guix: pack: Only wrap executable files.

* guix/scripts/pack.scm (wrapped-package)<build>: Build wrappers for
executable files and symlink others.
* tests/guix-pack-relocatable.sh: Test relocatable example of mixed
executable and non-executable files.

guix/scripts/pack.scm

@@ -749,12 +749,13 @@ (define build
                               (guix elf)))
       #~(begin
           (use-modules (guix build utils)
-                       ((guix build union) #:select (relative-file-name))
+                       ((guix build union) #:select (symlink-relative))
                        (guix elf)
                        (guix build gremlin)
                        (ice-9 binary-ports)
                        (ice-9 ftw)
                        (ice-9 match)
+                       (ice-9 receive)
                        (srfi srfi-1)
                        (rnrs bytevectors))
 
@@ -874,16 +875,27 @@ (define (build-wrapper program)
           (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
-                    ;; Note: Trailing slash in case these are symlinks.
-                    (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?
+			 ;; Note: Trailing slash in case these are symlinks.
+                         (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)

tests/guix-pack-relocatable.sh

@@ -1,5 +1,6 @@
 # GNU Guix --- Functional package management for GNU
 # Copyright © 2018, 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2020 Eric Bavier <bavier@posteo.net>
 #
 # This file is part of GNU Guix.
 #
@@ -98,6 +99,7 @@ case "`uname -m`" in
 	run_without_store GUIX_EXECUTION_ENGINE="fakechroot" \
 	"$test_directory/Bin/sed" --version > "$test_directory/output"
 	grep 'GNU sed' "$test_directory/output"
+	unset GUIX_EXECUTION_ENGINE
 
 	chmod -Rf +w "$test_directory"; rm -rf "$test_directory"/*
 
@@ -133,8 +135,41 @@ esac
 tarball="`guix pack -R -S /share=share groff:doc`"
 (cd "$test_directory"; tar xf "$tarball")
 test -d "$test_directory/share/doc/groff/html"
+chmod -Rf +w "$test_directory"; rm -rf "$test_directory"/*
 
 # Ensure '-R' applies to propagated inputs.  Failing to do that, it would fail
 # with a profile collision error in this case because 'python-scipy'
 # propagates 'python-numpy'.  See <https://bugs.gnu.org/42510>.
 guix pack -RR python-numpy python-scipy --no-grafts -n
+
+# Check that packages that mix executable and support files (e.g. git) in the
+# "binary" directories still work after wrapped.
+cat >"$test_directory/manifest.scm" <<'EOF'
+(use-modules (guix) (guix profiles) (guix search-paths)
+             (gnu packages bootstrap))
+(manifest
+ (list (manifest-entry
+        (name "test") (version "0")
+        (item (file-union "test"
+                          `(("bin/hello"
+                             ,(program-file
+                               "hello"
+                               #~(begin
+                                   (add-to-load-path (getenv "HELLO_EXEC_PATH"))
+                                   (display (load-from-path "msg"))(newline))
+                               #:guile %bootstrap-guile))
+                            ("libexec/hello/msg"
+                             ,(plain-file "msg" "42")))))
+        (search-paths
+         (list (search-path-specification
+                (variable "HELLO_EXEC_PATH")
+                (files '("libexec/hello"))
+                (separator #f)))))))
+EOF
+tarball="`guix pack -RR -S /opt= -m $test_directory/manifest.scm`"
+(cd "$test_directory"; tar xvf "$tarball")
+( export GUIX_PROFILE=$test_directory/opt
+  . $GUIX_PROFILE/etc/profile
+  run_without_store "$test_directory/opt/bin/hello" > "$test_directory/output" )
+cat "$test_directory/output"
+test "`cat $test_directory/output`" = "42"