Add ability for salt.utils.path_join to force the use of posixpath

Also remove unused and unnecessary behavior from this function when the
first path component is of single length. An empty first parameter to
this function will normalze to "." and result in an incorrectly-joined
result.

salt/utils/__init__.py

@@ -18,6 +18,7 @@ import json
 import logging
 import numbers
 import os
+import posixpath
 import pprint
 import random
 import re
@@ -870,16 +871,26 @@ def backup_minion(path, bkroot):
         os.chmod(bkpath, fstat.st_mode)
 
 
-def path_join(*parts):
+def path_join(*parts, **kwargs):
     '''
     This functions tries to solve some issues when joining multiple absolute
     paths on both *nix and windows platforms.
 
     See tests/unit/utils/path_join_test.py for some examples on what's being
     talked about here.
+
+    The "use_posixpath" kwarg can be be used to force joining using poxixpath,
+    which is useful for Salt fileserver paths on Windows masters.
     '''
+    kwargs = salt.utils.clean_kwargs(**kwargs)
+    use_posixpath = kwargs.pop('use_posixpath', False)
+    if kwargs:
+        invalid_kwargs(kwargs)
+
+    pathlib = posixpath if use_posixpath else os.path
+
     # Normalize path converting any os.sep as needed
-    parts = [os.path.normpath(p) for p in parts]
+    parts = [pathlib.normpath(p) for p in parts]
 
     try:
         root = parts.pop(0)
@@ -890,14 +901,9 @@ def path_join(*parts):
     if not parts:
         ret = root
     else:
-        if is_windows():
-            if len(root) == 1:
-                root += ':'
-            root = root.rstrip(os.sep) + os.sep
-
         stripped = [p.lstrip(os.sep) for p in parts]
         try:
-            ret = os.path.join(root, *stripped)
+            ret = pathlib.join(root, *stripped)
         except UnicodeDecodeError:
             # This is probably Python 2 and one of the parts contains unicode
             # characters in a bytestring. First try to decode to the system
@@ -907,13 +913,13 @@ def path_join(*parts):
             except NameError:
                 enc = sys.stdin.encoding or sys.getdefaultencoding()
             try:
-                ret = os.path.join(root.decode(enc),
+                ret = pathlib.join(root.decode(enc),
                                    *[x.decode(enc) for x in stripped])
             except UnicodeDecodeError:
                 # Last resort, try UTF-8
-                ret = os.path.join(root.decode('UTF-8'),
+                ret = pathlib.join(root.decode('UTF-8'),
                                    *[x.decode('UTF-8') for x in stripped])
-    return os.path.normpath(ret)
+    return pathlib.normpath(ret)
 
 
 def pem_finger(path=None, key=None, sum_type='sha256'):

tests/unit/utils/path_join_test.py

@@ -48,7 +48,6 @@ class PathJoinTestCase(TestCase):
         ((r'c:\\', r'\temp', r'\foo'), 'c:\\temp\\foo'),
         (('c:', r'\temp', r'\foo', 'bar'), 'c:\\temp\\foo\\bar'),
         (('c:', r'\temp', r'\foo\bar'), 'c:\\temp\\foo\\bar'),
-        (('c', r'\temp', r'\foo\bar'), 'c:\\temp\\foo\\bar')
     )
 
     @skipIf(True, 'Skipped until properly mocked')