Move operating system helpers from (guix build …) to (gnu build …).

* guix/build/activation.scm, guix/build/install.scm,
  guix/build/linux-initrd.scm, guix/build/vm.scm: Move to...
* gnu/build: ... here.
* Makefile.am (MODULES): Remove the above guix/build/ files.
* gnu-system.am (GNU_SYSTEM_MODULES): Add the above gnu/build/ files
  here.
* gnu/services/base.scm, gnu/services/dmd.scm, gnu/system.scm,
  gnu/system/linux-initrd.scm, gnu/system/vm.scm,
  guix/scripts/system.scm: Adjust to the new module names.

gnu/build/install.scm

@@ -0,0 +1,135 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.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 (gnu build install)
+  #:use-module (guix build utils)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:export (install-grub
+            populate-root-file-system
+            reset-timestamps
+            register-closure))
+
+;;; Commentary:
+;;;
+;;; This module supports the installation of the GNU system on a hard disk.
+;;; It is meant to be used both in a build environment (in derivations that
+;;; build VM images), and on the bare metal (when really installing the
+;;; system.)
+;;;
+;;; Code:
+
+(define* (install-grub grub.cfg device mount-point)
+  "Install GRUB with GRUB.CFG on DEVICE, which is assumed to be mounted on
+MOUNT-POINT."
+  (let* ((target (string-append mount-point "/boot/grub/grub.cfg"))
+         (pivot  (string-append target ".new")))
+    (mkdir-p (dirname target))
+
+    ;; Copy GRUB.CFG instead of just symlinking it since it's not a GC root.
+    ;; Do that atomically.
+    (copy-file grub.cfg pivot)
+    (rename-file pivot target)
+
+    (unless (zero? (system* "grub-install" "--no-floppy"
+                            "--boot-directory"
+                            (string-append mount-point "/boot")
+                            device))
+      (error "failed to install GRUB"))))
+
+(define (evaluate-populate-directive directive target)
+  "Evaluate DIRECTIVE, an sexp describing a file or directory to create under
+directory TARGET."
+  (let loop ((directive directive))
+    (match directive
+      (('directory name)
+       (mkdir-p (string-append target name)))
+      (('directory name uid gid)
+       (let ((dir (string-append target name)))
+         (mkdir-p dir)
+         (chown dir uid gid)))
+      (('directory name uid gid mode)
+       (loop `(directory ,name ,uid ,gid))
+       (chmod (string-append target name) mode))
+      ((new '-> old)
+       (symlink old (string-append target new))))))
+
+(define (directives store)
+  "Return a list of directives to populate the root file system that will host
+STORE."
+  `(;; Note: the store's GID is fixed precisely so we can set it here rather
+    ;; than at activation time.
+    (directory ,store 0 30000 #o1775)
+
+    (directory "/etc")
+    (directory "/var/log")                          ; for dmd
+    (directory "/var/guix/gcroots")
+    (directory "/var/empty")                        ; for no-login accounts
+    (directory "/var/db")                           ; for dhclient, etc.
+    (directory "/var/run")
+    (directory "/run")
+    (directory "/mnt")
+    (directory "/var/guix/profiles/per-user/root" 0 0)
+
+    ;; Link to the initial system generation.
+    ("/var/guix/profiles/system" -> "system-1-link")
+
+    ("/var/guix/gcroots/booted-system" -> "/run/booted-system")
+    ("/var/guix/gcroots/current-system" -> "/run/current-system")
+
+    (directory "/bin")
+    ("/bin/sh" -> "/run/current-system/profile/bin/bash")
+    (directory "/tmp" 0 0 #o1777)                 ; sticky bit
+
+    (directory "/root" 0 0)                       ; an exception
+    (directory "/home" 0 0)))
+
+(define (populate-root-file-system system target)
+  "Make the essential non-store files and directories on TARGET.  This
+includes /etc, /var, /run, /bin/sh, etc., and all the symlinks to SYSTEM."
+  (for-each (cut evaluate-populate-directive <> target)
+            (directives (%store-directory)))
+
+  ;; Add system generation 1.
+  (symlink system
+           (string-append target "/var/guix/profiles/system-1-link")))
+
+(define (reset-timestamps directory)
+  "Reset the timestamps of all the files under DIRECTORY, so that they appear
+as created and modified at the Epoch."
+  (display "clearing file timestamps...\n")
+  (for-each (lambda (file)
+              (let ((s (lstat file)))
+                ;; XXX: Guile uses libc's 'utime' function (not 'futime'), so
+                ;; the timestamp of symlinks cannot be changed, and there are
+                ;; symlinks here pointing to /gnu/store, which is the host,
+                ;; read-only store.
+                (unless (eq? (stat:type s) 'symlink)
+                  (utime file 0 0 0 0))))
+            (find-files directory "")))
+
+(define (register-closure store closure)
+  "Register CLOSURE in STORE, where STORE is the directory name of the target
+store and CLOSURE is the name of a file containing a reference graph as used
+by 'guix-register'.  As a side effect, this resets timestamps on store files."
+  (let ((status (system* "guix-register" "--prefix" store
+                         closure)))
+    (unless (zero? status)
+      (error "failed to register store items" closure))))
+
+;;; install.scm ends here