Jamie Flournoy > Mac-AppleSingleDouble-1.0 > Mac::AppleSingleDouble

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Module Version: 1.0   Source  

NAME ^

Mac::AppleSingleDouble - Read Mac files in AppleSingle or AppleDouble format.

SYNOPSIS ^

 use Mac::AppleSingleDouble;
 $foo = new Mac::AppleSingleDouble(shift);
 $finder_info = $foo->get_finder_info();
 print "The file Type is: $finder_info->{'Type'}\n";
 print "The file Creator is: $finder_info->{'Creator'}\n";
 print "The Finder label color is: $finder_info->{'LabelColor'}\n";
 $foo->close();

REQUIRES ^

Perl5 (tested with 5.005_03; may work with older versions of Perl 5), the FileHandle module.

EXPORTS ^

Nothing.

DESCRIPTION ^

Mac::AppleSingleDouble is a class which knows how to decode the AppleSingle and AppleDouble file formats. An instance of Mac::AppleSingleDouble represents one file on disk.

The structure of Macintosh files is unlike the structure of files on non-Macintosh operating systems. Most operating systems represent a file as a filename (with the file type appended as a suffix), a few attribute bits, and a single chunk of data. Macintosh files consist of a filename, attribute bits, a four-character file type code ('TEXT', 'APPL', 'JPEG', 'PDF ', etc.), a four-character file creator code ('MSWD' for Microsoft Word, '8BIM' for Photoshop, 'SIT!' for StuffIt, etc.), a chunk of unstructured data called the "Data Fork", and a chunk of structured data called the "Resource Fork". In order to store Macintosh files on other computers, some form of encoding must be used or the resource and attribute information will be lost (which is OK in some cases). MacBinary, BinHex, and AppleSingle all encode the original Mac file in a single chunk of data suitable for export to other operating systems. AppleDouble encodes all the Mac-only data in one file, but leaves the chunk of unstructured data in a separate file all by itself, which allows non-Mac-aware programs to read the unstructured data with no decoding step. AppleSingle and AppleDouble were originally developed for A/UX (an Apple Unix flavor discontinued long ago), and are used by netatalk (an AppleShare file server for Unix servers and Mac clients).

If you are working Mac files on a Mac (presumably with MacPerl), you probably do NOT need this class. If you are working with Mac files on a non-Mac, the files may be encoded in AppleSingle or AppleDouble format, and this class can be useful if you need to get at the Mac file attributes such as the Finder label, the type and creator codes, or the IsInvisible bit.

See the "AppleSingle/AppleDouble Formats for Foreign Files Developer's Note" and the book "Inside Macintosh: Finder Interface" from Apple Computer, Inc for more details on the formats themselves.

METHODS ^

Creation

$applefile = new Mac::AppleSingleDouble($filename)

Creates a new Mac::AppleSingleDouble object to represent the file named in $filename.

Cleanup

$applefile->close()

Closes the underlying AppleSingle or AppleDouble file.

Access

$applefile->get_finder_info()

Returns a hash containing Finder information decoded from the FInfo and FXInfo data structures.

$applefile->get_entry($id)

Returns the raw binary data of an entry, given its ID. Types defined by Apple are: 1: Data Fork 2: Resource Fork 3: Real Name 4: Comment 5: Icon, B&W 6: Icon, Color 8: File Dates Info 9: Finder Info 10: Macintosh File Info 11: ProDOS File Info 12: MS-DOS File Info 13: Short Name 14: AFP File Info 15: Directory ID

$applefile->get_file_format()

Returns 'AppleSingle', 'AppleDouble', or 'Plain' based on the "magic number" found at the beginning of the file. (0x00051600 is AppleSingle, 0x00051607 is AppleDouble, and anything else is Plain.)

$applefile->is_applesingle()

Returns 1 if the file format is AppleSingle. See get_file_format().

$applefile->is_appledouble()

Returns 1 if the file format is AppleDouble. See get_file_format().

$applefile->get_entry_descriptors()

Returns a hash with entry IDs as keys, and hash references as values. The references hashes contain three keys: EntryID, Offset, and Length. Offset is the offset from the start of the file to the entry data, and Length is the length of the data, both in bytes. (There are higher-level methods to access entry data so most users will not need to call this method.)

$applefile->get_all_entries()

Returns a hash with entry IDs as keys, and raw entry data as values. All entry IDs found in the file will be returned.

$applefile->dump()

Dump a formatted ASCII representation of the contents of the AppleSingle or AppleDouble file to STDOUT.

$applefile->dump_header()

Dump the filename and file size and header information to STDOUT. The header information includes: magic number, format version number, and all entry descriptors (entry ID, offset, and length of each).

$applefile->dump_entries()

Print a hex dump of the entry data for all entries in the file to STDOUT.

$applefile->dump_entry($id)

Print a hex dump of the entry data for the specified id to STDOUT.

Configuration

$applefile->set_labelnames(%new_labelnames)

Given a hash with keys 0 through 7 and string values, change the values corresponding to the LabelName key in the hash returned by get_finder_info(). Note that 0 should always be 'None' since it cannot be changed in the Finder, and the menu in the Finder lists labels in descending order (starting with 7 and counting down to 1).

$applefile->set_labelcolors(%new_labelcolors)

Given a hash with keys 0 through 7 and string values, change the values corresponding to the LabelColors key in the hash returned by get_finder_info(). Note that 0 should always be 'Black' or 'None' since it cannot be changed in the Finder, and the menu in the Finder lists labels in descending order (starting with 7 and counting down to 1).

$applefile->preload_entire_file()

Loads all the entry data from the file into memory and closes the underlying file.

$applefile->cache_entries()

Causes subsequent entry data accesses to be cached in memory in the object.

DIAGNOSTICS ^

The constructor (new) requires a filename as an argument!

(F) The constructor (new Mac::AppleSingleDouble($filename)) was called but the required filename argument was not defined. The path to the AppleSingle or AppleDouble file to be examined must be passed to the constructor.

File '/usr/bin/perl' is not in AppleSingle or AppleDouble format!

(F) The file was readable but did not start with the "magic number" denoting AppleSingle or AppleDouble format.

'..' is not a file!

(F) The filename specified in the constructor does not point to a file.

BUGS ^

The AppleSingle and AppleDouble formats come in two versions - 1 and 2. I was unable to find documentation for version 1 - supposedly there is a manual called "A/UX Toolbox: Macintosh ROM Interface", but I was unable to find it. However, netatalk uses version 1. So, this class was coded using the version 2 specification but it was tested on version 1 files written by netatalk. Entry ID 7 appears in version 1 files but I have no idea what it means. However, it seems to work...

RESTRICTIONS ^

This module can read AppleSingle and AppleDouble files, but it cannot create or modify them. It's not worth my time to change it so that it can (testing it thoroughly with other programs which use the files would be very time consuming), so I probably won't do it. If you want to make that enhancement and send your changes to me, I would be happy to integrate them into a new version and to give you credit for your work.

AUTHOR ^

Jamie Flournoy, jamie@white-mountain.org

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