October 2006 - Darwin-dev - lists.apple.com

Re: MacOS X equivalent of swapon/swapoff?
by Sam Vaughan 16 Oct '06

16 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com G'day Godfrey and Alison, Sam On 13/10/2006, at 8:46 AM, Godfrey van der Linden <gvdl(a)mac.com> wrote: I'd like to come at this problem a little differently. Are you a kernel hacker? It may be possible to modify the IOMediaBSDClient to stall I/O's for a few seconds until a convenient time in the future, this should work without to many problems. It seems to me that this is what you are really trying to do? Is that correct? Godfrey On 11/10/2006, at 04:08 , Alison Cassidy wrote: In any case, from that man page, I don't see how you can do both of "quiet all disk activity" and avoid the problem I mention above (which really isn't specific to your process; modern OSs have a lot of processes that can fire at any time to handle the exigencies of the moment; they need to be able to run, or the system crumbles). Right. I'll never quiet *all* disk activity; all I can hope for is to minimize it somehow. You could, as mentioned earlier in this thread, avoid enabling the paging daemon. With sufficient memory, you could run a full system, but things may start failing in strange ways without the elasticity provided by a backing store. In case you haven't looked in depth at the Mac OS X VM system, it's all handled by the paging daemon. There is no path to disk (for this purpose) within the kernel. Right (and thanks John and Graham for the info there). I'd considered messing about with dynamic_pager but wouldn't like to modify the boot args nor kill it outright for very obvious reasons. I need to look into the workings of the paging daemon some more ... _______________________________________________ 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… Would you actually want to modify/replace the IOMediaBSDClient at all? I've been down that path before and it's a maintenance nightmare! You could create a standard media filter to match on all the system's IOMedia objects. Each of those would create its own IOMedia child for IOMediaBSDClient to match on and it would simply pass requests straight through. Built into the same driver you'd have a single controller object that matches on IOResources and publishes an API through a char device. The top level controller would have a read-write lock that it shares with all the filter object instances. They all take it in read mode to do their I/Os, but when you tell the controller to pause the I/O stream, it'd take the lock in write mode until you tell it to release it again. You'd want to make sure to do nothing in the interim that depends on the I/O subsystem, or you'd deadlock very quickly. You'd somehow have to ensure that all the pages containing code you need to execute are in-core as well. If the purpose is to allow I/Os from your own special user space process to proceed, you could use proc_selfname() to allow them to pass through your IOMedia filters. If it's for a one-off solution or for research purposes, then it seems do-able. It'd certainly make for a fun little project! This email sent to site_archiver(a)lists.apple.com

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Re: how should a sockaddr struct be filled in for a normal web address?
by Gwynne 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com I want to call this function: Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; struct sockaddr_in { __uint8_t sin_len; sa_family_t sin_family; in_port_t sin_port; struct in_addr sin_addr; char sin_zero[8]; /* XXX bwg2001-004 */ }; -- Gwynne, daughter of the Code "This whole world is an asylum for the incurable." _______________________________________________ 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… On Oct 14, 2006, at 7:59 PM, Ben Dougall wrote: I don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? Others have answered this by pointing out a better function to use, but for the sake of completeness, here is the answer to your original question: You don't use an actual struct sockaddr. What you want is a struct sockaddr_in; that's why there's an int addrlen parameter, because sockaddr is a generic struct that you don't actually use except as a placeholder for passing "any kind of socket address". struct sockaddr_in looks like: sin_len - another duplication of the address structure length; set it to sizeof( struct sockaddr_in ) sin_family - PF_INET for IPv4. You can't use IPv6 addresses with this structure. sin_port - The port on which you will be contacting the address. For HTTP, usually 80, but if using a URL, you should first check the protocol and port if any are given therein. Note that this value must given in big endian regardless of host machine. sin_addr - A struct in_addr structure with one member: in_addr_t s_addr. This is the most important one, since it is a four-byte big- endian representation of the IPv4 address you wish to contact. You can't put a textual domain name such as "amazon.com" here; you must first resolve the hostname using the gethostbyname() family of APIs. These APIs are not reentrant and therefore can't be used safely in from multiple threads without an exclusive lock. Further, a single hostname can and often will resolve to more than one IPv4 address; a few may even resolve to IPv6 addresses that you can't pass here. sin_zero - As the name suggests, set this to zero; it exists to make the length of struct sockaddr_in equal to that of struct sockaddr. All in all, this is a great deal of unnecessary work that is better done by APIs designed for the purpose. You shouldn't have to deal with resolving names and filling out socket address structures unless you're doing your own socket I/O at the BSD level without help from Carbon or Cocoa. This email sent to site_archiver(a)lists.apple.com

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Re: how should a sockaddr struct be filled in for a normal web address?
by Ben Dougall 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Sunday, October 15, 2006, at 01:19 am, Shawn Erickson wrote: On Oct 14, 2006, at 5:16 PM, Shawn Erickson wrote: On Oct 14, 2006, at 4:59 PM, Ben Dougall wrote: I want to call this function: Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; Ah misread which function you are looking at using... Oh yes of course that's what I should use. Silly me. Thanks, Ben. _______________________________________________ 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 don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? Why not use SCNetworkReachabilityCreateWithName? ...use SCNetworkCheckReachabilityByName. This email sent to site_archiver(a)lists.apple.com

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Re: [APPL:DarwinDev] Re: cp -f option
by Uli Kusterer 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Presumably it actually will go ahead iff the user has write permissions in the containing directory and (the file is owned by the user or sticky is unset). You don't need write permissions on a file to delete the file, and cp could just delete the in-the-way file in order to create its new file. Jay, Cheers, -- M. Uli Kusterer http://www.zathras.de _______________________________________________ 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… Am 11.10.2006 um 23:18 schrieb Jay A. Kreibich: On Wed, Oct 11, 2006 at 10:15:40PM +0100, Graham J Lee scratched on the wall: Good point. I assume that's correct. no need to assume. My prof pretty much said the same way back in Sysadmin class :-) This email sent to site_archiver(a)lists.apple.com

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Re: Shipping a compiler with applications?
by Uli Kusterer 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com Cheers, -- M. Uli Kusterer http://www.zathras.de _______________________________________________ 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… Am 11.10.2006 um 10:46 schrieb Graham J Lee: 1) Is it true that all OSX boxes come with gcc / ld on them? No - they're part of the developer tools package. Is there no way you could depend on the developer tools? Note that the developer tools *installer* has been included on the system DVD since 10.4, and usually came in a folder somewhere in / Applications for preinstalled systems or on a separate CD with earlier releases. So, in general you can assume that every user has GCC and could be asked to install it (save for those kept small by admins who don't let them have the system CDs, but then those would probably not have admin privileges either). This email sent to site_archiver(a)lists.apple.com

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Re: how should a sockaddr struct be filled in for a normal web address?
by Shawn Erickson 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Oct 14, 2006, at 5:16 PM, Shawn Erickson wrote: On Oct 14, 2006, at 4:59 PM, Ben Dougall wrote: I want to call this function: Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; Ah misread which function you are looking at using... ...use SCNetworkCheckReachabilityByName. -Shawn _______________________________________________ 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 don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? Why not use SCNetworkReachabilityCreateWithName? This email sent to site_archiver(a)lists.apple.com

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Re: how should a sockaddr struct be filled in for a normal web address?
by Shawn Erickson 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com On Oct 14, 2006, at 4:59 PM, Ben Dougall wrote: I want to call this function: Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; Why not use SCNetworkReachabilityCreateWithName? -Shawn _______________________________________________ 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 don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? Also in an email on the Cocoa developer list you stated that you wanted to target 10.2 and later. The above API is only available on 10.3 and later (not that you couldn't use it on 10.3 and later and use something when running on 10.2). This email sent to site_archiver(a)lists.apple.com

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Re: how should a sockaddr struct be filled in for a normal web address?
by Sebastian Hagedorn 15 Oct '06

15 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com --On 15. Oktober 2006 00:59:33 +0100 Ben Dougall <bend(a)freenet.co.uk> wrote: No, you don't :-) Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; I don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? You actually want to call SCNetworkCheckReachabilityByName. -- .:.Sebastian Hagedorn - RZKR-R1 (Gebäude 52), Zimmer 18.:. Zentrum für angewandte Informatik - Universitätsweiter Service RRZK .:.Universität zu Köln / Cologne University - Tel. +49-221-478-5587.:. .:.:.:.Skype: shagedorn.:.:.:. _______________________________________________ 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 I want to call this function: Check out <http://developer.apple.com/documentation/Networking/Reference/SysConfig/SCN…> pgpXgWJ5Ala6c.pgp

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how should a sockaddr struct be filled in for a normal web address?
by Ben Dougall 14 Oct '06

14 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com I want to call this function: Boolean SCNetworkCheckReachabilityByAddress ( const struct sockaddr *address, int addrlen, SCNetworkConnectionFlags *flags ); A struct sockaddr is: struct sockaddr { u_char sa_len; /* total length */ u_char sa_family; /* address family */ char sa_data[14]; /* actually longer; address value */ }; Thanks, Ben. _______________________________________________ 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 don't know how the struct should be filled in in order to call the above function. Can anyone point me to some example code that fills that struct in for a normal web address e.g. amazon.com? This email sent to site_archiver(a)lists.apple.com

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Re: MacOS X equivalent of swapon/swapoff?
by Godfrey van der Linden 12 Oct '06

12 Oct '06

site_archiver(a)lists.apple.com Delivered-To: darwin-dev(a)lists.apple.com I'd like to come at this problem a little differently. Godfrey On 11/10/2006, at 04:08 , Alison Cassidy wrote: _______________________________________________ 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… Are you a kernel hacker? It may be possible to modify the IOMediaBSDClient to stall I/O's for a few seconds until a convenient time in the future, this should work without to many problems. It seems to me that this is what you are really trying to do? Is that correct? In any case, from that man page, I don't see how you can do both of "quiet all disk activity" and avoid the problem I mention above (which really isn't specific to your process; modern OSs have a lot of processes that can fire at any time to handle the exigencies of the moment; they need to be able to run, or the system crumbles). Right. I'll never quiet *all* disk activity; all I can hope for is to minimize it somehow. You could, as mentioned earlier in this thread, avoid enabling the paging daemon. With sufficient memory, you could run a full system, but things may start failing in strange ways without the elasticity provided by a backing store. In case you haven't looked in depth at the Mac OS X VM system, it's all handled by the paging daemon. There is no path to disk (for this purpose) within the kernel. Right (and thanks John and Graham for the info there). I'd considered messing about with dynamic_pager but wouldn't like to modify the boot args nor kill it outright for very obvious reasons. I need to look into the workings of the paging daemon some more ... This email sent to site_archiver(a)lists.apple.com

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