Package CedarBackup2 :: Package actions :: Module util

Module util

Implements action-related utilities

Author: Kenneth J. Pronovici <pronovic@ieee.org>

Functions

findDailyDirs(stagingDir, indicatorFile)
Returns a list of all daily staging directories that do not contain the indicated indicator file.

source code

createWriter(config)
Creates a writer object based on current configuration.

source code

writeIndicatorFile(targetDir, indicatorFile, backupUser, backupGroup)
Writes an indicator file into a target directory.

source code

getBackupFiles(targetDir)
Gets a list of backup files in a target directory.

source code

checkMediaState(storeConfig)
Checks state of the media in the backup device to confirm whether it has been initialized for use with Cedar Backup.

source code

initializeMediaState(config)
Initializes state of the media in the backup device so Cedar Backup can recognize it.

source code

buildMediaLabel()
Builds a media label to be used on Cedar Backup media.

source code

_getDeviceType(config)
Gets the device type that should be used for storing.

source code

_getMediaType(config)
Gets the media type that should be used for storing.

source code

Variables

[hide private]

logger = logging.getLogger("CedarBackup2.log.actions.util")

MEDIA_LABEL_PREFIX = 'CEDAR BACKUP'

__package__ = 'CedarBackup2.actions'

Function Details

[hide private]

findDailyDirs(stagingDir, indicatorFile)

source code

Returns a list of all daily staging directories that do not contain the indicated indicator file.

Parameters:

stagingDir - Configured staging directory (config.targetDir)

Returns:

List of absolute paths to daily staging directories.

createWriter(config)

source code

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.

Parameters:

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.

writeIndicatorFile(targetDir, indicatorFile, backupUser, backupGroup)

source code

Writes an indicator file into a target directory.

Parameters:

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

getBackupFiles(targetDir)

source code

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.

Parameters:

targetDir - Directory to look in

Returns:

List of backup files in the directory

Raises:

ValueError - If the target directory does not exist

checkMediaState(storeConfig)

source code

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.

Parameters:

storeConfig - Store configuration

Raises:

ValueError - If media is not initialized.

initializeMediaState(config)

source code

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.

Parameters:

config - Cedar Backup configuration

Raises:

ValueError - If media could not be initialized.
ValueError - If the configured media type is not rewritable

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.

buildMediaLabel()

source code

Builds a media label to be used on Cedar Backup media.

Returns:: Media label as a string.

_getDeviceType(config)

source code

Gets the device type that should be used for storing.

Use the configured device type if not None, otherwise use config.DEFAULT_DEVICE_TYPE.

Parameters:

config - Config object.

Returns:

Device type to be used.

_getMediaType(config)

source code

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

Parameters:

config - Config object.

Returns:

Media type to be used as a writer media type value.

Raises:

ValueError - If the media type is not valid.