Macintosh resource file

File Format
Name	Macintosh resource file
Ontology	Electronic File Formats Resources Macintosh resource file
Extension(s)	.rsrc, .dfont, others
Kaitai Struct Spec	resource_fork.ksy

The Macintosh resource file format was used by the Resource Manager in Mac OS Classic for storing resources used by Mac OS Classic applications as well as file associations and executable code. Traditionally, this format is used in the Resource Fork of a file on the HFS and HFS+ file systems; however, when resource files are still used in Mac OS X applications, the same format is used in a file with the extension .rsrc.

See Resource Fork for general information about Macintosh resource forks.

Format details

A resource has a four-character type code, an ID number, an optional name, and data. The type code is generally unique to the type of data stored within, but this may not be the case with application-specific formats.

Software

• Rezilla
• KSFL reads and writes Macintosh resource files
• Deark

Sample files

• dexvert samples — archive/rsrc

References

• Resource fork (Wikipedia)
• More Macintosh Toolbox (format is described on page 1-121 to 1-125)
• Description of the file format from the KSFL wiki
• The White Files: Mac OS Guides: Resources
• Mac OS X Resource Fork and Command Line Tips

See also

• Kaitai structs for a few resource fork files on [Macintosh resource file GitHub].
• Official Kaitai MacOS Structs.
• RSRC dump pure Python utility for reading resource data.
• Resource-fork hashtag on Github.