From 26b8cadf88aeb1dfbc8625f02bbc20ecc0c718de Mon Sep 17 00:00:00 2001
From: Ludovic Courtès <ludovic.courtes@inria.fr>
Date: Fri, 11 May 2018 16:56:19 +0200
Subject: pack: 'guix pack -S xxx' no longer adds entries twice to the tarball.

* guix/scripts/pack.scm (self-contained-tarball)[build](symlink->directives):
Do not add a 'directory' directive for "/".  Previously, as soon as we
were using '-S /bin=bin' or similar, we would add every entry a second
time in the tarball; this would translate as hard links in the tarball,
which tar < 1.30 sometimes fails to extract.
Pass symlinks defined in DIRECTIVES to 'tar'.
---
 guix/scripts/pack.scm | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

(limited to 'guix')

diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index db5609219f..6d648d1ac3 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -122,10 +122,17 @@ (define symlink->directives
             ;; parent directories.
             (match-lambda
               ((source '-> target)
-               (let ((target (string-append #$profile "/" target)))
-                 `((directory ,(dirname source))
+               (let ((target (string-append #$profile "/" target))
+                     (parent (dirname source)))
+                 ;; Never add a 'directory' directive for "/" so as to
+                 ;; preserve its ownnership when extracting the archive (see
+                 ;; below), and also because this would lead to adding the
+                 ;; same entries twice in the tarball.
+                 `(,@(if (string=? parent "/")
+                         '()
+                         `((directory ,parent)))
                    (,source
-                    -> ,(relative-file-name (dirname source) target)))))))
+                    -> ,(relative-file-name parent target)))))))
 
           (define directives
             ;; Fully-qualified symlinks.
@@ -146,9 +153,11 @@ (define tar-supports-sort?
                                        "")
                                  #$tar "/bin"))
 
-          ;; Note: there is not much to gain here with deduplication and
-          ;; there is the overhead of the '.links' directory, so turn it
-          ;; off.
+          ;; Note: there is not much to gain here with deduplication and there
+          ;; is the overhead of the '.links' directory, so turn it off.
+          ;; Furthermore GNU tar < 1.30 sometimes fails to extract tarballs
+          ;; with hard links:
+          ;; <http://lists.gnu.org/archive/html/bug-tar/2017-11/msg00009.html>.
           (populate-single-profile-directory %root
                                              #:profile #$profile
                                              #:closure "profile"
@@ -195,6 +204,8 @@ (define tar-supports-sort?
                             (filter-map (match-lambda
                                           (('directory directory)
                                            (string-append "." directory))
+                                          ((source '-> _)
+                                           (string-append "." source))
                                           (_ #f))
                                         directives)))))))))
 
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