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""" Miscellaneous useful utility functions, classes, etc., that are
used by both client and server. Stuff that doesn't fit anywhere
else. """
import shlex
import fcntl
import logging
import threading
import subprocess
from Bcfg2.Compat import any # pylint: disable=W0622
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__
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))
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
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
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
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
def run(self, command, inputdata=None, shell=False, timeout=None):
""" Run a command, given as a list, optionally giving it the
specified input data.
: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 shell: Run the given command in a shell (not recommended)
:type shell: bool
: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`
"""
if isinstance(command, str):
cmdstr = command
if not shell:
command = shlex.split(cmdstr)
else:
cmdstr = " ".join(command)
self.logger.debug("Running: %s" % cmdstr)
try:
proc = subprocess.Popen(command, shell=shell, bufsize=16384,
close_fds=True,
stdin=subprocess.PIPE,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
except OSError:
return ExecutorResult('', 'No such command: %s' % cmdstr,
127)
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')
if not isinstance(stderr, str):
stderr = stderr.decode('utf-8')
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())
finally:
if timeout is not None:
timer.cancel()
|
