2 files changed, 29 insertions, 13 deletions

diff --git a/guix/build/store-copy.scm b/guix/build/store-copy.scm
index 7f0672cd9de..01e1f41870f 100644
--- a/guix/build/store-copy.scm
+++ b/guix/build/store-copy.scm
@@ -38,6 +38,7 @@
 
             file-size
             closure-size
+            copy-store-item
             populate-store))
 
 ;;; Commentary:
@@ -242,6 +243,24 @@ permissions.  Write verbose output to the LOG port."
                         stat
                         lstat)))
 
+(define* (copy-store-item item target
+                          #:key
+                          (deduplicate? #t)
+                          (log-port (%make-void-port "w")))
+  "Copy ITEM, a store item, to the store under TARGET, the target root
+directory.  When DEDUPLICATE? is true, deduplicate it within TARGET."
+  (define store
+    (string-append target (%store-directory)))
+
+  (copy-recursively item (string-append target item)
+                    #:keep-mtime? #t
+                    #:keep-permissions? #t
+                    #:copy-file
+                    (if deduplicate?
+                        (cut copy-file/deduplicate <> <> #:store store)
+                        copy-file)
+                    #:log log-port))
+
 (define* (populate-store reference-graphs target
                          #:key
                          (deduplicate? #t)
@@ -273,16 +292,8 @@ regular files as they are copied to TARGET."
     (call-with-progress-reporter progress
       (lambda (report)
         (for-each (lambda (thing)
-                    (copy-recursively thing
-                                      (string-append target thing)
-                                      #:keep-mtime? #t
-                                      #:keep-permissions? #t
-                                      #:copy-file
-                                      (if deduplicate?
-                                          (cut copy-file/deduplicate <> <>
-                                               #:store store)
-                                          copy-file)
-                                      #:log (%make-void-port "w"))
+                    (copy-store-item thing target
+                                     #:deduplicate? deduplicate?)
                     (report))
                   things)))))
 
diff --git a/guix/scripts/system.scm b/guix/scripts/system.scm
index db80e0be8f5..c08929066b9 100644
--- a/guix/scripts/system.scm
+++ b/guix/scripts/system.scm
@@ -30,6 +30,7 @@
   #:use-module ((guix status) #:select (with-status-verbosity))
   #:use-module (guix store)
   #:autoload   (guix store database) (register-path)
+  #:autoload   (guix build store-copy) (copy-store-item)
   #:use-module (guix describe)
   #:use-module (guix grafts)
   #:use-module (guix gexp)
@@ -147,8 +148,8 @@ REFERENCES as its set of references."
                             #:directories? #t))
       (delete-file-recursively dest))
 
-    (copy-recursively item dest
-                      #:log (%make-void-port "w"))
+    (copy-store-item item target
+                     #:deduplicate? #t)
 
     ;; Register ITEM; as a side-effect, it resets timestamps, etc.
     ;; Explicitly use "TARGET/var/guix" as the state directory, to avoid
@@ -157,7 +158,11 @@ REFERENCES as its set of references."
     (unless (register-path item
                            #:prefix target
                            #:state-directory state
-                           #:references references)
+                           #:references references
+
+                           ;; Those are taken care of by 'copy-store-item'.
+                           #:reset-timestamps? #f
+                           #:deduplicate? #f)
       (leave (G_ "failed to register '~a' under '~a'~%")
              item target))))