Rename ports/winit package to servoshell (#30163)

* rename winit package to servoshell

* revert previous changes and rename only package

ports/servoshell/crash_handler.rs

@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#[cfg(not(any(target_os = "macos", target_os = "linux")))]
+pub fn install() {}
+
+#[cfg(any(target_os = "macos", target_os = "linux"))]
+pub fn install() {
+    use crate::backtrace;
+    use sig::ffi::Sig;
+    use std::{io::Write, sync::atomic, thread};
+
+    extern "C" fn handler(sig: i32) {
+        // Only print crash message and backtrace the first time, to avoid
+        // infinite recursion if the printing causes another signal.
+        static BEEN_HERE_BEFORE: atomic::AtomicBool = atomic::AtomicBool::new(false);
+        if !BEEN_HERE_BEFORE.swap(true, atomic::Ordering::SeqCst) {
+            // stderr is unbuffered, so we won’t lose output if we crash later
+            // in this handler, and the std::io::stderr() call never allocates.
+            // std::io::stdout() allocates the first time it’s called, which in
+            // practice will often segfault (see below).
+            let stderr = std::io::stderr();
+            let mut stderr = stderr.lock();
+            let _ = write!(&mut stderr, "Caught signal {sig}");
+            if let Some(name) = thread::current().name() {
+                let _ = write!(&mut stderr, " in thread \"{}\"", name);
+            }
+            let _ = writeln!(&mut stderr);
+
+            // This call always allocates, which in practice will segfault if
+            // we’re handling a non-main-thread (e.g. layout) segfault. Strictly
+            // speaking in POSIX terms, this is also undefined behaviour.
+            let _ = backtrace::print(&mut stderr);
+        }
+
+        // Outside the BEEN_HERE_BEFORE check, we must only call functions we
+        // know to be “async-signal-safe”, which includes sigaction(), raise(),
+        // and _exit(), but generally doesn’t include anything that allocates.
+        // https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03_03
+        unsafe {
+            // Reset the signal to the default action, and reraise the signal.
+            // Unlike libc::_exit(sig), which terminates the process normally,
+            // this terminates abnormally just like an uncaught signal, allowing
+            // mach (or your shell) to distinguish it from an ordinary exit, and
+            // allows your kernel to make a core dump if configured to do so.
+            let mut action: libc::sigaction = std::mem::zeroed();
+            action.sa_sigaction = libc::SIG_DFL;
+            libc::sigaction(sig, &action, std::ptr::null_mut());
+            libc::raise(sig);
+        }
+    }
+
+    signal!(Sig::SEGV, handler); // handle segfaults
+    signal!(Sig::ILL, handler); // handle stack overflow and unsupported CPUs
+    signal!(Sig::IOT, handler); // handle double panics
+    signal!(Sig::BUS, handler); // handle invalid memory access
+}