[PATCH] gnu: Add xdelta.

[Tobias Geerinckx-Rice]

* gnu/packages/compression.scm (xdelta): New variable.
---

Hullo Guix,

This patch adds xdelta, another tool that might be helpful when restoring
some entirely hypothetical back-ups.

The project was recently re-licenced under the Apache 2.0 licence, which
is why you'll find it listed as GPL in distributions such as Debian.

Now, the sources still include some autognu build files, which we do use
during building. They are all GPL2+ or GPL3+. I wasn't sure whether they
belonged in (license) as well.

Kind regards,

T G-R

 gnu/packages/compression.scm | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/gnu/packages/compression.scm b/gnu/packages/compression.scm
index 97f0546..4c4c66c 100644
--- a/gnu/packages/compression.scm
+++ b/gnu/packages/compression.scm
@@ -10,6 +10,7 @@
 ;;; Copyright © 2015, 2016 Efraim Flashner <address@hidden>
 ;;; Copyright © 2016 Ben Woodcroft <address@hidden>
 ;;; Copyright © 2016 Danny Milosavljevic <address@hidden>
+;;; Copyright © 2016 Tobias Geerinckx-Rice <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -796,3 +797,38 @@ respectively, based on the reference implementation from 
Google.")
     (description "Extracts files out of Microsoft Cabinet (.cab) archives")
     ;; Some source files specify gpl2+, lgpl2+, however COPYING is gpl3.
     (license license:gpl3+)))
+
+(define-public xdelta
+  (package
+    (name "xdelta")
+    (version "3.1.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "https://github.com/jmacd/xdelta/archive/v";
+                           version ".tar.gz"))
+       (sha256
+        (base32
+         "17g2pbbqy6h20qgdjq7ykib7kg5ajh8fwbsfgyjqg8pwg19wy5bm"))
+       (snippet
+        ;; This file isn't freely distributable and has no effect on building.
+        '(delete-file "xdelta3/draft-korn-vcdiff.txt"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("autoconf" ,autoconf)
+       ("automake" ,automake)))
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-after 'unpack 'enter-build-directory
+           (lambda _ (chdir "xdelta3")))
+         (add-before 'configure 'autoconf
+           (lambda _ (zero? (system* "autoreconf" "-vfi")))))))
+    (home-page "http://xdelta.com";)
+    (synopsis "Delta encoder for binary files")
+    (description "xdelta encodes only the differences between two binary files
+using the VCDIFF algorithm and patch file format described in RFC 3284.  It can
+also be used to apply such patches.  xdelta is similar to @command{diff} and
address@hidden, but is not limited to plain text and does not generate
+human-readable output.")
+    (license license:asl2.0)))
-- 
2.9.0