guix/tests/store-deduplication.scm

;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
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;;; 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.
;;;
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;;; 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 (test-store-deduplication)
  #:use-module (guix tests)
  #:use-module (guix store deduplication)
  #:use-module (gcrypt hash)
  #:use-module ((guix utils) #:select (call-with-temporary-directory))
  #:use-module (guix build utils)
  #:use-module (rnrs bytevectors)
  #:use-module (ice-9 binary-ports)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-64))

(test-begin "store-deduplication")

(test-equal "deduplicate"
  (cons* #t #f                                    ;inode comparisons
         2 (make-list 5 6))                       ;'nlink' values

  (call-with-temporary-directory
   (lambda (store)
     (let ((data      (string->utf8 "Hello, world!"))
           (identical (map (lambda (n)
                             (string-append store "/" (number->string n)
                                            "/a/b/c"))
                           (iota 5)))
           (unique    (string-append store "/unique")))
       (for-each (lambda (file)
                   (mkdir-p (dirname file))
                   (call-with-output-file file
                     (lambda (port)
                       (put-bytevector port data))))
                 identical)
       ;; Make the parent of IDENTICAL read-only.  This should not prevent
       ;; deduplication from inserting its hard link.
       (chmod (dirname (second identical)) #o544)

       (call-with-output-file unique
         (lambda (port)
           (put-bytevector port (string->utf8 "This is unique."))))

       (deduplicate store (nar-sha256 store) #:store store)

       ;; (system (string-append "ls -lRia " store))
       (cons* (apply = (map (compose stat:ino stat) identical))
              (= (stat:ino (stat unique))
                 (stat:ino (stat (car identical))))
              (stat:nlink (stat unique))
              (map (compose stat:nlink stat) identical))))))

(test-equal "deduplicate, ENOSPC"
  (cons* #f                                       ;inode comparison
         (append (make-list 3 4)
                 (make-list 7 1)))                ;'nlink' values

  ;; In this scenario the first 3 files are properly deduplicated and then we
  ;; simulate a full '.links' directory where link(2) gets ENOSPC, thereby
  ;; preventing deduplication of the subsequent files.
  (call-with-temporary-directory
   (lambda (store)
     (let ((true-link link)
           (links     0)
           (data1     (string->utf8 "Hello, world!"))
           (data2     (string->utf8 "Hi, world!"))
           (identical (map (lambda (n)
                             (string-append store "/" (number->string n)
                                            "/a/b/c"))
                           (iota 10)))
           (populate  (lambda (data)
                        (lambda (file)
                          (mkdir-p (dirname file))
                          (call-with-output-file file
                            (lambda (port)
                              (put-bytevector port data)))))))
       (for-each (populate data1) (take identical 5))
       (for-each (populate data2) (drop identical 5))
       (dynamic-wind
         (lambda ()
           (set! link (lambda (old new)
                        (set! links (+ links 1))
                        (if (<= links 3)
                            (true-link old new)
                            (throw 'system-error "link" "~A" '("Whaaat?!")
                                   (list ENOSPC))))))
         (lambda ()
           (deduplicate store (nar-sha256 store) #:store store))
         (lambda ()
           (set! link true-link)))

       (cons (apply = (map (compose stat:ino stat) identical))
             (map (compose stat:nlink stat) identical))))))

(test-end "store-deduplication")