Package CedarBackup2 :: Package writers :: Module util :: Class IsoImage
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Class IsoImage

source code

object --+
         |
        IsoImage

Represents an ISO filesystem image.

Summary

This object represents an ISO 9660 filesystem image. It is implemented in terms of the mkisofs program, which has been ported to many operating systems and platforms. A "sensible subset" of the mkisofs functionality is made available through the public interface, allowing callers to set a variety of basic options such as publisher id, application id, etc. as well as specify exactly which files and directories they want included in their image.

By default, the image is created using the Rock Ridge protocol (using the -r option to mkisofs) because Rock Ridge discs are generally more useful on UN*X filesystems than standard ISO 9660 images. However, callers can fall back to the default mkisofs functionality by setting the useRockRidge instance variable to False. Note, however, that this option is not well-tested.

Where Files and Directories are Placed in the Image

Although this class is implemented in terms of the mkisofs program, its standard "image contents" semantics are slightly different than the original mkisofs semantics. The difference is that files and directories are added to the image with some additional information about their source directory kept intact.

As an example, suppose you add the file /etc/profile to your image and you do not configure a graft point. The file /profile will be created in the image. The behavior for directories is similar. For instance, suppose that you add /etc/X11 to the image and do not configure a graft point. In this case, the directory /X11 will be created in the image, even if the original /etc/X11 directory is empty. This behavior differs from the standard mkisofs behavior!

If a graft point is configured, it will be used to modify the point at which a file or directory is added into an image. Using the examples from above, let's assume you set a graft point of base when adding /etc/profile and /etc/X11 to your image. In this case, the file /base/profile and the directory /base/X11 would be added to the image.

I feel that this behavior is more consistent than the original mkisofs behavior. However, to be fair, it is not quite as flexible, and some users might not like it. For this reason, the contentsOnly parameter to the addEntry method can be used to revert to the original behavior if desired.

Instance Methods [hide private]
 
__init__(self, device=None, boundaries=None, graftPoint=None)
Initializes an empty ISO image object.
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addEntry(self, path, graftPoint=None, override=False, contentsOnly=False)
Adds an individual file or directory into the ISO image.
source code
 
getEstimatedSize(self)
Returns the estimated size (in bytes) of the ISO image.
source code
 
_getEstimatedSize(self, entries)
Returns the estimated size (in bytes) for the passed-in entries dictionary.
source code
 
writeImage(self, imagePath)
Writes this image to disk using the image path.
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_buildGeneralArgs(self)
Builds a list of general arguments to be passed to a mkisofs command.
source code
 
_buildSizeArgs(self, entries)
Builds a list of arguments to be passed to a mkisofs command.
source code
 
_buildWriteArgs(self, entries, imagePath)
Builds a list of arguments to be passed to a mkisofs command.
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_setDevice(self, value)
Property target used to set the device value.
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_getDevice(self)
Property target used to get the device value.
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_setBoundaries(self, value)
Property target used to set the boundaries tuple.
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_getBoundaries(self)
Property target used to get the boundaries value.
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_setGraftPoint(self, value)
Property target used to set the graft point.
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_getGraftPoint(self)
Property target used to get the graft point.
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_setUseRockRidge(self, value)
Property target used to set the use RockRidge flag.
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_getUseRockRidge(self)
Property target used to get the use RockRidge flag.
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_setApplicationId(self, value)
Property target used to set the application id.
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_getApplicationId(self)
Property target used to get the application id.
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_setBiblioFile(self, value)
Property target used to set the biblio file.
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_getBiblioFile(self)
Property target used to get the biblio file.
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_setPublisherId(self, value)
Property target used to set the publisher id.
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_getPublisherId(self)
Property target used to get the publisher id.
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_setPreparerId(self, value)
Property target used to set the preparer id.
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_getPreparerId(self)
Property target used to get the preparer id.
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_setVolumeId(self, value)
Property target used to set the volume id.
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_getVolumeId(self)
Property target used to get the volume id.
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Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __sizeof__, __str__, __subclasshook__

Static Methods [hide private]
 
_buildDirEntries(entries)
Uses an entries dictionary to build a list of directory locations for use by mkisofs.
source code
Properties [hide private]
  device
Device that image will be written to (device path or SCSI id).
  boundaries
Session boundaries as required by mkisofs.
  graftPoint
Default image-wide graft point (see addEntry for details).
  useRockRidge
Indicates whether to use RockRidge (default is True).
  applicationId
Optionally specifies the ISO header application id value.
  biblioFile
Optionally specifies the ISO bibliographic file name.
  publisherId
Optionally specifies the ISO header publisher id value.
  preparerId
Optionally specifies the ISO header preparer id value.
  volumeId
Optionally specifies the ISO header volume id value.

Inherited from object: __class__

Method Details [hide private]

__init__(self, device=None, boundaries=None, graftPoint=None)
(Constructor)

source code 

Initializes an empty ISO image object.

Only the most commonly-used configuration items can be set using this constructor. If you have a need to change the others, do so immediately after creating your object.

The device and boundaries values are both required in order to write multisession discs. If either is missing or None, a multisession disc will not be written. The boundaries tuple is in terms of ISO sectors, as built by an image writer class and returned in a writer.MediaCapacity object.

Parameters:
  • device (Either be a filesystem path or a SCSI address) - Name of the device that the image will be written to
  • boundaries (Tuple (last_sess_start,next_sess_start) as returned from cdrecord -msinfo, or None) - Session boundaries as required by mkisofs
  • graftPoint (String representing a graft point path (see addEntry).) - Default graft point for this page.
Overrides: object.__init__

addEntry(self, path, graftPoint=None, override=False, contentsOnly=False)

source code 

Adds an individual file or directory into the ISO image.

The path must exist and must be a file or a directory. By default, the entry will be placed into the image at the root directory, but this behavior can be overridden using the graftPoint parameter or instance variable.

You can use the contentsOnly behavior to revert to the "original" mkisofs behavior for adding directories, which is to add only the items within the directory, and not the directory itself.

Parameters:
  • 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
  • override (Boolean true/false) - Override an existing entry with the same path.
  • contentsOnly (Boolean true/false) - Add directory contents only (standard mkisofs behavior).
Raises:
  • ValueError - If path is not a file or directory, or does not exist.
  • ValueError - If the path has already been added, and override is not set.
  • ValueError - If a path cannot be encoded properly.
Notes:
  • Things get odd if you try to add a directory to an image that will be written to a multisession disc, and the same directory already exists in an earlier session on that disc. Not all of the data gets written. You really wouldn't want to do this anyway, I guess.
  • An exception will be thrown if the path has already been added to the image, unless the override parameter is set to True.
  • The method graftPoints parameter overrides the object-wide instance variable. If neither the method parameter or object-wide value is set, the path will be written at the image root. The graft point behavior is determined by the value which is in effect at the time this method is called, so you must set the object-wide value before calling this method for the first time, or your image may not be consistent.
  • You cannot use the local graftPoint parameter to "turn off" an object-wide instance variable by setting it to None. Python's default argument functionality buys us a lot, but it can't make this method psychic. :)

getEstimatedSize(self)

source code 

Returns the estimated size (in bytes) of the ISO image.

This is implemented via the -print-size option to mkisofs, so it might take a bit of time to execute. However, the result is as accurate as we can get, since it takes into account all of the ISO overhead, the true cost of directories in the structure, etc, etc.

Returns:
Estimated size of the image, in bytes.
Raises:
  • IOError - If there is a problem calling mkisofs.
  • ValueError - If there are no filesystem entries in the image

_getEstimatedSize(self, entries)

source code 

Returns the estimated size (in bytes) for the passed-in entries dictionary.

Returns:
Estimated size of the image, in bytes.
Raises:
  • IOError - If there is a problem calling mkisofs.

writeImage(self, imagePath)

source code 

Writes this image to disk using the image path.

Parameters:
  • imagePath (String representing a path on disk) - Path to write image out as
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.

_buildDirEntries(entries)
Static Method

source code 

Uses an entries dictionary to build a list of directory locations for use by mkisofs.

We build a list of entries that can be passed to mkisofs. Each entry is either raw (if no graft point was configured) or in graft-point form as described above (if a graft point was configured). The dictionary keys are the path names, and the values are the graft points, if any.

Parameters:
  • entries - Dictionary of image entries (i.e. self.entries)
Returns:
List of directory locations for use by mkisofs

_buildGeneralArgs(self)

source code 

Builds a list of general arguments to be passed to a mkisofs command.

The various instance variables (applicationId, etc.) are filled into the list of arguments if they are set. By default, we will build a RockRidge disc. If you decide to change this, think hard about whether you know what you're doing. This option is not well-tested.

Returns:
List suitable for passing to util.executeCommand as args.

_buildSizeArgs(self, entries)

source code 

Builds a list of arguments to be passed to a mkisofs command.

The various instance variables (applicationId, etc.) are filled into the list of arguments if they are set. The command will be built to just return size output (a simple count of sectors via the -print-size option), rather than an image file on disk.

By default, we will build a RockRidge disc. If you decide to change this, think hard about whether you know what you're doing. This option is not well-tested.

Parameters:
  • entries - Dictionary of image entries (i.e. self.entries)
Returns:
List suitable for passing to util.executeCommand as args.

_buildWriteArgs(self, entries, imagePath)

source code 

Builds a list of arguments to be passed to a mkisofs command.

The various instance variables (applicationId, etc.) are filled into the list of arguments if they are set. The command will be built to write an image to disk.

By default, we will build a RockRidge disc. If you decide to change this, think hard about whether you know what you're doing. This option is not well-tested.

Parameters:
  • entries - Dictionary of image entries (i.e. self.entries)
  • imagePath (String representing a path on disk) - Path to write image out as
Returns:
List suitable for passing to util.executeCommand as args.

_setDevice(self, value)

source code 

Property target used to set the device value. If not None, the value can be either an absolute path or a SCSI id.

Raises:
  • ValueError - If the value is not valid

_setBoundaries(self, value)

source code 

Property target used to set the boundaries tuple. If not None, the value must be a tuple of two integers.

Raises:
  • ValueError - If the tuple values are not integers.
  • IndexError - If the tuple does not contain enough elements.

_setGraftPoint(self, value)

source code 

Property target used to set the graft point. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

_setUseRockRidge(self, value)

source code 

Property target used to set the use RockRidge flag. No validations, but we normalize the value to True or False.

_setApplicationId(self, value)

source code 

Property target used to set the application id. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

_setBiblioFile(self, value)

source code 

Property target used to set the biblio file. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

_setPublisherId(self, value)

source code 

Property target used to set the publisher id. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

_setPreparerId(self, value)

source code 

Property target used to set the preparer id. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

_setVolumeId(self, value)

source code 

Property target used to set the volume id. The value must be a non-empty string if it is not None.

Raises:
  • ValueError - If the value is an empty string.

Property Details [hide private]

device

Device that image will be written to (device path or SCSI id).

Get Method:
_getDevice(self) - Property target used to get the device value.
Set Method:
_setDevice(self, value) - Property target used to set the device value.

boundaries

Session boundaries as required by mkisofs.

Get Method:
_getBoundaries(self) - Property target used to get the boundaries value.
Set Method:
_setBoundaries(self, value) - Property target used to set the boundaries tuple.

graftPoint

Default image-wide graft point (see addEntry for details).

Get Method:
_getGraftPoint(self) - Property target used to get the graft point.
Set Method:
_setGraftPoint(self, value) - Property target used to set the graft point.

useRockRidge

Indicates whether to use RockRidge (default is True).

Get Method:
_getUseRockRidge(self) - Property target used to get the use RockRidge flag.
Set Method:
_setUseRockRidge(self, value) - Property target used to set the use RockRidge flag.

applicationId

Optionally specifies the ISO header application id value.

Get Method:
_getApplicationId(self) - Property target used to get the application id.
Set Method:
_setApplicationId(self, value) - Property target used to set the application id.

biblioFile

Optionally specifies the ISO bibliographic file name.

Get Method:
_getBiblioFile(self) - Property target used to get the biblio file.
Set Method:
_setBiblioFile(self, value) - Property target used to set the biblio file.

publisherId

Optionally specifies the ISO header publisher id value.

Get Method:
_getPublisherId(self) - Property target used to get the publisher id.
Set Method:
_setPublisherId(self, value) - Property target used to set the publisher id.

preparerId

Optionally specifies the ISO header preparer id value.

Get Method:
_getPreparerId(self) - Property target used to get the preparer id.
Set Method:
_setPreparerId(self, value) - Property target used to set the preparer id.

volumeId

Optionally specifies the ISO header volume id value.

Get Method:
_getVolumeId(self) - Property target used to get the volume id.
Set Method:
_setVolumeId(self, value) - Property target used to set the volume id.