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| | ;;; xdg.el --- XDG specification and standard support -*- lexical-binding: t -*-
;; Copyright (C) 2017 Free Software Foundation, Inc.
;; Author: Mark Oteiza <mvoteiza@udel.edu>
;; Created: 27 January 2017
;; Keywords: files, data
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published
;; by the Free Software Foundation; either version 3 of the License,
;; or (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; Library providing some convenience functions for the following XDG
;; standards and specifications
;;
;; - XDG Base Directory Specification
;; - Thumbnail Managing Standard
;; - xdg-user-dirs configuration
;;; Code:
\f
;; XDG Base Directory Specification
;; https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
(defmacro xdg--dir-home (environ default-path)
(declare (debug (stringp stringp)))
(let ((env (make-symbol "env")))
`(let ((,env (getenv ,environ)))
(if (or (null ,env) (not (file-name-absolute-p ,env)))
(expand-file-name ,default-path)
,env))))
(defun xdg-config-home ()
"Return the base directory for user specific configuration files."
(xdg--dir-home "XDG_CONFIG_HOME" "~/.config"))
(defun xdg-cache-home ()
"Return the base directory for user specific cache files."
(xdg--dir-home "XDG_CACHE_HOME" "~/.cache"))
(defun xdg-data-home ()
"Return the base directory for user specific data files."
(xdg--dir-home "XDG_DATA_HOME" "~/.local/share"))
(defun xdg-runtime-dir ()
"Return the value of $XDG_RUNTIME_DIR."
(getenv "XDG_RUNTIME_DIR"))
(defun xdg-config-dirs ()
"Return the config directory search path as a list."
(let ((env (getenv "XDG_CONFIG_DIRS")))
(if (or (null env) (string= env ""))
'("/etc/xdg")
(parse-colon-path env))))
(defun xdg-data-dirs ()
"Return the data directory search path as a list."
(let ((env (getenv "XDG_DATA_DIRS")))
(if (or (null env) (string= env ""))
'("/usr/local/share/" "/usr/share/")
(parse-colon-path env))))
\f
;; Thumbnail Managing Standard
;; https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html
(defun xdg-thumb-uri (filename)
"Return the canonical URI for FILENAME.
If FILENAME has absolute path /foo/bar.jpg, its canonical URI is
file:///foo/bar.jpg"
(concat "file://" (expand-file-name filename)))
(defun xdg-thumb-name (filename)
"Return the appropriate thumbnail filename for FILENAME."
(concat (md5 (xdg-thumb-uri filename)) ".png"))
(defun xdg-thumb-mtime (filename)
"Return modification time of FILENAME as integral seconds from the epoch."
(floor (float-time (nth 5 (file-attributes filename)))))
\f
;; XDG User Directories
;; https://www.freedesktop.org/wiki/Software/xdg-user-dirs/
(defconst xdg-line-regexp
(eval-when-compile
(rx "XDG_"
(group-n 1 (or "DESKTOP" "DOWNLOAD" "TEMPLATES" "PUBLICSHARE"
"DOCUMENTS" "MUSIC" "PICTURES" "VIDEOS"))
"_DIR=\""
(group-n 2 (or "/" "$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--substitute-home-env (str)
(if (file-name-absolute-p str) str
(save-match-data
(and (string-match "^$HOME/" str)
(replace-match "~/" t nil str 0)))))
(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 (xdg--substitute-home-env 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)))))
(let ((dir (cdr (assoc name xdg-user-dirs))))
(when dir (expand-file-name dir))))
(provide 'xdg)
;;; xdg.el ends here
|