Re: [PATCH] Add XDG utility library

[Mark Oteiza <mvoteiza@udel.edu>]

On 01/02/17 at 11:24am, Philipp Stephani wrote:
> Mark Oteiza <mvoteiza@udel.edu> schrieb am Mi., 1. Feb. 2017 um 01:28 Uhr:
> 
> >
> > +;; XDG User Directories
> > +;; https://www.freedesktop.org/wiki/Software/xdg-user-dirs/
> > +
> > +(defconst xdg-line-regexp
> > +  (eval-when-compile
> > +    (rx "XDG_"
> > +        (group-n 1 (or "DESKTOP" "DOWNLOAD" "TEMPLATES" "PUBLICSHARE"
> > +                       "DOCUMENTS" "MUSIC" "PICTURES" "VIDEOS"))
> > +        "_DIR=\""
> > +        (group-n 2 (or "/" "$HOME/") (*? (or (not (any "\"")) "\\\"")))
> > +        "\""))
> > +  "Regexp matching non-comment lines in xdg-user-dirs config files.")
> > +
> > +(defvar xdg-user-dirs nil
> > +  "Alist of directory keys and values.")
> > +
> > +(defun xdg--user-dirs-parse-line ()
> > +  "Return pair of user-dirs key to directory value in LINE, otherwise nil.
> > +This should be called at the beginning of a line."
> > +  (skip-chars-forward "[:blank:]")
> > +  (when (and (/= (following-char) ?#)
> > +             (looking-at xdg-line-regexp))
> > +    (let ((k (match-string 1))
> > +          (v (match-string 2)))
> > +      (when (and k v) (cons k v)))))
> > +
> > +(defun xdg--user-dirs-parse-file (filename)
> > +  "Return alist of xdg-user-dirs from FILENAME."
> > +  (let (elt res)
> > +    (with-temp-buffer
> > +      (insert-file-contents filename)
> > +      (goto-char (point-min))
> > +      (while (not (eobp))
> > +        (setq elt (xdg--user-dirs-parse-line))
> > +        (when (consp elt) (push elt res))
> > +        (forward-line)))
> > +    res))
> > +
> > +(defun xdg-user-dir (name)
> > +  "Return the path of user directory referred to by NAME."
> > +  (when (null xdg-user-dirs)
> > +    (setq xdg-user-dirs
> > +          (xdg--user-dirs-parse-file
> > +           (expand-file-name "user-dirs.dirs" (xdg-config-home)))))
> > +  (cdr (assoc name xdg-user-dirs)))
> >
> 
> This parsing seems a bit brittle (what if the file contains ${HOME} instead
> of $HOME?); probably this should call the xdg-user-dir program instead.

Then it's not valid.  There's no point in depending on a binary for
this.

https://cgit.freedesktop.org/xdg/xdg-user-dirs/tree/xdg-user-dir-lookup.c