Replace utils.ensure_(str|unicode) with strutils.safe(decode|encode)

Glanceclient implemented both functions before they landed into oslo.
Since both functions are already in oslo, it is now possible to pull
them in.

There's a small difference between glance's implementation and oslo's,
that is the later does not convert non-str objects - int, bool - to str
before trying to decode / encode them. This patch takes care of that
where necessary, more precisely, while encoding headers before doing a
new request.

Fixes bug: #1172253

Change-Id: I9a0dca31140bae28d8ec6aede515c5bb852b701b

glanceclient/openstack/common/strutils.py

@@ -0,0 +1,150 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011 OpenStack Foundation.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+System-level utilities and helper functions.
+"""
+
+import sys
+
+from glanceclient.openstack.common.gettextutils import _
+
+
+TRUE_STRINGS = ('1', 't', 'true', 'on', 'y', 'yes')
+FALSE_STRINGS = ('0', 'f', 'false', 'off', 'n', 'no')
+
+
+def int_from_bool_as_string(subject):
+    """
+    Interpret a string as a boolean and return either 1 or 0.
+
+    Any string value in:
+
+        ('True', 'true', 'On', 'on', '1')
+
+    is interpreted as a boolean True.
+
+    Useful for JSON-decoded stuff and config file parsing
+    """
+    return bool_from_string(subject) and 1 or 0
+
+
+def bool_from_string(subject, strict=False):
+    """
+    Interpret a string as a boolean.
+
+    A case-insensitive match is performed such that strings matching 't',
+    'true', 'on', 'y', 'yes', or '1' are considered True and, when
+    `strict=False`, anything else is considered False.
+
+    Useful for JSON-decoded stuff and config file parsing.
+
+    If `strict=True`, unrecognized values, including None, will raise a
+    ValueError which is useful when parsing values passed in from an API call.
+    Strings yielding False are 'f', 'false', 'off', 'n', 'no', or '0'.
+    """
+    if not isinstance(subject, basestring):
+        subject = str(subject)
+
+    lowered = subject.strip().lower()
+
+    if lowered in TRUE_STRINGS:
+        return True
+    elif lowered in FALSE_STRINGS:
+        return False
+    elif strict:
+        acceptable = ', '.join(
+            "'%s'" % s for s in sorted(TRUE_STRINGS + FALSE_STRINGS))
+        msg = _("Unrecognized value '%(val)s', acceptable values are:"
+                " %(acceptable)s") % {'val': subject,
+                                      'acceptable': acceptable}
+        raise ValueError(msg)
+    else:
+        return False
+
+
+def safe_decode(text, incoming=None, errors='strict'):
+    """
+    Decodes incoming str using `incoming` if they're
+    not already unicode.
+
+    :param incoming: Text's current encoding
+    :param errors: Errors handling policy. See here for valid
+        values http://docs.python.org/2/library/codecs.html
+    :returns: text or a unicode `incoming` encoded
+                representation of it.
+    :raises TypeError: If text is not an isntance of basestring
+    """
+    if not isinstance(text, basestring):
+        raise TypeError("%s can't be decoded" % type(text))
+
+    if isinstance(text, unicode):
+        return text
+
+    if not incoming:
+        incoming = (sys.stdin.encoding or
+                    sys.getdefaultencoding())
+
+    try:
+        return text.decode(incoming, errors)
+    except UnicodeDecodeError:
+        # Note(flaper87) If we get here, it means that
+        # sys.stdin.encoding / sys.getdefaultencoding
+        # didn't return a suitable encoding to decode
+        # text. This happens mostly when global LANG
+        # var is not set correctly and there's no
+        # default encoding. In this case, most likely
+        # python will use ASCII or ANSI encoders as
+        # default encodings but they won't be capable
+        # of decoding non-ASCII characters.
+        #
+        # Also, UTF-8 is being used since it's an ASCII
+        # extension.
+        return text.decode('utf-8', errors)
+
+
+def safe_encode(text, incoming=None,
+                encoding='utf-8', errors='strict'):
+    """
+    Encodes incoming str/unicode using `encoding`. If
+    incoming is not specified, text is expected to
+    be encoded with current python's default encoding.
+    (`sys.getdefaultencoding`)
+
+    :param incoming: Text's current encoding
+    :param encoding: Expected encoding for text (Default UTF-8)
+    :param errors: Errors handling policy. See here for valid
+        values http://docs.python.org/2/library/codecs.html
+    :returns: text or a bytestring `encoding` encoded
+                representation of it.
+    :raises TypeError: If text is not an isntance of basestring
+    """
+    if not isinstance(text, basestring):
+        raise TypeError("%s can't be encoded" % type(text))
+
+    if not incoming:
+        incoming = (sys.stdin.encoding or
+                    sys.getdefaultencoding())
+
+    if isinstance(text, unicode):
+        return text.encode(encoding, errors)
+    elif text and encoding != incoming:
+        # Decode text before encoding it with `encoding`
+        text = safe_decode(text, incoming, errors)
+        return text.encode(encoding, errors)
+
+    return text