Overview
Defines common features of all filesystem content objects.
Discussion
About Content Creation
Content creation provides an interface for dynamic filesystem creation, allowing
complex filesystem hierarchies to be created and burned on-the-fly without having
to generate a complete on-disk representation.
The root object for the objects contained in the Objective C
content creation hierarchy is DRFSObject . Through DRFSObject, file and folder objects
inherit a basic interface to getting and setting filesystem properties,
names and masks. The DRFSObject class is an abstract class, there are no
methods available to create a DRFSObject directly, you create DRFile and
DRFolder objects instead.
Real and Virtual Objects
The interface is designed around folder and file objects which are laid out
in a one-parent-many-children hierarchy - this should be a familiar concept for
anyone who's ever used a modern filesystem. There are two kinds of objects in
this API; "real" objects and "virtual" objects, and the distinction is important.
A real file or folder object corresponds directly to a file or folder
on disk. The data for a real file object comes directly from the on-disk file.
The hierarchy underneath a real folder object corresponds 1:1 to the
hierarchy underneath the folder in the on-disk filesystem.
A virtual file or folder object does not have any actual representation
on disk. The data for a virtual file object is specified through the API or
in a callback function. The hierarchy underneath a virtual folder object
is specified through the API.
Creating a Virtual Hierarchy
In the hierarchy specified through this API, only virtual folders may be assigned
children. Real files, virtual files, and real folders are all considered leaf
nodes and may not have children. (Real folders may of course contain files and
folders, but the files and folders are specified by the on-disk representation and
may not be changed through the API unless the real folder is made virtual first.)
A hierarchy may be as simple as a single real folder, or it can be as complicated
as needed - for example, a virtual folder with a deep hierarchy of children which are
a complex mix of real files, virtual files, real folders, and virtual folders.
Converting From Real To Virtual
A real folder can be dynamically converted to a virtual folder, in which case
its first level of children is read and converted into a virtual hierarchy. The children
thus created will all be real. For example: A real folder named root is converted
into a virtual folder. The on-disk folder contains a file named file1 and
a folder named folder2. After conversion, the result is a virtual folder named
root with two children: the real file file1 and the real folder folder2.
Base Names and Specific Names
Because the content creation API is able to generate multiple filesystems which
require multiple varied naming conventions, a sensible system for naming is required.
Thus each file has a base name which corresponds to its default name in any filesystem.
Whenever possible, the base name will be used in the generated filesystem without
modification.
The initial base name for a real object is the name of the corresponding object
on disk. The initial base name for a virtual object is specified when the object
is created. The base names for both real and virtual objects may be modified using the
setBaseName: method.
Inside a particular filesytem, if the base name cannot be used as-is (if, for example, it contains illegal
characters, exceeds the length requirements, or otherwise doesn't meet the required format)
then an acceptable name that meets the filesystem's criteria will be generated
automatically from the base name. The name which is acceptable to a given filesystem
is that file's specific name for that filesystem.
A specific name may be obtained and modified through this API, or may be left empty to
be automatically generated from the base name. When a specific name is set through the API,
it will be modified to ensure that the name is legal according to the particular filesystem.
Even when a specific name is set or generated through the API, it may not be the actual name
used on the disc. If an object's specific name conflicts with the specific name of another
of the object's siblings in that filesystem, one or both specific names will be mangled
to obtain a unique name before burning, usually by adding a numeric mangle code such as _001
to each name.
There are two APIs available for getting the specific name from an object:
specificNameForFilesystem: returns the unmodified specific name, which would be used if there were
no conflicts.
mangledNameForFilesystem: returns a modified specific name, mangled if necessary,
which is guaranteed to be unique amongst its siblings in the filesystem.
The filesystem keys are detailed in Filesystem data accessors. Most of the keys are
straightforward; however, ISO-9660
is a special case, since there are two possible naming conventions for ISO-9660, level 1
(8.3, limited charset) and level 2 (30 chars, marginally expanded charset). You can't
specify DRISO9660 when obtaining a name; instead, you must explicitly specify whether
you want the level 1 or level 2 name with DRISO9660LevelOne or DRISO9660LevelTwo.
If the object's
name does not conflict with any of its siblings, mangledNameForFilesystem: will return the same
value as specificNameForFilesystem: . The converse is not necessarily true -- one object may get
the actual specific name, and other files with name collisions will be mangled.
mangledNameForFilesystem: will check each of the object's siblings in the hierarchy and mangle to
resolve any filename conflicts, so it can be a much more expensive call than specificNameForFilesystem: ,
taking at worst O(N^2) time where N is the number of siblings. However, actual performance
tends to be much better, closer to O(N), particularly when there are only a few collisions.
mangledNameForFilesystem: has the advantage of allowing you to see (and to show the user) the exact
names which would be generated on the disc if the burn were started immediately.
Both specificNameForFilesystem: and mangledNameForFilesystem: will cache information when possible, so
that names are only generated and mangled when necessary. Adding or removing children
from a folder, or changing the base or specific name on an object, may cause
the cached names of the object's children or siblings to be recomputed.
Properties and Other Meta-Data
Properties are generally accessed similarly to names. Each object has overall
properties which apply to every filesystem, and it may also have different properties
in each filesystem. For example, a file which has no relevance for a MacOS user
may be marked invisible in the HFS+ tree, but be visible in the Joliet tree.
The properties, like names, are also differentiated by filesystem. There is one
properties dictionary for DRAllFilesystems , and one properties dictionary for each
individual filesystem - DRISO9660 , DRJoliet , DRHFSPlus , etc.
The properties for DRAllFilesystems are treated as the base value, and then the
properties in the specific filesystem dictionary are treated as overrides.
When obtaining properties with propertyForKey:inFilesystem:mergeWithOtherFilesystems: or
propertiesForFilesystem:mergeWithOtherFilesystems: , you can specify whether you want to
automatically coalesce the properties between the specified filesystem dictionary and
the "all filesystems" dictionary. This is useful if you want to obtain the effective
value of the property, because it will return the value from the "all filesystems"
dictionary if the specific filesystem does not assign an override.
Filesystem Masks
It's possible to suppress generation of particular items in a folder tree. For example,
you may want a MacOS application file or bundle to only appear in the HFS+ tree, and
want an .EXE file to only appear in the Joliet tree.
Filesystem-specific suppression is handled through the filesystem mask . The filesystem
mask is a bitfield which contains a 1 if the object will appear in the corresponding filesystem,
and 0 otherwise. This can be used to generate arbitrarily complex trees, where in the most
complex case each filesystem may theoretically have its own unique and disjoint tree.
(Such discs are discouraged, however, since they may be confusing to the user.)
An object can be considered to have two mask values. The first one is the explicit mask
which has been set by the client, and may be zero if no mask has been set. The other is the
effective mask, which is the actual mask which will be used.
If the explicit mask is non-zero, then the object's effective mask is equal to the
bitwise AND of the object's explicit mask and its parent's effective mask.
If the explicit mask is zero, the object will use the same mask as its parent. (In
other words, the effective mask is equal to the parent's effective mask.)
If the root of the hierarchy does not have an explicit mask set, the effective mask of
the root and all its descendants will be zero.
The explicit mask may be cleared by changing it to zero. By doing this, the
object's explicit mask becomes zero and its effective mask will be inherited
from its parent.
If an object's effective mask is zero, it will not be included in the burn. The major
exception to this rule is when the root folder's explicit/effective mask is zero - when
this happens, DiscRecording will assign a default mask, typically one which will result in
the most cross-platform disc possible.
If the effective mask of the root is zero at the time of the burn, DiscRecording will
automatically pick a default mask, typically one which will result in the most
cross-platform disc possible.
Some combinations of filesystem mask have special requirements; for example, Joliet is
based on ISO-9660, and requires that ISO-9660 be enabled on at least the root object.
(You can still have something appear in Joliet but not ISO-9660, however.) Some
combinations in the future may be mutually exclusive.
You do not have to set an explicit mask for anything but the root if you want all
filesystems to have the same data. Since DiscRecording will automatically assign
a mask if none is provided, you do not even have to set an explicit mask for the root.
Symbolic Link Translation
During the burn, when a symbolic link is encountered in the on-disk filesystem corresponding
to a real file or folder, the semantics of the link will be preserved as closely as possible.
If the link contains an absolute path, it will be copied unmodified. If the link contains a
relative path, it will be modified to contain an appropriate path. An important detail to
recognize is that since naming requirements vary between filesystems, the appropriate
path may be different for each filesystem.
For example, a relative link to
"my long, long directory/this: is an unusual$ filename.with_extension"
will be modified to contain something like the following. Note that each component of
the path has been modified to conform to the rules of the target filesystem.
ISO-9660 level 1: "MYLONGLO/THISISAN.WIT"
ISO-9660 level 2: "MY LONG LONG DIRECTORY/THIS: IS AN UNU.WITH_EXTENSION"
Joliet: "my long, long directory/this: is an unusual filename.with_extension"
HFS+: "my long, long directory/this: is an unusual$ filename.with_extension"
The burn engine will make an effort to appropriately translate each component of the path.
However, it's still possible that the symlink might break in complex cases.
(For example, in the case of a relative-path symlink which traverses through an absolute-path
symlink, or when there are filename conflicts along a symlink's path which the burn
engine has to resolve by mangling.)
The burn engine's symlink preservation is usually good enough for most situations in which
symlinks are used. And, when the source filesystem is the same as the target filesystem,
symlinks will be preserved perfectly. (For example, the HFS+ filesystem generated from
an HFS+ source should never have symlink problems.)
However, the odds of symlink failure go up when there are complex arrangements of symlinks,
or when there are filename collisions which the burn engine resolves by mangling.
This is expected behavior. At present, the only way to create a perfect symlink which
is guaranteed to have a correct path on all filesystems is to create a virtual symlink
using symLinkPointingTo:inFilesystem: .
Classes
- DRFSObject
- Abstract base class for the content creation framework
Constants
extern NSString* const DRAccessDate;
Discussion
NSDate containing the item's last-accessed date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRAllFilesystems;
Discussion
The key for accessing the name or properties for the file in
all filesystems together. When this key is used to refer to a name, it refers to the
base name (which has no naming restrictions).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRAttributeModificationDate;
Discussion
NSDate containing the item's attribute modification date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRBackupDate;
Discussion
NSDate containing the item's backup date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRContentModificationDate;
Discussion
NSDate containing the item's content modification date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRCreationDate;
Discussion
NSDate containing the item's creation date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DREffectiveDate;
Discussion
NSDate containing the item's effective date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRExpirationDate;
Discussion
NSDate containing the item's expiration date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRHFSPlus;
Discussion
The key for accessing the HFS+ name/properties for the file.
HFS+ names can be up to 255 decomposed unicode characters long.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRHFSPlusCatalogNodeID;
Discussion
NSNumber containing item's catalog node ID (HFS+ only).
Currently, this value if set is only a suggestion.
The burn engine will attempt to use this node ID, but may use another value
if it needs to resolve conflicts. Default behavior is to allocate node IDs
incrementally from kHFSFirstUserCatalogNodeID .
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRHFSPlusTextEncodingHint;
Discussion
NSNumber containing the item's text encoding hint (HFS+ only).
This value is used by the MacOS to help when converting
the natively UTF-16 filename into an 8-bit-per-character representation (such
as MacRoman, Shift-JIS, or UTF8). If not set, default behavior is to call
CFStringGetMostCompatibleMacStringEncoding (CFStringGetSmallestEncoding ()).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRInvisible;
Discussion
NSBoolean indicating whether the item is invisibile or not.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRISO9660;
Discussion
The key for accessing the ISO-9660 properties for the file.
This key is used to refer specifically to the properties for the file.
This key cannot be used to refer to the name of the file; it is ambiguous,
since the name may be in either level 1 or level 2 format.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRISO9660LevelOne;
Discussion
The key for accessing the ISO-9660 level 1 name for the file.
This key is used to refer specifically to the name generated for ISO-9660 if
the ISO level is set to 1. When used for a property, it is equivalent
in use to the DRISO9660 key and acts as a synonym for that key.
ISO9660 level 1 names are in the form typically known as 8.3 - eight
characters of name and three characters of extension (if it's a file;
directories can't have extensions). Character set is limited to
A-Z, 0-9, and _.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRISO9660LevelTwo;
Discussion
The key for accessing the ISO-9660 level 2 name for the file.
This key is used to refer specifically to the name generated for ISO-9660 if
the ISO level is set to 2. When used for a property, it is equivalent
in use to the DRISO9660 key and acts as a synonym for that key.
ISO9660 level 2 names can be 32 chars long, are limited to a subset
of the 7-bit ASCII chars (capital letters, numbers, space, punctuation),
and are only allowed one "." character.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRISO9660VersionNumber;
Discussion
NSNumber containing the ISO9660 version number for the object. Default value is 1.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRJoliet;
Discussion
The key for accessing the Joliet name/properties for the file.
Joliet names can be 64 precomposed unicode characters long, but are only
allowed one "." character and many punctuation characters are illegal.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacExtendedFinderFlags;
Discussion
NSNumber containing the item's extended Finder flags (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacFileCreator;
Discussion
NSData containing the OSType for the file creator (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacFileType;
Discussion
NSData containing the OSType for the file type (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacFinderFlags;
Discussion
NSNumber containing the item's Finder flags (MacOS only). The invisible bit is ignored - use DRInvisible instead.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacFinderHideExtension;
Discussion
A BOOL indicating whether the extension should be hidden in the Finder or not.
The default is false and only applies to files.
- Availability
- Introduced in Mac OS X v10.5.
extern NSString* const DRMacIconLocation;
Discussion
NSData containing a Point (not NSPoint) for the item's icon location in its parent folder (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacScrollPosition;
Discussion
NSData containing a Point (not NSPoint) for the folder's scroll position (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacWindowBounds;
Discussion
NSData containing a Rect (not NSRect) for the window bounds for a folder (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRMacWindowView;
Discussion
NSNumber containing the folder's window view type (MacOS only).
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRPosixFileMode;
Discussion
NSNumber containing the item's POSIX file mode.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRPosixGID;
Discussion
NSNumber containing the item's POSIX GID.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRPosixUID;
Discussion
NSNumber containing the item's POSIX UID.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRRecordingDate;
Discussion
NSDate containing the item's recording date.
- Availability
- Introduced in Mac OS X v10.2
extern NSString* const DRUDF;
Discussion
The key for accessing the UDF name/properties for the file.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFApplicationIdentifierSuffix;
Discussion
Optional key. NSData object of up to 8 bytes in length, for application use.
The presence of this key requires the DRApplicationIdentifier key.
- Availability
- Introduced in Mac OS X v10.4.
NSNumber indicating the extended UDF file permissions of this file.
extern NSString* const DRUDFExtendedFilePermissions;
Discussion
Bit 0: Change attributes for others (low order bit)
Bit 1: Delete permissions for others
Bit 2: Change attributes for group
Bit 3: Delete permissions for group
Bit 4: Change attributes for owner
Bit 5: Delete permissions for owner
Bit 6 & 7: Reserved
If this key is not present, DRPosixFileMode will be used with the above bits
being set to the corresponding write bit for owner, group, and others.
If DRPosixFileMode is not present, the file mode from the file on disc will
be used, again using the write bit for these permissions.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFInterchangeLevel;
Discussion
Optional key. NSNumber containing the volume interchange level.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFMaxInterchangeLevel;
Discussion
Optional key. NSNumber containing the maximum volume interchange level number.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFMaxVolumeSequenceNumber;
Discussion
Optional key. NSNumber containing the maximum volume sequence number.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFPrimaryVolumeDescriptorNumber;
Discussion
Optional key. NSNumber containing the primary volume sequence number.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFRealTimeFile;
Discussion
NSNumber indicating whether the file is a UDF Real-Time file.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFVersion102;
Discussion
This value is used in DRUDFWriteVersion .
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFVersion150;
Discussion
This value is used in DRUDFWriteVersion .
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFVolumeSequenceNumber;
Discussion
Optional key. NSNumber containing the volume sequence number.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFVolumeSetIdentifier;
Discussion
Optional key. The Volume Set Identifier for the UDF volume set. If this key
is not present, DRVolumeSet will be used if present.
The Volume Set Identifier is composed of the Volume Set Timestamp, the
Implementation Use, and a the string contained in this property.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString * const DRUDFVolumeSetImplementationUse;
Discussion
Optional key. An NSData object (8 bytes in length) for implementation use data.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFVolumeSetTimestamp;
Discussion
Optional key. An NSDate object for the volume set timestamp.
See the UDF specs for details.
- Availability
- Introduced in Mac OS X v10.4.
extern NSString* const DRUDFWriteVersion;
Discussion
Optional key. This property key defines the version for the UDF
structures written to disk. Values are definde in UDF Version types.
- Availability
- Introduced in Mac OS X v10.4.
Typedefs
Mask value determing the presence of a DRFSObject in a specific filesystem.
typedef UInt32 DRFilesystemInclusionMask;
Discussion
The filesystem
mask is a bitfield which contains a 1 if the object will appear in the corresponding filesystem,
and 0 otherwise.
Enumerations
enum {
DRFilesystemInclusionMaskISO9660 = (
1<<0),
DRFilesystemInclusionMaskJoliet = (
1<<1),
DRFilesystemInclusionMaskUDF = (
1<<2),
DRFilesystemInclusionMaskHFSPlus = (
1<<3)
};
Constants
DRFilesystemInclusionMaskISO9660- Indicates the object should be included in the ISO9660 filesytem
DRFilesystemInclusionMaskJoliet- Indicates the object should be included in the Joliet filesytem
DRFilesystemInclusionMaskUDF- Indicates the object should be included in the UDF filesytem
DRFilesystemInclusionMaskHFSPlus- Indicates the object should be included in the HFS+ filesytem
Discussion
Mask constants for determing the presence of a DRFSObject in a specific filesystem
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Last Updated: 2008-04-01