Re: Subclassing NSUserDefaultsController
Re: Subclassing NSUserDefaultsController
- Subject: Re: Subclassing NSUserDefaultsController
- From: Thomas Bauer <email@hidden>
- Date: Sun, 27 Sep 2009 12:23:34 +1300
Hi!
Thanks for your response.
Sorry, I did not point out clearly enough that in my case the code
would run with root privileges.
Thanks for the pointer to EUID. I was not aware of that... and that
might be a solution.
Independently - it still puzzles me that it does not seem to be
possible to override the class of the userdefaultscontroller.
Regards
Thomas
On 21/09/2009, at 3:44 AM, James Bucanek wrote:
Thomas Bauer <mailto:email@hidden> wrote (Sunday, September
20, 2009 2:39 AM +1200):
In some cases my application needs to modify and get the user
defaults from a
different user than the one it is launched under. Since this
affects not only
things done programmatically, but also parts of the user interface
that use
bindings, I was thinking an elegant solution would be to make the
SharedDefaults controller be a subclass and override the designated
init
method to either be initialized by sharedDefaults or a NSDefaults
object
created with initWithUser. Unfortunately this does not seem to work
on a basic
level.
At that basic level, this should never work. Your user (UID) should
never, under normal circumstances, have access to any non-public
files belonging to another user, especially not their ~/Library
folder. So even if you could coerce NSUserDefaults or CFPerferences
to access the file, the basic security model of Mac OS X / BSD would
prevent them from reading or changing it.
The straightforward solution is to create a SetUID helper or daemon
process that you can launch and will run as that other user. It
could be an SUID->root process that dynamically changes its EUID to
the user you need to affect, or be a pre-configured SUID->user
(probably the easiest solution) that always runs as that particular
user. Your process could launch the helper then communicate what
changes you need to make via inter-process messaging.
--
James Bucanek
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