Add bad-open-mode warning for invalid open modes specified on open/file calls.

1 files changed, 62 insertions, 0 deletions

diff --git a/checkers/stdlib.py b/checkers/stdlib.py
new file mode 100644
index 000000000..364633b74
--- /dev/null
+++ b/checkers/stdlib.py
@@ -0,0 +1,62 @@
+# Copyright 2012 Google Inc.
+#
+# http://www.logilab.fr/ -- mailto:contact@logilab.fr
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+"""Checkers for various standard library functions."""
+
+import re
+
+import astroid
+
+from pylint.interfaces import ITokenChecker, IAstroidChecker
+from pylint.checkers import BaseChecker, BaseTokenChecker
+from pylint.checkers import utils
+
+_VALID_OPEN_MODE_REGEX = r'^(r?U|[rwa]\+?b?)$'
+
+
+class OpenModeChecker(BaseChecker):
+    __implements__ = (IAstroidChecker,)
+    name = 'open_mode'
+
+    msgs = {
+        'W1501': ('"%s" is not a valid mode for open.',
+                  'bad-open-mode',
+                  'Python supports: r, w, a modes with b, +, and U options. '
+                  'See http://docs.python.org/2/library/functions.html#open'),
+        }
+    
+    @utils.check_messages('W1501')
+    def visit_callfunc(self, node):
+        """Visit a CallFunc node."""
+        if (hasattr(node, 'func') and utils.is_builtin_object(utils.safe_infer(node.func))):
+            if getattr(node.func, 'name', None) in ('open', 'file'):
+                self._check_open_mode(node)
+
+    def _check_open_mode(self, node):
+        """Check that the mode argument of an open or file call is valid."""
+        try:
+            mode_arg = utils.get_argument_from_call(node, position=1, keyword='mode')
+            if mode_arg:
+                mode_arg = utils.safe_infer(mode_arg)
+                if (isinstance(mode_arg, astroid.Const)
+                    and not re.match(_VALID_OPEN_MODE_REGEX, mode_arg.value)):
+                    self.add_message('W1501', node=node, args=(mode_arg.value))
+        except (utils.NoSuchArgumentError, TypeError):
+            pass
+
+def register(linter):
+    """required method to auto register this checker """
+    linter.register_checker(OpenModeChecker(linter))
+