Identifying bundles in MacOS X

Greg Ewing greg at
Tue Nov 16 03:46:01 CET 2004

Michael J. Fromberger wrote:
> Given the pathname of a directory in my filesystem, I would like a 
> graceful way to determine whether or not that directory represents a 
> "bundle", in the sense that, when you double-click on the directory's 
> icon in the Finder, it is launched rather than "opened" for viewing.
> Applications behave this way by default, but so do various other file 
> types (e.g., the "rtfd" files created by TextEdit, and the data files 
> for certain applications such as Quicken).

I think that a MacOSX-style application can be recognised
simply by the fact that it's a directory whose name ends
in ".app". (You don't usually see that extension in the
Finder, but all MacOSX application bundles seem to have it.)

A Classic-style application is a file with a type code
of "APPL".

As for other files, they can be associated with applications
using either the old type/creator code system, or the new
filename-extension-based system (which is disappointingly
Windows-like, but sadly seems to be the dictated Way of
the Future :-(.)

The type and creator of a file can be found using FSpGetInfo.
You're right that this doesn't work for directories, but
directories don't have type/creator codes anyway. MacOSX
bundles seem to be recognised purely by filename suffix
(and possibly also by having the right internal structure).

Greg Ewing, Computer Science Dept,
University of Canterbury,	
Christchurch, New Zealand

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