Merge pull request #5 from ext/feature/stdin

feat: support reading tarball from stdin

README.md

@@ -16,6 +16,11 @@ Default is to find `package.json` from current directory tree and derive tarball
 
 If `--tarball` is used `package.json` is extracted from the tarball.
 
+To read from stdin use `--tarball -`.
+This can be used to quickly examine packages from https://www.npmjs.com/:
+
+> curl -s \$(npm view lodash dist.tarball) | npx npm-pkg-lint -t -
+
 ## Disallowed files
 
 Disallows certain files from being included in the package tarball.

package.json

@@ -61,7 +61,8 @@
     "@html-validate/stylish": "^1.0.0",
     "argparse": "^2.0.1",
     "find-up": "^5.0.0",
-    "tar": "^6.0.5"
+    "tar": "^6.0.5",
+    "tmp": "^0.2.1"
   },
   "devDependencies": {
     "@commitlint/cli": "11.0.0",
@@ -75,6 +76,7 @@
     "@types/jest": "26.0.15",
     "@types/node": "11.15.35",
     "@types/tar": "4.0.3",
+    "@types/tmp": "^0.2.0",
     "@typescript-eslint/eslint-plugin": "4.7.0",
     "@typescript-eslint/parser": "4.7.0",
     "eslint": "7.13.0",

src/index.ts

@@ -1,9 +1,10 @@
 /* eslint-disable no-console, no-process-exit -- this is a cli tool */
 
-import { existsSync, promises as fs } from "fs";
+import { existsSync, createWriteStream, promises as fs } from "fs";
 import path from "path";
 import { ArgumentParser } from "argparse";
 import findUp from "find-up";
+import tmp from "tmp";
 import stylish from "@html-validate/stylish";
 import { setupBlacklist } from "./blacklist";
 import { verify } from "./verify";
@@ -24,6 +25,26 @@ interface GetPackageJsonResults {
 	pkgPath?: string;
 }
 
+async function preloadStdin(): Promise<string> {
+	return new Promise((resolve, reject) => {
+		tmp.file((err, path, fd) => {
+			if (err) {
+				reject(err);
+				return;
+			}
+
+			const st = createWriteStream(null, { fd, autoClose: true });
+			process.stdin.pipe(st);
+			st.on("finish", () => {
+				resolve(path);
+			});
+			st.on("error", (err) => {
+				reject(err);
+			});
+		});
+	});
+}
+
 async function getPackageJson(args: ParsedArgs): Promise<GetPackageJsonResults> {
 	/* get from explicit path passed as argument */
 	if (args.pkgfile) {
@@ -65,6 +86,14 @@ async function run(): Promise<void> {
 	parser.add_argument("-p", "--pkgfile", { help: "specify package.json location" });
 
 	const args: ParsedArgs = parser.parse_args();
+
+	/* this library assumes the file source can be randomly accessed but with
+	 * stdin this is not possible so stdin is read into a temporary file which is
+	 * used instead */
+	if (args.tarball === "-") {
+		args.tarball = await preloadStdin();
+	}
+
 	const { pkg, pkgPath } = await getPackageJson(args);
 
 	if (!pkg) {