From 9a1c7b2ecdb6f2eb8ef055ccfb74557662a55236 Mon Sep 17 00:00:00 2001
From: Hornwitser <github@hornwitser.no>
Date: Tue, 23 Aug 2022 18:35:41 +0200
Subject: [PATCH] Bad Windows names also apply with any extension

A file name con.zip is also treated in the same way as the special CON
redirection and may not be used as a normal filesystem path in Windows.
This includes any extension, even with multiple dots.  Fix checkFilename
and cleaneFilename not handling these cases.
---
 packages/lib/file_ops.js | 50 ++++++++++++++++++++--------------------
 test/lib/file_ops.js     | 12 ++++++++--
 2 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/packages/lib/file_ops.js b/packages/lib/file_ops.js
index cbed8df5..be007912 100644
--- a/packages/lib/file_ops.js
+++ b/packages/lib/file_ops.js
@@ -108,6 +108,18 @@ async function safeOutputFile(file, data, options={}) {
 	await fs.rename(temporary, file);
 }
 
+
+// Reserved names by allmost all filesystems
+const badNames = [".", ".."];
+
+// Reserved namespaces in Windows
+const oneToNine = [1, 2, 3, 4, 5, 6, 7, 8, 9];
+const badWinNamespaces = [
+	"CON", "PRN", "AUX", "NUL",
+	...oneToNine.map(n => `COM${n}`),
+	...oneToNine.map(n => `LPT${n}`),
+];
+
 /**
  * Check if a string is a valid file name
  *
@@ -120,17 +132,6 @@ function checkFilename(name) {
 	const badChars = /[<>:"\/\\|?*\x00-\x1f]/g;
 	const badEnd = /[. ]$/;
 
-	const oneToNine = [1, 2, 3, 4, 5, 6, 7, 8, 9];
-	const badNames = [
-		// Relative path components
-		".", "..",
-
-		// Reserved filenames in Windows
-		"CON", "PRN", "AUX", "NUL",
-		...oneToNine.map(n => `COM${n}`),
-		...oneToNine.map(n => `LPT${n}`),
-	];
-
 	if (typeof name !== "string") {
 		throw new Error("must be a string");
 	}
@@ -143,9 +144,15 @@ function checkFilename(name) {
 		throw new Error('cannot contain <>:"\\/|=* or control characters');
 	}
 
-	if (badNames.includes(name.toUpperCase())) {
+	if (badNames.includes(name)) {
 		throw new Error(
-			"cannot be named any of . .. CON PRN AUX NUL COM1-9 and LPT1-9"
+			`cannot be named ${name}`
+		);
+	}
+
+	if (badWinNamespaces.includes(name.toUpperCase().split(".")[0])) {
+		throw new Error(
+			"cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9"
 		);
 	}
 
@@ -161,21 +168,10 @@ function checkFilename(name) {
  * @returns {string} Filename suitable to use in the filesystem
  */
 function cleanFilename(name) {
-	// copied from checkFilename
+	// copied from checkFilename due to RegExp with global flag containing state.
 	const badChars = /[<>:"\/\\|?*\x00-\x1f]/g;
 	const badEnd = /[. ]$/;
 
-	const oneToNine = [1, 2, 3, 4, 5, 6, 7, 8, 9];
-	const badNames = [
-		// Relative path components
-		".", "..",
-
-		// Reserved filenames in Windows
-		"CON", "PRN", "AUX", "NUL",
-		...oneToNine.map(n => `COM${n}`),
-		...oneToNine.map(n => `LPT${n}`),
-	];
-
 	if (typeof name !== "string") {
 		throw new Error("name must be a string");
 	}
@@ -184,6 +180,10 @@ function cleanFilename(name) {
 		name += "_";
 	}
 
+	if (badWinNamespaces.includes(name.toUpperCase().split(".")[0])) {
+		name = [`${name.split(".")[0]}_`, ...name.split(".").slice(1)].join(".");
+	}
+
 	name = name.replace(badChars, "_");
 	name = name.replace(badEnd, "_");
 
diff --git a/test/lib/file_ops.js b/test/lib/file_ops.js
index 416c90a0..da256995 100644
--- a/test/lib/file_ops.js
+++ b/test/lib/file_ops.js
@@ -115,13 +115,17 @@ describe("lib/file_ops", function() {
 
 		it("should throw on CON, PRN, AUX, NUL, COM1, LPT1", function() {
 			for (let bad of ["CON", "PRN", "AUX", "NUL", "COM1", "LPT1"]) {
-				check(bad, "cannot be named any of . .. CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(bad, "cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(`${bad}.zip`, "cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(`${bad}.anything.txt`, "cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(`${bad}....a`, "cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(`${bad}.`, "cannot be named any of CON PRN AUX NUL COM1-9 and LPT1-9");
 			}
 		});
 
 		it("should throw on . and ..", function() {
 			for (let bad of [".", ".."]) {
-				check(bad, "cannot be named any of . .. CON PRN AUX NUL COM1-9 and LPT1-9");
+				check(bad, `cannot be named ${bad}`);
 			}
 		});
 
@@ -166,6 +170,10 @@ describe("lib/file_ops", function() {
 		it("should clean CON, PRN, AUX, NUL, COM1, LPT1", function() {
 			for (let bad of ["CON", "PRN", "AUX", "NUL", "COM1", "LPT1"]) {
 				clean(bad, `${bad}_`);
+				clean(`${bad}.zip`, `${bad}_.zip`);
+				clean(`${bad}.anything.txt`, `${bad}_.anything.txt`);
+				clean(`${bad}....a`, `${bad}_....a`);
+				clean(`${bad}.`, `${bad}__`);
 			}
 		});