Urania

A blog named for the muse of Astronomy containing musings by an astronomer

SAOImage DS9 versus Leopard Firewall

Posted on April 22, 2008 by Juan

Immediately after installing SAOImage DS9 5.2, I had a major failure of the application and initially I just thought it was some sort of build bug. This is what I posted at that time:

[HOLD OFF ON THIS UPDATE! I have discovered that at least on one of my systems, this version of ds9 is refusing to run properly. It launched once, but when I attempted to check the “About SAOImage DS9”, it triggered the following error:

 “An internal error has been detected local header mismatch couldn’t open “zvfsmntpt/doc/sun.gif”: no such file.

(this occurred in both Aqua and X11 versions). Furthermore, all future attempts to launch ds9 (again, either Aqua or X11) fail with the following error:

Error in startup script: couldn’t read file “./zvfsmntpt/src/ds9.tcl”: no such file or directory  

Even removing the preferences file at ~/.ds9.prf didn’t help.]

Apparently, my problems with SAOImage DS9 in Leopard are a known issue. If you configure the built-in Firewall to “Set access for specific services and applications” so that you can approve “holes” in your firewall on an Application by Application basis, your first launch of SAOImage DS9 will irreparably damage the application!  Unfortunately, Apple implements the application firewall in part by modifying the Application package of the Application you are running by digitally signing it if it was not digitally signed by the developer (adding a file called CodeResources to the Application package). According the Apple’s documentation on this:

If you run an unsigned application not in the Application Firewall list, you will be presented with a dialog with options to Allow or Deny connections for the application. If you choose Allow, Mac OS X 10.5 will sign the application and automatically add it to the Application Firewall list. If you choose Deny, Mac OS X 10.5 will sign the application, automatically add it to the Application Firewall list and deny the connection.

So basically,Apple doesn’t warn you in the dialog box that comes up that it has whatever decision you make, it will modify the application by digitally signing it and it doesn’t give you a way to avoid this. This is, in my opinion, is an incredibly boneheaded move on Apple’s programmer’s part. They readily admit that

  Some applications check their own integrity when they are run without using code signing.

They suggest the application firewall will try to automatically detect these and avoid modifying them, but they should give you, the user, the option instead of making the decision via some internal algorithm.  MacOS X shouldn’t assume its OK to change an application. In the case of SAOImage DS9, they are irreparably damaging the application without leaving you a way to avoid the damage once you trigger the application firewall. Shame on you Apple. The only way to fix it is to reinstall the application!

So when I figured this out (a tip of the hat to this post on IRAF.net). I reinstalled the SAOImage DS9 executables (both Aqua and X11 versions) and before launching them, I set the Firewall (via the Security Pane of the System Preferences) to “Allow all incoming connections” (this is the default mode, so it is as secure as MacOS Tiger was). Everything now appears to work just fine.

Personally, I believe an application that fails its checksum should present a message indicating that is the problem instead of just crapping out, but in this case, the fault lies mostly with Apple. Apple is damaging applications by making this critical decision in the background, without user intervention!

1 Trackbacks/Pingbacks

  1. 22 04 08 21:17

    Urania » Blog Archive » DS9 version 5.2 released

1 to “SAOImage DS9 versus Leopard Firewall”

  1. Tim says:
    You can also 'lock' the application so Mac OS X can't modify it. First, copy a fresh DS9 into your applications folder, then get info (Apple-i). Check the 'locked' checkbox and you're done. It does mean however you will be asked each time you start the application if you really want to, and to allow it in the firewall, but it also means you can keep the firewall enabled.


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