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Diffstat (limited to 'gnu/home/services/symlink-manager.scm')
| -rw-r--r-- | gnu/home/services/symlink-manager.scm | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/gnu/home/services/symlink-manager.scm b/gnu/home/services/symlink-manager.scm new file mode 100644 index 0000000000..f4251e1e6a --- /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 backs up files +;;; created by user, removes symlinks and directories created by a +;;; previous generation, and creates new directories and symlinks to +;;; configuration files according to the content of files/ directory +;;; (created by home-files-service) of the current home environment +;;; generation. +;;; +;;; 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 directories +before files located in those directories, otherwise directory 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* ((config-home (or (getenv "XDG_CONFIG_HOME") + (string-append (getenv "HOME") "/.config"))) + + (he-path (string-append (getenv "HOME") "/.guix-home")) + (new-he-path (string-append he-path ".new")) + (new-home (getenv "GUIX_NEW_HOME")) + (old-home (getenv "GUIX_OLD_HOME")) + + (new-files-path (string-append new-home "/files")) + ;; Trailing dot is required, because files itself is symlink and + ;; to make file-system-tree works it should be a directory. + (new-files-dir-path (string-append new-files-path "/.")) + + (home-path (getenv "HOME")) + (backup-dir (string-append home-path "/" + (number->string (current-time)) + "-guix-home-legacy-configs-backup")) + + (old-tree (if old-home + ((simplify-file-tree "") + (file-system-tree + (string-append old-home "/files/."))) + #f)) + (new-tree ((simplify-file-tree "") + (file-system-tree new-files-dir-path))) + + (get-source-path + (lambda (path) + (readlink (string-append new-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 is no longer + ;; a symlink to the store, 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) + + (symlink new-home new-he-path) + (rename-file new-he-path he-path) + + (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 creates symlinks to configuration files and directories +on every activation. If an existing file would be overwritten by a +symlink, backs up that file first."))) |