Merge pull request #365 from christian-intra2net/encoding-for-non-unicode-environments

Encoding for non unicode environments

Merge pull request #365 from christian-intra2net/encoding-for-non-unicode-environments
Encoding for non unicode environments
Philippe Lagadec · GitHub
2 parents afeead80 0b3af2da
Showing 9 changed files with 484 additions and 66 deletions
oletools/common/io_encoding.py
oletools/common/log_helper/log_helper.py
oletools/msodde.py
oletools/olemeta.py
oletools/oleobj.py
oletools/olevba.py
oletools/ooxml.py
tests/common/test_encoding_handler.py
tests/oleobj/test_basic.py
+#!/usr/bin/env python3
+
+"""
+Tool to help with input/output encoding
+
+Helpers to run smoothly in unicode-unfriendly environments like output redirect
+or unusual language settings.
+
+In such settings, output to console falls back to ASCII-only. Also open()
+suddenly fails to interprete non-ASCII characters.
+
+Therefore, at start of scripts can run :py:meth:`ensure_stdout_handles_unicode`
+and when opening text files use :py:meth:`uopen` to replace :py:meth:`open`.
+
+Part of the python-oletools package:
+http://www.decalage.info/python/oletools
+"""
+
+# === LICENSE =================================================================
+
+# msodde is copyright (c) 2017-2018 Philippe Lagadec (http://www.decalage.info)
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice,
+#    this list of conditions and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice,
+#    this list of conditions and the following disclaimer in the documentation
+#    and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+# -----------------------------------------------------------------------------
+# CHANGELOG:
+# 2018-11-04 v0.54 CH: - first version: ensure_stdout_handles_unicode, uopen
+
+# -- IMPORTS ------------------------------------------------------------------
+from __future__ import print_function
+import sys
+import codecs
+import os
+from locale import getpreferredencoding
+
+PY3 = sys.version_info.major >= 3
+
+if PY3:
+    from builtins import open as builtin_open
+else:
+    from __builtin__ import open as builtin_open
+
+# -- CONSTANTS ----------------------------------------------------------------
+#: encoding to use for redirection if no good encoding can be found
+FALLBACK_ENCODING_REDIRECT = 'utf8'
+
+#: encoding for reading text from files if preferred encoding is non-unicode
+FALLBACK_ENCODING_OPEN = 'utf8'
+
+#: print (pure-ascii) debug output to stdout
+DEBUG = False
+
+# the encoding specified in system environment
+try:
+    PREFERRED_ENCODING = getpreferredencoding()
+except Exception as exc:
+    if DEBUG:
+        print('Exception getting preferred encoding: {}'.format(exc))
+    PREFERRED_ENCODING = None
+
+
+# -- HELPERS =-----------------------------------------------------------------
+
+
+def ensure_stdout_handles_unicode():
+    """
+    Ensure that print()ing unicode does not lead to errors.
+
+    When print()ing unicode, python relies on the environment (e.g. in linux on
+    the setting of the LANG environment variable) to tell it how to encode
+    unicode. That works nicely for modern-day shells where encoding is usually
+    UTF-8. But as soon as LANG is unset or just "C", or output is redirected or
+    piped, the encoding falls back to 'ASCII', which cannot handle unicode
+    characters.
+
+    Based on solutions suggested on stackoverflow (c.f.
+    https://stackoverflow.com/q/27347772/4405656 ), wrap stdout in an encoder
+    that solves that problem.
+
+    Unfortunately, stderr cannot be handled the same way ( see e.g. https://
+    pythonhosted.org/kitchen/unicode-frustrations.html#frustration-5-exceptions
+    ), so we still have to hope there is only ascii in error messages
+    """
+    # do not re-wrap
+    if isinstance(sys.stdout, codecs.StreamWriter):
+        if DEBUG:
+            print('sys.stdout wrapped already')
+        return
+
+    # get output stream object
+    if PY3:
+        output_stream = sys.stdout.buffer
+    else:
+        output_stream = sys.stdout
+
+    # determine encoding of sys.stdout
+    try:
+        encoding = sys.stdout.encoding
+    except AttributeError:              # variable "encoding" might not exist
+        encoding = None
+    if DEBUG:
+        print('sys.stdout encoding is {}'.format(encoding))
+
+    if isinstance(encoding, str) and encoding.lower().startswith('utf'):
+        if DEBUG:
+            print('encoding is acceptable')
+        return     # everything alright, we are working in a good environment
+    elif os.isatty(output_stream.fileno()):   # e.g. C locale
+        # Do not output UTF8 since that might be mis-interpreted.
+        # Just replace chars that cannot be handled
+        print('Encoding for stdout is only {}, will replace other chars to '
+              'avoid unicode error'.format(encoding), file=sys.stderr)
+        sys.stdout = codecs.getwriter(encoding)(output_stream, errors='replace')
+    else:                                  # e.g. redirection, pipe in python2
+        new_encoding = PREFERRED_ENCODING
+        if DEBUG:
+            print('not a tty, try preferred encoding {}'.format(new_encoding))
+        if not isinstance(new_encoding, str) \
+                or not new_encoding.lower().startswith('utf'):
+            new_encoding = FALLBACK_ENCODING_REDIRECT
+            if DEBUG:
+                print('preferred encoding also unacceptable, fall back to {}'
+                      .format(new_encoding))
+        print('Encoding for stdout is only {}, will auto-encode text with {} '
+              'before output'.format(encoding, new_encoding), file=sys.stderr)
+        sys.stdout = codecs.getwriter(new_encoding)(output_stream)
+
+
+def uopen(filename, mode='r', *args, **kwargs):
+    """
+    Replacement for builtin open() that reads unicode even in ASCII environment
+
+    In order to read unicode from text, python uses locale.getpreferredencoding
+    to translate bytes to str. If the environment only provides ASCII encoding,
+    this will fail since most office files contain unicode.
+
+    Therefore, guess a good encoding here if necessary and open file with that.
+
+    :returns: same type as the builtin :py:func:`open`
+    """
+    # do not interfere if not necessary:
+    if 'b' in mode:
+        if DEBUG:
+            print('Opening binary file, do not interfere')
+        return builtin_open(filename, mode, *args, **kwargs)
+    if 'encoding' in kwargs:
+        if DEBUG:
+            print('Opening file with encoding {!r}, do not interfere'
+                  .format(kwargs['encoding']))
+        return builtin_open(filename, mode, *args, **kwargs)
+    if len(args) > 3:    # "encoding" is the 4th arg
+        if DEBUG:
+            print('Opening file with encoding {!r}, do not interfere'
+                  .format(args[3]))
+        return builtin_open(filename, mode, *args, **kwargs)
+
+    # determine preferred encoding
+    encoding = PREFERRED_ENCODING
+    if DEBUG:
+        print('preferred encoding is {}'.format(encoding))
+
+    if isinstance(encoding, str) and encoding.lower().startswith('utf'):
+        if DEBUG:
+            print('encoding is acceptable, open {} regularly'.format(filename))
+        return builtin_open(filename, mode, *args, **kwargs)
+
+    # so we want to read text from a file but can probably only deal with ASCII
+    # --> use fallback
+    if DEBUG:
+        print('Opening {} with fallback encoding {}'
+              .format(filename, FALLBACK_ENCODING_OPEN))
+    if PY3:
+        return builtin_open(filename, mode, *args,
+                            encoding=FALLBACK_ENCODING_OPEN, **kwargs)
+    else:
+        handle = builtin_open(filename, mode, *args, **kwargs)
+        return codecs.EncodedFile(handle, FALLBACK_ENCODING_OPEN)
@@ -44,6 +44,7 @@ General logging helpers
 from ._json_formatter import JsonFormatter
 from ._logger_adapter import OletoolsLoggerAdapter
 from . import _root_logger_wrapper
+from ..io_encoding import ensure_stdout_handles_unicode
 import logging
 import sys
@@ -92,6 +93,9 @@ class LogHelper:
         if self._is_enabled:
             raise ValueError('re-enabling logging. Not sure whether that is ok...')
+        if stream in (None, sys.stdout):
+            ensure_stdout_handles_unicode()
+
         log_level = LOG_LEVELS[level]
         logging.basicConfig(level=log_level, format=log_format, stream=stream)
         self._is_enabled = True
@@ -74,6 +74,7 @@ from oletools import xls_parser
 from oletools import rtfobj
 from oletools.ppt_record_parser import is_ppt
 from oletools import crypto
+from oletools.common.io_encoding import ensure_stdout_handles_unicode
 from oletools.common.log_helper import log_helper
 # -----------------------------------------------------------------------------
@@ -236,57 +237,6 @@ DEFAULT_LOG_LEVEL = &quot;warning&quot;  # Default log level
 logger = log_helper.get_or_create_silent_logger('msodde')
-# === UNICODE IN PY2 =========================================================
-
-def ensure_stdout_handles_unicode():
-    """ Ensure stdout can handle unicode by wrapping it if necessary
-
-    Required e.g. if output of this script is piped or redirected in a linux
-    shell, since then sys.stdout.encoding is ascii and cannot handle
-    print(unicode). In that case we need to find some compatible encoding and
-    wrap sys.stdout into a encoder following (many thanks!)
-    https://stackoverflow.com/a/1819009 or https://stackoverflow.com/a/20447935
-
-    Can be undone by setting sys.stdout = sys.__stdout__
-    """
-    import codecs
-    import locale
-
-    # do not re-wrap
-    if isinstance(sys.stdout, codecs.StreamWriter):
-        return
-
-    # try to find encoding for sys.stdout
-    encoding = None
-    try:
-        encoding = sys.stdout.encoding
-    except AttributeError:              # variable "encoding" might not exist
-        pass
-
-    if encoding not in (None, '', 'ascii'):
-        return   # no need to wrap
-
-    # try to find an encoding that can handle unicode
-    try:
-        encoding = locale.getpreferredencoding()
-    except Exception:
-        pass
-
-    # fallback if still no encoding available
-    if encoding in (None, '', 'ascii'):
-        encoding = 'utf8'
-
-    # logging is probably not initialized yet, but just in case
-    logger.debug('wrapping sys.stdout with encoder using {0}'.format(encoding))
-
-    wrapper = codecs.getwriter(encoding)
-    sys.stdout = wrapper(sys.stdout)
-
-
-if sys.version_info.major < 3:
-    ensure_stdout_handles_unicode()   # e.g. for print(text) in main()
-
-
 # === ARGUMENT PARSING =======================================================
 class ArgParserWithBanner(argparse.ArgumentParser):
@@ -820,10 +770,15 @@ def process_csv(filepath):
     chars the same way that excel does. Tested to some extend in unittests.
     This can only find DDE-links, no other "suspicious" constructs (yet).
-    """
+    Cannot deal with unicode files yet (need more than just use uopen()).
+    """
     results = []
-    with open(filepath, 'r') as file_handle:
+    if sys.version_info.major <= 2:
+        open_arg = dict(mode='rb')
+    else:
+        open_arg = dict(newline='')
+    with open(filepath, **open_arg) as file_handle:
         results, dialect = process_csv_dialect(file_handle, CSV_DELIMITERS)
         is_small = file_handle.tell() < CSV_SMALL_THRESH
@@ -854,7 +809,6 @@ def process_csv(filepath):
 def process_csv_dialect(file_handle, delimiters):
     """ helper for process_csv: process with a specific csv dialect """
-
     # determine dialect = delimiter chars, quote chars, ...
     dialect = csv.Sniffer().sniff(file_handle.read(CSV_SMALL_THRESH),
                                   delimiters=delimiters)
@@ -79,6 +79,7 @@ if not _parent_dir in sys.path:
 import olefile
 from oletools.thirdparty import xglob
 from oletools.thirdparty.tablestream import tablestream
+from oletools.common.io_encoding import ensure_stdout_handles_unicode
 #=== MAIN =================================================================
@@ -88,13 +89,12 @@ def process_ole(ole):
     meta = ole.get_metadata()
     # console output with UTF8 encoding:
-    # It looks like we do not need the UTF8 codec anymore, both for Python 2 and 3
-    console_utf8 = sys.stdout #codecs.getwriter('utf8')(sys.stdout)
+    ensure_stdout_handles_unicode()
     # TODO: move similar code to a function
     print('Properties from the SummaryInformation stream:')
-    t = tablestream.TableStream([21, 30], header_row=['Property', 'Value'], outfile=console_utf8)
+    t = tablestream.TableStream([21, 30], header_row=['Property', 'Value'])
     for prop in meta.SUMMARY_ATTRIBS:
         value = getattr(meta, prop)
         if value is not None:
@@ -111,7 +111,7 @@ def process_ole(ole):
     print('')
     print('Properties from the DocumentSummaryInformation stream:')
-    t = tablestream.TableStream([21, 30], header_row=['Property', 'Value'], outfile=console_utf8)
+    t = tablestream.TableStream([21, 30], header_row=['Property', 'Value'])
     for prop in meta.DOCSUM_ATTRIBS:
         value = getattr(meta, prop)
         if value is not None:
@@ -73,6 +73,7 @@ except ImportError:
 from oletools.ppt_record_parser import (is_ppt, PptFile,
                                         PptRecordExOleVbaActiveXAtom)
 from oletools.ooxml import XmlParser
+from oletools.common.io_encoding import ensure_stdout_handles_unicode
 # -----------------------------------------------------------------------------
 # CHANGELOG:
@@ -848,6 +849,7 @@ def main(cmd_line_args=None):
     provide other arguments.
     """
     # print banner with version
+    ensure_stdout_handles_unicode()
     print('oleobj %s - http://decalage.info/oletools' % __version__)
     print('THIS IS WORK IN PROGRESS - Check updates regularly!')
     print('Please report any issue at '
@@ -318,6 +318,7 @@ from oletools import ppt_parser
 from oletools import oleform
 from oletools import rtfobj
 from oletools import crypto
+from oletools.common.io_encoding import ensure_stdout_handles_unicode
 from oletools.common import codepages
 # monkeypatch email to fix issue #32:
@@ -4122,7 +4123,6 @@ def main(cmd_line_args=None):
     in process_args. Per default (cmd_line_args=None), sys.argv is used. Option
     mainly added for unit-testing
     """
-
     options, args = parse_args(cmd_line_args)
     # provide info about tool and its version
@@ -13,14 +13,47 @@ TODO: check what is duplicate here with oleid, maybe merge some day?
 TODO: "xml2003" == "flatopc"?
 .. codeauthor:: Intra2net AG <info@intra2net>
+License: BSD, see source code or documentation
+
+msodde is part of the python-oletools package:
+http://www.decalage.info/python/oletools
 """
+# === LICENSE =================================================================
+
+# msodde is copyright (c) 2017-2019 Philippe Lagadec (http://www.decalage.info)
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+#  * Redistributions of source code must retain the above copyright notice,
+#    this list of conditions and the following disclaimer.
+#  * Redistributions in binary form must reproduce the above copyright notice,
+#    this list of conditions and the following disclaimer in the documentation
+#    and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+# -- IMPORTS ------------------------------------------------------------------
+
 import sys
+from oletools.common.log_helper import log_helper
+from oletools.common.io_encoding import uopen
 from zipfile import ZipFile, BadZipfile, is_zipfile
 from os.path import splitext
 import io
 import re
-from oletools.common.log_helper import log_helper
 # import lxml or ElementTree for XML parsing:
 try:
@@ -29,6 +62,18 @@ try:
 except ImportError:
     import xml.etree.cElementTree as ET
+# -----------------------------------------------------------------------------
+# CHANGELOG:
+# 2018-12-06       CH: - ensure stdout can handle unicode
+
+__version__ = '0.54.2'
+
+
+###############################################################################
+# CONSTANTS
+###############################################################################
+
+
 logger = log_helper.get_or_create_silent_logger('ooxml')
 #: subfiles that have to be part of every ooxml file
@@ -127,7 +172,7 @@ def get_type(filename):
     parser = XmlParser(filename)
     if parser.is_single_xml():
         match = None
-        with open(filename, 'r') as handle:
+        with uopen(filename, 'r') as handle:
             match = re.search(OFFICE_XML_PROGID_REGEX, handle.read(1024))
         if not match:
             return DOCTYPE_NONE
@@ -416,7 +461,7 @@ class XmlParser(object):
         # find prog id in xml prolog
         match = None
-        with open(self.filename, 'r') as handle:
+        with uopen(self.filename, 'r') as handle:
             match = re.search(OFFICE_XML_PROGID_REGEX, handle.read(1024))
         if match:
             self._is_single_xml = True
@@ -424,11 +469,18 @@ class XmlParser(object):
         raise BadOOXML(self.filename, 'is no zip and has no prog_id')
     def iter_files(self, args=None):
-        """ Find files in zip or just give single xml file """
+        """
+        Find files in zip or just give single xml file
+
+        yields pairs (subfile-name, file-handle) where file-handle is an open
+        file-like object. (Do not care too much about encoding here, the xml
+        parser reads the encoding from the first lines in the file.)
+        """
         if self.is_single_xml():
             if args:
                 raise BadOOXML(self.filename, 'xml has no subfiles')
-            with open(self.filename, 'r') as handle:
+            # do not use uopen, xml parser determines encoding on its own
+            with open(self.filename, 'rb') as handle:
                 yield None, handle   # the subfile=None is needed in iter_xml
             self.did_iter_all = True
         else:
@@ -638,9 +690,10 @@ class XmlParser(object):
 def test():
-    """ Main function, called when running file as script
+    """
+    Test xml parsing; called when running this file as a script.
-    see module doc for more info
+    Prints every element found in input file (to be given as command line arg).
     """
     log_helper.enable_logging(False, 'debug')
     if len(sys.argv) != 2:
+"""Test common.ensure_stdout_handles_unicode"""
+
+from __future__ import print_function
+
+import unittest
+import sys
+from subprocess import check_call, CalledProcessError
+from tempfile import mkstemp
+import os
+from os.path import isfile
+from contextlib import contextmanager
+
+FILE_TEXT = u'The unicode check mark is \u2713.\n'
+
+@contextmanager
+def temp_file(just_name=True):
+    """Context manager that creates temp file and deletes it in the end"""
+    tmp_descriptor = None
+    tmp_name = None
+    tmp_handle = None
+    try:
+        tmp_descriptor, tmp_name = mkstemp()
+
+        # we create our own file handle since we want to be able to close the
+        # file and open it again for reading.
+        # We keep the os-level descriptor open so file name is still reserved
+        # for us
+        if just_name:
+            yield tmp_name
+        else:
+            tmp_handle = open(tmp_name, 'wb')
+            yield tmp_handle, tmp_name
+    except Exception:
+        raise
+    finally:
+        if tmp_descriptor is not None:
+            os.close(tmp_descriptor)
+        if tmp_handle is not None:
+            tmp_handle.close()
+        if tmp_name is not None and isfile(tmp_name):
+            os.unlink(tmp_name)
+
+
+class TestEncodingHandler(unittest.TestCase):
+    """Tests replacing stdout encoding in various scenarios"""
+
+    def test_print(self):
+        """Test regular unicode output not raise error"""
+        check_call('{python} {this_file} print'.format(python=sys.executable,
+                                                      this_file=__file__),
+                   shell=True)
+
+    def test_print_redirect(self):
+        """
+        Test redirection of unicode output to files does not raise error
+
+        TODO: test this on non-linux OSs
+        """
+        with temp_file() as tmp_file:
+            check_call('{python} {this_file} print > {tmp_file}'
+                       .format(python=sys.executable, this_file=__file__,
+                               tmp_file=tmp_file),
+                       shell=True)
+
+    @unittest.skipIf(not sys.platform.startswith('linux'),
+                     'Only tested on linux sofar')
+    def test_print_no_lang(self):
+        """
+        Test redirection of unicode output to files does not raise error
+
+        TODO: Adapt this for other OSs; for win create batch script
+        """
+        check_call('LANG=C {python} {this_file} print'
+                   .format(python=sys.executable, this_file=__file__),
+                   shell=True)
+
+    def test_uopen(self):
+        """Test that uopen in a nice environment is ok"""
+        with temp_file(False) as (tmp_handle, tmp_file):
+            tmp_handle.write(FILE_TEXT.encode('utf8'))
+            tmp_handle.close()
+
+            try:
+                check_call('{python} {this_file} read {tmp_file}'
+                           .format(python=sys.executable, this_file=__file__,
+                                   tmp_file=tmp_file),
+                           shell=True)
+            except CalledProcessError as cpe:
+                self.fail(cpe.output)
+
+    def test_uopen_redirect(self):
+        """
+        Test redirection of unicode output to files does not raise error
+
+        TODO: test this on non-linux OSs
+        """
+        with temp_file(False) as (tmp_handle, tmp_file):
+            tmp_handle.write(FILE_TEXT.encode('utf8'))
+            tmp_handle.close()
+
+            with temp_file() as redirect_file:
+                try:
+                    check_call(
+                        '{python} {this_file} read {tmp_file} >{redirect_file}'
+                        .format(python=sys.executable, this_file=__file__,
+                        tmp_file=tmp_file, redirect_file=redirect_file),
+                        shell=True)
+                except CalledProcessError as cpe:
+                    self.fail(cpe.output)
+
+    @unittest.skipIf(not sys.platform.startswith('linux'),
+                     'Only tested on linux sofar')
+    def test_uopen_no_lang(self):
+        """
+        Test that uopen in a C-LANG environment is ok
+
+        TODO: Adapt this for other OSs; for win create batch script
+        """
+        with temp_file(False) as (tmp_handle, tmp_file):
+            tmp_handle.write(FILE_TEXT.encode('utf8'))
+            tmp_handle.close()
+
+            try:
+                check_call('LANG=C {python} {this_file} read {tmp_file}'
+                           .format(python=sys.executable, this_file=__file__,
+                                   tmp_file=tmp_file),
+                           shell=True)
+            except CalledProcessError as cpe:
+                self.fail(cpe.output)
+
+
+def run_read(filename):
+    """This is called from test_uopen* tests as script. Reads text, compares"""
+    from oletools.common.io_encoding import uopen
+    # open file
+    with uopen(filename, 'rt') as reader:
+        # a few tests
+        if reader.closed:
+            raise ValueError('handle is closed!')
+        if reader.name != filename:
+            raise ValueError('Wrong filename {}'.format(reader.name))
+        if reader.isatty():
+            raise ValueError('Reader is a tty!')
+        if reader.tell() != 0:
+            raise ValueError('Reader.tell is not 0 at beginning')
+
+        # read text
+        text = reader.read()
+
+    # a few more tests
+    if not reader.closed:
+        raise ValueError('Reader is not closed outside context')
+    if reader.name != filename:
+        raise ValueError('Wrong filename {} after context'.format(reader.name))
+        if reader.isatty():
+            raise ValueError('Reader has become a tty!')
+
+    # compare text
+    if sys.version_info.major <= 2:      # in python2 get encoded byte string
+        expect = FILE_TEXT.encode('utf8')
+    else:                                # python3: should get real unicode
+        expect = FILE_TEXT
+    if text != expect:
+        raise ValueError('Wrong contents: {!r} != {!r}'
+                         .format(text, expect))
+    return 0
+
+
+def run_print():
+    """This is called from test_read* tests as script. Prints & logs unicode"""
+    from oletools.common.io_encoding import ensure_stdout_handles_unicode
+    from oletools.common.log_helper import log_helper
+    ensure_stdout_handles_unicode()
+    print(u'Check: \u2713')    # print check mark
+
+    # check logging as well
+    logger = log_helper.get_or_create_silent_logger('test_encoding_handler')
+    log_helper.enable_logging(False, 'debug', stream=sys.stdout)
+    logger.info(u'Check: \u2713')
+    return 0
+
+
+# tests call this file as script
+if __name__ == '__main__':
+    if len(sys.argv) < 2:
+        sys.exit(unittest.main())
+
+    # hack required to import common from parent dir, not system-wide one
+    # (usually unittest seems to do that for us)
+    from os.path import abspath, dirname, join
+    ole_base = dirname(dirname(dirname(abspath(__file__))))
+    sys.path.insert(0, ole_base)
+
+    if sys.argv[1] == 'print':
+        if len(sys.argv) > 2:
+            print('Expect no arg for "print"', file=sys.stderr)
+            sys.exit(2)
+        sys.exit(run_print())
+    elif sys.argv[1] == 'read':
+        if len(sys.argv) != 3:
+            print('Expect single arg for "read"', file=sys.stderr)
+            sys.exit(2)
+        sys.exit(run_read(sys.argv[2]))
+    else:
+        print('Unexpected argument: {}'.format(sys.argv[1]), file=sys.stderr)
+        sys.exit(2)
@@ -10,6 +10,7 @@ from glob import glob
 # Directory with test data, independent of current working directory
 from tests.test_utils import DATA_BASE_DIR, call_and_capture
 from oletools import oleobj
+from oletools.common.io_encoding import ensure_stdout_handles_unicode
 #: provide some more info to find errors
@@ -61,6 +62,7 @@ def calc_md5(filename):
 def preread_file(args):
     """helper for TestOleObj.test_non_streamed: preread + call process_file"""
+    ensure_stdout_handles_unicode()   # usually, main() call this
     ignore_arg, output_dir, filename = args
     if ignore_arg != '-d':
         raise ValueError('ignore_arg not as expected!')