milestone: desktop path Phases 1-5

Phase 1 (Runtime Substrate): 4 check binaries, --probe, POSIX tests
Phase 2 (Wayland Compositor): bounded scaffold, zero warnings
Phase 3 (KWin Session): preflight checker (KWin stub, gated on Qt6Quick)
Phase 4 (KDE Plasma): 18 KF6 enabled, preflight checker
Phase 5 (Hardware GPU): DRM/firmware/Mesa preflight checker

Build: zero warnings, all scripts syntax-clean. Oracle-verified.

recipes/core/base/ptyd/src/controlterm.rs

@@ -0,0 +1,129 @@
+use std::cell::RefCell;
+use std::rc::{Rc, Weak};
+
+use syscall::error::{Error, Result, EAGAIN, EINVAL, EWOULDBLOCK};
+use syscall::flag::{EventFlags, F_GETFL, F_SETFL, O_ACCMODE, O_NONBLOCK};
+
+use crate::pty::Pty;
+use crate::resource::Resource;
+
+/// Read side of a pipe
+pub struct PtyControlTerm {
+    pty: Rc<RefCell<Pty>>,
+    flags: usize,
+    notified_read: bool,
+    notified_write: bool,
+}
+
+impl PtyControlTerm {
+    pub fn new(pty: Rc<RefCell<Pty>>, flags: usize) -> Self {
+        PtyControlTerm {
+            pty,
+            flags,
+            notified_read: false,
+            notified_write: false,
+        }
+    }
+}
+
+impl Resource for PtyControlTerm {
+    fn pty(&self) -> Weak<RefCell<Pty>> {
+        Rc::downgrade(&self.pty)
+    }
+
+    fn flags(&self) -> usize {
+        self.flags
+    }
+
+    fn path(&mut self, buf: &mut [u8]) -> Result<usize> {
+        self.pty.borrow_mut().path(buf)
+    }
+
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+        self.notified_read = false;
+
+        let mut pty = self.pty.borrow_mut();
+
+        if let Some(packet) = pty.miso.pop_front() {
+            let mut i = 0;
+
+            while i < buf.len() && i < packet.len() {
+                buf[i] = packet[i];
+                i += 1;
+            }
+
+            if i < packet.len() {
+                let packet_remaining = &packet[i..];
+                let mut new_packet = Vec::with_capacity(packet_remaining.len() + 1);
+                new_packet.push(packet[0]);
+                new_packet.extend(packet_remaining);
+                pty.miso.push_front(new_packet);
+            }
+
+            Ok(i)
+        } else if self.flags & O_NONBLOCK == O_NONBLOCK || Rc::weak_count(&self.pty) == 0 {
+            Err(Error::new(EAGAIN))
+        } else {
+            Err(Error::new(EWOULDBLOCK))
+        }
+    }
+
+    fn write(&mut self, buf: &[u8]) -> Result<usize> {
+        let mut pty = self.pty.borrow_mut();
+
+        if pty.mosi.len() >= 64 {
+            return Err(Error::new(EWOULDBLOCK));
+        }
+
+        pty.input(buf);
+
+        Ok(buf.len())
+    }
+
+    fn sync(&mut self) -> Result<()> {
+        Ok(())
+    }
+
+    fn fcntl(&mut self, cmd: usize, arg: usize) -> Result<usize> {
+        match cmd {
+            F_GETFL => Ok(self.flags),
+            F_SETFL => {
+                self.flags = (self.flags & O_ACCMODE) | (arg & !O_ACCMODE);
+                Ok(0)
+            }
+            _ => Err(Error::new(EINVAL)),
+        }
+    }
+
+    fn fevent(&mut self) -> Result<EventFlags> {
+        self.notified_read = false; // resend
+        self.notified_write = false;
+        Ok(self.events())
+    }
+
+    fn events(&mut self) -> EventFlags {
+        let mut events = EventFlags::empty();
+
+        let pty = self.pty.borrow();
+        if pty.miso.front().is_some() {
+            if !self.notified_read {
+                self.notified_read = true;
+                events |= syscall::EVENT_READ;
+            }
+        } else {
+            self.notified_read = false;
+        }
+
+        if !self.notified_write {
+            self.notified_write = true;
+            events |= syscall::EVENT_WRITE;
+        }
+
+        events
+    }
+
+    fn timeout(&self, count: u64) {
+        let mut pty = self.pty.borrow_mut();
+        pty.timeout(count);
+    }
+}