path: fix win32 volume-relative paths

`path.resolve()` and `path.join()` are left alone in this commit due to
the lack of clear semantics.

PR-URL: https://github.com/nodejs/node/pull/14440
Fixes: https://github.com/nodejs/node/issues/14405
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

lib/path.js

@@ -908,6 +908,7 @@ const win32 = {
 
   extname: function extname(path) {
     assertPath(path);
+    var start = 0;
     var startDot = -1;
     var startPart = 0;
     var end = -1;
@@ -915,7 +916,20 @@ const win32 = {
     // Track the state of characters (if any) we see before our first dot and
     // after any path separator we find
     var preDotState = 0;
-    for (var i = path.length - 1; i >= 0; --i) {
+
+    // Check for a drive letter prefix so as not to mistake the following
+    // path separator as an extra separator at the end of the path that can be
+    // disregarded
+    if (path.length >= 2) {
+      const code = path.charCodeAt(0);
+      if (path.charCodeAt(1) === 58/*:*/ &&
+          ((code >= 65/*A*/ && code <= 90/*Z*/) ||
+           (code >= 97/*a*/ && code <= 122/*z*/))) {
+        start = startPart = 2;
+      }
+    }
+
+    for (var i = path.length - 1; i >= start; --i) {
       const code = path.charCodeAt(i);
       if (code === 47/*/*/ || code === 92/*\*/) {
         // If we reached a path separator that was not part of a set of path
@@ -978,15 +992,12 @@ const win32 = {
     var len = path.length;
     var rootEnd = 0;
     var code = path.charCodeAt(0);
-    var isAbsolute = false;
 
     // Try to match a root
     if (len > 1) {
       if (code === 47/*/*/ || code === 92/*\*/) {
         // Possible UNC root
 
-        isAbsolute = true;
-
         code = path.charCodeAt(1);
         rootEnd = 1;
         if (code === 47/*/*/ || code === 92/*\*/) {
@@ -1045,7 +1056,6 @@ const win32 = {
                 ret.root = ret.dir = path;
                 return ret;
               }
-              isAbsolute = true;
               rootEnd = 3;
             }
           } else {
@@ -1067,7 +1077,7 @@ const win32 = {
       ret.root = path.slice(0, rootEnd);
 
     var startDot = -1;
-    var startPart = 0;
+    var startPart = rootEnd;
     var end = -1;
     var matchedSlash = true;
     var i = path.length - 1;
@@ -1116,26 +1126,21 @@ const win32 = {
          startDot === end - 1 &&
          startDot === startPart + 1)) {
       if (end !== -1) {
-        if (startPart === 0 && isAbsolute)
+        ret.base = ret.name = path.slice(startPart, end);
-          ret.base = ret.name = path.slice(rootEnd, end);
-        else
-          ret.base = ret.name = path.slice(startPart, end);
       }
     } else {
-      if (startPart === 0 && isAbsolute) {
+      ret.name = path.slice(startPart, startDot);
-        ret.name = path.slice(rootEnd, startDot);
+      ret.base = path.slice(startPart, end);
-        ret.base = path.slice(rootEnd, end);
-      } else {
-        ret.name = path.slice(startPart, startDot);
-        ret.base = path.slice(startPart, end);
-      }
       ret.ext = path.slice(startDot, end);
     }
 
-    if (startPart > 0)
+    // If the directory is the root, use the entire root as the `dir` including
+    // the trailing slash if any (`C:\abc` -> `C:\`). Otherwise, strip out the
+    // trailing slash (`C:\abc\def` -> `C:\abc`).
+    if (startPart > 0 && startPart !== rootEnd)
       ret.dir = path.slice(0, startPart - 1);
-    else if (isAbsolute)
+    else
-      ret.dir = path.slice(0, rootEnd);
+      ret.dir = ret.root;
 
     return ret;
   },

test/parallel/test-path-parse-format.js

@@ -25,28 +25,33 @@ const assert = require('assert');
 const path = require('path');
 
 const winPaths = [
-  'C:\\path\\dir\\index.html',
+  // [path, root]
-  'C:\\another_path\\DIR\\1\\2\\33\\\\index',
+  ['C:\\path\\dir\\index.html', 'C:\\'],
-  'another_path\\DIR with spaces\\1\\2\\33\\index',
+  ['C:\\another_path\\DIR\\1\\2\\33\\\\index', 'C:\\'],
-  '\\foo\\C:',
+  ['another_path\\DIR with spaces\\1\\2\\33\\index', ''],
-  'file',
+  ['\\', '\\'],
-  '.\\file',
+  ['\\foo\\C:', '\\'],
-  'C:\\',
+  ['file', ''],
-  'C:',
+  ['file:stream', ''],
-  '\\',
+  ['.\\file', ''],
-  '',
+  ['C:', 'C:'],
+  ['C:.', 'C:'],
+  ['C:..', 'C:'],
+  ['C:abc', 'C:'],
+  ['C:\\', 'C:\\'],
+  ['C:\\abc', 'C:\\' ],
+  ['', ''],
 
   // unc
-  '\\\\server\\share\\file_path',
+  ['\\\\server\\share\\file_path', '\\\\server\\share\\'],
-  '\\\\server two\\shared folder\\file path.zip',
+  ['\\\\server two\\shared folder\\file path.zip',
-  '\\\\teela\\admin$\\system32',
+   '\\\\server two\\shared folder\\'],
-  '\\\\?\\UNC\\server\\share'
+  ['\\\\teela\\admin$\\system32', '\\\\teela\\admin$\\'],
+  ['\\\\?\\UNC\\server\\share', '\\\\?\\UNC\\']
 ];
 
 const winSpecialCaseParseTests = [
   ['/foo/bar', { root: '/' }],
-  ['C:', { root: 'C:', dir: 'C:', base: '' }],
-  ['C:\\', { root: 'C:\\', dir: 'C:\\', base: '' }]
 ];
 
 const winSpecialCaseFormatTests = [
@@ -60,26 +65,27 @@ const winSpecialCaseFormatTests = [
 ];
 
 const unixPaths = [
-  '/home/user/dir/file.txt',
+  // [path, root]
-  '/home/user/a dir/another File.zip',
+  ['/home/user/dir/file.txt', '/'],
-  '/home/user/a dir//another&File.',
+  ['/home/user/a dir/another File.zip', '/'],
-  '/home/user/a$$$dir//another File.zip',
+  ['/home/user/a dir//another&File.', '/'],
-  'user/dir/another File.zip',
+  ['/home/user/a$$$dir//another File.zip', '/'],
-  'file',
+  ['user/dir/another File.zip', ''],
-  '.\\file',
+  ['file', ''],
-  './file',
+  ['.\\file', ''],
-  'C:\\foo',
+  ['./file', ''],
-  '/',
+  ['C:\\foo', ''],
-  '',
+  ['/', '/'],
-  '.',
+  ['', ''],
-  '..',
+  ['.', ''],
-  '/foo',
+  ['..', ''],
-  '/foo.',
+  ['/foo', '/'],
-  '/foo.bar',
+  ['/foo.', '/'],
-  '/.',
+  ['/foo.bar', '/'],
-  '/.foo',
+  ['/.', '/'],
-  '/.foo.bar',
+  ['/.foo', '/'],
-  '/foo/bar.baz',
+  ['/.foo.bar', '/'],
+  ['/foo/bar.baz', '/']
 ];
 
 const unixSpecialCaseFormatTests = [
@@ -182,7 +188,7 @@ function checkErrors(path) {
 }
 
 function checkParseFormat(path, paths) {
-  paths.forEach(function(element) {
+  paths.forEach(function([element, root]) {
     const output = path.parse(element);
     assert.strictEqual(typeof output.root, 'string');
     assert.strictEqual(typeof output.dir, 'string');
@@ -190,6 +196,8 @@ function checkParseFormat(path, paths) {
     assert.strictEqual(typeof output.ext, 'string');
     assert.strictEqual(typeof output.name, 'string');
     assert.strictEqual(path.format(output), element);
+    assert.strictEqual(output.root, root);
+    assert(output.dir.startsWith(output.root));
     assert.strictEqual(output.dir, output.dir ? path.dirname(element) : '');
     assert.strictEqual(output.base, path.basename(element));
     assert.strictEqual(output.ext, path.extname(element));

test/parallel/test-path.js

@@ -72,6 +72,16 @@ assert.strictEqual(path.win32.basename('aaa\\bbb', 'bbb'), 'bbb');
 assert.strictEqual(path.win32.basename('aaa\\bbb\\\\\\\\', 'bbb'), 'bbb');
 assert.strictEqual(path.win32.basename('aaa\\bbb', 'bb'), 'b');
 assert.strictEqual(path.win32.basename('aaa\\bbb', 'b'), 'bb');
+assert.strictEqual(path.win32.basename('C:'), '');
+assert.strictEqual(path.win32.basename('C:.'), '.');
+assert.strictEqual(path.win32.basename('C:\\'), '');
+assert.strictEqual(path.win32.basename('C:\\dir\\base.ext'), 'base.ext');
+assert.strictEqual(path.win32.basename('C:\\basename.ext'), 'basename.ext');
+assert.strictEqual(path.win32.basename('C:basename.ext'), 'basename.ext');
+assert.strictEqual(path.win32.basename('C:basename.ext\\'), 'basename.ext');
+assert.strictEqual(path.win32.basename('C:basename.ext\\\\'), 'basename.ext');
+assert.strictEqual(path.win32.basename('C:foo'), 'foo');
+assert.strictEqual(path.win32.basename('file:stream'), 'file:stream');
 
 // On unix a backslash is just treated as any other character.
 assert.strictEqual(path.posix.basename('\\dir\\basename.ext'),
@@ -120,6 +130,8 @@ assert.strictEqual(path.win32.dirname('c:foo\\'), 'c:');
 assert.strictEqual(path.win32.dirname('c:foo\\bar'), 'c:foo');
 assert.strictEqual(path.win32.dirname('c:foo\\bar\\'), 'c:foo');
 assert.strictEqual(path.win32.dirname('c:foo\\bar\\baz'), 'c:foo\\bar');
+assert.strictEqual(path.win32.dirname('file:stream'), '.');
+assert.strictEqual(path.win32.dirname('dir\\file:stream'), 'dir');
 assert.strictEqual(path.win32.dirname('\\\\unc\\share'),
                    '\\\\unc\\share');
 assert.strictEqual(path.win32.dirname('\\\\unc\\share\\foo'),
@@ -187,6 +199,7 @@ assert.strictEqual(path.win32.dirname('foo'), '.');
   ['file./', '.'],
   ['file.//', '.'],
 ].forEach((test) => {
+  const expected = test[1];
   [path.posix.extname, path.win32.extname].forEach((extname) => {
     let input = test[0];
     let os;
@@ -197,12 +210,19 @@ assert.strictEqual(path.win32.dirname('foo'), '.');
       os = 'posix';
     }
     const actual = extname(input);
-    const expected = test[1];
     const message = `path.${os}.extname(${JSON.stringify(input)})\n  expect=${
       JSON.stringify(expected)}\n  actual=${JSON.stringify(actual)}`;
     if (actual !== expected)
       failures.push(`\n${message}`);
   });
+  {
+    const input = `C:${test[0].replace(slashRE, '\\')}`;
+    const actual = path.win32.extname(input);
+    const message = `path.win32.extname(${JSON.stringify(input)})\n  expect=${
+      JSON.stringify(expected)}\n  actual=${JSON.stringify(actual)}`;
+    if (actual !== expected)
+      failures.push(`\n${message}`);
+  }
 });
 assert.strictEqual(failures.length, 0, failures.join(''));
 
@@ -406,6 +426,12 @@ assert.strictEqual(path.win32.normalize('a//b//.'), 'a\\b');
 assert.strictEqual(path.win32.normalize('//server/share/dir/file.ext'),
                    '\\\\server\\share\\dir\\file.ext');
 assert.strictEqual(path.win32.normalize('/a/b/c/../../../x/y/z'), '\\x\\y\\z');
+assert.strictEqual(path.win32.normalize('C:'), 'C:.');
+assert.strictEqual(path.win32.normalize('C:..\\abc'), 'C:..\\abc');
+assert.strictEqual(path.win32.normalize('C:..\\..\\abc\\..\\def'),
+                   'C:..\\..\\def');
+assert.strictEqual(path.win32.normalize('C:\\.'), 'C:\\');
+assert.strictEqual(path.win32.normalize('file:stream'), 'file:stream');
 
 assert.strictEqual(path.posix.normalize('./fixtures///b/../b/c.js'),
                    'fixtures/b/c.js');