Source code for CedarBackup3.extend.split

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# Copyright (c) 2007,2010,2013,2015 Kenneth J. Pronovici.
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# Author   : Kenneth J. Pronovici <pronovic@ieee.org>
# Language : Python 3 (>= 3.4)
# Project  : Official Cedar Backup Extensions
# Purpose  : Provides an extension to split up large files in staging directories.
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# Module documentation
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"""
Provides an extension to split up large files in staging directories.

When this extension is executed, it will look through the configured Cedar
Backup staging directory for files exceeding a specified size limit, and split
them down into smaller files using the 'split' utility.  Any directory which
has already been split (as indicated by the ``cback.split`` file) will be
ignored.

This extension requires a new configuration section <split> and is intended
to be run immediately after the standard stage action or immediately before the
standard store action.  Aside from its own configuration, it requires the
options and staging configuration sections in the standard Cedar Backup
configuration file.

:author: Kenneth J. Pronovici <pronovic@ieee.org>
"""

########################################################################
# Imported modules
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# System modules
import os
import re
import logging
from functools import total_ordering

# Cedar Backup modules
from CedarBackup3.util import resolveCommand, executeCommand, changeOwnership
from CedarBackup3.xmlutil import createInputDom, addContainerNode
from CedarBackup3.xmlutil import readFirstChild
from CedarBackup3.actions.util import findDailyDirs, writeIndicatorFile, getBackupFiles
from CedarBackup3.config import ByteQuantity, readByteQuantity, addByteQuantityNode


########################################################################
# Module-wide constants and variables
########################################################################

logger = logging.getLogger("CedarBackup3.log.extend.split")

SPLIT_COMMAND = [ "split", ]
SPLIT_INDICATOR = "cback.split"


########################################################################
# SplitConfig class definition
########################################################################

@total_ordering
[docs]class SplitConfig(object): """ Class representing split configuration. Split configuration is used for splitting staging directories. The following restrictions exist on data in this class: - The size limit must be a ByteQuantity - The split size must be a ByteQuantity """
[docs] def __init__(self, sizeLimit=None, splitSize=None): """ Constructor for the ``SplitCOnfig`` class. Args: sizeLimit: Size limit of the files, in bytes splitSize: Size that files exceeding the limit will be split into, in bytes Raises: ValueError: If one of the values is invalid """ self._sizeLimit = None self._splitSize = None self.sizeLimit = sizeLimit self.splitSize = splitSize
def __repr__(self): """ Official string representation for class instance. """ return "SplitConfig(%s, %s)" % (self.sizeLimit, self.splitSize) def __str__(self): """ Informal string representation for class instance. """ return self.__repr__() def __eq__(self, other): """Equals operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) == 0 def __lt__(self, other): """Less-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) < 0 def __gt__(self, other): """Greater-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) > 0 def __cmp__(self, other): """ Original Python 2 comparison operator. Lists within this class are "unordered" for equality comparisons. Args: other: Other object to compare to Returns: -1/0/1 depending on whether self is ``<``, ``=`` or ``>`` other """ if other is None: return 1 if self.sizeLimit != other.sizeLimit: if (self.sizeLimit or ByteQuantity()) < (other.sizeLimit or ByteQuantity()): return -1 else: return 1 if self.splitSize != other.splitSize: if (self.splitSize or ByteQuantity()) < (other.splitSize or ByteQuantity()): return -1 else: return 1 return 0 def _setSizeLimit(self, value): """ Property target used to set the size limit. If not ``None``, the value must be a ``ByteQuantity`` object. Raises: ValueError: If the value is not a ``ByteQuantity`` """ if value is None: self._sizeLimit = None else: if not isinstance(value, ByteQuantity): raise ValueError("Value must be a ``ByteQuantity`` object.") self._sizeLimit = value def _getSizeLimit(self): """ Property target used to get the size limit. """ return self._sizeLimit def _setSplitSize(self, value): """ Property target used to set the split size. If not ``None``, the value must be a ``ByteQuantity`` object. Raises: ValueError: If the value is not a ``ByteQuantity`` """ if value is None: self._splitSize = None else: if not isinstance(value, ByteQuantity): raise ValueError("Value must be a ``ByteQuantity`` object.") self._splitSize = value def _getSplitSize(self): """ Property target used to get the split size. """ return self._splitSize sizeLimit = property(_getSizeLimit, _setSizeLimit, None, doc="Size limit, as a ByteQuantity") splitSize = property(_getSplitSize, _setSplitSize, None, doc="Split size, as a ByteQuantity")
######################################################################## # LocalConfig class definition ######################################################################## @total_ordering
[docs]class LocalConfig(object): """ Class representing this extension's configuration document. This is not a general-purpose configuration object like the main Cedar Backup configuration object. Instead, it just knows how to parse and emit split-specific configuration values. Third parties who need to read and write configuration related to this extension should access it through the constructor, ``validate`` and ``addConfig`` methods. *Note:* Lists within this class are "unordered" for equality comparisons. """
[docs] def __init__(self, xmlData=None, xmlPath=None, validate=True): """ Initializes a configuration object. If you initialize the object without passing either ``xmlData`` or ``xmlPath`` then configuration will be empty and will be invalid until it is filled in properly. No reference to the original XML data or original path is saved off by this class. Once the data has been parsed (successfully or not) this original information is discarded. Unless the ``validate`` argument is ``False``, the :any:`LocalConfig.validate` method will be called (with its default arguments) against configuration after successfully parsing any passed-in XML. Keep in mind that even if ``validate`` is ``False``, it might not be possible to parse the passed-in XML document if lower-level validations fail. *Note:* It is strongly suggested that the ``validate`` option always be set to ``True`` (the default) unless there is a specific need to read in invalid configuration from disk. Args: xmlData (String data): XML data representing configuration xmlPath (Absolute path to a file on disk): Path to an XML file on disk validate (Boolean true/false): Validate the document after parsing it Raises: ValueError: If both ``xmlData`` and ``xmlPath`` are passed-in ValueError: If the XML data in ``xmlData`` or ``xmlPath`` cannot be parsed ValueError: If the parsed configuration document is not valid """ self._split = None self.split = None if xmlData is not None and xmlPath is not None: raise ValueError("Use either xmlData or xmlPath, but not both.") if xmlData is not None: self._parseXmlData(xmlData) if validate: self.validate() elif xmlPath is not None: with open(xmlPath) as f: xmlData = f.read() self._parseXmlData(xmlData) if validate: self.validate()
def __repr__(self): """ Official string representation for class instance. """ return "LocalConfig(%s)" % (self.split) def __str__(self): """ Informal string representation for class instance. """ return self.__repr__() def __eq__(self, other): """Equals operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) == 0 def __lt__(self, other): """Less-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) < 0 def __gt__(self, other): """Greater-than operator, iplemented in terms of original Python 2 compare operator.""" return self.__cmp__(other) > 0 def __cmp__(self, other): """ Original Python 2 comparison operator. Lists within this class are "unordered" for equality comparisons. Args: other: Other object to compare to Returns: -1/0/1 depending on whether self is ``<``, ``=`` or ``>`` other """ if other is None: return 1 if self.split != other.split: if self.split < other.split: return -1 else: return 1 return 0 def _setSplit(self, value): """ Property target used to set the split configuration value. If not ``None``, the value must be a ``SplitConfig`` object. Raises: ValueError: If the value is not a ``SplitConfig`` """ if value is None: self._split = None else: if not isinstance(value, SplitConfig): raise ValueError("Value must be a ``SplitConfig`` object.") self._split = value def _getSplit(self): """ Property target used to get the split configuration value. """ return self._split split = property(_getSplit, _setSplit, None, "Split configuration in terms of a ``SplitConfig`` object.")
[docs] def validate(self): """ Validates configuration represented by the object. Split configuration must be filled in. Within that, both the size limit and split size must be filled in. Raises: ValueError: If one of the validations fails """ if self.split is None: raise ValueError("Split section is required.") if self.split.sizeLimit is None: raise ValueError("Size limit must be set.") if self.split.splitSize is None: raise ValueError("Split size must be set.")
[docs] def addConfig(self, xmlDom, parentNode): """ Adds a <split> configuration section as the next child of a parent. Third parties should use this function to write configuration related to this extension. We add the following fields to the document:: sizeLimit //cb_config/split/size_limit splitSize //cb_config/split/split_size Args: xmlDom: DOM tree as from ``impl.createDocument()`` parentNode: Parent that the section should be appended to """ if self.split is not None: sectionNode = addContainerNode(xmlDom, parentNode, "split") addByteQuantityNode(xmlDom, sectionNode, "size_limit", self.split.sizeLimit) addByteQuantityNode(xmlDom, sectionNode, "split_size", self.split.splitSize)
def _parseXmlData(self, xmlData): """ Internal method to parse an XML string into the object. This method parses the XML document into a DOM tree (``xmlDom``) and then calls a static method to parse the split configuration section. Args: xmlData (String data): XML data to be parsed Raises: ValueError: If the XML cannot be successfully parsed """ (xmlDom, parentNode) = createInputDom(xmlData) self._split = LocalConfig._parseSplit(parentNode) @staticmethod def _parseSplit(parent): """ Parses an split configuration section. We read the following individual fields:: sizeLimit //cb_config/split/size_limit splitSize //cb_config/split/split_size Args: parent: Parent node to search beneath Returns: ``EncryptConfig`` object or ``None`` if the section does not exist Raises: ValueError: If some filled-in value is invalid """ split = None section = readFirstChild(parent, "split") if section is not None: split = SplitConfig() split.sizeLimit = readByteQuantity(section, "size_limit") split.splitSize = readByteQuantity(section, "split_size") return split
######################################################################## # Public functions ######################################################################## ########################### # executeAction() function ########################### # pylint: disable=W0613
[docs]def executeAction(configPath, options, config): """ Executes the split backup action. Args: configPath (String representing a path on disk): Path to configuration file on disk options (Options object): Program command-line options config (Config object): Program configuration Raises: ValueError: Under many generic error conditions IOError: If there are I/O problems reading or writing files """ logger.debug("Executing split extended action.") if config.options is None or config.stage is None: raise ValueError("Cedar Backup configuration is not properly filled in.") local = LocalConfig(xmlPath=configPath) dailyDirs = findDailyDirs(config.stage.targetDir, SPLIT_INDICATOR) for dailyDir in dailyDirs: _splitDailyDir(dailyDir, local.split.sizeLimit, local.split.splitSize, config.options.backupUser, config.options.backupGroup) writeIndicatorFile(dailyDir, SPLIT_INDICATOR, config.options.backupUser, config.options.backupGroup) logger.info("Executed the split extended action successfully.")
############################## # _splitDailyDir() function ############################## def _splitDailyDir(dailyDir, sizeLimit, splitSize, backupUser, backupGroup): """ Splits large files in a daily staging directory. Files that match INDICATOR_PATTERNS (i.e. ``"cback.store"``, ``"cback.stage"``, etc.) are assumed to be indicator files and are ignored. All other files are split. Args: dailyDir: Daily directory to encrypt sizeLimit: Size limit, in bytes splitSize: Split size, in bytes backupUser: User that target files should be owned by backupGroup: Group that target files should be owned by Raises: ValueError: If the encrypt mode is not supported ValueError: If the daily staging directory does not exist """ logger.debug("Begin splitting contents of [%s].", dailyDir) fileList = getBackupFiles(dailyDir) # ignores indicator files for path in fileList: size = float(os.stat(path).st_size) if size > sizeLimit: _splitFile(path, splitSize, backupUser, backupGroup, removeSource=True) logger.debug("Completed splitting contents of [%s].", dailyDir) ######################## # _splitFile() function ######################## def _splitFile(sourcePath, splitSize, backupUser, backupGroup, removeSource=False): """ Splits the source file into chunks of the indicated size. The split files will be owned by the indicated backup user and group. If ``removeSource`` is ``True``, then the source file will be removed after it is successfully split. Args: sourcePath: Absolute path of the source file to split splitSize: Encryption mode (only "gpg" is allowed) backupUser: User that target files should be owned by backupGroup: Group that target files should be owned by removeSource: Indicates whether to remove the source file Raises: IOError: If there is a problem accessing, splitting or removing the source file """ cwd = os.getcwd() try: if not os.path.exists(sourcePath): raise ValueError("Source path [%s] does not exist." % sourcePath) dirname = os.path.dirname(sourcePath) filename = os.path.basename(sourcePath) prefix = "%s_" % filename bytes = int(splitSize.bytes) # pylint: disable=W0622 os.chdir(dirname) # need to operate from directory that we want files written to command = resolveCommand(SPLIT_COMMAND) args = [ "--verbose", "--numeric-suffixes", "--suffix-length=5", "--bytes=%d" % bytes, filename, prefix, ] (result, output) = executeCommand(command, args, returnOutput=True, ignoreStderr=False) if result != 0: raise IOError("Error [%d] calling split for [%s]." % (result, sourcePath)) pattern = re.compile(r"(creating file [`'])(%s)(.*)(')" % prefix) match = pattern.search(output[-1:][0]) if match is None: raise IOError("Unable to parse output from split command.") value = int(match.group(3).strip()) for index in range(0, value): path = "%s%05d" % (prefix, index) if not os.path.exists(path): raise IOError("After call to split, expected file [%s] does not exist." % path) changeOwnership(path, backupUser, backupGroup) if removeSource: if os.path.exists(sourcePath): try: os.remove(sourcePath) logger.debug("Completed removing old file [%s].", sourcePath) except: raise IOError("Failed to remove file [%s] after splitting it." % (sourcePath)) finally: os.chdir(cwd)