys::file_descriptor::{tty_fd_in, FileDesc};
 
 /// Holds a prototypical Waker and a receiver we can wait on when doing select().
 #[cfg(feature = "event-stream")]
@@ -57,7 +57,7 @@ fn nonblocking_unix_pair() -> io::Result<(UnixStream, UnixStream)> {
 
 impl UnixInternalEventSource {
     pub fn new() -> io::Result<Self> {
-        UnixInternalEventSource::from_file_descriptor(tty_fd()?)
+        UnixInternalEventSource::from_file_descriptor(tty_fd_in()?)
     }
 
     pub(crate) fn from_file_descriptor(input_fd: FileDesc<'static>) -> io::Result<Self> {

src/terminal/sys/file_descriptor.rs

@@ -64,6 +64,22 @@
         }
     }
 
+    pub fn write(&self, buffer: &[u8]) -> io::Result<usize> {
+        let result = unsafe {
+            libc::write(
+                self.fd,
+                buffer.as_ptr() as *const libc::c_void,
+                buffer.len() as size_t,
+            )
+        };
+
+        if result < 0 {
+            Err(io::Error::last_os_error())
+        } else {
+            Ok(result as usize)
+        }
+    }
+
     /// Returns the underlying file descriptor.
     pub fn raw_fd(&self) -> RawFd {
         self.fd
@@ -72,7 +88,7 @@
 
 #[cfg(not(feature = "libc"))]
 impl FileDesc<'_> {
     pub fn read(&self, buffer: &mut [u8]) -> io::Result<usize> {
         let fd = match self {
             FileDesc::Owned(fd) => fd.as_fd(),
             FileDesc::Borrowed(fd) => fd.as_fd(),
@@ -81,6 +97,15 @@
         Ok(result)
     }
 
+    pub fn write(&self, buffer: &[u8]) -> io::Result<usize> {
+        let fd = match self {
+            FileDesc::Owned(fd) => fd.as_fd(),
+            FileDesc::Borrowed(fd) => fd.as_fd(),
+        };
+        let result = rustix::io::write(fd, buffer)?;
+        Ok(result)
+    }
+
     pub fn raw_fd(&self) -> RawFd {
         match self {
             FileDesc::Owned(fd) => fd.as_raw_fd(),
@@ -121,34 +146,68 @@
 
 #[cfg(feature = "libc")]
 /// Creates a file descriptor pointing to the standard input or `/dev/tty`.
-pub fn tty_fd() -> io::Result<FileDesc<'static>> {
-    let (fd, close_on_drop) = if unsafe { libc::isatty(libc::STDIN_FILENO) == 1 } {
-        (libc::STDIN_FILENO, false)
+pub fn tty_fd_in() -> io::Result<FileDesc<'static>> {
+    let (fd, close_on_drop) = if let Ok(file) = fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .open("/dev/tty")
+    {
+        (file.into_raw_fd(), true)
     } else {
-        (
-            fs::OpenOptions::new()
-                .read(true)
-                .write(true)
-                .open("/dev/tty")?
-                .into_raw_fd(),
-            true,
-        )
+        (libc::STDIN_FILENO, false)
     };
+    Ok(FileDesc::new(fd, close_on_drop))
+}
 
+#[cfg(feature = "libc")]
+/// Creates a file descriptor pointing to the standard output or `/dev/tty`.
+pub fn tty_fd_out() -> io::Result<FileDesc<'static>> {
+    let (fd, close_on_drop) = if let Ok(file) = fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .open("/dev/tty")
+    {
+        (file.into_raw_fd(), true)
+    } else {
+        (libc::STDOUT_FILENO, false)
+    };
     Ok(FileDesc::new(fd, close_on_drop))
 }
 
 #[cfg(not(feature = "libc"))]
 /// Creates a file descriptor pointing to the standard input or `/dev/tty`.
-pub fn tty_fd() -> io::Result<FileDesc<'static>> {
+pub fn tty_fd_in() -> io::Result<FileDesc<'static>> {
+    use std::fs::File;
+
+    let file = File::options()
+        .read(true)
+        .write(true)
+        .open("/dev/tty")
+        .map(|file| (FileDesc::Owned(file.into())));
+    let fd = if let Ok(file) = file {
+        file
+    } else {
+        // Fallback to stdin if /dev/tty is missing
+        FileDesc::Borrowed(rustix::stdio::stdin())
+    };
+    Ok(fd)
+}
+
+#[cfg(not(feature = "libc"))]
+/// Creates a file descriptor pointing to the standard output or `/dev/tty`.
+pub fn tty_fd_out() -> io::Result<FileDesc<'static>> {
     use std::fs::File;
 
-    let stdin = rustix::stdio::stdin();
-    let fd = if rustix::termios::isatty(stdin) {
-        FileDesc::Borrowed(stdin)
+    let file = File::options()
+        .read(true)
+        .write(true)
+        .open("/dev/tty")
+        .map(|file| (FileDesc::Owned(file.into())));
+    let fd = if let Ok(file) = file {
+        file
     } else {
-        let dev_tty = File::options().read(true).write(true).open("/dev/tty")?;
-        FileDesc::Owned(dev_tty.into())
+        // Fallback to stdout if /dev/tty is missing
+        FileDesc::Borrowed(rustix::stdio::stdout())
     };
     Ok(fd)
 }