[PHP] Allow removing CWD during runtime rotation

packages/php-wasm/node/src/lib/node-fs-mount.ts

@@ -3,6 +3,7 @@ import {
 	FSHelpers,
 	type MountHandler,
 } from '@php-wasm/universal';
+import { isParentOf } from '@php-wasm/util';
 import { lstatSync } from 'fs';
 import { dirname } from 'path';
 
@@ -53,6 +54,12 @@ export function createNodeFsMountHandler(localPath: string): MountHandler {
 			FS!.unmount(vfsMountPoint);
 			if (removeVfsNode) {
 				if (FS.isDir(lookup.node.mode)) {
+					if (isParentOf(vfsMountPoint, FS.cwd())) {
+						throw new Error(
+							`Cannot remove the VFS directory "${vfsMountPoint}" on umount cleanup – it is a parent of the CWD "${FS.cwd()}". Change CWD before ` +
+								`unmounting or explicitly disable post-unmount node cleanup with createNodeFsMountHandler(path, {cleanupNodesOnUnmount: false}).`
+						);
+					}
 					FS.rmdir(vfsMountPoint);
 				} else {
 					FS.unlink(vfsMountPoint);

packages/php-wasm/node/src/test/rotate-php-runtime.spec.ts

@@ -51,7 +51,6 @@ describe.each([true, false])(
 
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 10,
 			});
@@ -88,7 +87,6 @@ describe.each([true, false])(
 
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 10,
 			});
@@ -121,7 +119,6 @@ describe.each([true, false])(
 
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/wordpress',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 10,
 			});
@@ -228,7 +225,6 @@ describe.each([true, false])(
 			// Rotate the PHP runtime
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 1000,
 			});
@@ -257,7 +253,6 @@ describe.each([true, false])(
 			const recreateRuntimeSpy = vitest.fn(recreateRuntime);
 			const php = new PHP(await recreateRuntimeSpy());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 1,
 			});
@@ -271,7 +266,6 @@ describe.each([true, false])(
 			const recreateRuntimeSpy = vitest.fn(recreateRuntime);
 			const php = new PHP(await recreateRuntimeSpy());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 1234,
 			});
@@ -289,7 +283,6 @@ describe.each([true, false])(
 			const recreateRuntimeSpy = vitest.fn(recreateRuntime);
 			const php = new PHP(await recreateRuntimeSpy());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 1234,
 			});
@@ -318,7 +311,6 @@ describe.each([true, false])(
 			});
 			const php = new PHP(await recreateRuntimeSpy());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime: recreateRuntimeSpy,
 				maxRequests: 1,
 			});
@@ -339,7 +331,6 @@ describe.each([true, false])(
 		it('Should preserve the custom SAPI name', async () => {
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime,
 				maxRequests: 1,
 			});
@@ -356,7 +347,6 @@ describe.each([true, false])(
 		it('Should preserve the MEMFS files', async () => {
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime,
 				maxRequests: 1,
 			});
@@ -379,7 +369,6 @@ describe.each([true, false])(
 		it('Should not overwrite the NODEFS files', async () => {
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime,
 				maxRequests: 1,
 			});
@@ -424,7 +413,6 @@ describe.each([true, false])(
 		it('Should preserve the spawn handler through PHP runtime recreation', async () => {
 			const php = new PHP(await recreateRuntime());
 			php.enableRuntimeRotation({
-				cwd: '/test-root',
 				recreateRuntime,
 				maxRequests: 1,
 			});
@@ -465,5 +453,63 @@ describe.each([true, false])(
 			expect(result2.text).toBe('Hello Again');
 			expect(spawnHandlerCallCount).toBe(2);
 		}, 30_000);
+
+		it('Should preserve NODEFS mount when CWD is the same as mount point', async () => {
+			const php = new PHP(await recreateRuntime());
+			php.enableRuntimeRotation({
+				recreateRuntime,
+				maxRequests: 1,
+			});
+
+			// Create a temporary directory to mount
+			const tempDir = fs.mkdtempSync(
+				path.join(os.tmpdir(), 'nodefs-mount-')
+			);
+			const testFile = path.join(tempDir, 'test.txt');
+			fs.writeFileSync(testFile, 'Hello from NODEFS');
+
+			try {
+				// Mount the temp directory at /wordpress
+				await php.mount(
+					'/wordpress',
+					createNodeFsMountHandler(tempDir)
+				);
+
+				// Set CWD to the mount point
+				php.chdir('/wordpress');
+				expect(php.cwd()).toBe('/wordpress');
+
+				// Verify the mounted file is accessible
+				expect(php.fileExists('/wordpress/test.txt')).toBe(true);
+				expect(php.readFileAsText('/wordpress/test.txt')).toBe(
+					'Hello from NODEFS'
+				);
+
+				// Trigger runtime rotation by making a request
+				await php.run({ code: `<?php echo "Triggering rotation";` });
+				await php.run({ code: `<?php echo "Triggering rotation";` });
+
+				// Verify CWD is preserved after rotation
+				expect(php.cwd()).toBe('/wordpress');
+
+				// Verify the mount is still accessible after rotation
+				expect(php.fileExists('/wordpress/test.txt')).toBe(true);
+				expect(php.readFileAsText('/wordpress/test.txt')).toBe(
+					'Hello from NODEFS'
+				);
+
+				// Test that we can still write to the mounted directory
+				php.writeFile(
+					'/wordpress/new-file.txt',
+					'Created after rotation'
+				);
+				expect(
+					fs.readFileSync(path.join(tempDir, 'new-file.txt'), 'utf8')
+				).toBe('Created after rotation');
+			} finally {
+				fs.rmSync(tempDir, { recursive: true });
+				php.exit();
+			}
+		}, 30_000);
 	}
 );

packages/php-wasm/universal/src/lib/php.ts

@@ -89,7 +89,6 @@ export class PHP implements Disposable {
 		needsRotating: boolean;
 		maxRequests: number;
 		requestsMade: number;
-		cwd?: string;
 	} = {
 		enabled: false,
 		recreateRuntime: () => 0,
@@ -1315,14 +1314,12 @@ export class PHP implements Disposable {
 	enableRuntimeRotation(options: {
 		recreateRuntime: () => Promise<number> | number;
 		maxRequests?: number;
-		cwd?: string;
 	}) {
 		this.#rotationOptions = {
 			...this.#rotationOptions,
 			enabled: true,
 			recreateRuntime: options.recreateRuntime,
 			maxRequests: options.maxRequests ?? 400,
-			cwd: options.cwd,
 		};
 	}
 
@@ -1358,6 +1355,27 @@ export class PHP implements Disposable {
 		const oldRootLevelPaths = this.listFiles('/').map((file) => `/${file}`);
 		const oldSpawnProcess = this[__private__dont__use].spawnProcess;
 
+		// Temporarily set CWD to / and restore it at the end of this method.
+		//
+		// There's a chance cleaning up old mounts via mount.unmount()
+		// will attempt removing the CWD. Normally, this would throw
+		// FS.ErrnoError(10) EBUSY and interrupt the PHP runtime rotation,
+		// leaving us in a broken state.
+		//
+		// Even though removing the CWD directory is not allowed by the
+		// filesystem, we don't care that much here – we're merely freeing
+		// all the resources allocated by the old filesystem before it's
+		// garbage collected. We are about to recreate the same filesystem
+		// structure and mounts in another PHP runtime.
+		//
+		// Therefore, let's suspend the strict EBUSY check by setting the CWD
+		// to / for the cleanup purposes. We'll attempt to restore the original
+		// CWD on the new runtime once we re-apply all the mounts there. We'll
+		// only have a real reason to throw an error if the CWD path does not
+		// exist in the new filesystem after the rotation.
+		const oldCWD = oldFS.cwd();
+		oldFS.chdir('/');
+
 		// Unmount all the mount handlers
 		const mountHandlers: { mountHandler: MountHandler; vfsPath: string }[] =
 			[];
@@ -1406,6 +1424,16 @@ export class PHP implements Disposable {
 			this.mkdir(vfsPath);
 			await this.mount(vfsPath, mountHandler);
 		}
+		try {
+			newFs.chdir(oldCWD);
+		} catch (e) {
+			throw new Error(
+				`Failed to restore CWD to ${oldCWD} after PHP runtime rotation.`,
+				{
+					cause: e,
+				}
+			);
+		}
 	}
 
 	/**

packages/php-wasm/universal/src/lib/rotate-php-runtime.ts

@@ -15,13 +15,11 @@ export interface RotateOptions {
  */
 export function rotatePHPRuntime({
 	php,
-	cwd,
 	recreateRuntime,
 	maxRequests = 400,
 }: RotateOptions) {
 	return php.enableRuntimeRotation({
 		recreateRuntime,
 		maxRequests,
-		cwd,
 	});
 }

packages/playground/wordpress/src/boot.ts

@@ -316,7 +316,6 @@ export async function bootRequestHandler(options: BootRequestHandlerOptions) {
 		// Rotate the PHP runtime periodically to avoid memory leak-related crashes.
 		// @see https://github.com/WordPress/wordpress-playground/pull/990 for more context
 		php.enableRuntimeRotation({
-			cwd: requestHandler.documentRoot,
 			recreateRuntime: options.createPhpRuntime,
 			maxRequests: 400,
 		});