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

getaddrinfo() starts failing with EAI_AGAIN (again)
by Jamus Jegier 07 Jul '08

07 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=simple/simple; d=jamus.com; s=dkim; t=1215445264; bh=Fc5PERbJJmH7jdqigdrT+/sFTLKbaxdWFyTW3CxbsiQ=; h=Message-Id:From:To:Content-Type:Content-Transfer-Encoding: Mime-Version:Subject:Date; b=nhUW6NUuQJ2ZD7cgR7hVPYa5e0dDlBPMpiN++ M8FGTkq9mJkKVPgCk+TGa4+GPWAce/b5zKYyNQe+WyHWTsH86PEikJTcIlxsL6miwtE 73lS1npMvT9UtLUky6BlmXRPYqAbx40lUXdraluMKbz8RJ7LpVAUEEYjaEy/MqcNPcQ = Domainkey-signature: a=rsa-sha1; s=dk; d=jamus.com; c=simple; q=dns; h=message-id:from:to:content-type: content-transfer-encoding:mime-version:subject:date:x-mailer; b=CCNfl9zJ8pmYIvZytfqsqW0hvJjbOjSbO9nUGsbiBH87f3EtKjlw3j8e5mDebjOjw 723+/gJc+lZ64x5HsgHLw== Jamus _______________________________________________ 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… A couple months ago, there was a post by Peter Oberauer about getaddrinfo() failing with EAI_AGAIN by processes under a specific process tree. I am running into the exact same problem, and was wondering if there was any resolution to the issue. I installed Nagios, which frequently forks processes to verify the status of network hosts. After about 8 hours, all child processes start failing with EAI_AGAIN. Under the Nagios parent process, dig works, but ping doesn't. Both DNS and Bonjour lookups begin to fail. Ping and the Nagios helper executables work fine when started under an unrelated process. The only other thing I can add is that I see this on 10.5.3 on a G4 system. I'm installing 10.5.4 now, and will post if I still see this. This email sent to site_archiver(a)lists.apple.com

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Converting to launchd user agent
by Steve Sisak 07 Jul '08

07 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Based on TN2083, it looks like I want to set: LimitLoadToSessionType = Aqua Also, if I set OnDemand = true RunAtLoad = false KeepAlive = false Is this correct? Thanks, -Steve _______________________________________________ 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 have a per-user service that is currently implemented as a global login item (as it needs GUI access and must support back to Mac OS 10.2.8), but really wants to be implemented as a GUI launchd agent on 10.5 and newer, but should not load as a launchd agent on 10.4.x (as it needs a graphic context and there are issues with this pre-10.5). I'd also like to cleanly handle the case where a user updates their OS from 10.4.x to 10.5.x w/o requiring a reinstallation if possible. I think I understand the pieces (I already have a load-on-demand daemon), but want to make sure I handle the edge cases properly so that I can install the LaunchAgent file on previous releases, but only load on 10.5 and newer. Bonus points if I can make it load on demand, although I'm not sure if I can do this cleanly as, for historical reasons, the mach port it registers contains the security session id of the process it's running in. Given that per-session bootstrap namespaces only exist on 10.5, I might be able to take advantage of that fact. and load on demand via a static port name per-session bootstrap namespace, then I shouldn't load on 10.4 and would load on 10.5. Can anyone point me to an example of setting up the plist and code to tickle the agent? This email sent to site_archiver(a)lists.apple.com

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Re: CFGetRetainCount question
by Dmitry Markman 05 Jul '08

05 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Jul 5, 2008, at 12:03 AM, Eli Bach wrote: On Jul 4, 2008, at 8:43 PM, Dmitry Markman wrote: but UINT_MAX is 4294967295 (0xFFFFFFFF) so what does 0x7FFFFFFF mean? Dmitry, Dmitry Markman _______________________________________________ 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… thanks, Eli it was clear from the context that I don't have to release object that I got from CFArray but I was just curious thanks again well I found some information in the NSObject's retainCount method documentation: "You rarely send a retainCount message; however, you might implement this method in a class to implement your own reference- counting scheme. For objects that never get released (that is, theirrelease method does nothing), this method should return UINT_MAX, as defined in <limits.h>" thanks I don't think this is explicitly spelled out anywhere, but for CF "constants", such as CFSTR("blah"), kCFBooleanFalse, and other constant 'things' like this, there is no real meaning to releasing them, but depending on your program's abstraction classes or whatever, you may retain/release these CF constants. I believe CF special-cases this specific retaincount as a do-nothing operation. And 0x7FFFFFFF would be INT_MAX or SINT_MAX (which is the maximum for a signed long (which is what a CFIndex is, which is the return type for CFGetRetainCount()) [at least for 32-bit architecture, probably for 64-bit architecture]. Technically, you could retain any given CF object enough to hit this value, but you're program probably would have other problems before you hit this limit. This email sent to site_archiver(a)lists.apple.com

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Re: CFGetRetainCount question
by Eli Bach 05 Jul '08

05 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:from:to :in-reply-to:content-type:content-transfer-encoding:mime-version :subject:date:references:x-mailer; bh=Ljoyw4HcsLfs1RFTo1tPuSlhe5e6lQC0BLQ7U4uU4s4=; b=MD66GXr04KDUc7knTrXE4pimn5Sud8++Mxqkw/RqzG+mFbZWswnGF6t9pK3WcpSrNP p8le3IFkNiaPM5E5clzMxtzEhfJybU1DqFO0OLtWYfLe2lV4Jj43Jn8MYve59CWf6+VE iuYhrVal/BY7T8/MSHobB9hV7j3YUK16xltJk= Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:from:to:in-reply-to:content-type :content-transfer-encoding:mime-version:subject:date:references :x-mailer; b=EeJr5gFLeR8Tf1nuIocUQuo6Xso1iY6CDRpAaQVaLhXomAsLZOlFahdyvQhfs2HN5q dnmZ6wI5Pmw6U+qfMOMYHdqurZ3PjgGKaxr42nBU0ndXkxCh3ovR8YWzX9riFwGNHfev aeEC1y7DUGL2EvHCb6bfqcwtgGJBgv8aD41tU= On Jul 4, 2008, at 8:43 PM, Dmitry Markman wrote: but UINT_MAX is 4294967295 (0xFFFFFFFF) so what does 0x7FFFFFFF mean? Dmitry, well I found some information in the NSObject's retainCount method documentation: "You rarely send a retainCount message; however, you might implement this method in a class to implement your own reference-counting scheme. For objects that never get released (that is, theirrelease method does nothing), this method should return UINT_MAX, as defined in <limits.h>" thanks I don't think this is explicitly spelled out anywhere, but for CF "constants", such as CFSTR("blah"), kCFBooleanFalse, and other constant 'things' like this, there is no real meaning to releasing them, but depending on your program's abstraction classes or whatever, you may retain/release these CF constants. I believe CF special-cases this specific retaincount as a do-nothing operation. And 0x7FFFFFFF would be INT_MAX or SINT_MAX (which is the maximum for a signed long (which is what a CFIndex is, which is the return type for CFGetRetainCount()) [at least for 32-bit architecture, probably for 64-bit architecture]. Technically, you could retain any given CF object enough to hit this value, but you're program probably would have other problems before you hit this limit. _______________________________________________ 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: CFGetRetainCount question
by Dmitry Markman 05 Jul '08

05 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com but UINT_MAX is 4294967295 (0xFFFFFFFF) so what does 0x7FFFFFFF mean? thanks On Jul 4, 2008, at 11:30 PM, Dmitry Markman wrote: Hi CFGetRetainCount returns 2147483647 (0x7FFFFFFF) what does it mean? CFGetRetainCount documentation doesn't have any info about that header (CFBase.h) doesn't have any comment thanks Dmitry Markman _______________________________________________ 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/dmarkman%40mac.com Dmitry Markman _______________________________________________ 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… well I found some information in the NSObject's retainCount method documentation: "You rarely send a retainCount message; however, you might implement this method in a class to implement your own reference-counting scheme. For objects that never get released (that is, theirrelease method does nothing), this method should return UINT_MAX, as defined in <limits.h>" This email sent to dmarkman(a)mac.com This email sent to site_archiver(a)lists.apple.com

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CFGetRetainCount question
by Dmitry Markman 05 Jul '08

05 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Hi CFGetRetainCount returns 2147483647 (0x7FFFFFFF) what does it mean? CFGetRetainCount documentation doesn't have any info about that header (CFBase.h) doesn't have any comment thanks Dmitry Markman _______________________________________________ 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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Advice on handling sleep with IOKit driver+daemon setup
by Tim Schooley 04 Jul '08

04 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com User-agent: Thunderbird 2.0.0.14 (X11/20080505) Hi folks! I'm after a little advice - I see people on the list be told "you shouldn't be doing it like that", so I thought I'd ask _before_ I go down the wrong route. Heres the basic idea: --- 1) I have an IOKit kext that creates IOBlockStorageDriver(s) and device(s). 2) The I/O of these devices are passed to and handled by a user-space daemon. 3) The devices require authentication of some form or another from the user. This is handled in user-space. --- The requirement is that when the system goes to sleep or the user logs off, we "prevent" access to these devices (note the ambiguity of "prevent" at this stage). The way I see it (and please feel free to correct me if I'm missing something or off-course), there are 2 different ways for preventing access to these devices: --- 1.1) In the kext, simply block IO to the devices. This seems the quickest and most elegant way, since a) it won't remove the device from the system, b) it won't run into "Volume Busy" errors that could occur using an unmount instead, c) Once unlocked, user-space applications that may have had files open on the device can continue on their merry way. BUT! Does the OS flush devices before sleeping? When "WillSleep" is called, has all flushing finished? 1.2) In user-space, try to eject all the devices before the 30 seconds are up. But that's not exactly elegant, is it? And what if it takes longer than 30 seconds? (Side-question: Does DADiskEject _require_ DADiskUnmount beforehand?) --- Also, there are a few different options for invoking the "prevention" available: --- 2.1) Use a launchd agent for the logged-in user, register for sleep events, and initiate "prevention" from there. 2.2) Register for sleep events in the daemon, and initiate "prevention" from there. 2.3) Handle "prevention" in the kext. --- My initial thoughts are to go with 1.1, as it seems simple and clean. But I don't know whether its "the right thing to do" or not. Any help/advice/suggestions would be most appreciated, 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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FW: compile from command line without xcode
by Mirek Rusin 04 Jul '08

04 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Organization: Ringley Ltd Thread-index: AcjdxC447Raftdt+SQC6MD9w9RyEnAAAjEog Dear All, Having my tool in a single file source.m: --- source.m --- #import <Foundation/Foundation.h> int main (void) { NSAutoreleasePool *pool = [NSAutoreleasePool new]; NSLog(@"hello!"); [pool release]; return 0; } --- source.m --- And make file looking like this: --- GNUmakefile --- MAKEFILEDIR = /Developer/Makefiles/project include ${MAKEFILEDIR}/common.make TOOL_NAME = App App_OBJC_FILES = source.m include ${MAKEFILEDIR}/tool.make --- GNUmakefile --- When typing `make`, nothing happens except obj/ directory is being created. How should GNUmakefile/Makefile look like in order to compile this example? Mirek Rusin _______________________________________________ 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: thread-local storage, especially on x86
by Ian Lister 01 Jul '08

01 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com http://lists.apple.com/archives/darwin-dev/2005/Sep/threads.html#00005 Thanks, Ian On Sun, 11 Sep 2005, Matt Watson wrote: I'm sorry, that wasn't clear from your message, to me at least. <http://people.redhat.com/drepper/tls.pdf> Ideally, yes, I'd like to see Apple's toolchain support TLS. I recognize that this would be a major undertaking, and want to try to to find a short-term solution. I think that it's possible to expose a fast TLS mechanism, keep the pthread implementation details opaque, and maintain ABI compatibility. Achieving these goals requires careful design; a lot of effort and review and redesign went into the Linux TLS design, and I think that it does a good job of balancing these goals. (If you ask IBM and Novell and RedHat whether they expect their developers to recompile frequently and pass the costs of doing so on to their customers, my guess is that they'd say "ummm, no.") I would also expect this to also take significant time: it should. The PowerPC version version of my software is able to keep some very frequently accessed thread-specific data in registers and can afford to keep more things that're slightly-less-frequently accessed in a structure addressed by dedicated register. Those options aren't (all) available on IA-32, and I have serious doubts about the viability of a design that would reqire very frequent calls to pthread_getspecific(). Some of my concerns are certainly application-specific, and I wouldn't expect those concerns to drive Apple's development efforts. I -suspect- (but don't know) that some other developers would have difficulty agreeing with the assertion that "pthread_getspecific() is good enough", and some of this may be hard to measure: people may structure programs differently depending on whether direct TLS access is available or not. In the short term, I've pretty much convinced myself that I have to burn a register. The register that I'd most -like- to burn is %fs, since it's just kind of sitting there uselessly. In order to be able to use it for lower-cost TLS that I think would be of critical importance, I -think- that the Mach kernel's "interface for the user level settable LDT entry feature" - the machine-dependent kernel call "thread_set_user_ldt()" - would need to be extended to make the entries it creates per-thread. Comments in the description of that function indicate that such an extension is considered as a future enhancement, but express doubt that there are real reasons for that extension. I certainly see such reasons, and hope to be able to convince whoever's responsible for extending thread_set_user_ldt() to consider doing so. Sorry if my original message didn't express all of that clearly; I hope that it's clear now. Gary Byers gb(a)clozure.com www.clozure.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/list-darwin-dev%40lister.… This email sent to list-darwin-dev(a)lister.dnsalias.net _______________________________________________ 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… Here's one from the archives: a few years back there was a thread about adding direct support for thread-local storage to the OS X toolchain (as distinct from pthread support). See the mail below or this archive URL for the context: Matt Watson's comments at the time sounded moderately positive about the possibility of adding this support, but I haven't seen any more recent developments. Have there been any? Is there any prospect of support for a __thread storage class in Apple's GCC in the foreseeable future? I presume it would be useful to file it in Radar regardless? On Sun, 11 Sep 2005, Gary Byers wrote: On Sep 11, 2005, at 11:12 AM, Gary Byers wrote: As I thought I explained in my message, I'm concerned about perfomance. There's a difference between "having a dedicated register point to TLS" and "having an API for fast access to TLS." An example of the latter is described in: So you would like our toolchain to support the __thread storage class? That is a reasonable request. Note that the implementation details in the paper are not designed to be exploited by application developers, but, rather, as a design for toolchain writers. It was not clear from your initial message that you were interested in this from any other aspect than as an application developer. Though I see now from your web site that your organization does a Common Lisp implementation, so you may fall into the latter category. As you can probably understand, allowing developers to inline the TLS routines greatly limits the ability to provide release-to-release binary compatibility. It would be tantamount to setting the implementation in stone for the lifetime of the ABI. On other platforms, such as Linux, developers are expected to recompile frequently. This is not the case with Mac OS X, so we are limited in the ways we can optimize such routines, and we must make certain concessions to performance to accommodate this requirement. More directly, is the overhead of pthread_getspecific() really that bad? Has it shown up in Shark samples or as a bottleneck in a critical routine for your software? This email sent to site_archiver(a)lists.apple.com

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To Answer My Own Question (was Re: Odd GCC Behavior)
by J. Aaron Pendergrass 01 Jul '08

01 Jul '08

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com ret = gimplify_expr (from_p, pre_p, post_p, rhs_predicate_for (*to_p), fb_rvalue); if (ret == GS_ERROR) return ret; -J. Aaron Pendergrass _______________________________________________ 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 Jun 30, 2008 at 4:05 PM, Andy Wiese wrote: Thank you Brian. That's the most useful thing I've learned from this thread! I'm not sure I can beat using -Wall, but after the luke warm list response I figured I'd just dive into the GCC source and find out for myself exactly what was going on. The short answer, this is behavior is specific to Apple's GCC 4.0.1 build 5465 (well > 5370, I don't know exactly when the change was made because Apple doesn't allow access to their GCC source control repository, just the current version). It is not specific to the PPC branch as I originally thought (the Intel compiler I had was just an older build). And, the cause of it does may actually impact the performance of completely defined (by the C specification) code. The long answer follows: Here's the code responsible for the behavior copied from gimplify_modify_expr() in gcc/gimplify.c (see: http://www.opensource.apple.com/darwinsource/10.5/gcc-5465/gcc/gimplify.c ): /* APPLE LOCAL begin 4228828 */ /* For stores to a pointer, keep computation of the address close to the pointer. Later optimizations should do this; the 'sink' pass in 4.2 does it, but that's not in 4.0. Temporary. */ if (TREE_CODE (*to_p) != INDIRECT_REF) { ret = gimplify_expr (to_p, pre_p, post_p, is_gimple_lvalue, fb_lvalue); if (ret == GS_ERROR) return ret; } /* APPLE LOCAL end 4228828 */ /* Now see if the above changed *from_p to something we handle specially. */ ret = gimplify_modify_expr_rhs (expr_p, from_p, to_p, pre_p, post_p, want_value); if (ret != GS_UNHANDLED) return ret; /* APPLE LOCAL begin 4228828 */ if (TREE_CODE (*to_p) == INDIRECT_REF) { ret = gimplify_expr (to_p, pre_p, post_p, is_gimple_lvalue, fb_lvalue); if (ret == GS_ERROR) return ret; } /* APPLE LOCAL end 4228828 */ gimplify_modify_expr() is the routine responsible for converting the language dependent syntax tree for an assignment operation into the language independent GIMPLE language/tree (side note: you can view the GIMPLE using the -fdump-tree-gimple option to GCC, this was a very helpful ability when trying to understand exactly why this was happening). As you can all see, Apple inserted a special check to see if the left- hand-side (called to_p) is an INDIRECT_REF (i.e., a pointer expression). If it is a pointer inspection then the right-hand-side is gimplified before the left, otherwise (as is the case in stock gcc) the left-hand-side is always gimplified first. In general, gimplification tends to proceed from left to right, so why did Apple change it here? The intent here AFAICT is to make register assignment a bit simpler (especially on a particular register-starved architecture) by ensuring that the storage location of the LHS is does not need to be stored to memory in order to perform the computation of the RHS. The "sink" pass referred to in the comment is applied after the SSA transformation (which is after GIMPLIFICATION), and like the other optimization passes won't (/isn't supposed) not to change the observable effects of its input, so mainline gcc which does not include this trickery computes the l-value first because the GIMPLE says to and none of the other optimizations will violate that ordering (due to the embedded assignments effect. A noteworthy bit about all this is that the INDIRECT_REF type does not include array subscripts (unless, I believe, the array being subscripted is a formal parameter of the current subroutine in which case all operations on it are converted to pointer ops by the C-frontend). (Here comes the piece that may have a performance impact): The effect is that the lvalue of the LHS of an assignment to an array element is likely to be computed before the r-value to be assigned, this in turn may force that l-value to be written to memory during the computation of the RHS and then read back in when the assignment is ready to proceed. I have not finished experimenting with the optimizer to try to force this behavior (my test programs have largely been trivial enough that the other optimizers have essentially wiped out the entire computation), but if the above code segment is the only solution to this problem, then it is definitely missing array element updates. I'm glad I took the time to track this down, understanding why things happen the way they do is always very rewarding. I had been meaning to tackle the GCC source code for some time, but had been somewhat daunted and didn't have any good questions to ask it. That said, this was clearly the wrong list to ask the question I did. I was looking for more of a gcc-devel list, but had an inkling this was an apple only phenomenon (and I was right), and the mainline folks tend to not be thrilled about supporting apple's bizarre forks. smime.p7s

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