Group WASI signal definitions in mod wasm

Move WASI-only types, constants, FFI, and handlers into `mod wasm` and re-export them with `#[cfg(target_os = "wasi")]`. Assisted-by: Grok 4.6
26eb85b15f2007bc96b77762351e1c6f44ab9140
commit 26eb85b15f2007bc96b77762351e1c6f44ab9140
diff --git a/crates/host_env/src/signal.rs b/crates/host_env/src/signal.rs
@@ -1,3 +1,4 @@
+#[cfg(any(unix, windows))]
 use std::io;
 #[cfg(windows)]
 use std::sync::Once;
@@ -27,36 +28,69 @@ pub const SIG_ERR: libc::sighandler_t = -1 as _;
 /// process's own code calls `raise()`, never from an outside interrupt.
 /// Numbering matches wasi-libc's `bits/signal.h`, the same values CPython's
 /// WASI build gets by linking the same library.
-#[allow(non_camel_case_types)]
 #[cfg(target_os = "wasi")]
-pub type sighandler_t = usize;
+mod wasm {
+    use std::io;
 
-#[cfg(target_os = "wasi")]
-pub const SIG_DFL: sighandler_t = 0;
-#[cfg(target_os = "wasi")]
-pub const SIG_IGN: sighandler_t = 1;
-#[cfg(target_os = "wasi")]
-pub const SIG_ERR: sighandler_t = -1isize as usize;
+    #[allow(non_camel_case_types)]
+    pub type sighandler_t = usize;
 
-#[cfg(target_os = "wasi")]
-pub const SIGINT: i32 = 2;
-#[cfg(target_os = "wasi")]
-pub const SIGILL: i32 = 4;
-#[cfg(target_os = "wasi")]
-pub const SIGABRT: i32 = 6;
-#[cfg(target_os = "wasi")]
-pub const SIGFPE: i32 = 8;
-#[cfg(target_os = "wasi")]
-pub const SIGSEGV: i32 = 11;
-#[cfg(target_os = "wasi")]
-pub const SIGTERM: i32 = 15;
+    pub const SIG_DFL: sighandler_t = 0;
+    pub const SIG_IGN: sighandler_t = 1;
+    pub const SIG_ERR: sighandler_t = -1isize as usize;
 
-#[cfg(target_os = "wasi")]
-unsafe extern "C" {
-    fn signal(signum: i32, handler: sighandler_t) -> sighandler_t;
-    fn raise(signum: i32) -> i32;
+    pub const SIGINT: i32 = 2;
+    pub const SIGILL: i32 = 4;
+    pub const SIGABRT: i32 = 6;
+    pub const SIGFPE: i32 = 8;
+    pub const SIGSEGV: i32 = 11;
+    pub const SIGTERM: i32 = 15;
+
+    unsafe extern "C" {
+        fn signal(signum: i32, handler: sighandler_t) -> sighandler_t;
+        fn raise(signum: i32) -> i32;
+    }
+
+    /// # Safety
+    ///
+    /// The caller must ensure `signalnum` is a valid platform signal number.
+    pub unsafe fn probe_handler(signalnum: i32) -> Option<sighandler_t> {
+        let handler = unsafe { signal(signalnum, SIG_IGN) };
+        if handler == SIG_ERR {
+            None
+        } else {
+            unsafe { signal(signalnum, handler) };
+            Some(handler)
+        }
+    }
+
+    /// # Safety
+    ///
+    /// The caller must ensure `signalnum` is a valid platform signal number and
+    /// `handler` is accepted by the platform signal ABI.
+    pub unsafe fn install_handler(
+        signalnum: i32,
+        handler: sighandler_t,
+    ) -> io::Result<sighandler_t> {
+        let old = unsafe { signal(signalnum, handler) };
+        if old == SIG_ERR {
+            return Err(io::Error::last_os_error());
+        }
+        Ok(old)
+    }
+
+    pub fn raise_signal(signalnum: i32) -> io::Result<()> {
+        if unsafe { raise(signalnum) } == 0 {
+            Ok(())
+        } else {
+            Err(io::Error::last_os_error())
+        }
+    }
 }
 
+#[cfg(target_os = "wasi")]
+pub use wasm::*;
+
 #[cfg(unix)]
 pub use libc::{SIG_BLOCK, SIG_SETMASK, SIG_UNBLOCK};
 
@@ -170,42 +204,6 @@ pub fn raise_signal(signalnum: i32) -> io::Result<()> {
     unsafe { libc::raise(signalnum) }.check_libc_zero()
 }
 
-/// # Safety
-///
-/// The caller must ensure `signalnum` is a valid platform signal number.
-#[cfg(target_os = "wasi")]
-pub unsafe fn probe_handler(signalnum: i32) -> Option<sighandler_t> {
-    let handler = unsafe { signal(signalnum, SIG_IGN) };
-    if handler == SIG_ERR {
-        None
-    } else {
-        unsafe { signal(signalnum, handler) };
-        Some(handler)
-    }
-}
-
-/// # Safety
-///
-/// The caller must ensure `signalnum` is a valid platform signal number and
-/// `handler` is accepted by the platform signal ABI.
-#[cfg(target_os = "wasi")]
-pub unsafe fn install_handler(signalnum: i32, handler: sighandler_t) -> io::Result<sighandler_t> {
-    let old = unsafe { signal(signalnum, handler) };
-    if old == SIG_ERR {
-        return Err(io::Error::last_os_error());
-    }
-    Ok(old)
-}
-
-#[cfg(target_os = "wasi")]
-pub fn raise_signal(signalnum: i32) -> io::Result<()> {
-    if unsafe { raise(signalnum) } == 0 {
-        Ok(())
-    } else {
-        Err(io::Error::last_os_error())
-    }
-}
-
 #[cfg(unix)]
 pub fn alarm(seconds: u32) -> u32 {
     unsafe { libc::alarm(seconds) }