Support zstd compressed files

* lisp/jka-cmpr-hook.el (jka-compr-compression-info-list): Add
zstd compression info: <http://facebook.github.io/zstd/>.
(jka-compr-mode-alist-additions): Handle .tzst suffix for zstd
compressed tar archives.  (Bug#24853)

Copyright-paperwork-exempt: yes

1 files changed, 11 insertions, 2 deletions

diff --git a/lisp/jka-cmpr-hook.el b/lisp/jka-cmpr-hook.el
index 39302f028e9..b023bcd601a 100644
--- a/lisp/jka-cmpr-hook.el
+++ b/lisp/jka-cmpr-hook.el
@@ -244,7 +244,15 @@ options through Custom does this automatically."
     ["\\.dz\\'"
      nil              nil            nil
      "uncompressing"      "gzip"         ("-c" "-q" "-d")
-     nil t "\037\213"]))
+     nil t "\037\213"]
+    ["\\.zst\\'"
+     "zstd compressing"   "zstd"         ("-c" "-q")
+     "zstd uncompressing" "zstd"         ("-c" "-q" "-d")
+     t t "\050\265\057\375"]
+    ["\\.tzst\\'"
+     "zstd compressing"   "zstd"         ("-c" "-q")
+     "zstd uncompressing" "zstd"         ("-c" "-q" "-d")
+     t nil "\050\265\057\375"]))
 
   "List of vectors that describe available compression techniques.
 Each element, which describes a compression technique, is a vector of
@@ -308,7 +316,8 @@ variables.  Setting this through Custom does that automatically."
 (defcustom jka-compr-mode-alist-additions
   (purecopy '(("\\.tgz\\'" . tar-mode)
               ("\\.tbz2?\\'" . tar-mode)
-              ("\\.txz\\'" . tar-mode)))
+              ("\\.txz\\'" . tar-mode)
+              ("\\.tzst\\'" . tar-mode)))
   "List of pairs added to `auto-mode-alist' when installing jka-compr.
 Uninstalling jka-compr removes all pairs from `auto-mode-alist' that
 installing added.