Split write_console() between pre-init and post-init handlers

Author: lionel-

crates/ark/src/interface.rs

@@ -119,6 +119,7 @@ use crate::srcref::ns_populate_srcref;
 use crate::srcref::resource_loaded_namespaces;
 use crate::startup;
 use crate::sys::console::console_to_utf8;
+use crate::sys::interface::complete_r_init;
 
 /// An enum representing the different modes in which the R session can run.
 #[derive(PartialEq, Clone)]
@@ -455,6 +456,9 @@ impl RMain {
         log::info!("Sending kernel info: {version}");
         self.kernel_init_tx.broadcast(kernel_info);
 
+        // Set post-init REPL handlers like `write_console()`
+        complete_r_init();
+
         // Thread-safe initialisation flag for R
         R_INIT.set(()).expect("`R_INIT` can only be set once");
     }
@@ -1318,12 +1322,6 @@ This is a Positron limitation we plan to fix. In the meantime, you can:
             Stream::Stderr
         };
 
-        if !RMain::is_initialized() {
-            // During init, consider all output to be part of the startup banner
-            self.banner_output.push_str(&content);
-            return;
-        }
-
         // If active execution request is silent don't broadcast
         // any output
         if let Some(ref req) = self.active_request {
@@ -1354,6 +1352,18 @@ This is a Positron limitation we plan to fix. In the meantime, you can:
         self.iopub_tx.send(message).unwrap();
     }
 
+    /// Invoked by R to write output to the console.
+    /// Only used during initialization to capture the startup banner.
+    fn write_console_init(&mut self, buf: *const c_char) {
+        let content = match console_to_utf8(buf) {
+            Ok(content) => content,
+            Err(err) => panic!("Failed to read from R buffer: {err:?}"),
+        };
+
+        // During init, consider all output to be part of the startup banner
+        self.banner_output.push_str(&content);
+    }
+
     /// Invoked by R to change busy state
     fn busy(&mut self, which: i32) {
         // Ensure signal handlers are initialized.
@@ -1679,6 +1689,12 @@ pub extern "C" fn r_write_console(buf: *const c_char, buflen: i32, otype: i32) {
     main.write_console(buf, buflen, otype);
 }
 
+#[no_mangle]
+pub extern "C" fn r_write_console_init(buf: *const c_char, _buflen: i32, _otype: i32) {
+    let main = RMain::get_mut();
+    main.write_console_init(buf);
+}
+
 #[no_mangle]
 pub extern "C" fn r_show_message(buf: *const c_char) {
     let main = RMain::get();

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

@@ -35,6 +35,7 @@ use crate::interface::r_read_console;
 use crate::interface::r_show_message;
 use crate::interface::r_suicide;
 use crate::interface::r_write_console;
+use crate::interface::r_write_console_init;
 use crate::signals::initialize_signal_handlers;
 
 pub fn setup_r(mut args: Vec<*mut c_char>) {
@@ -64,8 +65,10 @@ pub fn setup_r(mut args: Vec<*mut c_char>) {
         libr::set(R_Consolefile, std::ptr::null_mut());
         libr::set(R_Outputfile, std::ptr::null_mut());
 
+        // Set pre-init WriteConsole handler
         libr::set(ptr_R_WriteConsole, None);
-        libr::set(ptr_R_WriteConsoleEx, Some(r_write_console));
+        libr::set(ptr_R_WriteConsoleEx, Some(r_write_console_init));
+
         libr::set(ptr_R_ReadConsole, Some(r_read_console));
         libr::set(ptr_R_ShowMessage, Some(r_show_message));
         libr::set(ptr_R_Busy, Some(r_busy));
@@ -87,6 +90,12 @@ pub fn setup_r(mut args: Vec<*mut c_char>) {
     }
 }
 
+pub fn complete_r_init() {
+    unsafe {
+        libr::set(ptr_R_WriteConsoleEx, Some(r_write_console));
+    }
+}
+
 pub fn run_r() {
     unsafe {
         // Listen for polled events

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

@@ -69,8 +69,10 @@ pub fn setup_r(mut _args: Vec<*mut c_char>) {
         (*params).R_Interactive = 1;
         (*params).CharacterMode = libr::UImode_RGui;
 
+        // Set pre-init WriteConsole handler
         (*params).WriteConsole = None;
-        (*params).WriteConsoleEx = Some(r_write_console);
+        (*params).WriteConsoleEx = Some(r_write_console_init);
+
         (*params).ReadConsole = Some(r_read_console);
         (*params).ShowMessage = Some(r_show_message);
         (*params).YesNoCancel = Some(r_yes_no_cancel);
@@ -101,6 +103,13 @@ pub fn setup_r(mut _args: Vec<*mut c_char>) {
     }
 }
 
+pub fn complete_r_init() {
+    unsafe {
+        let params: libr::Rstart = params_struct.as_mut_ptr();
+        (*params).WriteConsoleEx = Some(r_write_console);
+    }
+}
+
 pub fn run_r() {
     unsafe {
         run_Rmainloop();