Messages in this thread | | | Date | Thu, 26 Aug 2004 11:46:33 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: silent semantic changes with reiser4 |
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On Thu, 26 Aug 2004, Denis Vlasenko wrote: > > Is it possible to sufficiently hide "dirs inside files" > so that old tools will be unable to see them?
Certainly possible.
> I just checked: > > ls -d /foo does lstat64("/foo", ...) > ls -d /foo/ does lstat64("/foo", ...) > but > ls -d /foo/. does lstat64("/foo/.", ...) > > Will it work out if "dir inside file" will only be visible when referred as "file/."?
That would likely be the _easiest_ approach for the kernel, and does solve the problem with some apps knowingly removing the trailing '/'.
Note that we could try this out with existing filesystems with very minimal changes:
- make directory bind mounts work on top of files ("graft_tree()") - make open_namei() and friend _not_ do the mount-point following for the last component if it's a non-directory. - probably some trivial fixups I haven't thought about. There might be some places that use "S_ISDIR()" to check for whether something can be looked up, but the main path walking already just checks whether there is a ".lookup" operation or not.
This would already allow people to "try out" how different applications would react to a file that can show up both as a directory and a file. The patch might end up being less than 25 lines or so, the difficulty is in finding all the right places.
Al, anything I missed?
(And yes, it's a quick hack, but it's a quick hack that would probably mimic a good part of what we would have to do internally in the VFS layer to support this notion anyway).
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