Re: "Safe" frameworks for privileged tools?

FROM : Michael Watson
DATE : Wed Apr 23 20:35:55 2008

Yes, it's a helper tool. It runs for a couple of seconds (under normal 
conditions) and exits immediately. It interacts with the file system 
by reading information about some directories, so its launched 
duration is, of course, bound to the responsiveness of the hard drive 
on which it's operating. As such, "a couple of seconds" might be "five 
or ten seconds" on machines where the drive is spinning up, otherwise 
busy, etc. It's certainly possible that someone might invoke fast user 
switching right in the middle of the tool running, but it's /probably/ 
not an issue. I'm still not quite convinced it isn't, just yet. I need 
to do more thinking about it. The discussion so far has been very 
helpful.

As far as connecting to the window server goes, Apple states:

http://developer.apple.com/technotes/tn2005/tn2083.html#SECWINDOWSERVER

"Apple plans to disable the global window server service in a future 
release of Mac OS X. Do not write any new code that uses the global 
window server service."

So when you say "default window server", are you speaking of the 
global window server, or the default window server associated with the 
current console session?


--
m-s


On 23 Apr, 2008, at 13:04, stephen joseph butler wrote:
> On Wed, Apr 23, 2008 at 11:42 AM, Dave Camp <<email_removed>> 
> wrote:
>

>> Unless I'm reading the OP wrong, he's writing a privileged helper 
>> tool,
>> not a daemon. Given that, I don't think the above documents are 
>> applicable.

>
>
> None of what I know is official, but just gathered and extrapolated 
> from
> years of reading information about this. So I might be wrong... who 
> knows.
>
> The unsafe frameworks make connections to the default window server. 
> As a
> program launched from Finder/Dock/et al, this will always work as 
> expected.
> Launched from ssh or root, there are some caveats.
>
> For ssh, they will work fine as long as the same user is logged onto 
> the
> GUI. As soon as the user logs out, your program loses its connection 
> and
> might crash.
>
> For root, they will work as long as the "console user" stays the 
> same. If
> someone uses fast user switching, or logs out, then the program's 
> connection
> changes and it might crash.
>
> In any event, none of the unsafe frameworks are documented as 
> working in any
> conditions other than the normal ones. People may get them to work 
> 90% of
> the time under other conditions, but that's unsupported and may 
> change.
>
> So unless DTS tells you otherwise, I'd stay away. But that's me... 
> maybe 90%
> is good enough for you.
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