fix(pkgman): honor XDG_CACHE_HOME and keep the previous install until the new one is complete

README.md

@@ -9,7 +9,7 @@ npm install camoufox-js
 ```
 
 The Camoufox browser itself is downloaded with `npx camoufox-js fetch` into the
-per-user cache directory (`~/.cache/camoufox` on Linux). Set the
+per-user cache directory (`$XDG_CACHE_HOME/camoufox` or `~/.cache/camoufox` on Linux). Set the
 `CAMOUFOX_INSTALL_DIR` environment variable to install and resolve it from a
 custom location instead — useful in containers and CI images where the home
 directory is ephemeral or persisted separately (similar to Playwright's

src/pkgman.ts

@@ -7,7 +7,7 @@ import type { Writable } from "node:stream";
 import { setTimeout } from "node:timers/promises";
 import { fileURLToPath } from "node:url";
 import AdmZip from "adm-zip";
-import cliProgress, { Options } from "cli-progress";
+import cliProgress, { type Options } from "cli-progress";
 import prettyBytes from "pretty-bytes";
 import { CONSTRAINTS } from "./__version__.js";
 import {
@@ -271,9 +271,12 @@ export class CamoufoxFetcher extends GitHubDownloader {
 		return Buffer.from(await response.arrayBuffer());
 	}
 
-	async extractZip(zipFile: string | Buffer): Promise<void> {
+	async extractZip(
+		zipFile: string | Buffer,
+		destDir: string = INSTALL_DIR.toString(),
+	): Promise<void> {
 		const zip = new AdmZip(zipFile);
-		zip.extractAllTo(INSTALL_DIR.toString(), true);
+		zip.extractAllTo(destDir, true);
 	}
 
 	static cleanup(): boolean {
@@ -284,37 +287,69 @@ export class CamoufoxFetcher extends GitHubDownloader {
 		return false;
 	}
 
-	setVersion(): void {
+	setVersion(destDir: string = INSTALL_DIR.toString()): void {
 		fs.writeFileSync(
-			path.join(INSTALL_DIR.toString(), "version.json"),
+			path.join(destDir, "version.json"),
 			JSON.stringify({ version: this.version, release: this.release }),
 		);
 	}
 
+	// Remove staging/backup dirs left behind by an interrupted install.
+	private static removeLeftovers(installDir: string): void {
+		const parent = path.dirname(installDir);
+		const base = path.basename(installDir);
+		for (const name of fs.readdirSync(parent)) {
+			if (
+				name.startsWith(`${base}.staging-`) ||
+				name.startsWith(`${base}.old-`)
+			) {
+				fs.rmSync(path.join(parent, name), { recursive: true, force: true });
+			}
+		}
+	}
+
+	// Swap the staged install in; restore the previous one if that fails.
+	private static swapIn(stagingDir: string, installDir: string): void {
+		const backupDir = fs.existsSync(installDir)
+			? `${installDir}.old-${process.pid}`
+			: undefined;
+		if (backupDir) fs.renameSync(installDir, backupDir);
+		try {
+			fs.renameSync(stagingDir, installDir);
+		} catch (e) {
+			if (backupDir) fs.renameSync(backupDir, installDir);
+			throw e;
+		}
+		if (backupDir) fs.rmSync(backupDir, { recursive: true, force: true });
+	}
+
 	async install(): Promise<void> {
 		await this.init();
-		await CamoufoxFetcher.cleanup();
-		// Set up outside the try so finally can always tear down the ~600MB staging dir.
+		const installDir = INSTALL_DIR.toString();
+		fs.mkdirSync(path.dirname(installDir), { recursive: true });
+		CamoufoxFetcher.removeLeftovers(installDir);
+		// Staged next to INSTALL_DIR so the final rename stays on one filesystem.
+		// Set up outside the try so finally can always tear down the ~600MB staging dirs.
+		const stagingDir = fs.mkdtempSync(`${installDir}.staging-`);
 		const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "camoufox-"));
 		const tempFilePath = path.join(tempDir, "camoufox.zip");
 		const tempFileStream = fs.createWriteStream(tempFilePath);
 		try {
-			fs.mkdirSync(INSTALL_DIR, { recursive: true });
-
 			await webdl(this.url, "Downloading Camoufox...", true, tempFileStream);
 			await new Promise((r) => tempFileStream.close(r));
 
-			await this.extractZip(tempFilePath);
-			this.setVersion();
+			await this.extractZip(tempFilePath, stagingDir);
+			this.setVersion(stagingDir);
 
 			if (OS_NAME !== "win") {
-				execFileSync("chmod", ["-R", "755", INSTALL_DIR.toString()]);
+				execFileSync("chmod", ["-R", "755", stagingDir]);
 			}
 
+			CamoufoxFetcher.swapIn(stagingDir, installDir);
+
 			console.log("Camoufox successfully installed.");
 		} catch (e) {
 			console.error(`Error installing Camoufox: ${e}`);
-			await CamoufoxFetcher.cleanup();
 			throw e;
 		} finally {
 			// Best-effort teardown: a throw here would mask the real result, and the caller is fire-and-forget.
@@ -326,8 +361,9 @@ export class CamoufoxFetcher extends GitHubDownloader {
 					);
 				}
 				fs.rmSync(tempDir, { recursive: true, force: true });
+				fs.rmSync(stagingDir, { recursive: true, force: true });
 			} catch (cleanupErr) {
-				console.error(`Failed to remove staging dir ${tempDir}: ${cleanupErr}`);
+				console.error(`Failed to remove staging dir: ${cleanupErr}`);
 			}
 		}
 	}
@@ -382,7 +418,12 @@ function userCacheDir(appName: string): string {
 	} else if (OS_NAME === "mac") {
 		return path.join(os.homedir(), "Library", "Caches", appName);
 	} else {
-		return path.join(os.homedir(), ".cache", appName);
+		// Per the XDG spec a relative XDG_CACHE_HOME is invalid and ignored.
+		const xdg = process.env.XDG_CACHE_HOME;
+		return path.join(
+			xdg && path.isAbsolute(xdg) ? xdg : path.join(os.homedir(), ".cache"),
+			appName,
+		);
 	}
 }
 

test/pkgman.test.ts

@@ -1,6 +1,7 @@
 import * as fs from "node:fs";
 import * as os from "node:os";
 import * as path from "node:path";
+import AdmZip from "adm-zip";
 import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
 
 // INSTALL_DIR is a module-level constant, so each case re-imports the module
@@ -19,6 +20,28 @@ describe("INSTALL_DIR", () => {
 		expect(path.isAbsolute(INSTALL_DIR.toString())).toBe(true);
 	});
 
+	test.skipIf(process.platform !== "linux")(
+		"honors an absolute XDG_CACHE_HOME on Linux",
+		async () => {
+			vi.stubEnv("CAMOUFOX_INSTALL_DIR", "");
+			vi.stubEnv("XDG_CACHE_HOME", "/xdg-cache");
+			vi.resetModules();
+			const { INSTALL_DIR } = await import("../src/pkgman");
+			expect(INSTALL_DIR).toBe(path.join("/xdg-cache", "camoufox"));
+		},
+	);
+
+	test.skipIf(process.platform !== "linux")(
+		"ignores a relative XDG_CACHE_HOME",
+		async () => {
+			vi.stubEnv("CAMOUFOX_INSTALL_DIR", "");
+			vi.stubEnv("XDG_CACHE_HOME", "relative/cache");
+			vi.resetModules();
+			const { INSTALL_DIR } = await import("../src/pkgman");
+			expect(INSTALL_DIR).toBe(path.join(os.homedir(), ".cache", "camoufox"));
+		},
+	);
+
 	test("CAMOUFOX_INSTALL_DIR overrides the install location", async () => {
 		const target = path.join("custom", "camoufox-install");
 		vi.stubEnv("CAMOUFOX_INSTALL_DIR", target);
@@ -63,13 +86,16 @@ function failingFetch() {
 	}));
 }
 
-// A fetch that writes a few bytes and completes cleanly.
+// A fetch that serves a small real zip and completes cleanly.
 function succeedingFetch() {
+	const zip = new AdmZip();
+	zip.addFile("camoufox", Buffer.from("binary"));
+	const bytes = new Uint8Array(zip.toBuffer());
 	return vi.fn(async () => ({
 		ok: true,
 		headers: { get: () => "0" },
 		body: (async function* () {
-			yield new Uint8Array([1, 2, 3]);
+			yield bytes;
 		})(),
 	}));
 }
@@ -99,40 +125,59 @@ describe("CamoufoxFetcher.install cleanup", () => {
 		fs.rmSync(tmp, { recursive: true, force: true });
 	});
 
-	// Staging dirs install() creates: <tmpdir>/camoufox-<6 random chars>.
+	// Dirs install() creates: <tmpdir>/camoufox-<6 random chars>,
+	// <install dir>.staging-<6 random chars> and <install dir>.old-<pid>.
 	function stagingDirs(): string[] {
 		return fs
 			.readdirSync(tmp)
-			.filter((n) => /^camoufox-[A-Za-z0-9]{6}$/.test(n));
+			.filter((n) =>
+				/^(camoufox-[A-Za-z0-9]{6}|install\.(staging|old)-.+)$/.test(n),
+			);
 	}
 
 	async function installWith(fetchImpl: ReturnType<typeof vi.fn>) {
 		const { CamoufoxFetcher } = await import("../src/pkgman");
 		const fetcher = new CamoufoxFetcher();
-		// Skip the release lookup; just hand install() a URL to download.
+		// Skip the release lookup; just hand install() a URL and version.
 		vi.spyOn(fetcher, "init").mockImplementation(async () => {
-			(fetcher as unknown as { _url: string })._url =
-				"https://example.test/camoufox.zip";
+			const f = fetcher as unknown as { _url: string; _version_obj: unknown };
+			f._url = "https://example.test/camoufox.zip";
+			f._version_obj = { version: "1.0", release: "beta.1" };
 		});
-		// Don't extract the placeholder zip or write a version file.
-		vi.spyOn(fetcher, "extractZip").mockResolvedValue(undefined);
-		vi.spyOn(fetcher, "setVersion").mockImplementation(() => {});
 		vi.stubGlobal("fetch", fetchImpl);
 		vi.stubGlobal("console", { ...console, error: vi.fn(), log: vi.fn() });
 		return fetcher;
 	}
 
-	test("removes the staging dir when the download fails", async () => {
+	test("keeps the previous install when the download fails", async () => {
+		const marker = path.join(installDir, "version.json");
+		fs.writeFileSync(marker, "{}");
 		const fetcher = await installWith(failingFetch());
 		// The original download error must survive, and no staging dir is left.
 		await expect(fetcher.install()).rejects.toThrow("connection reset");
 		expect(stagingDirs()).toEqual([]);
+		expect(fs.existsSync(marker)).toBe(true);
 	});
 
-	test("removes the staging dir after a successful install", async () => {
+	test("replaces the previous install after a successful install", async () => {
+		const marker = path.join(installDir, "old-file");
+		fs.writeFileSync(marker, "");
+		// Leftovers from an interrupted earlier install must be swept.
+		fs.mkdirSync(path.join(tmp, "install.staging-abc123"));
+		fs.mkdirSync(path.join(tmp, "install.old-1"));
 		const fetcher = await installWith(succeedingFetch());
 		// A successful install must resolve (not throw) and leave no staging dir.
 		await expect(fetcher.install()).resolves.toBeUndefined();
 		expect(stagingDirs()).toEqual([]);
+		expect(fs.existsSync(marker)).toBe(false);
+		expect(fs.readdirSync(installDir).sort()).toEqual([
+			"camoufox",
+			"version.json",
+		]);
+		expect(
+			JSON.parse(
+				fs.readFileSync(path.join(installDir, "version.json"), "utf8"),
+			),
+		).toEqual({ version: "1.0", release: "beta.1" });
 	});
 });