Re: [PATCH] Improve ant-build-system.

[Leo Famulari <leo@famulari.name>]

On Thu, Mar 24, 2016 at 03:50:38PM +0100, Ricardo Wurmus wrote:
> Hi Guix,
> 
> our ant-build-system currently throws away the jar manifest, because it
> was difficult to control its timestamp.  Without a manifest many jars
> cannot be used, though.  Oops!
> 
> The manifest and the directory it is in always get the current time,
> which is very annoying.  Since controlling the timestamp is not possible
> with “jar”, this patch repacks the jar archive with “zip”.  The only
> thing we need to take care of is to ensure that the manifest file
> appears first.

So, the timestamp issue is avoided by using "zip"? Just curious, I would
want to block this change regardless.

> 
> With these changes the jars actually work properly.
> 
> Thanks to Roel for reporting these issues to me privately and assisting
> in debugging all of this!
> 
> ~~ Ricardo
> 

> From 0839fc0c10f6ace360ff88a48951340b5b25e376 Mon Sep 17 00:00:00 2001
> From: Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>
> Date: Thu, 24 Mar 2016 15:33:21 +0100
> Subject: [PATCH 1/2] build-system/ant: Add zip.
> 
> * guix/build-system/ant.scm (default-zip): New variable.
> (lower): Add zip to native inputs.
> ---
>  guix/build-system/ant.scm | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/guix/build-system/ant.scm b/guix/build-system/ant.scm
> index d3054e5..f333aa5 100644
> --- a/guix/build-system/ant.scm
> +++ b/guix/build-system/ant.scm
> @@ -54,15 +54,22 @@
>    (let ((jdk-mod (resolve-interface '(gnu packages java))))
>      (module-ref jdk-mod 'ant)))
>  
> +(define (default-zip)
> +  "Return the default ZIP package."
> +  ;; Lazily resolve the binding to avoid a circular dependency.
> +  (let ((zip-mod (resolve-interface '(gnu packages zip))))
> +    (module-ref zip-mod 'zip)))
> +
>  (define* (lower name
>                  #:key source inputs native-inputs outputs system target
>                  (jdk (default-jdk))
>                  (ant (default-ant))
> +                (zip (default-zip))
>                  #:allow-other-keys
>                  #:rest arguments)
>    "Return a bag for NAME."
>    (define private-keywords
> -    '(#:source #:target #:jdk #:ant #:inputs #:native-inputs))
> +    '(#:source #:target #:jdk #:ant #:zip #:inputs #:native-inputs))
>  
>    (and (not target)                               ;XXX: no cross-compilation
>         (bag
> @@ -77,6 +84,7 @@
>                          ,@(standard-packages)))
>           (build-inputs `(("jdk" ,jdk "jdk")
>                           ("ant" ,ant)
> +                         ("zip" ,zip)
>                           ,@native-inputs))
>           (outputs outputs)
>           (build ant-build)
> -- 
> 2.1.0
> 

> From 7a3ac4d2eb7c7e9f3a96927f6c68c2a182082b6a Mon Sep 17 00:00:00 2001
> From: Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de>
> Date: Thu, 24 Mar 2016 15:39:45 +0100
> Subject: [PATCH 2/2] ant-build-system: Keep jar manifest.
> 
> * guix/build/ant-build-system.scm (default-build.xml): Generate default
> manifest.
> (strip-jar-timestamps): Repack jar archive with zip.
> ---
>  guix/build/ant-build-system.scm | 29 +++++++++++++++++------------
>  1 file changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/guix/build/ant-build-system.scm b/guix/build/ant-build-system.scm
> index d302b94..27277af 100644
> --- a/guix/build/ant-build-system.scm
> +++ b/guix/build/ant-build-system.scm
> @@ -65,13 +65,8 @@
>                   (target (@ (name "jar")
>                              (depends "compile"))
>                           (mkdir (@ (dir "${jar.dir}")))
> -                         ;; We cannot use the simpler "jar" task here, because
> -                         ;; there is no way to disable generation of a
> -                         ;; manifest.  We do not include a generated manifest
> -                         ;; to ensure determinism, because we cannot easily
> -                         ;; reset the ctime/mtime before creating the archive.
>                           (exec (@ (executable "jar"))
> -                               (arg (@ (line ,(string-append "-Mcf ${jar.dir}/" jar-name
> +                               (arg (@ (line ,(string-append "-cf ${jar.dir}/" jar-name
>                                                               " -C ${classes.dir} ."))))))
>  
>                   (target (@ (name "install"))
> @@ -105,16 +100,15 @@ INPUTS."
>    (zero? (apply system* `("ant" ,build-target ,@make-flags))))
>  
>  (define* (strip-jar-timestamps #:key outputs
> -                 #:allow-other-keys)
> +                               #: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")))
> +    (let* ((dir (mkdtemp! "jar-contents.XXXXXX"))
> +           (manifest (string-append dir "/META-INF/MANIFEST.MF")))
>        (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)
>             ;; XXX: copied from (gnu build install)
>             (for-each (lambda (file)
> @@ -122,8 +116,19 @@ repack them.  This is necessary to ensure that archives are reproducible."
>                           (unless (eq? (stat:type s) 'symlink)
>                             (utime file 0 0 0 0))))
>                       (find-files dir #:directories? #t))
> -           (unless (zero? (system* "jar" "-Mcf" jar "-C" dir "."))
> -             (error "'jar' failed"))
> +
> +           ;; The jar tool will always set the timestamp on the manifest file
> +           ;; and the containing directory to the current time, even when we
> +           ;; reuse an existing manifest file.  To avoid this we use "zip"
> +           ;; instead of "jar".  It is important that the manifest appears
> +           ;; first.
> +           (with-directory-excursion dir
> +             (let* ((files (find-files "." ".*" #:directories? #t))
> +                    (command (if (file-exists? manifest)
> +                                 `("zip" "-X" ,jar ,manifest ,@files)
> +                                 `("zip" "-X" ,jar ,@files))))
> +               (unless (zero? (apply system* command))
> +                 (error "'zip' failed"))))
>             (utime jar 0 0)
>             #t)))
>  
> -- 
> 2.1.0
>