ZFTP_Server/pyftpdlib/log.py

#!/usr/bin/env python
# $Id: log.py 1171 2013-02-19 10:13:09Z g.rodola $

#  ======================================================================
#  Copyright (C) 2007-2013 Giampaolo Rodola' <g.rodola@gmail.com>
#
#                         All Rights Reserved
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#

"""
Logging support for pyftpdlib, inspired from Tornado's
(http://www.tornadoweb.org/).

This is not supposed to be imported/used directly.
Instead you should use logging.basicConfig before serve_forever().
"""

import logging
import sys
import time
try:
    import curses
except ImportError:
    curses = None
    
from pyftpdlib._compat import unicode

# default logger

logger = logging.getLogger('pyftpdlib')

def _stderr_supports_color():
    color = False
    if curses is not None and sys.stderr.isatty():
        try:
            curses.setupterm()
            if curses.tigetnum("colors") > 0:
                color = True
        except Exception:
            pass
    return color

# configurable options
LEVEL = logging.INFO
PREFIX = '[%(levelname)1.1s %(asctime)s]'
COLOURED = _stderr_supports_color()
TIME_FORMAT = "%y-%m-%d %H:%M:%S"


# taken and adapted from Tornado
class LogFormatter(logging.Formatter):
    """Log formatter used in pyftpdlib.
    Key features of this formatter are:

    * Color support when logging to a terminal that supports it.
    * Timestamps on every log line.
    * Robust against str/bytes encoding problems.
    """
    def __init__(self, *args, **kwargs):
        logging.Formatter.__init__(self, *args, **kwargs)
        self._coloured = COLOURED and _stderr_supports_color()
        if self._coloured:
            curses.setupterm()
            # The curses module has some str/bytes confusion in
            # python3.  Until version 3.2.3, most methods return
            # bytes, but only accept strings.  In addition, we want to
            # output these strings with the logging module, which
            # works with unicode strings.  The explicit calls to
            # unicode() below are harmless in python2 but will do the
            # right conversion in python 3.
            fg_color = (curses.tigetstr("setaf") or curses.tigetstr("setf") or "")
            if (3, 0) < sys.version_info < (3, 2, 3):
                fg_color = unicode(fg_color, "ascii")
            self._colors = {
                logging.DEBUG: unicode(curses.tparm(fg_color, 4), "ascii"),   # blue
                logging.INFO: unicode(curses.tparm(fg_color, 2),  "ascii"),   # green
                logging.WARNING: unicode(curses.tparm(fg_color, 3), "ascii"), # yellow
                logging.ERROR: unicode(curses.tparm(fg_color, 1), "ascii")    # red
            }
            self._normal = unicode(curses.tigetstr("sgr0"), "ascii")

    def format(self, record):
        try:
            record.message = record.getMessage()
        except Exception:
            err = sys.exc_info()[1]
            record.message = "Bad message (%r): %r" % (err, record.__dict__)

        record.asctime = time.strftime(TIME_FORMAT,
                                       self.converter(record.created))
        prefix = PREFIX % record.__dict__
        if self._coloured:
            prefix = (self._colors.get(record.levelno, self._normal) +
                      prefix + self._normal)

        # Encoding notes:  The logging module prefers to work with character
        # strings, but only enforces that log messages are instances of
        # basestring.  In python 2, non-ascii bytestrings will make
        # their way through the logging framework until they blow up with
        # an unhelpful decoding error (with this formatter it happens
        # when we attach the prefix, but there are other opportunities for
        # exceptions further along in the framework).
        #
        # If a byte string makes it this far, convert it to unicode to
        # ensure it will make it out to the logs.  Use repr() as a fallback
        # to ensure that all byte strings can be converted successfully,
        # but don't do it by default so we don't add extra quotes to ascii
        # bytestrings.  This is a bit of a hacky place to do this, but
        # it's worth it since the encoding errors that would otherwise
        # result are so useless (and tornado is fond of using utf8-encoded
        # byte strings wherever possible).
        try:
            message = unicode(record.message)
        except UnicodeDecodeError:
            message = repr(record.message)

        formatted = prefix + " " + message
        if record.exc_info:
            if not record.exc_text:
                record.exc_text = self.formatException(record.exc_info)
        if record.exc_text:
            formatted = formatted.rstrip() + "\n" + record.exc_text
        return formatted.replace("\n", "\n    ")

def _config_logging():
    channel = logging.StreamHandler()
    channel.setFormatter(LogFormatter())
    logger = logging.getLogger()
    logger.setLevel(LEVEL)
    logger.addHandler(channel)