[bug#50208] [PATCH] home-services: Add symlink-manager

[Andrew Tropin]

On 2021-08-26 13:58, Oleg Pykhalov wrote:

> Hi Andrew,
>
> Andrew Tropin <andrew@trop.in> writes:
>
>> ---
>> This patch is targeted against wip-guix-home branch.
>>
>> It's not a part of any patch series to make sure it will get enough 
>> attention,
>> because it's most unpure part of the Guix Home and operates on user's files.
>>
>>  gnu/home-services/symlink-manager.scm | 248 ++++++++++++++++++++++++++
>>  1 file changed, 248 insertions(+)
>>  create mode 100644 gnu/home-services/symlink-manager.scm
>>
>
> […]
>
> I applied your patch, replaces tabs with spaces, modified commit message
> according to GNU standards, added the file to gnu/local.mk for
> compilation (I forgot to do it for previous patch series, apologies).
>

Thank you!

>
>
> I would like to squash the patch for home-services.scm with a previous
> series (hope force push will work), but I should ask you could I do it?
> Otherwise I could just push two patches to wip-guix-home.
>

Yes, squash works for me.

> 
> Updated patches are attached below.
>
> From 99f1b412fd76d9813dccc96cf30a943375d0d5a8 Mon Sep 17 00:00:00 2001
> From: Oleg Pykhalov <go.wigust@gmail.com>
> Date: Thu, 26 Aug 2021 13:18:54 +0300
> Subject: [PATCH 1/2] gnu: Compile home-services.
>
> This commit follows b784de19.
>
> * gnu/local.mk (GNU_SYSTEM_MODULES): Add home-services.scm.
> ---
>  gnu/local.mk | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/gnu/local.mk b/gnu/local.mk
> index 14cd1cc6ad..bd3aed77e8 100644
> --- a/gnu/local.mk
> +++ b/gnu/local.mk
> @@ -72,6 +72,7 @@ GNU_SYSTEM_MODULES =                                \
>    %D%/bootloader/u-boot.scm                     \
>    %D%/bootloader/depthcharge.scm                \
>    %D%/ci.scm                                 \
> +  %D%/home-services.scm                         \
>    %D%/image.scm                                      \
>    %D%/packages.scm                           \
>    %D%/packages/abduco.scm                    \
> -- 
> 2.32.0
>
> From 8938342edec4dda6ff2b7b5d47f63809bb309084 Mon Sep 17 00:00:00 2001
> From: Andrew Tropin <andrew@trop.in>
> Date: Thu, 26 Aug 2021 09:39:38 +0300
> Subject: [PATCH 2/2] home-services: Add symlink-manager.
>
> * gnu/home-services/symlink-manager.scm: New file.
> * gnu/local.mk (GNU_SYSTEM_MODULES): Add this.
>
> Signed-off-by: Oleg Pykhalov <go.wigust@gmail.com>
> ---
>  gnu/home-services/symlink-manager.scm | 247 ++++++++++++++++++++++++++
>  gnu/local.mk                          |   1 +
>  2 files changed, 248 insertions(+)
>  create mode 100644 gnu/home-services/symlink-manager.scm
>
> diff --git a/gnu/home-services/symlink-manager.scm 
> b/gnu/home-services/symlink-manager.scm
> new file mode 100644
> index 0000000000..47fee8db3b
> --- /dev/null
> +++ b/gnu/home-services/symlink-manager.scm
> @@ -0,0 +1,247 @@
> +;;; GNU Guix --- Functional package management for GNU
> +;;; Copyright © 2021 Andrew Tropin <andrew@trop.in>
> +;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
> +;;;
> +;;; This file is part of GNU Guix.
> +;;;
> +;;; GNU Guix 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 Guix 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 Guix.  If not, see <http://www.gnu.org/licenses/>.
> +
> +(define-module (gnu home-services symlink-manager)
> +  #:use-module (gnu home-services)
> +  #:use-module (guix gexp)
> +  #:export (home-symlink-manager-service-type))
> +
> +;;; Comment:
> +;;;
> +;;; symlink-manager cares about configuration files: it backups files
> +;;; created by user, removes symlinks and directories created by
> +;;; previous generation, and creates new directories and symlinks to
> +;;; configs according to content of files/ directory of current home
> +;;; environment generation (created by home-files-service).
> +;;;
> +;;; Code:
> +
> +(define (update-symlinks-script)
> +  (program-file
> +   "update-symlinks"
> +   #~(begin
> +       (use-modules (ice-9 ftw)
> +                    (ice-9 curried-definitions)
> +                    (ice-9 match)
> +                    (srfi srfi-1))
> +       (define ((simplify-file-tree parent) file)
> +         "Convert the result produced by `file-system-tree' to less
> +verbose and more suitable for further processing format.
> +
> +Extract dir/file info from stat and compose a relative path to the
> +root of the file tree.
> +
> +Sample output:
> +
> +((dir . \".\")
> + ((dir . \"config\")
> +  ((dir . \"config/fontconfig\")
> +   (file . \"config/fontconfig/fonts.conf\"))
> +  ((dir . \"config/isync\")
> +   (file . \"config/isync/mbsyncrc\"))))
> +"
> +         (match file
> +           ((name stat) `(file . ,(string-append parent name)))
> +           ((name stat children ...)
> +            (cons `(dir . ,(string-append parent name))
> +                  (map (simplify-file-tree
> +                        (if (equal? name ".")
> +                            ""
> +                            (string-append parent name "/")))
> +                       children)))))
> +
> +       (define ((file-tree-traverse preordering) node)
> +         "Traverses the file tree in different orders, depending on 
> PREORDERING.
> +
> +if PREORDERING is @code{#t} resulting list will contain folders before
> +files located in those folders, otherwise folders will appear only
> +after all nested items already listed."
> +         (let ((prepend (lambda (a b) (append b a))))
> +           (match node
> +             (('file . path) (list node))
> +             ((('dir . path) . rest)
> +              ((if preordering append prepend)
> +               (list (cons 'dir path))
> +               (append-map (file-tree-traverse preordering) rest))))))
> +
> +       (use-modules (guix build utils))
> +
> +       (let* ((he-path (string-append (getenv "HOME") "/.guix-home"))
> +              (new-he-tmp-path (string-append he-path ".new"))
> +              (new-home (getenv "GUIX_NEW_HOME")))
> +         (symlink new-home new-he-tmp-path)
> +         (rename-file new-he-tmp-path he-path))
> +
> +       (let* ((config-home    (or (getenv "XDG_CONFIG_HOME")
> +                                  (string-append (getenv "HOME") 
> "/.config")))
> +
> +              (he-path (string-append (getenv "HOME") "/.guix-home"))
> +              (new-he-tmp-path (string-append he-path ".new"))
> +
> +              (files-path (string-append he-path "/files"))
> +              ;; Leading dot is required, because files itself is symlink and
> +              ;; to make file-system-tree works it should be a directory.
> +              (files-dir-path (string-append files-path "/."))
> +              (new-files-path (string-append new-he-tmp-path "/files"))
> +              (new-files-dir-path (string-append files-path "/."))
> +
> +              (home-path (getenv "HOME"))
> +              (backup-dir (string-append home-path "/"
> +                                         (number->string (current-time))
> +                                         "-guix-home-legacy-configs-backup"))
> +
> +              (old-tree (if (file-exists? files-dir-path)
> +                          ((simplify-file-tree "")
> +                           (file-system-tree files-dir-path))
> +                          #f))
> +              (new-tree ((simplify-file-tree "")
> +                         (file-system-tree new-files-dir-path)))
> +
> +              (get-source-path
> +               (lambda (path)
> +                 (readlink (string-append files-path "/" path))))
> +
> +              (get-target-path
> +               (lambda (path)
> +                 (string-append home-path "/." path)))
> +
> +              (get-backup-path
> +               (lambda (path)
> +                 (string-append backup-dir "/." path)))
> +
> +              (directory?
> +               (lambda (path)
> +                 (equal? (stat:type (stat path)) 'directory)))
> +
> +              (empty-directory?
> +               (lambda (dir)
> +                 (equal? (scandir dir) '("." ".."))))
> +
> +              (symlink-to-store?
> +               (lambda (path)
> +                 (and
> +                  (equal? (stat:type (lstat path)) 'symlink)
> +                  (store-file-name? (readlink path)))))
> +
> +              (backup-file
> +               (lambda (path)
> +                 (mkdir-p backup-dir)
> +                 (format #t "Backing up ~a..." (get-target-path path))
> +                 (mkdir-p (dirname (get-backup-path path)))
> +                 (rename-file (get-target-path path) (get-backup-path path))
> +                 (display " done\n")))
> +
> +              (cleanup-symlinks
> +               (lambda ()
> +                 (let ((to-delete ((file-tree-traverse #f) old-tree)))
> +                   (display
> +                    "Cleaning up symlinks from previous 
> home-environment.\n\n")
> +                   (map
> +                    (match-lambda
> +                      (('dir . ".")
> +                       (display "Cleanup finished.\n\n"))
> +
> +                      (('dir . path)
> +                       (if (and
> +                            (file-exists? (get-target-path path))
> +                            (directory? (get-target-path path))
> +                            (empty-directory? (get-target-path path)))
> +                           (begin
> +                             (format #t "Removing ~a..."
> +                                     (get-target-path path))
> +                             (rmdir (get-target-path path))
> +                             (display " done\n"))
> +                           (format
> +                            #t "Skipping ~a (not an empty directory)... 
> done\n"
> +                            (get-target-path path))))
> +
> +                      (('file . path)
> +                       (when (file-exists? (get-target-path path))
> +                         ;; DO NOT remove the file if it was modified
> +                         ;; by user (not a symlink to the /gnu/store
> +                         ;; anymore) it will be backed up later during
> +                         ;; create-symlinks phase.
> +                         (if (symlink-to-store? (get-target-path path))
> +                             (begin
> +                               (format #t "Removing ~a..." (get-target-path 
> path))
> +                               (delete-file (get-target-path path))
> +                               (display " done\n"))
> +                             (format
> +                              #t
> +                              "Skipping ~a (not a symlink to store)... 
> done\n"
> +                              (get-target-path path))))))
> +                    to-delete))))
> +
> +              (create-symlinks
> +               (lambda ()
> +                 (let ((to-create ((file-tree-traverse #t) new-tree)))
> +                   (map
> +                    (match-lambda
> +                      (('dir . ".")
> +                       (display
> +                        "New symlinks to home-environment will be created 
> soon.\n")
> +                       (format
> +                        #t "All conflicting files will go to ~a.\n\n" 
> backup-dir))
> +
> +                      (('dir . path)
> +                       (let ((target-path (get-target-path path)))
> +                         (when (and (file-exists? target-path)
> +                                    (not (directory? target-path)))
> +                           (backup-file path))
> +
> +                         (if (file-exists? target-path)
> +                             (format
> +                              #t "Skipping   ~a (directory already 
> exists)... done\n"
> +                              target-path)
> +                             (begin
> +                               (format #t "Creating   ~a..." target-path)
> +                               (mkdir target-path)
> +                               (display " done\n")))))
> +
> +                      (('file . path)
> +                       (when (file-exists? (get-target-path path))
> +                         (backup-file path))
> +                       (format #t "Symlinking ~a -> ~a..."
> +                               (get-target-path path) (get-source-path path))
> +                       (symlink (get-source-path path) (get-target-path 
> path))
> +                       (display " done\n")))
> +                    to-create)))))
> +
> +         (when old-tree
> +           (cleanup-symlinks))
> +
> +         (create-symlinks)
> +
> +         (display " done\nFinished updating symlinks.\n\n")))))
> +
> +
> +(define (update-symlinks-gexp _)
> +  #~(primitive-load #$(update-symlinks-script)))
> +
> +(define home-symlink-manager-service-type
> +  (service-type (name 'home-symlink-manager)
> +                (extensions
> +                 (list
> +                  (service-extension
> +                   home-activation-service-type
> +                   update-symlinks-gexp)))
> +                (default-value #f)
> +                (description "Provide an @code{update-symlinks}
> +script, which create and remove symlinks on every activation.  If the
> +target is occupied by a file created by user, back it up.")))
> diff --git a/gnu/local.mk b/gnu/local.mk
> index bd3aed77e8..91c3b0da3d 100644
> --- a/gnu/local.mk
> +++ b/gnu/local.mk
> @@ -73,6 +73,7 @@ GNU_SYSTEM_MODULES =                                \
>    %D%/bootloader/depthcharge.scm                \
>    %D%/ci.scm                                 \
>    %D%/home-services.scm                         \
> +  %D%/home-services/symlink-manager.scm         \
>    %D%/image.scm                                      \
>    %D%/packages.scm                           \
>    %D%/packages/abduco.scm                    \

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