add :CHROOT and :CHROOT.SHELL connection types

Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>

1 files changed, 42 insertions, 0 deletions

diff --git a/src/connection/chroot.lisp b/src/connection/chroot.lisp
new file mode 100644
index 0000000..b597333
--- /dev/null
+++ b/src/connection/chroot.lisp
@@ -0,0 +1,42 @@
+;;; Consfigurator -- Lisp declarative configuration management system
+
+;;; Copyright (C) 2021  Sean Whitton <spwhitton@spwhitton.name>
+
+;;; This file 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, or (at your option)
+;;; any later version.
+
+;;; This file 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+(in-package :consfigurator.connection.chroot)
+
+;; currently we only check whether we're root, but, for example, on Linux, we
+;; might have a CAP_* which lets us chroot as non-root
+(defun can-chroot ()
+  (zerop (foreign-funcall "geteuid" :int)))
+
+(defun can-probably-fork ()
+  "Return nil if we can detect other running threads, and the Lisp
+implementation is known not to support forking when there are other threads.
+A return value other than nil indicates only that we couldn't detect
+circumstances in which it is known that we cannot fork, not that we are sure
+we can fork -- a thread might be only partly initialised at the time we check,
+for example, such that we don't see it."
+  (and
+   #+sbcl (not (sb-thread:list-all-threads))))
+
+(defmethod establish-connection ((type (eql :chroot)) remaining &key into)
+  (establish-connection (if (and (lisp-connection-p)
+				 (can-chroot)
+				 (can-probably-fork))
+			    :chroot.fork
+			    :chroot.shell)
+			remaining
+			:into into))