Fix a cross-device mv error by using a tmp directory inside document …

…root (#886)

Solves the [error discovered by
@sejas](WordPress/playground-tools#116 (comment))
caused by calling `php.mv(fromPath, toPath)` when `fromPath` is a
mounted local directory and `toPath` is a MEMFS directory. Emscripten
doesn't support such a scenario:

```
Proceeding without the Notification plugin. Could not install it in wp-admin. The original error was: Error: Could not move "/tmp/assets/Notification/notification": Cross-device link.
Error: Could not move "/tmp/assets/Notification/notification": Cross-device link.
    at descriptor.value (/playground-tools/node_modules/@php-wasm/node/index.cjs:67481:17)
```

The solution proposed in this PR replaces a `/tmp` directory with a
randomly-named temporary directory inside `wp-content`. `/tmp` doesn't
necessarily point to a system temp directory and needs to be revisited
anyway. Whether we should use a temporary directory inside `wp-content`
is another matter, but that part may be revisited once the [recursive
cp](#846) feature
is added.

packages/playground/blueprints/src/lib/steps/install-asset.ts

@@ -1,4 +1,5 @@
 import type { UniversalPHP } from '@php-wasm/universal';
+import { joinPaths } from '@php-wasm/util';
 import { writeFile } from './write-file';
 import { unzip } from './unzip';
 
@@ -29,30 +30,26 @@ export async function installAsset(
 	assetFolderName: string;
 }> {
 	// Extract to temporary folder so we can find asset folder name
-
 	const zipFileName = zipFile.name;
 	const assetNameGuess = zipFileName.replace(/\.zip$/, '');
 
-	const tmpUnzippedFilesPath = `/tmp/assets/${assetNameGuess}`;
-	const tmpZipPath = `/tmp/${zipFileName}`;
+	const wpContent = joinPaths(await playground.documentRoot, 'wp-content');
+	const tmpDir = joinPaths(wpContent, crypto.randomUUID());
+	const tmpZipPath = joinPaths(tmpDir, zipFileName);
+	const tmpUnzippedFilesPath = joinPaths(tmpDir, 'assets', assetNameGuess);
 
-	const removeTmpFolder = () =>
-		playground.rmdir(tmpUnzippedFilesPath, {
+	if (await playground.fileExists(tmpUnzippedFilesPath)) {
+		await playground.rmdir(tmpDir, {
 			recursive: true,
 		});
-
-	if (await playground.fileExists(tmpUnzippedFilesPath)) {
-		await removeTmpFolder();
 	}
+	await playground.mkdir(tmpDir);
 
 	await writeFile(playground, {
 		path: tmpZipPath,
 		data: zipFile,
 	});
 
-	const cleanup = () =>
-		Promise.all([removeTmpFolder, () => playground.unlink(tmpZipPath)]);
-
 	try {
 		await unzip(playground, {
 			zipPath: tmpZipPath,
@@ -84,14 +81,14 @@ export async function installAsset(
 		// Move asset folder to target path
 		const assetFolderPath = `${targetPath}/${assetFolderName}`;
 		await playground.mv(tmpAssetPath, assetFolderPath);
-		await cleanup();
 
 		return {
 			assetFolderPath,
 			assetFolderName,
 		};
-	} catch (error) {
-		await cleanup();
-		throw error;
+	} finally {
+		await playground.rmdir(tmpDir, {
+			recursive: true,
+		});
 	}
 }