On Thu, Feb 07, 2013 at 05:23:22PM +0100, Corinna Vinschen wrote: >On Feb 7 17:10, Thomas Wolff wrote: >> Am 07.02.2013 16:30, schrieb Eric Blake: >> >... >> > >> >... >> >the fact that cygwin's handling of .. is not POSIX-compliant. I think a >> >better fix would be to change file_exists() itself instead of adding a >> >misnamed wrapper function; then bashline.c wouldn't even need patching. >> > The string 'tilde' need not even be in the patch; what you are really >> >after is a function that says that if '..' is found within a string >> >being probed for existence, then add an additional check to see if the >> >prefix of that string exists as a directory. >> > >> >But I don't mind experimenting with the idea - it remains to be seen >> >whether people will complain that bash is noticeably slower because it >> >takes time to double-check instead of rely on cygwin's non-POSIX >> >shortcut. And the slowdown would only be on paths containing a '..'; I >> >would NOT be checking for symlinks (even though symlinks containing .. >> >are also being interpreted in a non-POSIX manner, it is much more >> >expensive to second-guess if you have to check every name for being a >> >symlink than it is to just check for literal ..). >> Do I interpret correctly that you talk about bash filename completion here? >> Referring to http://cygwin.com/ml/cygwin/2013-01/msg00201.html, >> I'd like to point out that while this ".." thing is a cygwin bug, or >> known downside as Corinna says, >> the same issue occurs on Linux precisely with filename completion >> which isn't consistent there either. >> So it would be "over-fixing" to handle that specifically in bash. >> >> On the other hand, considering again this "downside": >> If the core cygwin filesystem function would follow this approach, >> simply checking for an occurrence of ".." first before resolving the >> filename, >> wouldn't that be an acceptable fix without inappropriate penalty? > >You don't know what you're asking for (can of worms, etc.) > >This is some kind of chicken egg problem. > >- The path must be normalized, otherwise we can't reliably convert > the POSIX path prefix to a Windows pathname. > >- Only after converting to a Windows path, we can perform file checks. > >- Rinse and repeat. > >Also, the path normalization is performed in an entirely distinct >function from the mount point conversion, and this in turn is another >function than the path function handling symlinks and devices. >Changing that requires to implement the path conversion functionality >almost from scratch. Given the age of some of these functions, I'd >like to have done that for a long time, but I'm constantly shying away >since I don't want to break what is working today. There's, of course, >still the aforementioned chicken-egg problem.
What she said. cgf -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
