07/07: build-system/gnu: Make 'first-subdirectory' deterministic.

[guix-commits]

civodul pushed a commit to branch core-updates
in repository guix.

commit cfd4e4d06e3cda0f3eed8d6b9277ce53e55404b8
Author: Ludovic Courtès <address@hidden>
Date:   Fri Jun 14 23:02:28 2019 +0200

    build-system/gnu: Make 'first-subdirectory' deterministic.
    
    Fixes <https://bugs.gnu.org/35387>.
    Reported by Christopher Baines <address@hidden>.
    
    * guix/build/gnu-build-system.scm (first-subdirectory): Rewrite using
    'scandir' so that the result is deterministic.
---
 guix/build/gnu-build-system.scm | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/guix/build/gnu-build-system.scm b/guix/build/gnu-build-system.scm
index afa1886..4df0bb4 100644
--- a/guix/build/gnu-build-system.scm
+++ b/guix/build/gnu-build-system.scm
@@ -25,6 +25,7 @@
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
   #:use-module (ice-9 format)
+  #:use-module (ice-9 ftw)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-19)
   #:use-module (srfi srfi-34)
@@ -58,19 +59,14 @@ See 
https://reproducible-builds.org/specs/source-date-epoch/.";
   (setenv "SOURCE_DATE_EPOCH" "1")
   #t)
 
-(define (first-subdirectory dir)
-  "Return the path of the first sub-directory of DIR."
-  (file-system-fold (lambda (path stat result)
-                      (string=? path dir))
-                    (lambda (path stat result) result) ; leaf
-                    (lambda (path stat result) result) ; down
-                    (lambda (path stat result) result) ; up
-                    (lambda (path stat result)         ; skip
-                      (or result path))
-                    (lambda (path stat errno result)   ; error
-                      (error "first-subdirectory" (strerror errno)))
-                    #f
-                    dir))
+(define (first-subdirectory directory)
+  "Return the file name of the first sub-directory of DIRECTORY."
+  (match (scandir directory
+                  (lambda (file)
+                    (and (not (member file '("." "..")))
+                         (file-is-directory? (string-append directory "/"
+                                                            file)))))
+    ((first . _) first)))
 
 (define* (set-paths #:key target inputs native-inputs
                     (search-paths '()) (native-search-paths '())