bug#550: 23.0.60; A case where file-truename ignores case on w32

[Lennart Borgman (gmail)]

Jason Rumney wrote:
> Lennart Borgman (gmail) wrote:
> > I got a bug report from a user concerning nXhtml. The problem seems to
> > be that Emacs ignores case in an existing directory name.
>
> Only when the file does not exist. In that case, w32-long-file-name
> returns nil and the original string that was passed in to file-truename
> is used. The solution is probably to recursively descend the directory
> heirarchy until we find a directory that exists, and call
> w32-long-file-name on that.

I suggest replacing

  (or (w32-long-file-name filename) filename)))

in `true-filename' with

  (let ((w32-filename (w32-long-file-name filename))
        (root filename)
        w32-root)
    (while (not w32-filename)
      (when (eq ?/ (car (last (append root nil))))
        (setq root (substring root 0 -1)))
      (setq root (file-name-directory root))
      (if (not root)
          (setq w32-filename filename)
        (setq w32-root (w32-long-file-name root))
        (when w32-root
          (setq w32-filename
                (concat w32-root
                        (substring filename (length w32-root)))))))
    w32-filename)