[bug#39807] [PATCH] guix: pack: Only wrap executable files.

[Eric Bavier <bavier@posteo.net>]

From: Eric Bavier <bavier@member.fsf.org>

Hello Guix,

This patch fixes some uses of relocatable git (e.g.  octopus merge). 
Previously, guix pack would wrap all files in "bin", "sbin", and "libexec",
even non-executable files.  This would cause issues for git when its shell
scripts in libexec would try to source other shell files that had been
wrapped and were no longer a valid shell file.

I feel like a test should be added to tests/guix-pack-relocatable.sh, but
I'm not sure how to do that while keeping the test lightweight.  Suggestions
welcome.

Cheers,
`~Eric


* guix/scripts/pack.scm (wrapped-package)<build>: Build wrappers for
executable files and symlink others.
---
 guix/scripts/pack.scm | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/guix/scripts/pack.scm b/guix/scripts/pack.scm
index c8d8546e29..3634326102 100644
--- a/guix/scripts/pack.scm
+++ b/guix/scripts/pack.scm
@@ -4,6 +4,7 @@
 ;;; Copyright © 2018 Konrad Hinsen <konrad.hinsen@fastmail.net>
 ;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
 ;;; Copyright © 2018 Efraim Flashner <efraim@flashner.co.il>
+;;; Copyright © 2020 Eric Bavier <bavier@posteo.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -673,9 +674,11 @@ last resort for relocation."
                               (guix build union)))
       #~(begin
           (use-modules (guix build utils)
-                       ((guix build union) #:select (relative-file-name))
+                       ((guix build union) #:select (symlink-relative))
+                       (srfi srfi-1)
                        (ice-9 ftw)
-                       (ice-9 match))
+                       (ice-9 match)
+                       (ice-9 receive))
 
           (define input
             ;; The OUTPUT* output of PACKAGE.
@@ -726,15 +729,26 @@ last resort for relocation."
           (mkdir target)
           (for-each (lambda (file)
                       (unless (member file '("." ".." "bin" "sbin" "libexec"))
-                        (let ((file* (string-append input "/" file)))
-                          (symlink (relative-file-name target file*)
-                                   (string-append target "/" file)))))
+                        (symlink-relative (string-append input  "/" file)
+                                          (string-append target "/" file))))
                     (scandir input))
 
-          (for-each build-wrapper
-                    (append (find-files (string-append input "/bin"))
-                            (find-files (string-append input "/sbin"))
-                            (find-files (string-append input "/libexec")))))))
+          (receive (executables others)
+              (partition executable-file?
+                         (append (find-files (string-append input "/bin"))
+                                 (find-files (string-append input "/sbin"))
+                                 (find-files (string-append input "/libexec"))))
+            ;; Wrap only executables, since the wrapper will eventually need
+            ;; to execve them.  E.g. git's "libexec" directory contains many
+            ;; shell scripts that are source'd from elsewhere, which fails if
+            ;; they are wrapped.
+            (for-each build-wrapper executables)
+            ;; Link any other non-executable files
+            (for-each (lambda (old)
+                        (let ((new (string-append target (strip-store-prefix old))))
+                          (mkdir-p (dirname new))
+                          (symlink-relative old new)))
+                      others)))))
 
   (computed-file (string-append
                   (cond ((package? package)
-- 
2.25.1