Add support for 'cvs-fetch' method in origins.

* guix/cvs-download.scm, guix/build/cvs.scm: New files.
* Makefile.am (MODULES): Add them.

Makefile.am

@@ -60,6 +60,7 @@ MODULES =					\
   guix/gnupg.scm				\
   guix/elf.scm					\
   guix/store.scm				\
+  guix/cvs-download.scm				\
   guix/svn-download.scm				\
   guix/ui.scm					\
   guix/build/download.scm			\
@@ -76,6 +77,7 @@ MODULES =					\
   guix/build/union.scm				\
   guix/build/pull.scm				\
   guix/build/rpath.scm				\
+  guix/build/cvs.scm				\
   guix/build/svn.scm				\
   guix/build/syscalls.scm			\
   guix/build/emacs-utils.scm			\

guix/build/cvs.scm

@@ -0,0 +1,66 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;;
+;;; 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 cvs)
+  #:use-module (guix build utils)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 ftw)
+  #:export (cvs-fetch))
+
+;;; Commentary:
+;;;
+;;; This is the build-side support code of (guix cvs-download).  It allows a
+;;; CVS repository to be checked out at a specific revision or date.
+;;;
+;;; Code:
+
+(define (find-cvs-directories)
+  (define (enter? path st result)
+    (not (string-suffix? "/CVS" path)))
+  (define (leaf path st result) result)
+  (define (down path st result) result)
+  (define (up   path st result) result)
+  (define (skip path st result)
+    (if (and (string-suffix? "/CVS" path)
+             (eqv? 'directory (stat:type st)))
+        (cons path result)
+        result))
+  (define (error path st errno result)
+    (format (current-error-port) "cvs-fetch: ~a: ~a~%"
+            path (strerror errno)))
+  (sort (file-system-fold enter? leaf down up skip error '() "." lstat)
+        string<?))
+
+(define* (cvs-fetch cvs-root-directory module revision directory
+                    #:key (cvs-command "cvs"))
+  "Fetch REVISION from MODULE of CVS-ROOT-DIRECTORY into DIRECTORY.  REVISION
+must either be a date in ISO-8601 format (e.g. \"2012-12-21\") or a CVS tag.
+Return #t on success, #f otherwise."
+  (and (zero? (system* cvs-command "-z3"
+                       "-d" cvs-root-directory
+                       "checkout"
+                       (if (string-match "^[0-9]{4}-[0-9]{2}-[0-9]{2}$" revision)
+                           "-D" "-r")
+                       revision
+                       module))
+       (rename-file module directory)
+       (with-directory-excursion directory
+         (for-each delete-file-recursively (find-cvs-directories)))
+       #t))
+
+;;; cvs.scm ends here

guix/cvs-download.scm

@@ -0,0 +1,82 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2014, 2015 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2014 Sree Harsha Totakura <sreeharsha@totakura.in>
+;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;;
+;;; 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 cvs-download)
+  #:use-module (guix records)
+  #:use-module (guix gexp)
+  #:use-module (guix store)
+  #:use-module (guix monads)
+  #:use-module (guix packages)
+  #:use-module (ice-9 match)
+  #:export (cvs-reference
+            cvs-reference?
+            cvs-reference-url
+            cvs-reference-revision
+            cvs-fetch))
+
+;;; Commentary:
+;;;
+;;; An <origin> method that fetches a specific revision or date from a CVS
+;;; repository.  The CVS-ROOT-DIRECTORY, MODULE and REVISION are specified
+;;; with a <cvs-reference> object.  REVISION should be specified as either a
+;;; date string in ISO-8601 format (e.g. "2012-12-21") or a CVS tag.
+;;;
+;;; Code:
+
+(define-record-type* <cvs-reference>
+  cvs-reference make-cvs-reference
+  cvs-reference?
+  (root-directory cvs-reference-root-directory)         ; string
+  (module         cvs-reference-module)                 ; string
+  (revision       cvs-reference-revision))              ; string
+
+(define (cvs-package)
+  "Return the default CVS package."
+  (let ((distro (resolve-interface '(gnu packages version-control))))
+    (module-ref distro 'cvs)))
+
+(define* (cvs-fetch ref hash-algo hash
+                    #:optional name
+                    #:key (system (%current-system)) (guile (default-guile))
+                    (cvs (cvs-package)))
+  "Return a fixed-output derivation that fetches REF, a <cvs-reference>
+object.  The output is expected to have recursive hash HASH of type
+HASH-ALGO (a symbol).  Use NAME as the file name, or a generic name if #f."
+  (define build
+    #~(begin
+        (use-modules (guix build cvs))
+        (cvs-fetch '#$(cvs-reference-root-directory ref)
+                   '#$(cvs-reference-module ref)
+                   '#$(cvs-reference-revision ref)
+                   #$output
+                   #:cvs-command (string-append #$cvs "/bin/cvs"))))
+
+  (mlet %store-monad ((guile (package->derivation guile system)))
+    (gexp->derivation (or name "cvs-checkout") build
+                      #:system system
+                      #:hash-algo hash-algo
+                      #:hash hash
+                      #:recursive? #t
+                      #:modules '((guix build cvs)
+                                  (guix build utils))
+                      #:guile-for-build guile
+                      #:local-build? #t)))
+
+;;; cvs-download.scm ends here