From e00ade3fb81f89cd7c030f998ccd3e07ef2628f0 Mon Sep 17 00:00:00 2001
From: Ludovic Courtès <ludo@gnu.org>
Date: Sat, 28 Apr 2018 22:20:36 +0200
Subject: profiles: Optionally use relative file names for symlink targets.

* guix/build/union.scm (symlink-relative): New procedure.
* guix/build/profiles.scm: Re-export it.
(build-profile): Add #:symlink and pass it to 'union-build'.
* guix/profiles.scm (profile-derivation): Add #:relative-symlinks?.
Pass #:symlink to 'build-profile'.
* tests/profiles.scm ("profile-derivation relative symlinks, one entry")
("profile-derivation relative symlinks, two entries"): New tests.
---
 guix/build/profiles.scm | 14 +++++++++-----
 guix/build/union.scm    |  9 ++++++++-
 guix/profiles.scm       |  7 +++++++
 3 files changed, 24 insertions(+), 6 deletions(-)

(limited to 'guix')

diff --git a/guix/build/profiles.scm b/guix/build/profiles.scm
index b4160fba1b..819688a913 100644
--- a/guix/build/profiles.scm
+++ b/guix/build/profiles.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2015, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -24,6 +24,7 @@ (define-module (guix build profiles)
   #:use-module (ice-9 ftw)
   #:use-module (ice-9 match)
   #:use-module (ice-9 pretty-print)
+  #:re-export (symlink-relative)                  ;for convenience
   #:export (ensure-writable-directory
             build-profile))
 
@@ -129,12 +130,15 @@ (define (unsymlink link)
             (apply throw args))))))
 
 (define* (build-profile output inputs
-                        #:key manifest search-paths)
-  "Build a user profile from INPUTS in directory OUTPUT.  Write MANIFEST, an
-sexp, to OUTPUT/manifest.  Create OUTPUT/etc/profile with Bash definitions for
--all the variables listed in SEARCH-PATHS."
+                        #:key manifest search-paths
+                        (symlink symlink))
+  "Build a user profile from INPUTS in directory OUTPUT, using SYMLINK to
+create symlinks.  Write MANIFEST, an sexp, to OUTPUT/manifest.  Create
+OUTPUT/etc/profile with Bash definitions for -all the variables listed in
+SEARCH-PATHS."
   ;; Make the symlinks.
   (union-build output inputs
+               #:symlink symlink
                #:log-port (%make-void-port "w"))
 
   ;; Store meta-data.
diff --git a/guix/build/union.scm b/guix/build/union.scm
index 82d6199d9e..24b366af45 100644
--- a/guix/build/union.scm
+++ b/guix/build/union.scm
@@ -29,7 +29,8 @@ (define-module (guix build union)
 
             warn-about-collision
 
-            relative-file-name))
+            relative-file-name
+            symlink-relative))
 
 ;;; Commentary:
 ;;;
@@ -213,4 +214,10 @@ (define (finish)
                   (finish)))))))
       file))
 
+(define (symlink-relative old new)
+  "Assuming both OLD and NEW are absolute file names, make NEW a symlink to
+OLD, but using a relative file name."
+  (symlink (relative-file-name (dirname new) old)
+           new))
+
 ;;; union.scm ends here
diff --git a/guix/profiles.scm b/guix/profiles.scm
index 95dc9746bd..c17961c987 100644
--- a/guix/profiles.scm
+++ b/guix/profiles.scm
@@ -1202,6 +1202,7 @@ (define* (profile-derivation manifest
                              (hooks %default-profile-hooks)
                              (locales? #t)
                              (allow-collisions? #f)
+                             (relative-symlinks? #f)
                              system target)
   "Return a derivation that builds a profile (aka. 'user environment') with
 the given MANIFEST.  The profile includes additional derivations returned by
@@ -1213,6 +1214,9 @@ (define* (profile-derivation manifest
 When LOCALES? is true, the build is performed under a UTF-8 locale; this adds
 a dependency on the 'glibc-utf8-locales' package.
 
+When RELATIVE-SYMLINKS? is true, use relative file names for symlink targets.
+This is one of the things to do for the result to be relocatable.
+
 When TARGET is true, it must be a GNU triplet, and the packages in MANIFEST
 are cross-built for TARGET."
   (mlet* %store-monad ((system (if system
@@ -1275,6 +1279,9 @@ (define search-paths
                                         (manifest-entries manifest))))))
 
             (build-profile #$output '#$inputs
+                           #:symlink #$(if relative-symlinks?
+                                           #~symlink-relative
+                                           #~symlink)
                            #:manifest '#$(manifest->gexp manifest)
                            #:search-paths search-paths))))
 
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