build-systems/gnu: Allow unpacking/repacking more kind of files.

Before this change, only plain directories, tar or zip archives were supported
as the source of a package for the GNU build system; anything else would cause
the unpack phase to fail.  Origins relying on snippets would suffer from the
same problem.

This change adds the support to use files of the following extensions: .gz,
.Z, .bz2, .lz, and .xz, even when they are not tarballs.  Files of unknown
extensions are treated as uncompressed files and supported as well.

* guix/packages.scm (patch-and-repack): Only add the compressor utility to the
PATH when the file is compressed.  Bind more inputs in the mlet, and use them
for decompressing single files.  Adjust the decompression and compression
routines.
[decompression-type]: Remove nested variable.
* guix/build/utils.scm (compressor, tarball?): New procedures.  Move
%xz-parallel-args to the new 'compression helpers' section.
* tests/packages.scm: Add tests.  Add missing copyright year for Jan.
* guix/build/gnu-build-system.scm (first-subdirectory): Return #f when no
sub-directory was found.
(unpack): Support more file types, including uncompressed plain files.

1 files changed, 32 insertions, 15 deletions

diff --git a/guix/build/utils.scm b/guix/build/utils.scm
index 6c40d70e21..6c37021673 100644
--- a/guix/build/utils.scm
+++ b/guix/build/utils.scm
@@ -6,7 +6,7 @@
 ;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
 ;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
-;;; Copyright © 2020 Maxim Cournoyer <maxim.cournoyer@gmail.com>
+;;; Copyright © 2020, 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -51,6 +51,10 @@
             package-name->name+version
             parallel-job-count
 
+            compressor
+            tarball?
+            %xz-parallel-args
+
             directory-exists?
             executable-file?
             symbolic-link?
@@ -113,9 +117,7 @@
 
             make-desktop-entry-file
 
-            locale-category->string
-
-            %xz-parallel-args))
+            locale-category->string))
 
 
 ;;;
@@ -139,6 +141,32 @@
 
 
 ;;;
+;;; Compression helpers.
+;;;
+
+(define (compressor file-name)
+  "Return the name of the compressor package/binary used to compress or
+decompress FILE-NAME, based on its file extension, else false."
+  (cond ((string-suffix? "gz"  file-name)  "gzip")
+        ((string-suffix? "Z"   file-name)  "gzip")
+        ((string-suffix? "bz2" file-name)  "bzip2")
+        ((string-suffix? "lz"  file-name)  "lzip")
+        ((string-suffix? "zip" file-name)  "unzip")
+        ((string-suffix? "xz"  file-name)  "xz")
+        (else #f)))                ;no compression used/unknown file extension
+
+(define (tarball? file-name)
+  "True when FILE-NAME has a tar file extension."
+  (string-match "\\.(tar(\\..*)?|tgz|tbz)$" file-name))
+
+(define (%xz-parallel-args)
+  "The xz arguments required to enable bit-reproducible, multi-threaded
+compression."
+  (list "--memlimit=50%"
+        (format #f "--threads=~a" (max 2 (parallel-job-count)))))
+
+
+;;;
 ;;; Directories.
 ;;;
 
@@ -1537,17 +1565,6 @@ returned."
              LC_NAME LC_NUMERIC LC_PAPER LC_TELEPHONE
              LC_TIME)))
 
-
-;;;
-;;; Others.
-;;;
-
-(define (%xz-parallel-args)
-  "The xz arguments required to enable bit-reproducible, multi-threaded
-compression."
-  (list "--memlimit=50%"
-        (format #f "--threads=~a" (max 2 (parallel-job-count)))))
-
 ;;; Local Variables:
 ;;; eval: (put 'call-with-output-file/atomic 'scheme-indent-function 1)
 ;;; eval: (put 'call-with-ascii-input-file 'scheme-indent-function 1)