guix: Add downloader for Mercurial repositories.

* guix/build/hg.scm: New file.
* guix/hg-download.scm: New file.
* Makefile.am (MODULES): Add them.

1 files changed, 51 insertions, 0 deletions

diff --git a/guix/build/hg.scm b/guix/build/hg.scm
new file mode 100644
index 0000000000..ae4574de57
--- /dev/null
+++ b/guix/build/hg.scm
@@ -0,0 +1,51 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2016 Ricardo Wurmus <rekado@elephly.net>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build hg)
+  #:use-module (guix build utils)
+  #:export (hg-fetch))
+
+;;; Commentary:
+;;;
+;;; This is the build-side support code of (guix hg-download).  It allows a
+;;; Mercurial repository to be cloned and checked out at a specific changeset
+;;; identifier.
+;;;
+;;; Code:
+
+(define* (hg-fetch url changeset directory
+                   #:key (hg-command "hg"))
+  "Fetch CHANGESET from URL into DIRECTORY.  CHANGESET must be a valid
+Mercurial changeset identifier.  Return #t on success, #f otherwise."
+
+  (and (zero? (system* hg-command
+                       "clone" url
+                       "--rev" changeset
+                       ;; Disable TLS certificate verification.  The hash of
+                       ;; the checkout is known in advance anyway.
+                       "--insecure"
+                       directory))
+       (with-directory-excursion directory
+         (begin
+           ;; The contents of '.hg' vary as a function of the current
+           ;; status of the Mercurial repo.  Since we want a fixed
+           ;; output, this directory needs to be taken out.
+           (delete-file-recursively ".hg")
+           #t))))
+
+;;; hg.scm ends here