From a363509fbb5b0fc72c1ae43369640ce21b03a041 Mon Sep 17 00:00:00 2001
From: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Date: Sun, 5 Jul 2015 08:48:40 +0000
Subject: [PATCH] path: Throwing error on zero length strings

The path module's `'join', 'normalize', 'isAbsolute', 'relative'`
functions return/use the current directory or ignore the path,
if they are passed zero length strings.

    > process.version
    'v2.3.4-pre'
    > path.join('')
    '.'
    > path.win32.join('')
    '.'
    > path.posix.join('')
    '.'
    > path.win32.normalize('')
    '.'
    > path.posix.normalize('')
    '.'
    > path.win32.isAbsolute('')
    false
    > path.posix.isAbsolute('')
    false
    > path.win32.relative('', '')
    ''
    > path.posix.relative('', '')
    ''
    > path.win32relative('.', '')
    ''
    > path.posix.relative('.', '')
    ''

But that is unintuitive. This PR throws an error if any of the
parameters to those functions are zero length strings.
---
 lib/path.js                | 14 ++++++++------
 test/parallel/test-path.js | 18 ++++++++++++++++--
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/lib/path.js b/lib/path.js
index b7e28b22250791..6041ae7e405cf6 100644
--- a/lib/path.js
+++ b/lib/path.js
@@ -3,10 +3,12 @@
 const util = require('util');
 const isWindows = process.platform === 'win32';
 
-function assertPath(path) {
+function assertPath(path, allowEmpty) {
   if (typeof path !== 'string') {
     throw new TypeError('Path must be a string. Received ' +
                         util.inspect(path));
+  } else if (!path && !allowEmpty) {
+    throw new Error('path must not be a zero length string');
   }
 }
 
@@ -92,7 +94,7 @@ win32.resolve = function() {
       }
     }
 
-    assertPath(path);
+    assertPath(path, true);
 
     // Skip empty entries
     if (path === '') {
@@ -410,7 +412,7 @@ posix.resolve = function() {
   for (var i = arguments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
     var path = (i >= 0) ? arguments[i] : process.cwd();
 
-    assertPath(path);
+    assertPath(path, true);
 
     // Skip empty entries
     if (path === '') {
@@ -463,9 +465,9 @@ posix.join = function() {
   var path = '';
   for (var i = 0; i < arguments.length; i++) {
     var segment = arguments[i];
-    if (typeof segment !== 'string') {
-      throw new TypeError('Arguments to path.join must be strings');
-    }
+
+    assertPath(segment, true);
+
     if (segment) {
       if (!path) {
         path += segment;
diff --git a/test/parallel/test-path.js b/test/parallel/test-path.js
index b1209d762a53d3..9fd5daf0d600fa 100644
--- a/test/parallel/test-path.js
+++ b/test/parallel/test-path.js
@@ -178,8 +178,6 @@ var joinTests =
      [['/', '.'], '/'],
      [['/', '..'], '/'],
      [['/', '..', '..'], '/'],
-     [[''], '.'],
-     [['', ''], '.'],
      [[' /foo'], ' /foo'],
      [[' ', 'foo'], ' /foo'],
      [[' ', '.'], ' '],
@@ -413,3 +411,19 @@ if (isWindows)
   assert.deepEqual(path, path.win32, 'should be win32 path module');
 else
   assert.deepEqual(path, path.posix, 'should be posix path module');
+
+const err = /path must not be a zero length string/;
+const os = ['win32', 'posix'];
+const functions = ['join', 'normalize', 'isAbsolute', 'relative'];
+const params = [[['']], [['']], [['']], [['', ''], ['.', ''], ['', '.']]];
+
+os.forEach(function(os) {
+  functions.forEach(function(fn, idx) {
+    params[idx].forEach(function(args) {
+      const call = `path.${os}.${fn}(${args.map(JSON.stringify).join(', ')})`;
+      assert.throws(function() {
+        path[os][fn].apply(null, args);
+      }, err, `${call} didn't throw expected Error`);
+    });
+  });
+});