Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: Why side-effects on open(2) are evil. (was Re: [RFD w/info-PATCH]device arguments from lookup) | Date | Sun, 27 May 2001 22:45:17 +0200 |
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On Sunday 27 May 2001 15:32, Edgar Toernig wrote: > Daniel Phillips wrote: > > It won't, the open for "." is handled in the VFS, not the > > filesystem - it will open the directory. (Without needing to be > > told it's a directory via O_DIRECTORY.) If you do open("magicdev") > > you'll get the device, because that's handled by magicdevfs. > > You really mean that "magicdev" is a directory and: > > open("magicdev/.", O_RDONLY); > open("magicdev", O_RDONLY); > > would both succeed but open different objects?
Yes, and:
open("magicdev/.", O_RDONLY | O_DIRECTORY); open("magicdev", O_RDONLY | O_DIRECTORY);
will both succeed and open the same object.
> > I'm not claiming there isn't breakage somewhere, > > you break UNIX fundamentals. But I'm quite relieved now because I'm > pretty sure that something like that will never go into the kernel.
OK, I'll take that as "I couldn't find a piece of code that breaks, so it's on to the legal issues".
SUS doesn't seem to have a lot to say about this. The nearest thing to a ruling I found was "The special filename dot refers to the directory specified by its predecessor". Which is not the same thing as:
open("foo", O_RDONLY) == open ("foo/.", O_RDONLY)
I don't know about POSIX (I don't have it: a pox on standards organizations that don't make their standards freely available) but SUS doesn't seem to forbid this.
-- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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