Newtype SignalHandlers (#8089)

crates/vm/src/signal.rs

@@ -1,7 +1,10 @@
 use crate::{PyObjectRef, PyResult, VirtualMachine};
-use alloc::fmt;
-use core::cell::{Cell, RefCell};
-use core::sync::atomic::{AtomicBool, Ordering};
+use core::{
+    cell::{Cell, RefCell},
+    fmt,
+    ops::{Deref, DerefMut},
+    sync::atomic::{AtomicBool, Ordering},
+};
 use std::sync::mpsc;
 
 #[cfg(windows)]
@@ -22,10 +25,6 @@ pub(crate) static TRIGGERS: [AtomicBool; NSIG] = [ATOMIC_FALSE; NSIG];
 #[cfg(windows)]
 static SIGINT_EVENT: AtomicIsize = AtomicIsize::new(0);
 
-pub(crate) fn new_signal_handlers() -> Box<RefCell<[Option<PyObjectRef>; NSIG]>> {
-    Box::new(const { RefCell::new([const { None }; NSIG]) })
-}
-
 thread_local! {
     /// Prevent recursive signal handler invocation. When a Python signal
     /// handler is running, new signals are deferred until it completes.
@@ -190,3 +189,25 @@ pub fn get_sigint_event() -> Option<isize> {
     let handle = SIGINT_EVENT.load(Ordering::Acquire);
     if handle == 0 { None } else { Some(handle) }
 }
+
+pub struct SignalHandlers(Box<RefCell<[Option<PyObjectRef>; NSIG]>>);
+
+impl Default for SignalHandlers {
+    fn default() -> Self {
+        Self(Box::new(const { RefCell::new([const { None }; NSIG]) }))
+    }
+}
+
+impl Deref for SignalHandlers {
+    type Target = Box<RefCell<[Option<PyObjectRef>; NSIG]>>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for SignalHandlers {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}

crates/vm/src/stdlib/_signal.rs

@@ -6,7 +6,10 @@ pub(crate) use _signal::module_def;
 pub(crate) mod _signal {
     #![allow(unreachable_pub)]
 
-    use crate::{Py, PyObjectRef, PyResult, VirtualMachine, signal};
+    use crate::{
+        Py, PyObjectRef, PyResult, VirtualMachine,
+        signal::{self, SignalHandlers},
+    };
     use core::{
         ops::Range,
         sync::atomic::{self, Ordering},
@@ -193,7 +196,7 @@ pub(crate) mod _signal {
                 };
 
                 vm.signal_handlers
-                    .get_or_init(signal::new_signal_handlers)
+                    .get_or_init(SignalHandlers::default)
                     .borrow_mut()[signum as usize] = py_handler;
             }
 
@@ -247,7 +250,7 @@ pub(crate) mod _signal {
         unsafe { host_signal::install_handler(signalnum, sig_handler) }
             .map_err(|_| vm.new_os_error("Failed to set signal"))?;
 
-        let signal_handlers = vm.signal_handlers.get_or_init(signal::new_signal_handlers);
+        let signal_handlers = vm.signal_handlers.get_or_init(SignalHandlers::default);
         let old_handler = signal_handlers.borrow_mut()[signalnum as usize].replace(handler);
         Ok(old_handler)
     }
@@ -255,7 +258,7 @@ pub(crate) mod _signal {
     #[pyfunction]
     fn getsignal(signalnum: i32, vm: &VirtualMachine) -> PyResult {
         signal::assert_in_range(signalnum, vm)?;
-        let signal_handlers = vm.signal_handlers.get_or_init(signal::new_signal_handlers);
+        let signal_handlers = vm.signal_handlers.get_or_init(SignalHandlers::default);
         let handler = signal_handlers.borrow()[signalnum as usize]
             .clone()
             .unwrap_or_else(|| vm.ctx.none());

crates/vm/src/stdlib/posix.rs

@@ -670,7 +670,7 @@ pub mod module {
         // Initialize signal handlers for the child's main thread.
         // When forked from a worker thread, the OnceCell is empty.
         vm.signal_handlers
-            .get_or_init(crate::signal::new_signal_handlers);
+            .get_or_init(crate::signal::SignalHandlers::default);
 
         // Phase 4: Run Python-level at-fork callbacks.
         let after_forkers_child: Vec<PyObjectRef> = vm.state.after_forkers_child.lock().clone();

crates/vm/src/vm/mod.rs

@@ -36,7 +36,8 @@ use crate::{
     import,
     protocol::PyIterIter,
     scope::Scope,
-    signal, stdlib,
+    signal::{self, SignalHandlers},
+    stdlib,
     warn::WarningsState,
 };
 use alloc::{borrow::Cow, collections::BTreeMap};
@@ -82,7 +83,7 @@ pub struct VirtualMachine {
     pub trace_func: RefCell<PyObjectRef>,
     pub use_tracing: Cell<bool>,
     pub recursion_limit: Cell<usize>,
-    pub(crate) signal_handlers: OnceCell<Box<RefCell<[Option<PyObjectRef>; signal::NSIG]>>>,
+    pub(crate) signal_handlers: OnceCell<SignalHandlers>,
     pub(crate) signal_rx: Option<signal::UserSignalReceiver>,
     pub repr_guards: RefCell<HashSet<usize>>,
     pub state: PyRc<PyGlobalState>,
@@ -723,7 +724,7 @@ impl VirtualMachine {
         let importlib = ctx.none();
         let profile_func = RefCell::new(ctx.none());
         let trace_func = RefCell::new(ctx.none());
-        let signal_handlers = OnceCell::from(signal::new_signal_handlers());
+        let signal_handlers = OnceCell::from(SignalHandlers::default());
 
         let vm = Self {
             builtins,