August 2008 - Darwin-dev - lists.apple.com

Writing driver for 3D input device, treating as a joystick?
by Andre-John Mas 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Hi, Andre _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… I am have 3D pointing device, for which I have the documentation and would be interested in writing a driver for it. Given that I would like it be recognized by any application that handles joysticks, such as a flight simulator, what is the best approach. Are there any existing drivers that I could base this on. The device would be communicating via serial port (tty device). Specifically this device is similar to the Magellan or 3Dconnexion Spaceball, so if anyone knows of any open source drivers for MacOS X, this would be handy. This email sent to site_archiver(a)lists.apple.com

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Re: obtain uid from task_t in kernel extension?
by Terry Lambert 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Yes, sorta. What is it that you are actually trying to do? -- Terry On Aug 15, 2008, at 9:24 AM, Tim Schooley <tim(a)sbdev.net> wrote: Just to answer my own question, I think I can get away with using kauth_getuid(). Is this an acceptable solution? Cheers, Tim _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/tlambert%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This will get the effective UID of the credential fron the current vfs_context associated with the current thread. This will be the same as the credential associated with the task in which that thread lives, unless some other thread in the task has subsequently performed an operation to change the task credential while the current thread was blocked somewhere, or unless the current thread is using per-thread credentials. If the current thread is a kernel thread, as in a thread in a driver, and the operation is a proxy operation, then it will get you a "root" equal to that of the kernel task (which is why we pass around vfs_context_t's). The whole area of credentials is rather intricately choreographed, and is/should be tied solely to authorization, and not so much about authenticatipn, authority, or nonrepudiation. It identifies the actor in an actor/object/action relationship, and persists once the kernel is entered until it exits again. This isn't generally well understood by most people, and I've been meaning to put together a "Where do baby credentials come from, and what do they do all their lives?"-type talk for a couple years now. I would probably have to call it something dry like "Mac OS X kernel security architecture", though. 8-). You actually probably don't want to know the UID, you probably are asking whether or not something should be allowed instead, which is a completely different question that should be asked a different way; the effective UID is rarely at all useful below the BSD system call layer, or to code outside that layer. The way to ask is to ask whether a given actor is allowed to perform the requested action on an object or objects, and you should generally limit yourself to inserting yourself at a particular check and, when asked, saying "allow"/"deny"/"I don't care". On Fri, 15 Aug 2008 16:47:20 +0100, Tim Schooley wrote: Any way of obtaining a uid_t from a task_t in a kernel extension? This email sent to tlambert(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: obtain uid from task_t in kernel extension?
by Chris Sarcone 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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Re: obtain uid from task_t in kernel extension?
by Tim Schooley 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Fri, 15 Aug 2008 16:47:20 +0100, Tim Schooley wrote: > Any way of obtaining a uid_t from a task_t in a kernel extension? Just to answer my own question, I think I can get away with using kauth_getuid(). Is this an acceptable solution? Cheers, Tim _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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obtain uid from task_t in kernel extension?
by Tim Schooley 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Hi folks, quick question: Any way of obtaining a uid_t from a task_t in a kernel extension? Thanks for any help! Kind regards, Tim _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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Re: IOCommandGate vs ISyncer
by Godfrey van der Linden 15 Aug '08

15 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com G'day Duane, Cheers Godfrey van der Linden On 2008-08-13, at 12:30 , Duane Murphy wrote: Thanks Chris. I get the gist of how this works... --- At Wed, 13 Aug 2008 10:27:53 -0700, Chris Sarcone wrote: Duane - Easy recipe: Sync Call is made done = false; Send I/O asynchronously IOCommandGate::runAction() while (!done) IOCommandGate::commandSleep(&done,TH_UNINT); On workloop completion thread: done = true; IOCommandGate::commandWakeup(&done); This is the part that I'm usually confused on. Does the thread have to have the gate to call commandWakeup or can commandWakeup be called anytime? Thanks again. This was very helpful. ...Duane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/gvdl%40mac.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… I pretty sure that all block storage completion routines are called from a workloop context. I.e. the runAction() is actually performed for you by an interrupt event source way, way down on the stack. This is the basic model of threading in I/O Kit, your completion routines are always called in a 'gated' context. So if you want to synchronise with such a routine you also need to use a commandGate. Thus when you need to block a thread --- aka put to sleep --- decision to block the thread must be made while gated, this is where the command gate::runAction comes into use as described be ChrisS. Once you decide that you need to sleep here it is simply a matter of blocking the thread with commandSleep, which blocks your thread and drops the gate so other threads can make progress. When the threading model was designed we modelled the gated target/ action concepts on the Java Synchronous routine threading, though without language support there was never any easy way to make it elegant. Any action routine called by an event source, like interrupt, timeout of even command actions are guaranteed to be single threaded against the IOWorkLoop that are registered with. No matter how many drivers there are on a stack there usually all synch against one workloop. It can, and has been with some force, argued that this model is both unconventional and over engineered. However it does have a couple of very nice advantages over lock based threading. There is no way to lose count of how many times a recursive lock is taken so error paths always release locks cleanly. Another huge advantage is that taking the lock --- closing the gate in IOKit speak --- is always represented with a function call on the stack. So if you think you have caused a deadlock 'showallstacks' in gdb will always show it. This dug Apple out of the poo many many times during Darwin's early development. What is the recipe for this seemingly simple task (that IOSyncer handles very nicely) with IOCommandGate. The completion thread is the callback for the completion of IO (IOStorageCompletion). Can that callback just call commandWakeup or do I have to enter the gate first using runAction and call commandWakeup from the runAction call back? This email sent to gvdl(a)mac.com This email sent to site_archiver(a)lists.apple.com

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Re: IOCommandGate vs ISyncer
by Chris Sarcone 13 Aug '08

13 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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Re: Mac OS 10.5.4, CF Lite, and iPhone 2.0 Source Posting
by William Siegrist 13 Aug '08

13 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com You can find it all at the usual location: http://www.opensource.apple.com/darwinsource/ CF-476.14 has been posted, but it did not have any changes from 476-13. -Bill -- William Siegrist Darwin Team _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com On Jul 18, 2008, at 6:08 PM, William Siegrist wrote: The Darwin Team is pleased to announce the release of the open source components for Mac OS 10.5.4 and iPhone 2.0 (SDK included). As usual, CF Lite for 10.5.4 has not been posted yet, but we _did_ post CF Lite for 10.5.3. We'll have the latest CF Lite up soon hopefully. smime.p7s

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Re: IOCommandGate vs ISyncer
by Duane Murphy 13 Aug '08

13 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Thanks Chris. I get the gist of how this works... --- At Wed, 13 Aug 2008 10:27:53 -0700, Chris Sarcone wrote: >Duane - > >What is the recipe for this seemingly simple task (that IOSyncer handles >very nicely) with IOCommandGate. > >Easy recipe: > >Sync Call is made >done = false; >Send I/O asynchronously >IOCommandGate::runAction() > while (!done) > IOCommandGate::commandSleep(&done,TH_UNINT); > >On workloop completion thread: >done = true; >IOCommandGate::commandWakeup(&done); This is the part that I'm usually confused on. Does the thread have to have the gate to call commandWakeup or can commandWakeup be called anytime? The completion thread is the callback for the completion of IO (IOStorageCompletion). Can that callback just call commandWakeup or do I have to enter the gate first using runAction and call commandWakeup from the runAction call back? Thanks again. This was very helpful. ...Duane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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Re: IOCommandGate vs ISyncer
by Chris Sarcone 13 Aug '08

13 Aug '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-dev mailing list (Darwin-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-dev/site_archiver%40lists.app… This email sent to site_archiver(a)lists.apple.com

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