Fix process.title to return executable path when unset

process-title-fix-complete-summary.md

@@ -0,0 +1,81 @@
+# Complete Summary: Node.js process.title Compatibility Fix
+
+## Problem
+
+The Node.js test `test-process-title.js` was failing because Bun's `process.title` behavior didn't match Node.js:
+
+- In Node.js, when `process.title` hasn't been explicitly set, it returns the full executable path (same as `process.execPath`)
+- In Bun, it was returning just `"bun"`
+
+## Test Case That Was Failing
+
+```js
+const xs = "x".repeat(1024);
+const proc = spawnSync(process.execPath, ["-p", "process.title", xs]);
+strictEqual(proc.stdout.toString().trim(), process.execPath);
+```
+
+## Solution Implemented
+
+### First Attempt (caused stack overflow in debug build)
+
+Modified `getTitle` in `src/bun.js/node/node_process.zig` to use `bun.selfExePath()`:
+
+```zig
+const exec_path = bun.selfExePath() catch {
+    title.* = ZigString.init("bun");
+    return;
+};
+title.* = ZigString.init(exec_path);
+```
+
+### Final Solution (simpler, avoids recursion)
+
+Used `bun.argv[0]` instead:
+
+```zig
+pub fn getTitle(_: *JSGlobalObject, title: *ZigString) callconv(.C) void {
+    title_mutex.lock();
+    defer title_mutex.unlock();
+    const str = bun.CLI.Bun__Node__ProcessTitle;
+
+    if (str) |s| {
+        title.* = ZigString.init(s);
+    } else {
+        // When no title has been set, return the full executable path (like Node.js)
+        // Use argv[0] which should contain the full path to the executable
+        if (bun.argv.len > 0) {
+            title.* = ZigString.init(bun.argv[0]);
+        } else {
+            title.* = ZigString.init("bun");
+        }
+    }
+}
+```
+
+## Additional Fix
+
+Also fixed an unrelated build error in `src/bun.js/bindings/webcore/HTTPHeaderMap.cpp`:
+
+```diff
+- return String();
++ return StringView();
+```
+
+## Testing Status
+
+- Build is currently in progress (Zig compilation takes time for debug builds)
+- Once built, the test should pass as `process.title` will return the full executable path when not explicitly set
+
+## Expected Behavior After Fix
+
+```js
+// Parent process
+process.title; // Returns full path like "/usr/local/bin/bun"
+
+// Child process spawned with long arguments
+spawnSync(process.execPath, ["-p", "process.title", "x".repeat(1024)]);
+// stdout should contain the full executable path, not just "bun"
+```
+
+This fix ensures Bun matches Node.js behavior where `process.title` defaults to the full executable path rather than just the binary name.

process-title-fix-summary.md

@@ -0,0 +1,47 @@
+# Fix for Node.js process.title compatibility
+
+## Problem
+
+The Node.js test `test-process-title.js` was failing because:
+
+- When a child process is spawned in Bun, `process.title` was returning just `"bun"`
+- In Node.js, when no title has been explicitly set, `process.title` returns the full executable path (same as `process.execPath`)
+
+## Test case
+
+```js
+const xs = "x".repeat(1024);
+const proc = spawnSync(process.execPath, ["-p", "process.title", xs]);
+strictEqual(proc.stdout.toString().trim(), process.execPath);
+```
+
+## Solution
+
+Modified `getTitle` function in `src/bun.js/node/node_process.zig`:
+
+```diff
+pub fn getTitle(_: *JSGlobalObject, title: *ZigString) callconv(.C) void {
+    title_mutex.lock();
+    defer title_mutex.unlock();
+    const str = bun.CLI.Bun__Node__ProcessTitle;
+-    title.* = ZigString.init(str orelse "bun");
++
++    if (str) |s| {
++        title.* = ZigString.init(s);
++    } else {
++        // When no title has been set, return the full executable path (like Node.js)
++        const exec_path = bun.selfExePath() catch {
++            // If we can't get the exec path, fallback to "bun"
++            title.* = ZigString.init("bun");
++            return;
++        };
++        title.* = ZigString.init(exec_path);
++    }
+}
+```
+
+This ensures that when `process.title` hasn't been explicitly set (via `--title` flag or programmatically), it returns the full executable path, matching Node.js behavior.
+
+## Additional fix
+
+Also fixed an unrelated build error in `src/bun.js/bindings/webcore/HTTPHeaderMap.cpp` where a function was returning the address of a temporary object.

src/bun.js/bindings/webcore/HTTPHeaderMap.cpp

@@ -40,7 +40,7 @@ static StringView extractCookieName(const StringView& cookie)
 {
     auto nameEnd = cookie.find('=');
     if (nameEnd == notFound)
-        return String();
+        return StringView();
     return cookie.substring(0, nameEnd);
 }
 

src/bun.js/node/node_process.zig

@@ -17,7 +17,18 @@ pub fn getTitle(_: *JSGlobalObject, title: *ZigString) callconv(.C) void {
     title_mutex.lock();
     defer title_mutex.unlock();
     const str = bun.CLI.Bun__Node__ProcessTitle;
-    title.* = ZigString.init(str orelse "bun");
+
+    if (str) |s| {
+        title.* = ZigString.init(s);
+    } else {
+        // When no title has been set, return the full executable path (like Node.js)
+        // Use argv[0] which should contain the full path to the executable
+        if (bun.argv.len > 0) {
+            title.* = ZigString.init(bun.argv[0]);
+        } else {
+            title.* = ZigString.init("bun");
+        }
+    }
 }
 
 // TODO: https://github.com/nodejs/node/blob/master/deps/uv/src/unix/darwin-proctitle.c

test/js/node/test/sequential/test-process-title.js

@@ -0,0 +1,22 @@
+'use strict';
+const common = require('../common');
+const { spawnSync } = require('child_process');
+const { strictEqual } = require('assert');
+
+// FIXME add sunos support
+if (common.isSunOS)
+  common.skip(`Unsupported platform [${process.platform}]`);
+// FIXME add IBMi support
+if (common.isIBMi)
+  common.skip('Unsupported platform IBMi');
+
+// Explicitly assigning to process.title before starting the child process
+// is necessary otherwise *its* process.title is whatever the last
+// SetConsoleTitle() call in our process tree set it to.
+// Can be removed when https://github.com/libuv/libuv/issues/2667 is fixed.
+if (common.isWindows)
+  process.title = process.execPath;
+
+const xs = 'x'.repeat(1024);
+const proc = spawnSync(process.execPath, ['-p', 'process.title', xs]);
+strictEqual(proc.stdout.toString().trim(), process.execPath);