Switch from extern "C" to extern "C-unwind" (#718)

* Minimal but almost certainly wrong Windows unwind solution

* Tweak unix specific definition

* Change from `extern "C"` to `extern "C-unwind"`

* Add note about `extern "C" fn handle_interrupt`

* Remove pinning to Rust 1.83

Author: DavisVaughan

.github/workflows/release-windows.yml

@@ -32,12 +32,6 @@ jobs:
             - name: Checkout sources
               uses: actions/checkout@v4
 
-            - name: Install Rust temporarily pinned to 1.83 (https://github.com/posit-dev/ark/issues/678)
-              uses: dtolnay/[email protected]
-
-            - name: Report Rust version
-              run: rustc --version
-
             - name: Compile ARK
               env:
                   ARK_BUILD_TYPE: ${{ matrix.flavor }}

crates/ark/src/browser.rs

@@ -16,7 +16,7 @@ use crate::help::message::ShowHelpUrlParams;
 use crate::interface::RMain;
 
 #[harp::register]
-pub unsafe extern "C" fn ps_browse_url(url: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_browse_url(url: SEXP) -> anyhow::Result<SEXP> {
     ps_browse_url_impl(url).or_else(|err| {
         log::error!("Failed to browse url due to: {err}");
         Ok(Rf_ScalarLogical(0))

crates/ark/src/connections/r_connection.rs

@@ -297,7 +297,7 @@ impl RConnection {
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_connection_opened(
+pub unsafe extern "C-unwind" fn ps_connection_opened(
     name: SEXP,
     host: SEXP,
     r#type: SEXP,
@@ -333,7 +333,7 @@ pub unsafe extern "C" fn ps_connection_opened(
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_connection_closed(id: SEXP) -> Result<SEXP, anyhow::Error> {
+pub unsafe extern "C-unwind" fn ps_connection_closed(id: SEXP) -> Result<SEXP, anyhow::Error> {
     let main = RMain::get();
     let id_ = RObject::view(id).to::<String>()?;
 
@@ -344,7 +344,7 @@ pub unsafe extern "C" fn ps_connection_closed(id: SEXP) -> Result<SEXP, anyhow::
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_connection_updated(id: SEXP) -> Result<SEXP, anyhow::Error> {
+pub unsafe extern "C-unwind" fn ps_connection_updated(id: SEXP) -> Result<SEXP, anyhow::Error> {
     let main = RMain::get();
     let comm_id: String = RObject::view(id).to::<String>()?;
 

crates/ark/src/data_explorer/r_data_explorer.rs

@@ -1088,7 +1088,7 @@ fn table_info_or_bail(x: SEXP) -> anyhow::Result<TableInfo> {
 ///   environment; optional.
 /// - `env`: The environment containing the R object; optional.
 #[harp::register]
-pub unsafe extern "C" fn ps_view_data_frame(
+pub unsafe extern "C-unwind" fn ps_view_data_frame(
     x: SEXP,
     title: SEXP,
     var: SEXP,

crates/ark/src/errors.rs

@@ -20,7 +20,7 @@ use stdext::unwrap;
 use crate::interface::RMain;
 
 #[harp::register]
-unsafe extern "C" fn ps_record_error(evalue: SEXP, traceback: SEXP) -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_record_error(evalue: SEXP, traceback: SEXP) -> anyhow::Result<SEXP> {
     let main = RMain::get_mut();
 
     // Convert to `RObject` for access to `try_from()` / `try_into()` methods.
@@ -45,7 +45,7 @@ unsafe extern "C" fn ps_record_error(evalue: SEXP, traceback: SEXP) -> anyhow::R
 }
 
 #[harp::register]
-unsafe extern "C" fn ps_format_traceback(calls: SEXP) -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_format_traceback(calls: SEXP) -> anyhow::Result<SEXP> {
     Ok(r_format_traceback(calls.into())?.sexp)
 }
 
@@ -62,7 +62,7 @@ pub unsafe fn initialize() {
 }
 
 #[harp::register]
-unsafe extern "C" fn ps_rust_backtrace() -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_rust_backtrace() -> anyhow::Result<SEXP> {
     let trace = std::backtrace::Backtrace::force_capture();
     let trace = format!("{trace}");
     Ok(*RObject::from(trace))

crates/ark/src/interface.rs

@@ -1989,7 +1989,7 @@ pub(crate) fn console_inputs() -> anyhow::Result<ConsoleInputs> {
 // global `RMain` singleton.
 
 #[no_mangle]
-pub extern "C" fn r_read_console(
+pub extern "C-unwind" fn r_read_console(
     prompt: *const c_char,
     buf: *mut c_uchar,
     buflen: c_int,
@@ -2034,38 +2034,38 @@ fn new_cstring(x: String) -> CString {
 }
 
 #[no_mangle]
-pub extern "C" fn r_write_console(buf: *const c_char, buflen: i32, otype: i32) {
+pub extern "C-unwind" fn r_write_console(buf: *const c_char, buflen: i32, otype: i32) {
     RMain::write_console(buf, buflen, otype);
 }
 
 #[no_mangle]
-pub extern "C" fn r_show_message(buf: *const c_char) {
+pub extern "C-unwind" fn r_show_message(buf: *const c_char) {
     let main = RMain::get();
     main.show_message(buf);
 }
 
 #[no_mangle]
-pub extern "C" fn r_busy(which: i32) {
+pub extern "C-unwind" fn r_busy(which: i32) {
     let main = RMain::get_mut();
     main.busy(which);
 }
 
 #[no_mangle]
-pub extern "C" fn r_suicide(buf: *const c_char) {
+pub extern "C-unwind" fn r_suicide(buf: *const c_char) {
     let msg = unsafe { CStr::from_ptr(buf) };
     panic!("Suicide: {}", msg.to_str().unwrap());
 }
 
 #[no_mangle]
-pub unsafe extern "C" fn r_polled_events() {
+pub unsafe extern "C-unwind" fn r_polled_events() {
     let main = RMain::get_mut();
     main.polled_events();
 }
 
 // This hook is called like a user onLoad hook but for every package to be
 // loaded in the session
 #[harp::register]
-unsafe extern "C" fn ps_onload_hook(pkg: SEXP, _path: SEXP) -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_onload_hook(pkg: SEXP, _path: SEXP) -> anyhow::Result<SEXP> {
     // NOTE: `_path` might be NULL for a compat reason, see comments on the R side
 
     let pkg: String = RObject::view(pkg).try_into()?;

crates/ark/src/json.rs

@@ -10,7 +10,7 @@ use libr::SEXP;
 
 /// Convenience method to convert a JSON object to a string
 #[harp::register]
-pub unsafe extern "C" fn ps_to_json(obj: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_to_json(obj: SEXP) -> anyhow::Result<SEXP> {
     let obj = RObject::view(obj);
 
     // Convert the object to a JSON value; this is the core serialization step

crates/ark/src/lsp/util.rs

@@ -14,7 +14,7 @@ use libr::SEXP;
 
 /// Shows a message in the Positron frontend
 #[harp::register]
-pub unsafe extern "C" fn ps_log_error(message: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_log_error(message: SEXP) -> anyhow::Result<SEXP> {
     let message = RObject::view(message).to::<String>();
     if let Ok(message) = message {
         log::error!("{}", message);
@@ -24,7 +24,7 @@ pub unsafe extern "C" fn ps_log_error(message: SEXP) -> anyhow::Result<SEXP> {
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_object_id(object: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_object_id(object: SEXP) -> anyhow::Result<SEXP> {
     let value = format!("{:p}", object);
     return Ok(Rf_mkString(value.as_ptr() as *const c_char));
 }

crates/ark/src/modules_utils.rs

@@ -1,13 +1,13 @@
 use libr::SEXP;
 
 #[harp::register]
-pub unsafe extern "C" fn ark_node_poke_cdr(node: SEXP, cdr: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ark_node_poke_cdr(node: SEXP, cdr: SEXP) -> anyhow::Result<SEXP> {
     libr::SETCDR(node, cdr);
     return Ok(harp::r_null());
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_deep_sleep(secs: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_deep_sleep(secs: SEXP) -> anyhow::Result<SEXP> {
     let secs = libr::Rf_asInteger(secs);
     let secs = std::time::Duration::from_secs(secs as u64);
     std::thread::sleep(secs);

crates/ark/src/plots/graphics_device.rs

@@ -77,11 +77,11 @@ pub(crate) fn init_graphics_device() {
 #[derive(Debug, Default)]
 #[allow(non_snake_case)]
 struct DeviceCallbacks {
-    pub activate: Cell<Option<unsafe extern "C" fn(pDevDesc)>>,
-    pub deactivate: Cell<Option<unsafe extern "C" fn(pDevDesc)>>,
-    pub holdflush: Cell<Option<unsafe extern "C" fn(pDevDesc, i32) -> i32>>,
-    pub mode: Cell<Option<unsafe extern "C" fn(i32, pDevDesc)>>,
-    pub newPage: Cell<Option<unsafe extern "C" fn(pGEcontext, pDevDesc)>>,
+    pub activate: Cell<Option<unsafe extern "C-unwind" fn(pDevDesc)>>,
+    pub deactivate: Cell<Option<unsafe extern "C-unwind" fn(pDevDesc)>>,
+    pub holdflush: Cell<Option<unsafe extern "C-unwind" fn(pDevDesc, i32) -> i32>>,
+    pub mode: Cell<Option<unsafe extern "C-unwind" fn(i32, pDevDesc)>>,
+    pub newPage: Cell<Option<unsafe extern "C-unwind" fn(pGEcontext, pDevDesc)>>,
 }
 
 #[derive(Default)]
@@ -473,7 +473,7 @@ pub unsafe fn on_did_execute_request(
 
 // NOTE: May be called when rendering a plot to file, since this is done by
 // copying the graphics display list to a new plot device, and then closing that device.
-unsafe extern "C" fn gd_activate(dev: pDevDesc) {
+unsafe extern "C-unwind" fn gd_activate(dev: pDevDesc) {
     log::trace!("gd_activate");
 
     DEVICE_CONTEXT.with_borrow(|cell| {
@@ -485,7 +485,7 @@ unsafe extern "C" fn gd_activate(dev: pDevDesc) {
 
 // NOTE: May be called when rendering a plot to file, since this is done by
 // copying the graphics display list to a new plot device, and then closing that device.
-unsafe extern "C" fn gd_deactivate(dev: pDevDesc) {
+unsafe extern "C-unwind" fn gd_deactivate(dev: pDevDesc) {
     log::trace!("gd_deactivate");
 
     DEVICE_CONTEXT.with_borrow(|cell| {
@@ -495,7 +495,7 @@ unsafe extern "C" fn gd_deactivate(dev: pDevDesc) {
     });
 }
 
-unsafe extern "C" fn gd_hold_flush(dev: pDevDesc, mut holdflush: i32) -> i32 {
+unsafe extern "C-unwind" fn gd_hold_flush(dev: pDevDesc, mut holdflush: i32) -> i32 {
     log::trace!("gd_hold_flush");
 
     DEVICE_CONTEXT.with_borrow(|cell| {
@@ -511,7 +511,7 @@ unsafe extern "C" fn gd_hold_flush(dev: pDevDesc, mut holdflush: i32) -> i32 {
 // mode = 0, graphics off
 // mode = 1, graphics on
 // mode = 2, graphical input on (ignored by most drivers)
-unsafe extern "C" fn gd_mode(mode: i32, dev: pDevDesc) {
+unsafe extern "C-unwind" fn gd_mode(mode: i32, dev: pDevDesc) {
     log::trace!("gd_mode: {mode}");
 
     DEVICE_CONTEXT.with_borrow(|cell| {
@@ -522,7 +522,7 @@ unsafe extern "C" fn gd_mode(mode: i32, dev: pDevDesc) {
     });
 }
 
-unsafe extern "C" fn gd_new_page(dd: pGEcontext, dev: pDevDesc) {
+unsafe extern "C-unwind" fn gd_new_page(dd: pGEcontext, dev: pDevDesc) {
     log::trace!("gd_new_page");
 
     DEVICE_CONTEXT.with_borrow(|cell| {
@@ -590,15 +590,15 @@ unsafe fn ps_graphics_device_impl() -> anyhow::Result<SEXP> {
 }
 
 #[harp::register]
-unsafe extern "C" fn ps_graphics_device() -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_graphics_device() -> anyhow::Result<SEXP> {
     ps_graphics_device_impl().or_else(|err| {
         log::error!("{}", err);
         Ok(R_NilValue)
     })
 }
 
 #[harp::register]
-unsafe extern "C" fn ps_graphics_event(_name: SEXP) -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_graphics_event(_name: SEXP) -> anyhow::Result<SEXP> {
     let id = unwrap!(DEVICE_CONTEXT.with_borrow(|cell| cell._id.borrow().clone()), None => {
         return Ok(Rf_ScalarLogical(0));
     });

crates/ark/src/reticulate.rs

@@ -85,7 +85,7 @@ impl ReticulateService {
 // Further actions that reticulate can ask the front-end can be requested through
 // the comm_id that is returned by this function.
 #[harp::register]
-pub unsafe extern "C" fn ps_reticulate_open(input: SEXP) -> Result<SEXP, anyhow::Error> {
+pub unsafe extern "C-unwind" fn ps_reticulate_open(input: SEXP) -> Result<SEXP, anyhow::Error> {
     let main = RMain::get();
 
     let input: RObject = input.try_into()?;

crates/ark/src/srcref.rs

@@ -43,7 +43,7 @@ unsafe extern "C" fn ps_resource_namespaces(pkgs: SEXP) -> anyhow::Result<SEXP>
 }
 
 #[harp::register]
-unsafe extern "C" fn ps_ns_populate_srcref(ns_name: SEXP) -> anyhow::Result<SEXP> {
+unsafe extern "C-unwind" fn ps_ns_populate_srcref(ns_name: SEXP) -> anyhow::Result<SEXP> {
     let ns_name: String = RObject::view(ns_name).try_into()?;
     futures::executor::block_on(ns_populate_srcref(ns_name))?;
     Ok(harp::r_null())
@@ -194,6 +194,6 @@ fn generate_source(
 }
 
 #[harp::register]
-pub extern "C" fn ark_zap_srcref(x: SEXP) -> anyhow::Result<SEXP> {
+pub extern "C-unwind" fn ark_zap_srcref(x: SEXP) -> anyhow::Result<SEXP> {
     Ok(harp::attrib::zap_srcref(x).sexp)
 }

crates/ark/src/sys/unix/signals.rs

@@ -64,6 +64,13 @@ pub fn set_interrupts_pending(pending: bool) {
     }
 }
 
+/// Unix interrupt handler
+///
+/// # Safety
+///
+/// Note that this can't be `"C-unwind"` because [SigHandler::Handler] takes a `"C"`
+/// function, so make absolute sure that the contents of this function can't Rust panic or
+/// C longjmp.
 pub extern "C" fn handle_interrupt(_signal: libc::c_int) {
     set_interrupts_pending(true);
 }

crates/ark/src/sys/windows/interface.rs

@@ -180,12 +180,12 @@ fn get_user_home() -> String {
 }
 
 #[no_mangle]
-extern "C" fn r_callback() {
+extern "C-unwind" fn r_callback() {
     // Do nothing!
 }
 
 #[no_mangle]
-extern "C" fn r_yes_no_cancel(question: *const c_char) -> c_int {
+extern "C-unwind" fn r_yes_no_cancel(question: *const c_char) -> c_int {
     // This seems to only be used on Windows during R's default `CleanUp` when
     // `SA_SAVEASK` is used. We should replace `Cleanup` with our own version
     // that resolves `SA_SAVEASK`, changes `saveact` to the resolved value,

crates/ark/src/traps.rs

@@ -22,7 +22,7 @@
 // and set this up now.
 pub use crate::sys::traps::register_trap_handlers;
 
-pub extern "C" fn backtrace_handler(signum: libc::c_int) {
+pub extern "C-unwind" fn backtrace_handler(signum: libc::c_int) {
     // Prevent infloop into the handler
     unsafe {
         libc::signal(signum, libc::SIG_DFL);

crates/ark/src/ui/events.rs

@@ -20,7 +20,7 @@ use libr::SEXP;
 use crate::interface::RMain;
 
 #[harp::register]
-pub unsafe extern "C" fn ps_ui_show_message(message: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_ui_show_message(message: SEXP) -> anyhow::Result<SEXP> {
     let params = ShowMessageParams {
         message: RObject::view(message).try_into()?,
     };
@@ -37,7 +37,7 @@ pub unsafe extern "C" fn ps_ui_show_message(message: SEXP) -> anyhow::Result<SEX
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_ui_open_workspace(
+pub unsafe extern "C-unwind" fn ps_ui_open_workspace(
     path: SEXP,
     new_window: SEXP,
 ) -> anyhow::Result<SEXP> {
@@ -58,7 +58,7 @@ pub unsafe extern "C" fn ps_ui_open_workspace(
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_ui_navigate_to_file(
+pub unsafe extern "C-unwind" fn ps_ui_navigate_to_file(
     file: SEXP,
     _line: SEXP,
     _column: SEXP,
@@ -81,7 +81,7 @@ pub unsafe extern "C" fn ps_ui_navigate_to_file(
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_ui_set_selection_ranges(ranges: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_ui_set_selection_ranges(ranges: SEXP) -> anyhow::Result<SEXP> {
     let selections = ps_ui_robj_as_ranges(ranges)?;
     let params = SetEditorSelectionsParams { selections };
 
@@ -97,7 +97,7 @@ pub unsafe extern "C" fn ps_ui_set_selection_ranges(ranges: SEXP) -> anyhow::Res
 }
 
 #[harp::register]
-pub unsafe extern "C" fn ps_ui_show_url(url: SEXP) -> anyhow::Result<SEXP> {
+pub unsafe extern "C-unwind" fn ps_ui_show_url(url: SEXP) -> anyhow::Result<SEXP> {
     let params = ShowUrlParams {
         url: RObject::view(url).try_into()?,
     };