Source code for CedarBackup3.writers.cdwriter

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#              C E D A R
#          S O L U T I O N S       "Software done right."
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# Copyright (c) 2004-2008,2010,2015 Kenneth J. Pronovici.
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# Author   : Kenneth J. Pronovici <pronovic@ieee.org>
# Language : Python 3 (>= 3.4)
# Project  : Cedar Backup, release 3
# Purpose  : Provides functionality related to CD writer devices.
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# Module documentation
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"""
Provides functionality related to CD writer devices.

Module Attributes
=================

Attributes:
   MEDIA_CDRW_74: Constant representing 74-minute CD-RW media
   MEDIA_CDR_74: Constant representing 74-minute CD-R media
   MEDIA_CDRW_80: Constant representing 80-minute CD-RW media
   MEDIA_CDR_80: Constant representing 80-minute CD-R media

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

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

# Cedar Backup modules
from CedarBackup3.util import resolveCommand, executeCommand
from CedarBackup3.util import convertSize, displayBytes, encodePath
from CedarBackup3.util import UNIT_SECTORS, UNIT_BYTES, UNIT_KBYTES, UNIT_MBYTES
from CedarBackup3.writers.util import validateDevice, validateScsiId, validateDriveSpeed
from CedarBackup3.writers.util import IsoImage


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

logger = logging.getLogger("CedarBackup3.log.writers.cdwriter")

MEDIA_CDRW_74  = 1
MEDIA_CDR_74   = 2
MEDIA_CDRW_80  = 3
MEDIA_CDR_80   = 4

CDRECORD_COMMAND = [ "cdrecord", ]
EJECT_COMMAND    = [ "eject", ]
MKISOFS_COMMAND  = [ "mkisofs", ]


########################################################################
# MediaDefinition class definition
########################################################################

[docs]class MediaDefinition(object): """ Class encapsulating information about CD media definitions. The following media types are accepted: - ``MEDIA_CDR_74``: 74-minute CD-R media (650 MB capacity) - ``MEDIA_CDRW_74``: 74-minute CD-RW media (650 MB capacity) - ``MEDIA_CDR_80``: 80-minute CD-R media (700 MB capacity) - ``MEDIA_CDRW_80``: 80-minute CD-RW media (700 MB capacity) Note that all of the capacities associated with a media definition are in terms of ISO sectors (``util.ISO_SECTOR_SIZE)``. """
[docs] def __init__(self, mediaType): """ Creates a media definition for the indicated media type. Args: mediaType: Type of the media, as discussed above Raises: ValueError: If the media type is unknown or unsupported """ self._mediaType = None self._rewritable = False self._initialLeadIn = 0. self._leadIn = 0.0 self._capacity = 0.0 self._setValues(mediaType)
def _setValues(self, mediaType): """ Sets values based on media type. Args: mediaType: Type of the media, as discussed above Raises: ValueError: If the media type is unknown or unsupported """ if mediaType not in [MEDIA_CDR_74, MEDIA_CDRW_74, MEDIA_CDR_80, MEDIA_CDRW_80]: raise ValueError("Invalid media type %d." % mediaType) self._mediaType = mediaType self._initialLeadIn = 11400.0 # per cdrecord's documentation self._leadIn = 6900.0 # per cdrecord's documentation if self._mediaType == MEDIA_CDR_74: self._rewritable = False self._capacity = convertSize(650.0, UNIT_MBYTES, UNIT_SECTORS) elif self._mediaType == MEDIA_CDRW_74: self._rewritable = True self._capacity = convertSize(650.0, UNIT_MBYTES, UNIT_SECTORS) elif self._mediaType == MEDIA_CDR_80: self._rewritable = False self._capacity = convertSize(700.0, UNIT_MBYTES, UNIT_SECTORS) elif self._mediaType == MEDIA_CDRW_80: self._rewritable = True self._capacity = convertSize(700.0, UNIT_MBYTES, UNIT_SECTORS) def _getMediaType(self): """ Property target used to get the media type value. """ return self._mediaType def _getRewritable(self): """ Property target used to get the rewritable flag value. """ return self._rewritable def _getInitialLeadIn(self): """ Property target used to get the initial lead-in value. """ return self._initialLeadIn def _getLeadIn(self): """ Property target used to get the lead-in value. """ return self._leadIn def _getCapacity(self): """ Property target used to get the capacity value. """ return self._capacity mediaType = property(_getMediaType, None, None, doc="Configured media type.") rewritable = property(_getRewritable, None, None, doc="Boolean indicating whether the media is rewritable.") initialLeadIn = property(_getInitialLeadIn, None, None, doc="Initial lead-in required for first image written to media.") leadIn = property(_getLeadIn, None, None, doc="Lead-in required on successive images written to media.") capacity = property(_getCapacity, None, None, doc="Total capacity of the media before any required lead-in.")
######################################################################## # MediaCapacity class definition ########################################################################
[docs]class MediaCapacity(object): """ Class encapsulating information about CD media capacity. Space used includes the required media lead-in (unless the disk is unused). Space available attempts to provide a picture of how many bytes are available for data storage, including any required lead-in. The boundaries value is either ``None`` (if multisession discs are not supported or if the disc has no boundaries) or in exactly the form provided by ``cdrecord -msinfo``. It can be passed as-is to the ``IsoImage`` class. """
[docs] def __init__(self, bytesUsed, bytesAvailable, boundaries): """ Initializes a capacity object. Raises: IndexError: If the boundaries tuple does not have enough elements ValueError: If the boundaries values are not integers ValueError: If the bytes used and available values are not floats """ self._bytesUsed = float(bytesUsed) self._bytesAvailable = float(bytesAvailable) if boundaries is None: self._boundaries = None else: self._boundaries = (int(boundaries[0]), int(boundaries[1]))
def __str__(self): """ Informal string representation for class instance. """ return "utilized %s of %s (%.2f%%)" % (displayBytes(self.bytesUsed), displayBytes(self.totalCapacity), self.utilized) def _getBytesUsed(self): """ Property target to get the bytes-used value. """ return self._bytesUsed def _getBytesAvailable(self): """ Property target to get the bytes-available value. """ return self._bytesAvailable def _getBoundaries(self): """ Property target to get the boundaries tuple. """ return self._boundaries def _getTotalCapacity(self): """ Property target to get the total capacity (used + available). """ return self.bytesUsed + self.bytesAvailable def _getUtilized(self): """ Property target to get the percent of capacity which is utilized. """ if self.bytesAvailable <= 0.0: return 100.0 elif self.bytesUsed <= 0.0: return 0.0 return (self.bytesUsed / self.totalCapacity) * 100.0 bytesUsed = property(_getBytesUsed, None, None, doc="Space used on disc, in bytes.") bytesAvailable = property(_getBytesAvailable, None, None, doc="Space available on disc, in bytes.") boundaries = property(_getBoundaries, None, None, doc="Session disc boundaries, in terms of ISO sectors.") totalCapacity = property(_getTotalCapacity, None, None, doc="Total capacity of the disc, in bytes.") utilized = property(_getUtilized, None, None, "Percentage of the total capacity which is utilized.")
######################################################################## # _ImageProperties class definition ######################################################################## class _ImageProperties(object): """ Simple value object to hold image properties for ``DvdWriter``. """ def __init__(self): self.newDisc = False self.tmpdir = None self.mediaLabel = None self.entries = None # dict mapping path to graft point ######################################################################## # CdWriter class definition ########################################################################
[docs]class CdWriter(object): ###################### # Class documentation ###################### """ Class representing a device that knows how to write CD media. This is a class representing a device that knows how to write CD media. It provides common operations for the device, such as ejecting the media, writing an ISO image to the media, or checking for the current media capacity. It also provides a place to store device attributes, such as whether the device supports writing multisession discs, etc. This class is implemented in terms of the ``eject`` and ``cdrecord`` programs, both of which should be available on most UN*X platforms. **Image Writer Interface** The following methods make up the "image writer" interface shared with other kinds of writers (such as DVD writers):: __init__ initializeImage() addImageEntry() writeImage() setImageNewDisc() retrieveCapacity() getEstimatedImageSize() Only these methods will be used by other Cedar Backup functionality that expects a compatible image writer. The media attribute is also assumed to be available. **Media Types** This class knows how to write to two different kinds of media, represented by the following constants: - ``MEDIA_CDR_74``: 74-minute CD-R media (650 MB capacity) - ``MEDIA_CDRW_74``: 74-minute CD-RW media (650 MB capacity) - ``MEDIA_CDR_80``: 80-minute CD-R media (700 MB capacity) - ``MEDIA_CDRW_80``: 80-minute CD-RW media (700 MB capacity) Most hardware can read and write both 74-minute and 80-minute CD-R and CD-RW media. Some older drives may only be able to write CD-R media. The difference between the two is that CD-RW media can be rewritten (erased), while CD-R media cannot be. I do not support any other configurations for a couple of reasons. The first is that I've never tested any other kind of media. The second is that anything other than 74 or 80 minute is apparently non-standard. **Device Attributes vs. Media Attributes** A given writer instance has two different kinds of attributes associated with it, which I call device attributes and media attributes. Device attributes are things which can be determined without looking at the media, such as whether the drive supports writing multisession disks or has a tray. Media attributes are attributes which vary depending on the state of the media, such as the remaining capacity on a disc. In general, device attributes are available via instance variables and are constant over the life of an object, while media attributes can be retrieved through method calls. **Talking to Hardware** This class needs to talk to CD writer hardware in two different ways: through cdrecord to actually write to the media, and through the filesystem to do things like open and close the tray. Historically, CdWriter has interacted with cdrecord using the scsiId attribute, and with most other utilities using the device attribute. This changed somewhat in Cedar Backup 2.9.0. When Cedar Backup was first written, the only way to interact with cdrecord was by using a SCSI device id. IDE devices were mapped to pseudo-SCSI devices through the kernel. Later, extended SCSI "methods" arrived, and it became common to see ``ATA:1,0,0`` or ``ATAPI:0,0,0`` as a way to address IDE hardware. By late 2006, ``ATA`` and ``ATAPI`` had apparently been deprecated in favor of just addressing the IDE device directly by name, i.e. ``/dev/cdrw``. Because of this latest development, it no longer makes sense to require a CdWriter to be created with a SCSI id -- there might not be one. So, the passed-in SCSI id is now optional. Also, there is now a hardwareId attribute. This attribute is filled in with either the SCSI id (if provided) or the device (otherwise). The hardware id is the value that will be passed to cdrecord in the ``dev=`` argument. **Testing** It's rather difficult to test this code in an automated fashion, even if you have access to a physical CD writer drive. It's even more difficult to test it if you are running on some build daemon (think of a Debian autobuilder) which can't be expected to have any hardware or any media that you could write to. Because of this, much of the implementation below is in terms of static methods that are supposed to take defined actions based on their arguments. Public methods are then implemented in terms of a series of calls to simplistic static methods. This way, we can test as much as possible of the functionality via testing the static methods, while hoping that if the static methods are called appropriately, things will work properly. It's not perfect, but it's much better than no testing at all. """ ############## # Constructor ##############
[docs] def __init__(self, device, scsiId=None, driveSpeed=None, mediaType=MEDIA_CDRW_74, noEject=False, refreshMediaDelay=0, ejectDelay=0, unittest=False): """ Initializes a CD writer object. The current user must have write access to the device at the time the object is instantiated, or an exception will be thrown. However, no media-related validation is done, and in fact there is no need for any media to be in the drive until one of the other media attribute-related methods is called. The various instance variables such as ``deviceType``, ``deviceVendor``, etc. might be ``None``, if we're unable to parse this specific information from the ``cdrecord`` output. This information is just for reference. The SCSI id is optional, but the device path is required. If the SCSI id is passed in, then the hardware id attribute will be taken from the SCSI id. Otherwise, the hardware id will be taken from the device. If cdrecord improperly detects whether your writer device has a tray and can be safely opened and closed, then pass in ``noEject=False``. This will override the properties and the device will never be ejected. *Note:* The ``unittest`` parameter should never be set to ``True`` outside of Cedar Backup code. It is intended for use in unit testing Cedar Backup internals and has no other sensible purpose. Args: device (Absolute path to a filesystem device, i.e. ``/dev/cdrw``): Filesystem device associated with this writer scsiId (If provided, SCSI id in the form ``[<method>:]scsibus,target,lun``): SCSI id for the device (optional) driveSpeed (Use ``2`` for 2x device, etc. or ``None`` to use device default): Speed at which the drive writes mediaType (One of the valid media type as discussed above): Type of the media that is assumed to be in the drive noEject (Boolean true/false): Overrides properties to indicate that the device does not support eject refreshMediaDelay (Number of seconds, an integer >= 0): Refresh media delay to use, if any ejectDelay (Number of seconds, an integer >= 0): Eject delay to use, if any unittest (Boolean true/false): Turns off certain validations, for use in unit testing Raises: ValueError: If the device is not valid for some reason ValueError: If the SCSI id is not in a valid form ValueError: If the drive speed is not an integer >= 1 IOError: If device properties could not be read for some reason """ self._image = None # optionally filled in by initializeImage() self._device = validateDevice(device, unittest) self._scsiId = validateScsiId(scsiId) self._driveSpeed = validateDriveSpeed(driveSpeed) self._media = MediaDefinition(mediaType) self._noEject = noEject self._refreshMediaDelay = refreshMediaDelay self._ejectDelay = ejectDelay if not unittest: (self._deviceType, self._deviceVendor, self._deviceId, self._deviceBufferSize, self._deviceSupportsMulti, self._deviceHasTray, self._deviceCanEject) = self._retrieveProperties()
############# # Properties ############# def _getDevice(self): """ Property target used to get the device value. """ return self._device def _getScsiId(self): """ Property target used to get the SCSI id value. """ return self._scsiId def _getHardwareId(self): """ Property target used to get the hardware id value. """ if self._scsiId is None: return self._device return self._scsiId def _getDriveSpeed(self): """ Property target used to get the drive speed. """ return self._driveSpeed def _getMedia(self): """ Property target used to get the media description. """ return self._media def _getDeviceType(self): """ Property target used to get the device type. """ return self._deviceType def _getDeviceVendor(self): """ Property target used to get the device vendor. """ return self._deviceVendor def _getDeviceId(self): """ Property target used to get the device id. """ return self._deviceId def _getDeviceBufferSize(self): """ Property target used to get the device buffer size. """ return self._deviceBufferSize def _getDeviceSupportsMulti(self): """ Property target used to get the device-support-multi flag. """ return self._deviceSupportsMulti def _getDeviceHasTray(self): """ Property target used to get the device-has-tray flag. """ return self._deviceHasTray def _getDeviceCanEject(self): """ Property target used to get the device-can-eject flag. """ return self._deviceCanEject def _getRefreshMediaDelay(self): """ Property target used to get the configured refresh media delay, in seconds. """ return self._refreshMediaDelay def _getEjectDelay(self): """ Property target used to get the configured eject delay, in seconds. """ return self._ejectDelay device = property(_getDevice, None, None, doc="Filesystem device name for this writer.") scsiId = property(_getScsiId, None, None, doc="SCSI id for the device, in the form ``[<method>:]scsibus,target,lun``.") hardwareId = property(_getHardwareId, None, None, doc="Hardware id for this writer, either SCSI id or device path.") driveSpeed = property(_getDriveSpeed, None, None, doc="Speed at which the drive writes.") media = property(_getMedia, None, None, doc="Definition of media that is expected to be in the device.") deviceType = property(_getDeviceType, None, None, doc="Type of the device, as returned from ``cdrecord -prcap``.") deviceVendor = property(_getDeviceVendor, None, None, doc="Vendor of the device, as returned from ``cdrecord -prcap``.") deviceId = property(_getDeviceId, None, None, doc="Device identification, as returned from ``cdrecord -prcap``.") deviceBufferSize = property(_getDeviceBufferSize, None, None, doc="Size of the device's write buffer, in bytes.") deviceSupportsMulti = property(_getDeviceSupportsMulti, None, None, doc="Indicates whether device supports multisession discs.") deviceHasTray = property(_getDeviceHasTray, None, None, doc="Indicates whether the device has a media tray.") deviceCanEject = property(_getDeviceCanEject, None, None, doc="Indicates whether the device supports ejecting its media.") refreshMediaDelay = property(_getRefreshMediaDelay, None, None, doc="Refresh media delay, in seconds.") ejectDelay = property(_getEjectDelay, None, None, doc="Eject delay, in seconds.") ################################################# # Methods related to device and media attributes #################################################
[docs] def isRewritable(self): """Indicates whether the media is rewritable per configuration.""" return self._media.rewritable
def _retrieveProperties(self): """ Retrieves properties for a device from ``cdrecord``. The results are returned as a tuple of the object device attributes as returned from :any:`_parsePropertiesOutput`: C{(deviceType, deviceVendor, deviceId, deviceBufferSize, deviceSupportsMulti, deviceHasTray, deviceCanEject)}. Returns: Results tuple as described above Raises: IOError: If there is a problem talking to the device """ args = CdWriter._buildPropertiesArgs(self.hardwareId) command = resolveCommand(CDRECORD_COMMAND) (result, output) = executeCommand(command, args, returnOutput=True, ignoreStderr=True) if result != 0: raise IOError("Error (%d) executing cdrecord command to get properties." % result) return CdWriter._parsePropertiesOutput(output)
[docs] def retrieveCapacity(self, entireDisc=False, useMulti=True): """ Retrieves capacity for the current media in terms of a ``MediaCapacity`` object. If ``entireDisc`` is passed in as ``True`` the capacity will be for the entire disc, as if it were to be rewritten from scratch. If the drive does not support writing multisession discs or if ``useMulti`` is passed in as ``False``, the capacity will also be as if the disc were to be rewritten from scratch, but the indicated boundaries value will be ``None``. The same will happen if the disc cannot be read for some reason. Otherwise, the capacity (including the boundaries) will represent whatever space remains on the disc to be filled by future sessions. Args: entireDisc (Boolean true/false): Indicates whether to return capacity for entire disc useMulti (Boolean true/false): Indicates whether a multisession disc should be assumed, if possible Returns: ``MediaCapacity`` object describing the capacity of the media Raises: IOError: If the media could not be read for some reason """ boundaries = self._getBoundaries(entireDisc, useMulti) return CdWriter._calculateCapacity(self._media, boundaries)
def _getBoundaries(self, entireDisc=False, useMulti=True): """ Gets the ISO boundaries for the media. If ``entireDisc`` is passed in as ``True`` the boundaries will be ``None``, as if the disc were to be rewritten from scratch. If the drive does not support writing multisession discs, the returned value will be ``None``. The same will happen if the disc can't be read for some reason. Otherwise, the returned value will be represent the boundaries of the disc's current contents. The results are returned as a tuple of (lower, upper) as needed by the ``IsoImage`` class. Note that these values are in terms of ISO sectors, not bytes. Clients should generally consider the boundaries value opaque, however. Args: entireDisc (Boolean true/false): Indicates whether to return capacity for entire disc useMulti (Boolean true/false): Indicates whether a multisession disc should be assumed, if possible Returns: Boundaries tuple or ``None``, as described above Raises: IOError: If the media could not be read for some reason """ if not self._deviceSupportsMulti: logger.debug("Device does not support multisession discs; returning boundaries None.") return None elif not useMulti: logger.debug("Use multisession flag is False; returning boundaries None.") return None elif entireDisc: logger.debug("Entire disc flag is True; returning boundaries None.") return None else: args = CdWriter._buildBoundariesArgs(self.hardwareId) command = resolveCommand(CDRECORD_COMMAND) (result, output) = executeCommand(command, args, returnOutput=True, ignoreStderr=True) if result != 0: logger.debug("Error (%d) executing cdrecord command to get capacity.", result) logger.warning("Unable to read disc (might not be initialized); returning boundaries of None.") return None boundaries = CdWriter._parseBoundariesOutput(output) if boundaries is None: logger.debug("Returning disc boundaries: None") else: logger.debug("Returning disc boundaries: (%d, %d)", boundaries[0], boundaries[1]) return boundaries @staticmethod def _calculateCapacity(media, boundaries): """ Calculates capacity for the media in terms of boundaries. If ``boundaries`` is ``None`` or the lower bound is 0 (zero), then the capacity will be for the entire disc minus the initial lead in. Otherwise, capacity will be as if the caller wanted to add an additional session to the end of the existing data on the disc. Args: media: MediaDescription object describing the media capacity boundaries: Session boundaries as returned from :any:`_getBoundaries` Returns: ``MediaCapacity`` object describing the capacity of the media """ if boundaries is None or boundaries[1] == 0: logger.debug("Capacity calculations are based on a complete disc rewrite.") sectorsAvailable = media.capacity - media.initialLeadIn if sectorsAvailable < 0: sectorsAvailable = 0.0 bytesUsed = 0.0 bytesAvailable = convertSize(sectorsAvailable, UNIT_SECTORS, UNIT_BYTES) else: logger.debug("Capacity calculations are based on a new ISO session.") sectorsAvailable = media.capacity - boundaries[1] - media.leadIn if sectorsAvailable < 0: sectorsAvailable = 0.0 bytesUsed = convertSize(boundaries[1], UNIT_SECTORS, UNIT_BYTES) bytesAvailable = convertSize(sectorsAvailable, UNIT_SECTORS, UNIT_BYTES) logger.debug("Used [%s], available [%s].", displayBytes(bytesUsed), displayBytes(bytesAvailable)) return MediaCapacity(bytesUsed, bytesAvailable, boundaries) ####################################################### # Methods used for working with the internal ISO image #######################################################
[docs] def initializeImage(self, newDisc, tmpdir, mediaLabel=None): """ Initializes the writer's associated ISO image. This method initializes the ``image`` instance variable so that the caller can use the ``addImageEntry`` method. Once entries have been added, the ``writeImage`` method can be called with no arguments. Args: newDisc (Boolean true/false): Indicates whether the disc should be re-initialized tmpdir (String representing a directory path on disk): Temporary directory to use if needed mediaLabel (String, no more than 25 characters long): Media label to be applied to the image, if any """ self._image = _ImageProperties() self._image.newDisc = newDisc self._image.tmpdir = encodePath(tmpdir) self._image.mediaLabel = mediaLabel self._image.entries = {} # mapping from path to graft point (if any)
[docs] def addImageEntry(self, path, graftPoint): """ Adds a filepath entry to the writer's associated ISO image. The contents of the filepath -- but not the path itself -- will be added to the image at the indicated graft point. If you don't want to use a graft point, just pass ``None``. *Note:* Before calling this method, you must call :any:`initializeImage`. Args: path (String representing a path on disk): File or directory to be added to the image graftPoint (String representing a graft point path, as described above): Graft point to be used when adding this entry Raises: ValueError: If initializeImage() was not previously called """ if self._image is None: raise ValueError("Must call initializeImage() before using this method.") if not os.path.exists(path): raise ValueError("Path [%s] does not exist." % path) self._image.entries[path] = graftPoint
[docs] def setImageNewDisc(self, newDisc): """ Resets (overrides) the newDisc flag on the internal image. Args: newDisc: New disc flag to set Raises: ValueError: If initializeImage() was not previously called """ if self._image is None: raise ValueError("Must call initializeImage() before using this method.") self._image.newDisc = newDisc
[docs] def getEstimatedImageSize(self): """ Gets the estimated size of the image associated with the writer. Returns: Estimated size of the image, in bytes Raises: IOError: If there is a problem calling ``mkisofs`` ValueError: If initializeImage() was not previously called """ if self._image is None: raise ValueError("Must call initializeImage() before using this method.") image = IsoImage() for path in list(self._image.entries.keys()): image.addEntry(path, self._image.entries[path], override=False, contentsOnly=True) return image.getEstimatedSize()
###################################### # Methods which expose device actions ######################################
[docs] def openTray(self): """ Opens the device's tray and leaves it open. This only works if the device has a tray and supports ejecting its media. We have no way to know if the tray is currently open or closed, so we just send the appropriate command and hope for the best. If the device does not have a tray or does not support ejecting its media, then we do nothing. If the writer was constructed with ``noEject=True``, then this is a no-op. Starting with Debian wheezy on my backup hardware, I started seeing consistent problems with the eject command. I couldn't tell whether these problems were due to the device management system or to the new kernel (3.2.0). Initially, I saw simple eject failures, possibly because I was opening and closing the tray too quickly. I worked around that behavior with the new ejectDelay flag. Later, I sometimes ran into issues after writing an image to a disc: eject would give errors like "unable to eject, last error: Inappropriate ioctl for device". Various sources online (like Ubuntu bug #875543) suggested that the drive was being locked somehow, and that the workaround was to run 'eject -i off' to unlock it. Sure enough, that fixed the problem for me, so now it's a normal error-handling strategy. Raises: IOError: If there is an error talking to the device """ if not self._noEject: if self._deviceHasTray and self._deviceCanEject: args = CdWriter._buildOpenTrayArgs(self._device) result = executeCommand(EJECT_COMMAND, args)[0] if result != 0: logger.debug("Eject failed; attempting kludge of unlocking the tray before retrying.") self.unlockTray() result = executeCommand(EJECT_COMMAND, args)[0] if result != 0: raise IOError("Error (%d) executing eject command to open tray (failed even after unlocking tray)." % result) logger.debug("Kludge was apparently successful.") if self.ejectDelay is not None: logger.debug("Per configuration, sleeping %d seconds after opening tray.", self.ejectDelay) time.sleep(self.ejectDelay)
[docs] def unlockTray(self): """ Unlocks the device's tray. Raises: IOError: If there is an error talking to the device """ args = CdWriter._buildUnlockTrayArgs(self._device) command = resolveCommand(EJECT_COMMAND) result = executeCommand(command, args)[0] if result != 0: raise IOError("Error (%d) executing eject command to unlock tray." % result)
[docs] def closeTray(self): """ Closes the device's tray. This only works if the device has a tray and supports ejecting its media. We have no way to know if the tray is currently open or closed, so we just send the appropriate command and hope for the best. If the device does not have a tray or does not support ejecting its media, then we do nothing. If the writer was constructed with ``noEject=True``, then this is a no-op. Raises: IOError: If there is an error talking to the device """ if not self._noEject: if self._deviceHasTray and self._deviceCanEject: args = CdWriter._buildCloseTrayArgs(self._device) command = resolveCommand(EJECT_COMMAND) result = executeCommand(command, args)[0] if result != 0: raise IOError("Error (%d) executing eject command to close tray." % result)
[docs] def refreshMedia(self): """ Opens and then immediately closes the device's tray, to refresh the device's idea of the media. Sometimes, a device gets confused about the state of its media. Often, all it takes to solve the problem is to eject the media and then immediately reload it. (There are also configurable eject and refresh media delays which can be applied, for situations where this makes a difference.) This only works if the device has a tray and supports ejecting its media. We have no way to know if the tray is currently open or closed, so we just send the appropriate command and hope for the best. If the device does not have a tray or does not support ejecting its media, then we do nothing. The configured delays still apply, though. Raises: IOError: If there is an error talking to the device """ self.openTray() self.closeTray() self.unlockTray() # on some systems, writing a disc leaves the tray locked, yikes! if self.refreshMediaDelay is not None: logger.debug("Per configuration, sleeping %d seconds to stabilize media state.", self.refreshMediaDelay) time.sleep(self.refreshMediaDelay) logger.debug("Media refresh complete; hopefully media state is stable now.")
[docs] def writeImage(self, imagePath=None, newDisc=False, writeMulti=True): """ Writes an ISO image to the media in the device. If ``newDisc`` is passed in as ``True``, we assume that the entire disc will be overwritten, and the media will be blanked before writing it if possible (i.e. if the media is rewritable). If ``writeMulti`` is passed in as ``True``, then a multisession disc will be written if possible (i.e. if the drive supports writing multisession discs). if ``imagePath`` is passed in as ``None``, then the existing image configured with ``initializeImage`` will be used. Under these circumstances, the passed-in ``newDisc`` flag will be ignored. By default, we assume that the disc can be written multisession and that we should append to the current contents of the disc. In any case, the ISO image must be generated appropriately (i.e. must take into account any existing session boundaries, etc.) Args: imagePath (String representing a path on disk): Path to an ISO image on disk, or ``None`` to use writer's image newDisc (Boolean true/false): Indicates whether the entire disc will overwritten writeMulti (Boolean true/false): Indicates whether a multisession disc should be written, if possible Raises: ValueError: If the image path is not absolute ValueError: If some path cannot be encoded properly IOError: If the media could not be written to for some reason ValueError: If no image is passed in and initializeImage() was not previously called """ if imagePath is None: if self._image is None: raise ValueError("Must call initializeImage() before using this method with no image path.") try: imagePath = self._createImage() self._writeImage(imagePath, writeMulti, self._image.newDisc) finally: if imagePath is not None and os.path.exists(imagePath): try: os.unlink(imagePath) except: pass else: imagePath = encodePath(imagePath) if not os.path.isabs(imagePath): raise ValueError("Image path must be absolute.") self._writeImage(imagePath, writeMulti, newDisc)
def _createImage(self): """ Creates an ISO image based on configuration in self._image. Returns: Path to the newly-created ISO image on disk Raises: IOError: If there is an error writing the image to disk ValueError: If there are no filesystem entries in the image ValueError: If a path cannot be encoded properly """ path = None capacity = self.retrieveCapacity(entireDisc=self._image.newDisc) image = IsoImage(self.device, capacity.boundaries) image.volumeId = self._image.mediaLabel # may be None, which is also valid for key in list(self._image.entries.keys()): image.addEntry(key, self._image.entries[key], override=False, contentsOnly=True) size = image.getEstimatedSize() logger.info("Image size will be %s.", displayBytes(size)) available = capacity.bytesAvailable logger.debug("Media capacity: %s", displayBytes(available)) if size > available: logger.error("Image [%s] does not fit in available capacity [%s].", displayBytes(size), displayBytes(available)) raise IOError("Media does not contain enough capacity to store image.") try: (handle, path) = tempfile.mkstemp(dir=self._image.tmpdir) try: os.close(handle) except: pass image.writeImage(path) logger.debug("Completed creating image [%s].", path) return path except Exception as e: if path is not None and os.path.exists(path): try: os.unlink(path) except: pass raise e def _writeImage(self, imagePath, writeMulti, newDisc): """ Write an ISO image to disc using cdrecord. The disc is blanked first if ``newDisc`` is ``True``. Args: imagePath: Path to an ISO image on disk writeMulti: Indicates whether a multisession disc should be written, if possible newDisc: Indicates whether the entire disc will overwritten """ if newDisc: self._blankMedia() args = CdWriter._buildWriteArgs(self.hardwareId, imagePath, self._driveSpeed, writeMulti and self._deviceSupportsMulti) command = resolveCommand(CDRECORD_COMMAND) result = executeCommand(command, args)[0] if result != 0: raise IOError("Error (%d) executing command to write disc." % result) self.refreshMedia() def _blankMedia(self): """ Blanks the media in the device, if the media is rewritable. Raises: IOError: If the media could not be written to for some reason """ if self.isRewritable(): args = CdWriter._buildBlankArgs(self.hardwareId) command = resolveCommand(CDRECORD_COMMAND) result = executeCommand(command, args)[0] if result != 0: raise IOError("Error (%d) executing command to blank disc." % result) self.refreshMedia() ####################################### # Methods used to parse command output ####################################### @staticmethod def _parsePropertiesOutput(output): """ Parses the output from a ``cdrecord`` properties command. The ``output`` parameter should be a list of strings as returned from ``executeCommand`` for a ``cdrecord`` command with arguments as from ``_buildPropertiesArgs``. The list of strings will be parsed to yield information about the properties of the device. The output is expected to be a huge long list of strings. Unfortunately, the strings aren't in a completely regular format. However, the format of individual lines seems to be regular enough that we can look for specific values. Two kinds of parsing take place: one kind of parsing picks out out specific values like the device id, device vendor, etc. The other kind of parsing just sets a boolean flag ``True`` if a matching line is found. All of the parsing is done with regular expressions. Right now, pretty much nothing in the output is required and we should parse an empty document successfully (albeit resulting in a device that can't eject, doesn't have a tray and doesnt't support multisession discs). I had briefly considered erroring out if certain lines weren't found or couldn't be parsed, but that seems like a bad idea given that most of the information is just for reference. The results are returned as a tuple of the object device attributes: C{(deviceType, deviceVendor, deviceId, deviceBufferSize, deviceSupportsMulti, deviceHasTray, deviceCanEject)}. Args: output: Output from a ``cdrecord -prcap`` command Returns: Results tuple as described above Raises: IOError: If there is problem parsing the output """ deviceType = None deviceVendor = None deviceId = None deviceBufferSize = None deviceSupportsMulti = False deviceHasTray = False deviceCanEject = False typePattern = re.compile(r"(^Device type\s*:\s*)(.*)(\s*)(.*$)") vendorPattern = re.compile(r"(^Vendor_info\s*:\s*'\s*)(.*?)(\s*')(.*$)") idPattern = re.compile(r"(^Identifikation\s*:\s*'\s*)(.*?)(\s*')(.*$)") bufferPattern = re.compile(r"(^\s*Buffer size in KB:\s*)(.*?)(\s*$)") multiPattern = re.compile(r"^\s*Does read multi-session.*$") trayPattern = re.compile(r"^\s*Loading mechanism type: tray.*$") ejectPattern = re.compile(r"^\s*Does support ejection.*$") for line in output: if typePattern.search(line): deviceType = typePattern.search(line).group(2) logger.info("Device type is [%s].", deviceType) elif vendorPattern.search(line): deviceVendor = vendorPattern.search(line).group(2) logger.info("Device vendor is [%s].", deviceVendor) elif idPattern.search(line): deviceId = idPattern.search(line).group(2) logger.info("Device id is [%s].", deviceId) elif bufferPattern.search(line): try: sectors = int(bufferPattern.search(line).group(2)) deviceBufferSize = convertSize(sectors, UNIT_KBYTES, UNIT_BYTES) logger.info("Device buffer size is [%d] bytes.", deviceBufferSize) except TypeError: pass elif multiPattern.search(line): deviceSupportsMulti = True logger.info("Device does support multisession discs.") elif trayPattern.search(line): deviceHasTray = True logger.info("Device has a tray.") elif ejectPattern.search(line): deviceCanEject = True logger.info("Device can eject its media.") return (deviceType, deviceVendor, deviceId, deviceBufferSize, deviceSupportsMulti, deviceHasTray, deviceCanEject) @staticmethod def _parseBoundariesOutput(output): """ Parses the output from a ``cdrecord`` capacity command. The ``output`` parameter should be a list of strings as returned from ``executeCommand`` for a ``cdrecord`` command with arguments as from ``_buildBoundaryArgs``. The list of strings will be parsed to yield information about the capacity of the media in the device. Basically, we expect the list of strings to include just one line, a pair of values. There isn't supposed to be whitespace, but we allow it anyway in the regular expression. Any lines below the one line we parse are completely ignored. It would be a good idea to ignore ``stderr`` when executing the ``cdrecord`` command that generates output for this method, because sometimes ``cdrecord`` spits out kernel warnings about the actual output. The results are returned as a tuple of (lower, upper) as needed by the ``IsoImage`` class. Note that these values are in terms of ISO sectors, not bytes. Clients should generally consider the boundaries value opaque, however. *Note:* If the boundaries output can't be parsed, we return ``None``. Args: output: Output from a ``cdrecord -msinfo`` command Returns: Boundaries tuple as described above Raises: IOError: If there is problem parsing the output """ if len(output) < 1: logger.warning("Unable to read disc (might not be initialized); returning full capacity.") return None boundaryPattern = re.compile(r"(^\s*)([0-9]*)(\s*,\s*)([0-9]*)(\s*$)") parsed = boundaryPattern.search(output[0]) if not parsed: raise IOError("Unable to parse output of boundaries command.") try: boundaries = ( int(parsed.group(2)), int(parsed.group(4)) ) except TypeError: raise IOError("Unable to parse output of boundaries command.") return boundaries ################################# # Methods used to build commands ################################# @staticmethod def _buildOpenTrayArgs(device): """ Builds a list of arguments to be passed to a ``eject`` command. The arguments will cause the ``eject`` command to open the tray and eject the media. No validation is done by this method as to whether this action actually makes sense. Args: device: Filesystem device name for this writer, i.e. ``/dev/cdrw`` Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append(device) return args @staticmethod def _buildUnlockTrayArgs(device): """ Builds a list of arguments to be passed to a ``eject`` command. The arguments will cause the ``eject`` command to unlock the tray. Args: device: Filesystem device name for this writer, i.e. ``/dev/cdrw`` Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-i") args.append("off") args.append(device) return args @staticmethod def _buildCloseTrayArgs(device): """ Builds a list of arguments to be passed to a ``eject`` command. The arguments will cause the ``eject`` command to close the tray and reload the media. No validation is done by this method as to whether this action actually makes sense. Args: device: Filesystem device name for this writer, i.e. ``/dev/cdrw`` Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-t") args.append(device) return args @staticmethod def _buildPropertiesArgs(hardwareId): """ Builds a list of arguments to be passed to a ``cdrecord`` command. The arguments will cause the ``cdrecord`` command to ask the device for a list of its capacities via the ``-prcap`` switch. Args: hardwareId: Hardware id for the device (either SCSI id or device path) Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-prcap") args.append("dev=%s" % hardwareId) return args @staticmethod def _buildBoundariesArgs(hardwareId): """ Builds a list of arguments to be passed to a ``cdrecord`` command. The arguments will cause the ``cdrecord`` command to ask the device for the current multisession boundaries of the media using the ``-msinfo`` switch. Args: hardwareId: Hardware id for the device (either SCSI id or device path) Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-msinfo") args.append("dev=%s" % hardwareId) return args @staticmethod def _buildBlankArgs(hardwareId, driveSpeed=None): """ Builds a list of arguments to be passed to a ``cdrecord`` command. The arguments will cause the ``cdrecord`` command to blank the media in the device identified by ``hardwareId``. No validation is done by this method as to whether the action makes sense (i.e. to whether the media even can be blanked). Args: hardwareId: Hardware id for the device (either SCSI id or device path) driveSpeed: Speed at which the drive writes Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-v") args.append("blank=fast") if driveSpeed is not None: args.append("speed=%d" % driveSpeed) args.append("dev=%s" % hardwareId) return args @staticmethod def _buildWriteArgs(hardwareId, imagePath, driveSpeed=None, writeMulti=True): """ Builds a list of arguments to be passed to a ``cdrecord`` command. The arguments will cause the ``cdrecord`` command to write the indicated ISO image (``imagePath``) to the media in the device identified by ``hardwareId``. The ``writeMulti`` argument controls whether to write a multisession disc. No validation is done by this method as to whether the action makes sense (i.e. to whether the device even can write multisession discs, for instance). Args: hardwareId: Hardware id for the device (either SCSI id or device path) imagePath: Path to an ISO image on disk driveSpeed: Speed at which the drive writes writeMulti: Indicates whether to write a multisession disc Returns: List suitable for passing to :any:`util.executeCommand` as ``args`` """ args = [] args.append("-v") if driveSpeed is not None: args.append("speed=%d" % driveSpeed) args.append("dev=%s" % hardwareId) if writeMulti: args.append("-multi") args.append("-data") args.append(imagePath) return args