nar: Produce archives with files sorted in C collation order.

* guix/nar.scm (write-file) <directory>: Pass 'string<?' as the second
  argument to 'scandir'.
* tests/nar.scm ("write-file puts file in C locale collation order"):
  New test.

1 files changed, 7 insertions, 2 deletions

diff --git a/guix/nar.scm b/guix/nar.scm
index 9ba6e4ce2c..5bf174554c 100644
--- a/guix/nar.scm
+++ b/guix/nar.scm
@@ -177,8 +177,13 @@ sub-directories of FILE as needed."
         ((directory)
          (write-string "type" p)
          (write-string "directory" p)
-         (let ((entries (remove (cut member <> '("." ".."))
-                                (scandir f))))
+         (let* ((select? (negate (cut member <> '("." ".."))))
+
+                ;; 'scandir' defaults to 'string-locale<?' to sort files, but
+                ;; this happens to be case-insensitive (at least in 'en_US'
+                ;; locale on libc 2.18.)  Conversely, we want files to be
+                ;; sorted in a case-sensitive fashion.
+                (entries (scandir f select? string<?)))
            (for-each (lambda (e)
                        (let ((f (string-append f "/" e)))
                          (write-string "entry" p)