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August 2016

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2 discussions

Re: [launchd-dev] Mysterious problem with [NSURL getResourceValue:forKey:error:]
by James Bucanek 25 Aug '16

25 Aug '16

> Quinn "The Eskimo!" <mailto:eskimo1@apple.com> > August 23, 2016 at 5:27 AM > > Its sounds like you’re well on the way to a solution but I’m curious > about the above. In general the `UserName` property for a launchd > daemon is for role accounts. Putting a user account there is weird > because what user do specify? If there are two users simultaneously > logged in (via fast user switching, or truly simultaneously via screen > sharing), surely one of them has to miss out. Each daemon is named after its user: com.qrecall.switchboard.501, com.qrecall.switchboard.502, and so on. Each user connects only with its switchboard, and that switchboard only manages endpoints belonging to that user. Again, the *only* reason this is installed as a system daemon is that I have root processes (executed from another system daemon) that have to connect with it, and the only mach services namespace that I can make that work is the system's. James P.S. I would be nice if the UserName launchd property would also accept a number and interpret it as a UID: <key>UserName</key><integer>501</integer>.

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Mysterious problem with [NSURL getResourceValue:forKey:error:]
by James Bucanek 23 Aug '16

23 Aug '16

Greetings, I've stumbled across a strange problem with [NSURL getResourceValue:forKey:error:] returning blank icons when executed within the context of a system daemon. I'm using this method to get the NSURLEffectiveIconKey (an NSImage) value for items. The process is launched by a privileged helper (installed a la EvenBetterAuthorizationSample). It's a SetUID executable, so its effective UID is the user (let's say 501) for which I want to get the icons (and other localized information). When the process is launched by the privielged helper, every NSImage returned by -getResourceValue:forKey:error: is a valid image, but the icons are all blank. When the process is launched from the shell (or via Xcode) as the regular user, the returned NSImages contain the correct icons. If the process is launched via sudo from the user's shell, the returned NSImages are also OK. I suspect that this is somehow a security or bootstrap context issue, but I'll defer to expert opinion on the cause or what can be done about it. James Bucanek

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