""" Miscellaneous useful utility functions, classes, etc., that are
used by both client and server. Stuff that doesn't fit anywhere
else. """
import fcntl
import logging
import os
import re
import select
import shlex
import sys
import subprocess
import threading
from Bcfg2.Compat import input, any # pylint: disable=W0622
[docs]class ClassName(object):
""" This very simple descriptor class exists only to get the name
of the owner class. This is used because, for historical reasons,
we expect every server plugin and every client tool to have a
``name`` attribute that is in almost all cases the same as the
``__class__.__name__`` attribute of the plugin object. This makes
that more dynamic so that each plugin and tool isn't repeating its own
name."""
def __get__(self, inst, owner):
return owner.__name__
[docs]class PackedDigitRange(object): # pylint: disable=E0012,R0924
""" Representation of a set of integer ranges. A range is
described by a comma-delimited string of integers and ranges,
e.g.::
1,10-12,15-20
Ranges are inclusive on both bounds, and may include 0. Negative
numbers are not supported."""
def __init__(self, *ranges):
""" May be instantiated in one of two ways::
PackedDigitRange(<comma-delimited list of ranges>)
Or::
PackedDigitRange(<int_or_range>[, <int_or_range>[, ...]])
E.g., both of the following are valid::
PackedDigitRange("1-5,7, 10-12")
PackedDigitRange("1-5", 7, "10-12")
"""
self.ranges = []
self.ints = []
self.str = ",".join(str(r) for r in ranges)
if len(ranges) == 1 and "," in ranges[0]:
ranges = ranges[0].split(",")
for item in ranges:
item = str(item).strip()
if item.endswith("-"):
self.ranges.append((int(item[:-1]), None))
elif '-' in str(item):
self.ranges.append(tuple(int(x) for x in item.split('-')))
else:
self.ints.append(int(item))
[docs] def includes(self, other):
""" Return True if ``other`` is included in this range.
Functionally equivalent to ``other in range``, which should be
used instead. """
return other in self
def __contains__(self, other):
other = int(other)
if other in self.ints:
return True
return any((end is None and other >= start) or
(end is not None and other >= start and other <= end)
for start, end in self.ranges)
def __repr__(self):
return "%s:%s" % (self.__class__.__name__, str(self))
def __str__(self):
return "[%s]" % self.str
[docs]def locked(fd):
""" Acquire a lock on a file.
:param fd: The file descriptor to lock
:type fd: int
:returns: bool - True if the file is already locked, False
otherwise """
try:
fcntl.lockf(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
return True
return False
[docs]class ExecutorResult(object):
""" Returned as the result of a call to
:func:`Bcfg2.Utils.Executor.run`. The result can be accessed via
the instance variables, documented below, as a boolean (which is
equivalent to :attr:`Bcfg2.Utils.ExecutorResult.success`), or as a
tuple, which, for backwards compatibility, is equivalent to
``(result.retval, result.stdout.splitlines())``."""
def __init__(self, stdout, stderr, retval):
#: The output of the command
if isinstance(stdout, str):
self.stdout = stdout
else:
self.stdout = stdout.decode('utf-8')
#: The error produced by the command
if isinstance(stdout, str):
self.stderr = stderr
else:
self.stderr = stderr.decode('utf-8')
#: The return value of the command.
self.retval = retval
#: Whether or not the command was successful. If the
#: ExecutorResult is used as a boolean, ``success`` is
#: returned.
self.success = retval == 0
#: A friendly error message
self.error = None
if self.retval:
if self.stderr:
self.error = "%s (rv: %s)" % (self.stderr, self.retval)
elif self.stdout:
self.error = "%s (rv: %s)" % (self.stdout, self.retval)
else:
self.error = "No output or error; return value %s" % \
self.retval
def __repr__(self):
if self.error:
return "Errored command result: %s" % self.error
elif self.stdout:
return "Successful command result: %s" % self.stdout
else:
return "Successful command result: No output"
def __getitem__(self, idx):
""" This provides compatibility with the old Executor, which
returned a tuple of (return value, stdout split by lines). """
return (self.retval, self.stdout.splitlines())[idx]
def __len__(self):
""" This provides compatibility with the old Executor, which
returned a tuple of (return value, stdout split by lines). """
return 2
def __delitem__(self, _):
raise TypeError("'%s' object doesn't support item deletion" %
self.__class__.__name__)
def __setitem__(self, idx, val):
raise TypeError("'%s' object does not support item assignment" %
self.__class__.__name__)
def __nonzero__(self):
return self.__bool__()
def __bool__(self):
return self.success
[docs]class Executor(object):
""" A convenient way to run external commands with
:class:`subprocess.Popen` """
def __init__(self, timeout=None):
"""
:param timeout: Set a default timeout for all commands run by
this Executor object
:type timeout: float
"""
self.logger = logging.getLogger(self.__class__.__name__)
self.timeout = timeout
def _timeout(self, proc):
""" A function suitable for passing to
:class:`threading.Timer` that kills the given process.
:param proc: The process to kill upon timeout.
:type proc: subprocess.Popen
:returns: None """
if proc.poll() is None:
try:
proc.kill()
self.logger.warning("Process exceeeded timeout, killing")
except OSError:
pass
[docs] def run(self, command, inputdata=None, timeout=None, **kwargs):
""" Run a command, given as a list, optionally giving it the
specified input data. All additional keyword arguments are
passed through to :class:`subprocess.Popen`.
:param command: The command to run, as a list (preferred) or
as a string. See :class:`subprocess.Popen` for
details.
:type command: list or string
:param inputdata: Data to pass to the command on stdin
:type inputdata: string
:param timeout: Kill the command if it runs longer than this
many seconds. Set to 0 or -1 to explicitly
override a default timeout.
:type timeout: float
:returns: :class:`Bcfg2.Utils.ExecutorResult`
"""
shell = False
if 'shell' in kwargs:
shell = kwargs['shell']
if isinstance(command, str):
cmdstr = command
if not shell:
command = shlex.split(cmdstr)
else:
cmdstr = " ".join(command)
self.logger.debug("Running: %s" % cmdstr)
args = dict(shell=shell, bufsize=16384, close_fds=True)
args.update(kwargs)
args.update(stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
proc = subprocess.Popen(command, **args)
if timeout is None:
timeout = self.timeout
if timeout is not None:
timer = threading.Timer(float(timeout), self._timeout, [proc])
timer.start()
try:
if inputdata:
for line in inputdata.splitlines():
self.logger.debug('> %s' % line)
(stdout, stderr) = proc.communicate(input=inputdata)
# py3k fixes
if not isinstance(stdout, str):
stdout = stdout.decode('utf-8') # pylint: disable=E1103
if not isinstance(stderr, str):
stderr = stderr.decode('utf-8') # pylint: disable=E1103
for line in stdout.splitlines(): # pylint: disable=E1103
self.logger.debug('< %s' % line)
for line in stderr.splitlines(): # pylint: disable=E1103
self.logger.info(line)
return ExecutorResult(stdout, stderr,
proc.wait()) # pylint: disable=E1101
finally:
if timeout is not None:
timer.cancel()
[docs]def list2range(lst):
''' convert a list of integers to a set of human-readable ranges. e.g.:
[1, 2, 3, 6, 9, 10, 11] -> "[1-3,6,9-11]" '''
ilst = sorted(int(i) for i in lst)
ranges = []
start = None
last = None
for i in ilst:
if not last or i != last + 1:
if start:
if start == last:
ranges.append(str(start))
else:
ranges.append("%d-%d" % (start, last))
start = i
last = i
if start:
if start == last:
ranges.append(str(start))
else:
ranges.append("%d-%d" % (start, last))
if not ranges:
return ""
elif len(ranges) > 1 or "-" in ranges[0]:
return "[%s]" % ",".join(ranges)
else:
# only one range consisting of only a single number
return ranges[0]
[docs]def hostnames2ranges(hostnames):
''' convert a list of hostnames to a set of human-readable ranges. e.g.:
["foo1.example.com", "foo2.example.com", "foo3.example.com",
"foo6.example.com"] -> ["foo[1-3,6].example.com"]'''
hosts = {}
hostre = re.compile(r'(\w+?)(\d+)(\..*)$')
for host in hostnames:
match = hostre.match(host)
if match:
key = (match.group(1), match.group(3))
try:
hosts[key].append(match.group(2))
except KeyError:
hosts[key] = [match.group(2)]
ranges = []
for name, nums in hosts.items():
ranges.append(name[0] + list2range(nums) + name[1])
return ranges
[docs]def safe_module_name(prefix, module):
""" Munge the name of a module with prefix to avoid collisions
with other Python modules. E.g., if you want to import user
defined helper modules and someone has a helper named 'ldap.py',
it should not be added to ``sys.modules`` as ``ldap``, but rather
as something more obscure. """
return '__%s_%s' % (prefix, module)
[docs]class classproperty(object): # pylint: disable=C0103
""" Decorator that can be used to create read-only class
properties. """
def __init__(self, getter):
self.getter = getter
def __get__(self, instance, owner):
return self.getter(owner)
[docs]def is_string(strng, encoding):
""" Returns true if the string contains no ASCII control
characters and can be decoded from the specified encoding. """
for char in strng:
if ord(char) < 9 or ord(char) > 13 and ord(char) < 32:
return False
if not hasattr(strng, "decode"):
# py3k
return True
try:
strng.decode(encoding)
return True
except: # pylint: disable=W0702
return False
