frappy/secop/lib/__init__.py

#  -*- coding: utf-8 -*-
# *****************************************************************************
#
# 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
#
# Module authors:
#   Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
#
# *****************************************************************************
"""Define helpers"""

import os
import re
import sys
import errno
import signal
import socket
import fnmatch
import linecache
import threading
import traceback
import subprocess
import unicodedata
from os import path


repodir = path.abspath(path.join(path.dirname(__file__), '..', '..'))

CONFIG = {
    'piddir': os.path.join(repodir, 'pid'),
    'logdir': os.path.join(repodir, 'log'),
    'confdir': os.path.join(repodir, 'etc'),
} if os.path.exists(os.path.join(repodir, '.git')) else {
    'piddir': '/var/run/secop',
    'logdir': '/var/log',
    'confdir': '/etc/secop',
}


unset_value = object()

class lazy_property(object):
    """A property that calculates its value only once."""

    def __init__(self, func):
        self._func = func
        self.__name__ = func.__name__
        self.__doc__ = func.__doc__

    def __get__(self, obj, obj_class):
        if obj is None:
            return obj
        obj.__dict__[self.__name__] = self._func(obj)
        return obj.__dict__[self.__name__]


class attrdict(dict):
    """a normal dict, providing access also via attributes"""

    def __getattr__(self, key):
        return self[key]

    def __setattr__(self, key, value):
        self[key] = value


def clamp(_min, value, _max):
    """return the median of 3 values,

    i.e. value if min <= value <= max, else min or max depending on which side
    value lies outside the [min..max] interval
    """
    # return median, i.e. clamp the the value between min and max
    return sorted([_min, value, _max])[1]


def get_class(spec):
    """loads a class given by string in dotted notaion (as python would do)"""
    modname, classname = spec.rsplit('.', 1)
    import importlib
    if modname.startswith('secop'):
        module = importlib.import_module(modname)
    else:
        # rarely needed by now....
        module = importlib.import_module('secop.' + modname)
    return getattr(module, classname)


def mkthread(func, *args, **kwds):
    t = threading.Thread(
        name='%s:%s' % (func.__module__, func.__name__),
        target=func,
        args=args,
        kwargs=kwds)
    t.daemon = True
    t.start()
    return t


def formatExtendedFrame(frame):
    ret = []
    for key, value in frame.f_locals.items():
        try:
            valstr = repr(value)[:256]
        except Exception:
            valstr = '<cannot be displayed>'
        ret.append('        %-20s = %s\n' % (key, valstr))
    ret.append('\n')
    return ret


def formatExtendedTraceback(exc_info=None):
    if exc_info is None:
        etype, value, tb = sys.exc_info()
    else:
        etype, value, tb = exc_info
    ret = ['Traceback (most recent call last):\n']
    while tb is not None:
        frame = tb.tb_frame
        filename = frame.f_code.co_filename
        item = '  File "%s", line %d, in %s\n' % (filename, tb.tb_lineno,
                                                  frame.f_code.co_name)
        linecache.checkcache(filename)
        line = linecache.getline(filename, tb.tb_lineno, frame.f_globals)
        if line:
            item = item + '    %s\n' % line.strip()
        ret.append(item)
        if filename not in ('<script>', '<string>'):
            ret += formatExtendedFrame(tb.tb_frame)
        tb = tb.tb_next
    ret += traceback.format_exception_only(etype, value)
    return ''.join(ret).rstrip('\n')


def formatExtendedStack(level=1):
    f = sys._getframe(level)
    ret = ['Stack trace (most recent call last):\n\n']
    while f is not None:
        lineno = f.f_lineno
        co = f.f_code
        filename = co.co_filename
        name = co.co_name
        item = '  File "%s", line %d, in %s\n' % (filename, lineno, name)
        linecache.checkcache(filename)
        line = linecache.getline(filename, lineno, f.f_globals)
        if line:
            item = item + '    %s\n' % line.strip()
        ret.insert(1, item)
        if filename != '<script>':
            ret[2:2] = formatExtendedFrame(f)
        f = f.f_back
    return ''.join(ret).rstrip('\n')


def formatException(cut=0, exc_info=None, verbose=False):
    """Format an exception with traceback, but leave out the first `cut`
    number of frames.
    """
    if verbose:
        return formatExtendedTraceback(exc_info)
    if exc_info is None:
        typ, val, tb = sys.exc_info()
    else:
        typ, val, tb = exc_info
    res = ['Traceback (most recent call last):\n']
    tbres = traceback.format_tb(tb, sys.maxsize)
    res += tbres[cut:]
    res += traceback.format_exception_only(typ, val)
    return ''.join(res)


def parseHostPort(host, defaultport):
    """Parse host[:port] string and tuples

    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
    If the port specification is missing, the value of the defaultport is used.
    """

    if isinstance(host, (tuple, list)):
        host, port = host
    elif ':' in host:
        host, port = host.rsplit(':', 1)
        port = int(port)
    else:
        port = defaultport
    assert 0 < port < 65536
    assert ':' not in host
    return host, port


def tcpSocket(host, defaultport, timeout=None):
    """Helper for opening a TCP client socket to a remote server.

    Specify 'host[:port]' or a (host, port) tuple for the mandatory argument.
    If the port specification is missing, the value of the defaultport is used.
    If timeout is set to a number, the timout of the connection is set to this
    number, else the socket stays in blocking mode.
    """
    host, port = parseHostPort(host, defaultport)

    # open socket and set options
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    if timeout:
        s.settimeout(timeout)
    # connect
    s.connect((host, int(port)))
    return s


# keep a reference to socket to avoid (interpreter) shut-down problems
def closeSocket(sock, socket=socket):  # pylint: disable=redefined-outer-name
    """Do our best to close a socket."""
    if sock is None:
        return
    try:
        sock.shutdown(socket.SHUT_RDWR)
    except socket.error:
        pass
    try:
        sock.close()
    except socket.error:
        pass


def getfqdn(name=''):
    """Get fully qualified hostname."""
    return socket.getfqdn(name)


def getGeneralConfig():
    return CONFIG