feat: add native windows beta support

1 files changed, 94 insertions, 0 deletions

diff --git a/src/pty/backend/unix.rs b/src/pty/backend/unix.rs
new file mode 100644
index 00000000..5871004a
--- /dev/null
+++ b/src/pty/backend/unix.rs
@@ -0,0 +1,94 @@
+use std::os::fd::{FromRawFd, OwnedFd};
+
+use portable_pty::{native_pty_system, Child, CommandBuilder, PtySize};
+
+use crate::pty::fd;
+
+pub(crate) struct SpawnedPty {
+    pub master_fd: OwnedFd,
+    pub child: Box<dyn Child + Send + Sync>,
+}
+
+pub(crate) fn spawn_with_portable_pty(
+    rows: u16,
+    cols: u16,
+    cmd: CommandBuilder,
+) -> std::io::Result<SpawnedPty> {
+    let pty_system = native_pty_system();
+    let pair = pty_system
+        .openpty(PtySize {
+            rows,
+            cols,
+            pixel_width: 0,
+            pixel_height: 0,
+        })
+        .map_err(|err| std::io::Error::other(err.to_string()))?;
+    let master_fd = pair
+        .master
+        .as_raw_fd()
+        .ok_or_else(|| std::io::Error::other("pty master fd is unavailable"))?;
+    let actor_fd = fd::duplicate_cloexec_fd(master_fd)?;
+    let actor_fd = unsafe { OwnedFd::from_raw_fd(actor_fd) };
+    let child = pair
+        .slave
+        .spawn_command(cmd)
+        .map_err(|err| std::io::Error::other(err.to_string()))?;
+    drop(pair);
+
+    Ok(SpawnedPty {
+        master_fd: actor_fd,
+        child,
+    })
+}
+
+#[cfg(all(test, target_os = "linux"))]
+mod tests {
+    use super::*;
+    use std::sync::{Mutex, OnceLock};
+
+    fn pty_fd_test_lock() -> &'static Mutex<()> {
+        static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
+        LOCK.get_or_init(|| Mutex::new(()))
+    }
+
+    fn parent_pty_fd_targets() -> Vec<String> {
+        let Ok(entries) = std::fs::read_dir("/proc/self/fd") else {
+            return Vec::new();
+        };
+        let mut targets: Vec<String> = entries
+            .filter_map(Result::ok)
+            .filter_map(|entry| std::fs::read_link(entry.path()).ok())
+            .map(|target| target.to_string_lossy().into_owned())
+            .filter(|target| target.starts_with("/dev/pts/") || target == "/dev/ptmx")
+            .collect();
+        targets.sort();
+        targets
+    }
+
+    fn parent_pty_fd_count() -> usize {
+        parent_pty_fd_targets().len()
+    }
+
+    #[test]
+    fn portable_pty_setup_leaves_one_parent_pty_fd() {
+        let _guard = pty_fd_test_lock().lock().expect("pty fd test lock");
+        let before = parent_pty_fd_count();
+        let mut cmd = CommandBuilder::new("/bin/cat");
+        cmd.env(crate::HERDR_ENV_VAR, crate::HERDR_ENV_VALUE);
+
+        let mut spawned =
+            spawn_with_portable_pty(24, 80, cmd).expect("portable pty setup succeeds");
+        let after_spawn = parent_pty_fd_count();
+
+        assert_eq!(
+            after_spawn,
+            before + 1,
+            "portable-pty setup should leave only the Herdr-owned master fd in the parent: {:?}",
+            parent_pty_fd_targets()
+        );
+
+        let _ = spawned.child.kill();
+        let _ = spawned.child.wait();
+        drop(spawned.master_fd);
+    }
+}