bug#583: Use XDG basedir spec for configuration files?

[Sven Joachim <svenjoac@gmx.de>]

On 2019-08-31 14:51 -0700, Paul Eggert wrote:

> Glenn Morris wrote:
>> I guess user-emacs-directory is being set at build time, not run time.
>
> Thanks for reporting that. I installed the attached to fix it. I plan
> to follow up soon on the other issues raised here.

FWIW, this patch broke auto-save-list-file-prefix, at least when
user-emacs-directory is "~/.emacs.d/".  See bug #37354.

,----
| auto-save-list-file-prefix is a variable defined in ‘startup.el’.
| Its value is "auto-save-list/.saves-"
| Original value was
| "~/.emacs.d/auto-save-list/.saves-"
`----

Cheers,
       Sven


> From 2befb4f0a1494f699f56215d5f28ba055663d881 Mon Sep 17 00:00:00 2001
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Sat, 31 Aug 2019 14:47:04 -0700
> Subject: [PATCH] Calculate user-emacs-directory on startup
>
> Problem reported by Glenn Morris (Bug#583#56).
> * lisp/startup.el (startup--xdg-config-default): New constant.
> (startup--xdg-config-home-emacs): New var.
> (startup--xdg-or-homedot): New function.
> (normal-top-level): Use it to set user-emacs-directory early on.
> (command-line): Also use it to determine the startup init directory.
> * lisp/subr.el (user-emacs-directory): Just initialize to nil.
> ---
>  lisp/startup.el | 51 +++++++++++++++++++++++++++++++++++++------------
>  lisp/subr.el    | 14 ++------------
>  2 files changed, 41 insertions(+), 24 deletions(-)
>
> diff --git a/lisp/startup.el b/lisp/startup.el
> index c1e429b8db..a16db242da 100644
> --- a/lisp/startup.el
> +++ b/lisp/startup.el
> @@ -490,6 +490,27 @@ normal-top-level-add-to-load-path
>      (when tail
>        (setcdr tail (append (mapcar 'expand-file-name dirs) (cdr tail))))))
>  
> +;; The default location for XDG-convention Emacs init files.
> +(defconst startup--xdg-config-default "~/.config/emacs/")
> +;; The location for XDG-convention Emacs init files.
> +(defvar startup--xdg-config-home-emacs)
> +
> +;; Return the name of the init file directory for Emacs, assuming
> +;; XDG-DIR is the XDG location and USER-NAME is the user name.
> +;; If USER-NAME is nil or "", use the current user.
> +;; Prefer the XDG location unless it does does not exist and the
> +;; .emacs.d location does exist.
> +(defun startup--xdg-or-homedot (xdg-dir user-name)
> +  (if (file-exists-p xdg-dir)
> +      xdg-dir
> +    (let ((emacs-d-dir (concat "~" user-name
> +			       (if (eq system-type 'ms-dos)
> +				   "/_emacs.d/"
> +				 "/.emacs.d/"))))
> +      (if (file-exists-p emacs-d-dir)
> +	  emacs-d-dir
> +	xdg-dir))))
> +
>  (defun normal-top-level ()
>    "Emacs calls this function when it first starts up.
>  It sets `command-line-processed', processes the command-line,
> @@ -499,6 +520,14 @@ normal-top-level
>        (message internal--top-level-message)
>      (setq command-line-processed t)
>  
> +    (setq startup--xdg-config-home-emacs
> +	  (let ((xdg-config-home (getenv-internal "XDG_CONFIG_HOME")))
> +	    (if xdg-config-home
> +		(concat xdg-config-home "/emacs/")
> +	      startup--xdg-config-default)))
> +    (setq user-emacs-directory
> +	  (startup--xdg-or-homedot startup--xdg-config-home-emacs nil))
> +
>      ;; Look in each dir in load-path for a subdirs.el file.  If we
>      ;; find one, load it, which will add the appropriate subdirs of
>      ;; that dir into load-path.  This needs to be done before setting
> @@ -1167,19 +1196,17 @@ command-line
>                           :error))))
>  
>    ;; Calculate the name of the Emacs init directory.
> -  ;; This is typically equivalent to ~/.config/emacs if the user is
> -  ;; following the XDG convention, and is ~INIT-FILE-USER/.emacs.d
> -  ;; on other systems.
> -  (setq xdg-dir (concat (or (getenv "XDG_CONFIG_HOME")
> -			    (concat "~" init-file-user "/.config"))
> -			"/emacs/"))
> +  ;; This is typically ~INIT-FILE-USER/.config/emacs unless the user
> +  ;; is following the ~INIT-FILE-USER/.emacs.d convention.
> +  (setq xdg-dir startup--xdg-config-home-emacs)
>    (setq startup-init-directory
> -	(if (file-exists-p xdg-dir)
> -	    xdg-dir
> -	  (let ((emacs-d-dir (concat "~" init-file-user "/.emacs.d/")))
> -	    (if (file-exists-p emacs-d-dir)
> -		emacs-d-dir
> -	      xdg-dir))))
> +	(if (or (zerop (length init-file-user))
> +		(and (eq xdg-dir user-emacs-directory)
> +		     (not (eq xdg-dir startup--xdg-config-default))))
> +	    user-emacs-directory
> +	  ;; The name is not obvious, so access more directories to calculate it.
> +	  (setq xdg-dir (concat "~" init-file-user "/.config/emacs/"))
> +	  (startup--xdg-or-homedot xdg-dir init-file-user)))
>  
>    ;; Load the early init file, if found.
>    (startup--load-user-init-file
> diff --git a/lisp/subr.el b/lisp/subr.el
> index 566a3fc758..cf6fb108e9 100644
> --- a/lisp/subr.el
> +++ b/lisp/subr.el
> @@ -2938,18 +2938,8 @@ temp-buffer-setup-hook
>  mode.")
>  
>  (defconst user-emacs-directory
> -  (let ((config-dir (concat (or (getenv-internal "XDG_CONFIG_HOME")
> -				"~/.config")
> -			    "/emacs/")))
> -    (if (file-exists-p config-dir)
> -	config-dir
> -      (let ((emacs-d-dir (if (eq system-type 'ms-dos)
> -			     ;; MS-DOS cannot have initial dot.
> -			     "~/_emacs.d/"
> -			   "~/.emacs.d/")))
> -	(if (file-exists-p emacs-d-dir)
> -	    emacs-d-dir
> -	  config-dir))))
> +  ;; The value does not matter since Emacs sets this at startup.
> +  nil
>    "Directory beneath which additional per-user Emacs-specific files are placed.
>  Various programs in Emacs store information in this directory.
>  Note that this should end with a directory separator.
> -- 
> 2.17.1