Messages in this thread | | | Date | Thu, 27 Jul 2006 11:03:42 -0700 | From | "H. Peter Anvin" <> | Subject | Re: O_CAREFUL flag to disable open() side effects |
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Alan Cox wrote: > Ar Iau, 2006-07-27 am 10:33 -0700, ysgrifennodd H. Peter Anvin: >> For a conventional file, directory, or block device O_CAREFUL is a >> no-op. For ttys it would typically behave similar to O_NONBLOCK >> followed immediately by a fcntl to clear the nonblock flag. > > Linus long ago suggested O_NONE to go with RO/RW/WO. Its not that hard > to do with the current file op stuff but you have to work out what the > access permission semantics of it are and what it means for ioctl etc
O_NONE might be a good thing to do with that, but I think the "careful" semantics should be a separate flag (we shouldn't have different side effects depending on the individual mode.)
O_NONE would be a useful complement to O_CAREFUL though; for some devices O_CAREFUL with anything *other than* O_NONE might be an invalid operation.
The semantics would obviously be device dependent, but the basic idea should be that opening with O_CAREFUL should not disturb the global state of the device; it should only create a handle.
-hpa
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