fix(ext/node): windows cancel stdin read in line mode (#23969)

This patch fixes stdin read hanging on user input when switching tty
mode on Windows

Fixes #21111

On Windows, when switching from line to raw mode:
- Cancel ongoing console read by writing a return keypress to its input
buffer. This blocks the main thread until any ongoing read has been
cancelled to prevent interference with the screen state.
- On the read thread, restore the cursor position to where it was before
writing the enter, undoing its effect on the screen state.
- Restart reading and notify the main thread.

2 files changed, 35 insertions, 0 deletions

diff --git a/tests/integration/run_tests.rs b/tests/integration/run_tests.rs
index 91370a87c..f7aaa9daf 100644
--- a/tests/integration/run_tests.rs
+++ b/tests/integration/run_tests.rs
@@ -3142,6 +3142,20 @@ itest!(byte_order_mark {
 });
 
 #[test]
+#[cfg(windows)]
+fn process_stdin_read_unblock() {
+  TestContext::default()
+    .new_command()
+    .args_vec(["run", "run/process_stdin_unblock.mjs"])
+    .with_pty(|mut console| {
+      console.write_raw("b");
+      console.human_delay();
+      console.write_line_raw("s");
+      console.expect_all(&["1", "1"]);
+    });
+}
+
+#[test]
 fn issue9750() {
   TestContext::default()
     .new_command()
diff --git a/tests/testdata/run/process_stdin_unblock.mjs b/tests/testdata/run/process_stdin_unblock.mjs
new file mode 100644
index 000000000..bbeea2afb
--- /dev/null
+++ b/tests/testdata/run/process_stdin_unblock.mjs
@@ -0,0 +1,21 @@
+import process from "node:process";
+
+function prompt() {
+  process.stdin.setRawMode(true);
+
+  const { promise, resolve } = Promise.withResolvers();
+
+  const onData = (buf) => {
+    process.stdin.setRawMode(false);
+    process.stdin.removeListener("data", onData);
+    console.log(buf.length);
+    resolve();
+  };
+
+  process.stdin.on("data", onData);
+  return promise;
+}
+
+await prompt();
+await prompt();
+Deno.exit(0);