Source code for CedarBackup3.actions.util

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#          S O L U T I O N S       "Software done right."
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# Copyright (c) 2007,2010,2015 Kenneth J. Pronovici.
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# This program is free software; you can redistribute it and/or
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# Author   : Kenneth J. Pronovici <pronovic@ieee.org>
# Language : Python 3 (>= 3.4)
# Project  : Cedar Backup, release 3
# Purpose  : Implements action-related utilities
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# Module documentation
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"""
Implements action-related utilities
:author: Kenneth J. Pronovici <pronovic@ieee.org>
"""


########################################################################
# Imported modules
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# System modules
import os
import time
import tempfile
import logging

# Cedar Backup modules
from CedarBackup3.filesystem import FilesystemList
from CedarBackup3.util import changeOwnership
from CedarBackup3.util import deviceMounted
from CedarBackup3.writers.util import readMediaLabel
from CedarBackup3.writers.cdwriter import CdWriter
from CedarBackup3.writers.dvdwriter import DvdWriter
from CedarBackup3.writers.cdwriter import MEDIA_CDR_74, MEDIA_CDR_80, MEDIA_CDRW_74, MEDIA_CDRW_80
from CedarBackup3.writers.dvdwriter import MEDIA_DVDPLUSR, MEDIA_DVDPLUSRW
from CedarBackup3.config import DEFAULT_MEDIA_TYPE, DEFAULT_DEVICE_TYPE, REWRITABLE_MEDIA_TYPES
from CedarBackup3.actions.constants import INDICATOR_PATTERN


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# Module-wide constants and variables
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logger = logging.getLogger("CedarBackup3.log.actions.util")
MEDIA_LABEL_PREFIX   = "CEDAR BACKUP"


########################################################################
# Public utility functions
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###########################
# findDailyDirs() function
###########################

[docs]def findDailyDirs(stagingDir, indicatorFile): """ Returns a list of all daily staging directories that do not contain the indicated indicator file. Args: stagingDir: Configured staging directory (config.targetDir) Returns: List of absolute paths to daily staging directories """ results = FilesystemList() yearDirs = FilesystemList() yearDirs.excludeFiles = True yearDirs.excludeLinks = True yearDirs.addDirContents(path=stagingDir, recursive=False, addSelf=False) for yearDir in yearDirs: monthDirs = FilesystemList() monthDirs.excludeFiles = True monthDirs.excludeLinks = True monthDirs.addDirContents(path=yearDir, recursive=False, addSelf=False) for monthDir in monthDirs: dailyDirs = FilesystemList() dailyDirs.excludeFiles = True dailyDirs.excludeLinks = True dailyDirs.addDirContents(path=monthDir, recursive=False, addSelf=False) for dailyDir in dailyDirs: if os.path.exists(os.path.join(dailyDir, indicatorFile)): logger.debug("Skipping directory [%s]; contains %s.", dailyDir, indicatorFile) else: logger.debug("Adding [%s] to list of daily directories.", dailyDir) results.append(dailyDir) # just put it in the list, no fancy operations return results
########################### # createWriter() function ###########################
[docs]def createWriter(config): """ Creates a writer object based on current configuration. This function creates and returns a writer based on configuration. This is done to abstract action functionality from knowing what kind of writer is in use. Since all writers implement the same interface, there's no need for actions to care which one they're working with. Currently, the ``cdwriter`` and ``dvdwriter`` device types are allowed. An exception will be raised if any other device type is used. This function also checks to make sure that the device isn't mounted before creating a writer object for it. Experience shows that sometimes if the device is mounted, we have problems with the backup. We may as well do the check here first, before instantiating the writer. Args: config: Config object Returns: Writer that can be used to write a directory to some media Raises: ValueError: If there is a problem getting the writer IOError: If there is a problem creating the writer object """ devicePath = config.store.devicePath deviceScsiId = config.store.deviceScsiId driveSpeed = config.store.driveSpeed noEject = config.store.noEject refreshMediaDelay = config.store.refreshMediaDelay ejectDelay = config.store.ejectDelay deviceType = _getDeviceType(config) mediaType = _getMediaType(config) if deviceMounted(devicePath): raise IOError("Device [%s] is currently mounted." % (devicePath)) if deviceType == "cdwriter": return CdWriter(devicePath, deviceScsiId, driveSpeed, mediaType, noEject, refreshMediaDelay, ejectDelay) elif deviceType == "dvdwriter": return DvdWriter(devicePath, deviceScsiId, driveSpeed, mediaType, noEject, refreshMediaDelay, ejectDelay) else: raise ValueError("Device type [%s] is invalid." % deviceType)
################################ # writeIndicatorFile() function ################################
[docs]def writeIndicatorFile(targetDir, indicatorFile, backupUser, backupGroup): """ Writes an indicator file into a target directory. Args: targetDir: Target directory in which to write indicator indicatorFile: Name of the indicator file backupUser: User that indicator file should be owned by backupGroup: Group that indicator file should be owned by Raises: IOException: If there is a problem writing the indicator file """ filename = os.path.join(targetDir, indicatorFile) logger.debug("Writing indicator file [%s].", filename) try: with open(filename, "w") as f: f.write("") changeOwnership(filename, backupUser, backupGroup) except Exception as e: logger.error("Error writing [%s]: %s", filename, e) raise e
############################ # getBackupFiles() function ############################
[docs]def getBackupFiles(targetDir): """ Gets a list of backup files in a target directory. Files that match INDICATOR_PATTERN (i.e. ``"cback.store"``, ``"cback.stage"``, etc.) are assumed to be indicator files and are ignored. Args: targetDir: Directory to look in Returns: List of backup files in the directory Raises: ValueError: If the target directory does not exist """ if not os.path.isdir(targetDir): raise ValueError("Target directory [%s] is not a directory or does not exist." % targetDir) fileList = FilesystemList() fileList.excludeDirs = True fileList.excludeLinks = True fileList.excludeBasenamePatterns = INDICATOR_PATTERN fileList.addDirContents(targetDir) return fileList
#################### # checkMediaState() ####################
[docs]def checkMediaState(storeConfig): """ Checks state of the media in the backup device to confirm whether it has been initialized for use with Cedar Backup. We can tell whether the media has been initialized by looking at its media label. If the media label starts with MEDIA_LABEL_PREFIX, then it has been initialized. The check varies depending on whether the media is rewritable or not. For non-rewritable media, we also accept a ``None`` media label, since this kind of media cannot safely be initialized. Args: storeConfig: Store configuration Raises: ValueError: If media is not initialized """ mediaLabel = readMediaLabel(storeConfig.devicePath) if storeConfig.mediaType in REWRITABLE_MEDIA_TYPES: if mediaLabel is None: raise ValueError("Media has not been initialized: no media label available") elif not mediaLabel.startswith(MEDIA_LABEL_PREFIX): raise ValueError("Media has not been initialized: unrecognized media label [%s]" % mediaLabel) else: if mediaLabel is None: logger.info("Media has no media label; assuming OK since media is not rewritable.") elif not mediaLabel.startswith(MEDIA_LABEL_PREFIX): raise ValueError("Media has not been initialized: unrecognized media label [%s]" % mediaLabel)
######################### # initializeMediaState() #########################
[docs]def initializeMediaState(config): """ Initializes state of the media in the backup device so Cedar Backup can recognize it. This is done by writing an mostly-empty image (it contains a "Cedar Backup" directory) to the media with a known media label. *Note:* Only rewritable media (CD-RW, DVD+RW) can be initialized. It doesn't make any sense to initialize media that cannot be rewritten (CD-R, DVD+R), since Cedar Backup would then not be able to use that media for a backup. Args: config: Cedar Backup configuration Raises: ValueError: If media could not be initialized ValueError: If the configured media type is not rewritable """ if not config.store.mediaType in REWRITABLE_MEDIA_TYPES: raise ValueError("Only rewritable media types can be initialized.") mediaLabel = buildMediaLabel() writer = createWriter(config) writer.refreshMedia() writer.initializeImage(True, config.options.workingDir, mediaLabel) # always create a new disc tempdir = tempfile.mkdtemp(dir=config.options.workingDir) try: writer.addImageEntry(tempdir, "CedarBackup") writer.writeImage() finally: if os.path.exists(tempdir): try: os.rmdir(tempdir) except: pass
#################### # buildMediaLabel() ####################
[docs]def buildMediaLabel(): """ Builds a media label to be used on Cedar Backup media. Returns: Media label as a string """ currentDate = time.strftime("%d-%b-%Y").upper() return "%s %s" % (MEDIA_LABEL_PREFIX, currentDate)
######################################################################## # Private attribute "getter" functions ######################################################################## ############################ # _getDeviceType() function ############################ def _getDeviceType(config): """ Gets the device type that should be used for storing. Use the configured device type if not ``None``, otherwise use :any:`config.DEFAULT_DEVICE_TYPE`. Args: config: Config object Returns: Device type to be used """ if config.store.deviceType is None: deviceType = DEFAULT_DEVICE_TYPE else: deviceType = config.store.deviceType logger.debug("Device type is [%s]", deviceType) return deviceType ########################### # _getMediaType() function ########################### def _getMediaType(config): """ Gets the media type that should be used for storing. Use the configured media type if not ``None``, otherwise use ``DEFAULT_MEDIA_TYPE``. Once we figure out what configuration value to use, we return a media type value that is valid in one of the supported writers:: MEDIA_CDR_74 MEDIA_CDRW_74 MEDIA_CDR_80 MEDIA_CDRW_80 MEDIA_DVDPLUSR MEDIA_DVDPLUSRW Args: config: Config object Returns: Media type to be used as a writer media type value Raises: ValueError: If the media type is not valid """ if config.store.mediaType is None: mediaType = DEFAULT_MEDIA_TYPE else: mediaType = config.store.mediaType if mediaType == "cdr-74": logger.debug("Media type is MEDIA_CDR_74.") return MEDIA_CDR_74 elif mediaType == "cdrw-74": logger.debug("Media type is MEDIA_CDRW_74.") return MEDIA_CDRW_74 elif mediaType == "cdr-80": logger.debug("Media type is MEDIA_CDR_80.") return MEDIA_CDR_80 elif mediaType == "cdrw-80": logger.debug("Media type is MEDIA_CDRW_80.") return MEDIA_CDRW_80 elif mediaType == "dvd+r": logger.debug("Media type is MEDIA_DVDPLUSR.") return MEDIA_DVDPLUSR elif mediaType == "dvd+rw": logger.debug("Media type is MEDIA_DVDPLUSRW.") return MEDIA_DVDPLUSRW else: raise ValueError("Media type [%s] is not valid." % mediaType)