>From 089b9741a734f0682a671df6c0c36dfefcbd407c Mon Sep 17 00:00:00 2001
From: nee <address@hidden>
Date: Mon, 9 Oct 2017 22:49:12 +0200
Subject: [PATCH] guix: gnu-build-system: warn about missing unzip input during
 unpack.

---
 guix/build/gnu-build-system.scm | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/guix/build/gnu-build-system.scm b/guix/build/gnu-build-system.scm
index e37b75140..c16d15964 100644
--- a/guix/build/gnu-build-system.scm
+++ b/guix/build/gnu-build-system.scm
@@ -67,6 +67,21 @@ See https://reproducible-builds.org/specs/source-date-epoch/."
                     #f
                     dir))
 
+(define (unzip filepath)
+  "Unzip archive file.
+Warn the user when unzip fails and the executable is not present."
+  (define exit-code (system* "unzip" filepath))
+  (define program-not-found-code 32512)
+  (cond ((zero? exit-code) #t)
+        ((eqv? exit-code program-not-found-code)
+         (format (current-error-port)
+                 "warning: Archive with .zip suffix failed to unpack.
+Please add unzip as native-input to the package,
+e.g. (native-inputs `((\"unzip\" ,unzip)))")
+         (newline (current-error-port))
+         #f)
+        (else #f)))
+
 (define* (set-paths #:key target inputs native-inputs
                     (search-paths '()) (native-search-paths '())
                     #:allow-other-keys)
@@ -154,7 +169,7 @@ working directory."
                           #:keep-mtime? #t)
         #t)
       (and (if (string-suffix? ".zip" source)
-               (zero? (system* "unzip" source))
+               (unzip source)
                (zero? (system* "tar" "xvf" source)))
            (chdir (first-subdirectory ".")))))
 
-- 
2.14.1