Merge; Fix according to review

7 files changed, 72 insertions, 8 deletions

diff --git a/checkers/stdlib.py b/checkers/stdlib.py
index d8b5fde..54f8c1a 100644
--- a/checkers/stdlib.py
+++ b/checkers/stdlib.py
@@ -16,6 +16,7 @@
 """Checkers for various standard library functions."""
 
 import re
+import six
 import sys
 
 import astroid
@@ -25,13 +26,50 @@ from pylint.interfaces import IAstroidChecker
 from pylint.checkers import BaseChecker
 from pylint.checkers import utils
 
-_VALID_OPEN_MODE_REGEX = re.compile(r'^(r?U|[rwa]\+?b?)$')
 
 if sys.version_info >= (3, 0):
     OPEN_MODULE = '_io'
 else:
     OPEN_MODULE = '__builtin__'
 
+
+def _check_mode_str(mode):
+    # check type
+    if not isinstance(mode, six.string_types):
+        return False
+    # check syntax
+    modes = set(mode)
+    _mode = "rwatb+U"
+    if six.PY3:
+        _mode += "x"
+        creating = "x" in modes
+    if modes - set(_mode) or len(mode) > len(modes):
+        return False
+    # check logic
+    creating = False
+    reading = "r" in modes
+    writing = "w" in modes
+    appending = "a" in modes
+    updating = "+" in modes
+    text = "t" in modes
+    binary = "b" in modes
+    if "U" in modes:
+        if writing or appending or creating and six.PY3:
+            return False
+        reading = True
+    if text and binary:
+        return False
+    total = reading + writing + appending + (creating if six.PY3 else 0)
+    if total > 1:
+        return False
+    if not (reading or writing or appending or creating and six.PY3):
+        return False
+    # 2.x constraints
+    if not six.PY3:
+        return mode[0] in ("r", "w", "a", "U")
+    return True
+
+
 class StdlibChecker(BaseChecker):
     __implements__ = (IAstroidChecker,)
     name = 'stdlib'
@@ -89,6 +127,7 @@ class StdlibChecker(BaseChecker):
                 infered.qname() == 'datetime.time'):
             self.add_message('boolean-datetime', node=node)
 
+
     def _check_open_mode(self, node):
         """Check that the mode argument of an open or file call is valid."""
         try:
@@ -96,7 +135,7 @@ class StdlibChecker(BaseChecker):
             if mode_arg:
                 mode_arg = utils.safe_infer(mode_arg)
                 if (isinstance(mode_arg, astroid.Const)
-                        and not _VALID_OPEN_MODE_REGEX.match(mode_arg.value)):
+                        and not _check_mode_str(mode_arg.value)):
                     self.add_message('bad-open-mode', node=node,
                                      args=(mode_arg.value))
         except (utils.NoSuchArgumentError, TypeError):
@@ -105,4 +144,3 @@ class StdlibChecker(BaseChecker):
 def register(linter):
     """required method to auto register this checker """
     linter.register_checker(StdlibChecker(linter))
-
diff --git a/test/functional/bad_open_mode.py b/test/functional/bad_open_mode.py
index dfbf037..26d25c9 100644
--- a/test/functional/bad_open_mode.py
+++ b/test/functional/bad_open_mode.py
@@ -4,10 +4,15 @@ open('foo.bar', 'w', 2)
 open('foo.bar', 'rw')  # [bad-open-mode]
 open(name='foo.bar', buffering=10, mode='rw')  # [bad-open-mode]
 open(mode='rw', name='foo.bar')  # [bad-open-mode]
-open('foo.bar', 'U+')  # [bad-open-mode]
-open('foo.bar', 'rb+')  # [bad-open-mode]
+open('foo.bar', 'U+')
+open('foo.bar', 'rb+')
 open('foo.bar', 'Uw')  # [bad-open-mode]
-open('foo.bar', 2)
+open('foo.bar', 2)  # [bad-open-mode]
 open('foo.bar', buffering=2)
 WRITE_MODE = 'w'
 open('foo.bar', 'U' + WRITE_MODE + 'z')  # [bad-open-mode]
+open('foo.bar', 'br')  # [bad-open-mode]
+open('foo.bar', 'wU') # [bad-open-mode]
+open('foo.bar', 'r+b')
+open('foo.bar', 'r+')
+open('foo.bar', 'w+')
diff --git a/test/functional/bad_open_mode.rc b/test/functional/bad_open_mode.rc
new file mode 100644
index 0000000..b9ab977
--- /dev/null
+++ b/test/functional/bad_open_mode.rc
@@ -0,0 +1,2 @@
+[testoptions]

+max_pyver=3.0

diff --git a/test/functional/bad_open_mode.txt b/test/functional/bad_open_mode.txt
index d0bb8bb..cd8c14b 100644
--- a/test/functional/bad_open_mode.txt
+++ b/test/functional/bad_open_mode.txt
@@ -1,7 +1,8 @@
 bad-open-mode:4::"""rw"" is not a valid mode for open."
 bad-open-mode:5::"""rw"" is not a valid mode for open."
 bad-open-mode:6::"""rw"" is not a valid mode for open."
-bad-open-mode:7::"""U+"" is not a valid mode for open."
-bad-open-mode:8::"""rb+"" is not a valid mode for open."
 bad-open-mode:9::"""Uw"" is not a valid mode for open."
+bad-open-mode:10::"""2"" is not a valid mode for open."
 bad-open-mode:13::"""Uwz"" is not a valid mode for open."
+bad-open-mode:14::"""br"" is not a valid mode for open."
+bad-open-mode:15::"""wU"" is not a valid mode for open."
diff --git a/test/functional/bad_open_mode_py3.py b/test/functional/bad_open_mode_py3.py
new file mode 100644
index 0000000..c8bfb0e
--- /dev/null
+++ b/test/functional/bad_open_mode_py3.py
@@ -0,0 +1,13 @@
+"""Warnings for using open() with an invalid mode string."""

+

+NAME = "foo.bar"

+open(NAME, "wb")

+open(NAME, "w")

+open(NAME, "rb")

+open(NAME, "x")

+open(NAME, "br")

+open(NAME, "+r")

+open(NAME, "xb")

+open(NAME, "rwx")  # [bad-open-mode]

+open(NAME, "rr")  # [bad-open-mode]

+open(NAME, "+")  # [bad-open-mode]

diff --git a/test/functional/bad_open_mode_py3.rc b/test/functional/bad_open_mode_py3.rc
new file mode 100644
index 0000000..c4033f8
--- /dev/null
+++ b/test/functional/bad_open_mode_py3.rc
@@ -0,0 +1,2 @@
+[testoptions]

+min_pyver=3.0

diff --git a/test/functional/bad_open_mode_py3.txt b/test/functional/bad_open_mode_py3.txt
new file mode 100644
index 0000000..d712ec5
--- /dev/null
+++ b/test/functional/bad_open_mode_py3.txt
@@ -0,0 +1,3 @@
+bad-open-mode:11::"""rwx"" is not a valid mode for open."

+bad-open-mode:12::"""rr"" is not a valid mode for open."

+bad-open-mode:13::"""+"" is not a valid mode for open."