path: fix win32.isAbsolute() inconsistency

This commit fixes an inconsistency in absolute path checking compared
to the absolute path detection used by the other path.win32 functions.

Fixes: https://github.com/nodejs/node/issues/6027
PR-URL: https://github.com/nodejs/node/pull/6028
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/path.js

@@ -439,57 +439,17 @@ const win32 = {
     if (len === 0)
       return false;
     var code = path.charCodeAt(0);
-    if (len > 1) {
-      if (code === 47/*/*/ || code === 92/*\*/) {
-        // Possible UNC root
-
-        code = path.charCodeAt(1);
-        if (code === 47/*/*/ || code === 92/*\*/) {
-          // Matched double path separator at beginning
-          var j = 2;
-          var last = j;
-          // Match 1 or more non-path separators
-          for (; j < len; ++j) {
-            code = path.charCodeAt(j);
-            if (code === 47/*/*/ || code === 92/*\*/)
-              break;
-          }
-          if (j < len && j !== last) {
-            // Matched!
-            last = j;
-            // Match 1 or more path separators
-            for (; j < len; ++j) {
-              code = path.charCodeAt(j);
-              if (code !== 47/*/*/ && code !== 92/*\*/)
-                break;
-            }
-            if (j < len && j !== last) {
-              // Matched!
-              last = j;
-              // Match 1 or more non-path separators
-              for (; j < len; ++j) {
-                code = path.charCodeAt(j);
-                if (code === 47/*/*/ || code === 92/*\*/)
-                  break;
-              }
-              if (j !== last)
-                return true;
-            }
-          }
-        }
-      } else if ((code >= 65/*A*/ && code <= 90/*Z*/) ||
-                 (code >= 97/*a*/ && code <= 122/*z*/)) {
-        // Possible device root
-
-        code = path.charCodeAt(1);
-        if (path.charCodeAt(1) === 58/*:*/ && len > 2) {
-          code = path.charCodeAt(2);
-          if (code === 47/*/*/ || code === 92/*\*/)
-            return true;
-        }
-      }
-    } else if (code === 47/*/*/ || code === 92/*\*/) {
+    if (code === 47/*/*/ || code === 92/*\*/) {
       return true;
+    } else if ((code >= 65/*A*/ && code <= 90/*Z*/) ||
+               (code >= 97/*a*/ && code <= 122/*z*/)) {
+      // Possible device root
+
+      if (len > 2 && path.charCodeAt(1) === 58/*:*/) {
+        code = path.charCodeAt(2);
+        if (code === 47/*/*/ || code === 92/*\*/)
+          return true;
+      }
     }
     return false;
   },

test/parallel/test-path.js

@@ -442,8 +442,18 @@ assert.equal(failures.length, 0, failures.join(''));
 
 
 // path.isAbsolute tests
+assert.equal(path.win32.isAbsolute('/'), true);
+assert.equal(path.win32.isAbsolute('//'), true);
+assert.equal(path.win32.isAbsolute('//server'), true);
 assert.equal(path.win32.isAbsolute('//server/file'), true);
 assert.equal(path.win32.isAbsolute('\\\\server\\file'), true);
+assert.equal(path.win32.isAbsolute('\\\\server'), true);
+assert.equal(path.win32.isAbsolute('\\\\'), true);
+assert.equal(path.win32.isAbsolute('c'), false);
+assert.equal(path.win32.isAbsolute('c:'), false);
+assert.equal(path.win32.isAbsolute('c:\\'), true);
+assert.equal(path.win32.isAbsolute('c:/'), true);
+assert.equal(path.win32.isAbsolute('c://'), true);
 assert.equal(path.win32.isAbsolute('C:/Users/'), true);
 assert.equal(path.win32.isAbsolute('C:\\Users\\'), true);
 assert.equal(path.win32.isAbsolute('C:cwd/another'), false);