site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com <http://developer.apple.com/qa/qa2001/qa1242.html> <http://www.opensource.apple.com/darwinsource/10.4/system_cmds-336/iostat.tproj/iostat.c> S+E -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware At 13:48 +0100 11/10/06, Arvind Dalvi wrote: wondering....if I/O Media Filter puts the application on hot path, how are filesystem filter drivers (example: on-access antivirus scanners) implemented ? Mac OS X does not support file system filter drivers ("stacking file systems" in Mac OS X terminology). See Q&A 1242 for the details. On-the-fly AV scanners are mostly implemented at the kauth level. Kauth tells you when files are opened and closed [1], not when individual reads and writes are done. Getting into the read/write hot path just to gather statistics is not recommended. There are plenty of other mechanisms. For example: At 9:12 -0700 11/10/06, Shawn Erickson wrote: IOBlockStorageDriver already does this and that information is readable via the ioregistry. And this is exactly what <x-man-page://8/iostat> does. Take a look at the "devstats" routine in the following source file. [1] Actually, that's a simplification. Some kauth operations are actual notifications (stuff in the "file operation scope"), but others (stuff in the "vnode scope") only occur when an operation is authorised, and authorisations can be cached (so there's no one-to-one correspondence between operations and kauth callback invocations). _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com