feat: Add Deno.exitCode API (#23609)

This commits adds the ability to set a would-be exit code 
for the Deno process without forcing an immediate exit, 
through the new `Deno.exitCode` API.

- **Implements `Deno.exitCode` getter and setter**: Adds support for
setting
and retrieving a would-be exit code via `Deno.exitCode`.
This allows for asynchronous cleanup before process termination 
without immediately exiting.
- **Ensures type safety**: The setter for `Deno.exitCode` validates that
the provided value is a number, throwing a TypeError if not, to ensure
that
only valid exit codes are set.

Closes to #23605

---------

Co-authored-by: Bartek Iwańczuk <[email protected]>

Author: lukeed

cli/js/40_test.js

@@ -28,6 +28,10 @@ const {
 
 import { setExitHandler } from "ext:runtime/30_os.js";
 
+// Capture `Deno` global so that users deleting or mangling it, won't
+// have impact on our sanitizers.
+const DenoNs = globalThis.Deno;
+
 /**
  * @typedef {{
  *   id: number,
@@ -101,7 +105,20 @@ function assertExit(fn, isTest) {
 
     try {
       const innerResult = await fn(...new SafeArrayIterator(params));
-      if (innerResult) return innerResult;
+      const exitCode = DenoNs.exitCode;
+      if (exitCode !== 0) {
+        // Reset the code to allow other tests to run...
+        DenoNs.exitCode = 0;
+        // ...and fail the current test.
+        throw new Error(
+          `${
+            isTest ? "Test case" : "Bench"
+          } finished with exit code set to ${exitCode}.`,
+        );
+      }
+      if (innerResult) {
+        return innerResult;
+      }
     } finally {
       setExitHandler(null);
     }

cli/tests/unit/os_test.ts

@@ -0,0 +1,94 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import { assertEquals, assertThrows } from "../../testing/asserts.ts";
+
+Deno.test("Deno.exitCode getter and setter", () => {
+  // Initial value is 0
+  assertEquals(Deno.exitCode, 0);
+
+  // Set a new value
+  Deno.exitCode = 5;
+  assertEquals(Deno.exitCode, 5);
+
+  // Reset to initial value
+  Deno.exitCode = 0;
+  assertEquals(Deno.exitCode, 0);
+});
+
+Deno.test("Setting Deno.exitCode to NaN throws TypeError", () => {
+  // @ts-expect-error;
+  Deno.exitCode = "123";
+  assertEquals(Deno.exitCode, 123);
+
+  // Reset
+  Deno.exitCode = 0;
+  assertEquals(Deno.exitCode, 0);
+
+  // Throws on non-number values
+  assertThrows(
+    () => {
+      // @ts-expect-error Testing for runtime error
+      Deno.exitCode = "not a number";
+    },
+    TypeError,
+    "Exit code must be a number.",
+  );
+});
+
+Deno.test("Setting Deno.exitCode does not cause an immediate exit", () => {
+  let exited = false;
+  const originalExit = Deno.exit;
+
+  // @ts-expect-error; read-only
+  Deno.exit = () => {
+    exited = true;
+  };
+
+  Deno.exitCode = 1;
+  assertEquals(exited, false);
+
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Running Deno.exit(value) overrides Deno.exitCode", () => {
+  let args: unknown[] | undefined;
+
+  const originalExit = Deno.exit;
+  // @ts-expect-error; read-only
+  Deno.exit = (...x) => {
+    args = x;
+  };
+
+  Deno.exitCode = 42;
+  Deno.exit(0);
+
+  assertEquals(args, [0]);
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Running Deno.exit() uses Deno.exitCode as fallback", () => {
+  let args: unknown[] | undefined;
+
+  const originalExit = Deno.exit;
+  // @ts-expect-error; read-only
+  Deno.exit = (...x) => {
+    args = x;
+  };
+
+  Deno.exitCode = 42;
+  Deno.exit();
+
+  assertEquals(args, [42]);
+  // @ts-expect-error; read-only
+  Deno.exit = originalExit;
+});
+
+Deno.test("Retrieving the set exit code before process termination", () => {
+  Deno.exitCode = 42;
+  assertEquals(Deno.exitCode, 42);
+
+  // Reset to initial value
+  Deno.exitCode = 0;
+});

cli/tsc/dts/lib.deno.ns.d.ts

@@ -1466,6 +1466,23 @@ declare namespace Deno {
    */
   export function exit(code?: number): never;
 
+  /** The exit code for the Deno process.
+   *
+   * If no exit code has been supplied, then Deno will assume a return code of `0`.
+   *
+   * When setting an exit code value, a number or non-NaN string must be provided,
+   * otherwise a TypeError will be thrown.
+   *
+   * ```ts
+   * console.log(Deno.exitCode); //-> 0
+   * Deno.exitCode = 1;
+   * console.log(Deno.exitCode); //-> 1
+   * ```
+   *
+   * @category Runtime
+   */
+  export var exitCode: number;
+
   /** An interface containing methods to interact with the process environment
    * variables.
    *

ext/node/polyfills/process.ts

@@ -10,7 +10,6 @@ import {
   op_geteuid,
   op_node_process_kill,
   op_process_abort,
-  op_set_exit_code,
 } from "ext:core/ops";
 
 import { warnNotImplemented } from "ext:deno_node/_utils.ts";
@@ -49,6 +48,7 @@ import {
 } from "ext:deno_node/_next_tick.ts";
 import { isWindows } from "ext:deno_node/_util/os.ts";
 import * as io from "ext:deno_io/12_io.js";
+import * as denoOs from "ext:runtime/30_os.js";
 
 export let argv0 = "";
 
@@ -74,28 +74,31 @@ const notImplementedEvents = [
 ];
 
 export const argv: string[] = ["", ""];
-let globalProcessExitCode: number | undefined = undefined;
+
+// In Node, `process.exitCode` is initially `undefined` until set.
+// And retains any value as long as it's nullish or number-ish.
+let ProcessExitCode: undefined | null | string | number;
 
 /** https://nodejs.org/api/process.html#process_process_exit_code */
 export const exit = (code?: number | string) => {
   if (code || code === 0) {
-    if (typeof code === "string") {
-      const parsedCode = parseInt(code);
-      globalProcessExitCode = isNaN(parsedCode) ? undefined : parsedCode;
-    } else {
-      globalProcessExitCode = code;
-    }
+    denoOs.setExitCode(code);
+  } else if (Number.isNaN(code)) {
+    denoOs.setExitCode(1);
   }
 
+  ProcessExitCode = denoOs.getExitCode();
   if (!process._exiting) {
     process._exiting = true;
     // FIXME(bartlomieju): this is wrong, we won't be using syscall to exit
     // and thus the `unload` event will not be emitted to properly trigger "emit"
     // event on `process`.
-    process.emit("exit", process.exitCode || 0);
+    process.emit("exit", ProcessExitCode);
   }
 
-  process.reallyExit(process.exitCode || 0);
+  // Any valid thing `process.exitCode` set is already held in Deno.exitCode.
+  // At this point, we don't have to pass around Node's raw/string exit value.
+  process.reallyExit(ProcessExitCode);
 };
 
 /** https://nodejs.org/api/process.html#processumaskmask */
@@ -433,14 +436,42 @@ Process.prototype._exiting = _exiting;
 /** https://nodejs.org/api/process.html#processexitcode_1 */
 Object.defineProperty(Process.prototype, "exitCode", {
   get() {
-    return globalProcessExitCode;
+    return ProcessExitCode;
   },
-  set(code: number | undefined) {
-    globalProcessExitCode = code;
-    code = parseInt(code) || 0;
-    if (!isNaN(code)) {
-      op_set_exit_code(code);
+  set(code: number | string | null | undefined) {
+    let parsedCode;
+
+    if (typeof code === "number") {
+      if (Number.isNaN(code)) {
+        parsedCode = 1;
+        denoOs.setExitCode(parsedCode);
+        ProcessExitCode = parsedCode;
+        return;
+      }
+
+      // This is looser than `denoOs.setExitCode` which requires exit code
+      // to be decimal or string of a decimal, but Node accept eg. 0x10.
+      parsedCode = parseInt(code);
+      denoOs.setExitCode(parsedCode);
+      ProcessExitCode = parsedCode;
+      return;
     }
+
+    if (typeof code === "string") {
+      parsedCode = parseInt(code);
+      if (Number.isNaN(parsedCode)) {
+        throw new TypeError(
+          `The "code" argument must be of type number. Received type ${typeof code} (${code})`,
+        );
+      }
+      denoOs.setExitCode(parsedCode);
+      ProcessExitCode = parsedCode;
+      return;
+    }
+
+    // TODO(bartlomieju): hope for the best here. This should be further tightened.
+    denoOs.setExitCode(code);
+    ProcessExitCode = code;
   },
 });
 

runtime/js/30_os.js

@@ -7,6 +7,7 @@ import {
   op_exec_path,
   op_exit,
   op_get_env,
+  op_get_exit_code,
   op_gid,
   op_hostname,
   op_loadavg,
@@ -21,7 +22,9 @@ import {
 const {
   Error,
   FunctionPrototypeBind,
+  NumberParseInt,
   SymbolFor,
+  TypeError,
 } = primordials;
 
 import { Event, EventTarget } from "ext:deno_web/02_event.js";
@@ -75,7 +78,7 @@ function exit(code) {
   if (typeof code === "number") {
     op_set_exit_code(code);
   } else {
-    code = 0;
+    code = op_get_exit_code();
   }
 
   // Dispatches `unload` only when it's not dispatched yet.
@@ -94,6 +97,20 @@ function exit(code) {
   throw new Error("Code not reachable");
 }
 
+function getExitCode() {
+  return op_get_exit_code();
+}
+
+function setExitCode(value) {
+  const code = NumberParseInt(value, 10);
+  if (typeof code !== "number") {
+    throw new TypeError(
+      `Exit code must be a number, got: ${code} (${typeof code}).`,
+    );
+  }
+  op_set_exit_code(code);
+}
+
 function setEnv(key, value) {
   op_set_env(key, value);
 }
@@ -126,12 +143,14 @@ export {
   env,
   execPath,
   exit,
+  getExitCode,
   gid,
   hostname,
   loadavg,
   networkInterfaces,
   osRelease,
   osUptime,
+  setExitCode,
   setExitHandler,
   systemMemoryInfo,
   uid,

runtime/js/99_main.js

@@ -674,6 +674,14 @@ ObjectDefineProperties(finalDenoNs, {
       return internals.future ? undefined : customInspect;
     },
   },
+  exitCode: {
+    get() {
+      return os.getExitCode();
+    },
+    set(value) {
+      os.setExitCode(value);
+    },
+  },
 });
 
 const {

runtime/ops/os/mod.rs

@@ -32,6 +32,7 @@ deno_core::extension!(
     op_os_uptime,
     op_set_env,
     op_set_exit_code,
+    op_get_exit_code,
     op_system_memory_info,
     op_uid,
     op_runtime_memory_usage,
@@ -60,12 +61,13 @@ deno_core::extension!(
     op_os_uptime,
     op_set_env,
     op_set_exit_code,
+    op_get_exit_code,
     op_system_memory_info,
     op_uid,
     op_runtime_memory_usage,
   ],
   middleware = |op| match op.name {
-    "op_exit" | "op_set_exit_code" =>
+    "op_exit" | "op_set_exit_code" | "op_get_exit_code" =>
       op.with_implementation_from(&deno_core::op_void_sync()),
     _ => op,
   },
@@ -164,6 +166,12 @@ fn op_set_exit_code(state: &mut OpState, #[smi] code: i32) {
   state.borrow_mut::<ExitCode>().set(code);
 }
 
+#[op2(fast)]
+#[smi]
+fn op_get_exit_code(state: &mut OpState) -> i32 {
+  state.borrow_mut::<ExitCode>().get()
+}
+
 #[op2(fast)]
 fn op_exit(state: &mut OpState) {
   let code = state.borrow::<ExitCode>().get();

tests/specs/run/exit_code/__test__.jsonc

@@ -0,0 +1,5 @@
+{
+  "args": "run main.js",
+  "exitCode": 42,
+  "output": "main.out"
+}

tests/specs/run/exit_code/main.js

@@ -0,0 +1,7 @@
+if (Deno.exitCode != 0) {
+  throw new Error("boom!");
+}
+
+Deno.exitCode = 42;
+
+console.log("Deno.exitCode", Deno.exitCode);

tests/specs/run/exit_code/main.out

@@ -0,0 +1 @@
+Deno.exitCode 42

tests/specs/test/exit_code/__test__.jsonc

@@ -0,0 +1,5 @@
+{
+  "args": "test main.js",
+  "exitCode": 1,
+  "output": "main.out"
+}

tests/specs/test/exit_code/main.js

@@ -0,0 +1,3 @@
+Deno.test("Deno.exitCode", () => {
+  Deno.exitCode = 42;
+});