From ddd1633f12cd53bbe6a8f2ccfbfa02678365f486 Mon Sep 17 00:00:00 2001
From: Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>
Date: Thu, 10 Mar 2016 11:50:52 +0100
Subject: [PATCH] Changes to the ant-build-system.

Do this in a new build phase after "install": Unpack jar, reset
timestamps, repack jar.
---
 guix/build-system/ant.scm       |  1 +
 guix/build/ant-build-system.scm | 37 +++++++++++++++++++++++++++++--------
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/guix/build-system/ant.scm b/guix/build-system/ant.scm
index 5240ff6..ac5546c 100644
--- a/guix/build-system/ant.scm
+++ b/guix/build-system/ant.scm
@@ -39,6 +39,7 @@
 (define %ant-build-system-modules
   ;; Build-side modules imported by default.
   `((guix build ant-build-system)
+    (guix build syscalls)
     ,@%gnu-build-system-modules))
 
 (define (default-jdk)
diff --git a/guix/build/ant-build-system.scm b/guix/build/ant-build-system.scm
index 1e3a1ea..7cb620b 100644
--- a/guix/build/ant-build-system.scm
+++ b/guix/build/ant-build-system.scm
@@ -18,6 +18,7 @@
 
 (define-module (guix build ant-build-system)
   #:use-module ((guix build gnu-build-system) #:prefix gnu:)
+  #:use-module (guix build syscalls)
   #:use-module (guix build utils)
   #:use-module (sxml simple)
   #:use-module (ice-9 match)
@@ -61,14 +62,8 @@
                                    (destdir "${classes.dir}")
                                    (classpath (@ (refid "classpath"))))))
 
-                 ;; Reset the ctime/mtime on all files to ensure that the
-                 ;; jar archive for the same class files is bit-identical.
-                 (target (@ (name "touch"))
-                         (exec (@ (executable "find"))
-                               (arg (@ (line "${classes.dir} -exec touch -d @0 {} ;")))))
-
                  (target (@ (name "jar")
-                            (depends "compile,touch"))
+                            (depends "compile"))
                          (mkdir (@ (dir "${jar.dir}")))
                          ;; We cannot use the simpler "jar" task here, because
                          ;; there is no way to disable generation of a
@@ -109,6 +104,31 @@ INPUTS."
                 #:allow-other-keys)
   (zero? (apply system* `("ant" ,build-target ,@make-flags))))
 
+(define* (repack #:key outputs
+                 #:allow-other-keys)
+  "Unpack all jar archives, reset the timestamp of all contained files, and
+repack them.  This is necessary to ensure that archives are reproducible."
+  (define (repack-archive jar)
+    (format #t "repacking ~a\n" jar)
+    (let ((dir (mkdtemp! "jar-contents.XXXXXX")))
+      (and (with-directory-excursion dir
+             (zero? (system* "jar" "xf" jar)))
+           ;; The manifest file contains timestamps
+           (for-each delete-file (find-files dir "MANIFEST.MF"))
+           (delete-file jar)
+           (ftw dir (lambda (file stat flag)
+                      (utime file 0 0)
+                      #t))
+           (format #t "~a\n" (string-join (list "jar" "-Mcf" jar "-C" dir ".")))
+           (zero? (system* "jar" "-Mcf" jar "-C" dir "."))
+           (utime jar 0 0)
+           #t)))
+
+  (every (match-lambda
+           ((output . directory)
+            (every repack-archive (find-files directory "\\.jar$"))))
+         outputs))
+
 (define* (check #:key target (make-flags '()) (tests? (not target))
                 (test-target "check")
                 #:allow-other-keys)
@@ -126,7 +146,8 @@ INPUTS."
     (replace 'configure configure)
     (replace 'build build)
     (replace 'check check)
-    (replace 'install install)))
+    (replace 'install install)
+    (add-after 'install 'repack repack)))
 
 (define* (ant-build #:key inputs (phases %standard-phases)
                     #:allow-other-keys #:rest args)
-- 
2.1.0