site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com On Jul 5, 2005, at 1:17 PM, Thomas Tempelmann wrote: Since there seem to be a few people here knowing enough about file systems and BSD, I like to ask this rather general question: I don't have plans to work on this right now but would rather know if this is feasible at all in Tiger, and how difficult it would be. Depending on what your answers to the above were, it might be fairly easy, or quite hard. Not generally, no. It's fairly straightforward to have your non-kernel service waiting for data all the time, so you won't have to buffer all that much in-kernel (although be aware of the possibilities for endless recursion implicit in this model). = Mike _______________________________________________ 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... Consider I'd want to write a service that logs the time and path (or node ID) of any file that got written. Does Tiger now provide some API that I can use from outside the kernel or would I still have to write a kext that hooks into the file system stack? You can't "write a kext that hooks into the file system stack". The VFS KPI is a one-to-one contract between the kernel and a filesystem; it does not support interposition by a third party. What do you mean by "got written"? Created? Modfied? Do you want one log entry for each operation, or just a summary? What do you plan to do about files that move after they are opened? Deleted after they are opened? Opened twice via different paths? Not opened by path at all? Opened on remote filesystems without persistent IDs? Opened via context- sensitive paths? What about device nodes? Symbolic links that change after the file is opened? Opened via relative paths? You can't approach this by halves; if you plan to write something that works this closely with the system, you must understand how files actually work. For said logging service, I'd have to have some way to store the information, i.e. eventually writing it to a file. If I'd have to write a kext - would I then be able to call the file systems below me to write to a file? If not, do I have at least virtual, dynamic, memory (i.e. a memory mapped file) so that I can at least save the data to "RAM" until a non-kernel service can pull the data out and save it "properly"? This email sent to site_archiver@lists.apple.com