hostattrs accessors: call PREPROCESS-HOST in some situations

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

2 files changed, 19 insertions, 2 deletions

diff --git a/src/host.lisp b/src/host.lisp
index acda791..a449d3c 100644
--- a/src/host.lisp
+++ b/src/host.lisp
@@ -80,6 +80,10 @@ attributes, so that implementations of ESTABLISH-CONNECTION can push new
 attributes (typically to request prerequisite data) without disturbing host
 values higher up the call stack."))
 
+(defparameter *preprocessing-host* nil
+  "HOST value currently being preprocessed.
+Used by GET-HOSTATTRS to break infinite loops.")
+
 (defmethod preprocess-host ((host preprocessed-host))
   (shallow-copy-host host))
 
@@ -87,7 +91,8 @@ values higher up the call stack."))
   (let ((*host* (make-instance
                  'preprocessed-host
                  :hostattrs (copy-list (hostattrs host))
-                 :propspec (preprocess-propspec (host-propspec host)))))
+                 :propspec (preprocess-propspec (host-propspec host))))
+        (*preprocessing-host* host))
     (propappattrs (eval-propspec (host-propspec *host*)))
     *host*))
 
diff --git a/src/property.lisp b/src/property.lisp
index 2abb5e9..c3a6a5d 100644
--- a/src/property.lisp
+++ b/src/property.lisp
@@ -457,7 +457,19 @@ install an apt package but the host is FreeBSD.")
   "Retrieve the list of static informational attributes of type KEY.
 
 Called by property :HOSTATTRS, :APPLY and :UNAPPLY subroutines."
-  (getf (slot-value host 'hostattrs) k))
+  ;; Ensure the host is preprocessed so the desired hostattrs are actually
+  ;; there, assuming we're not already preprocessing it.  Avoid calling
+  ;; PREPROCESS-HOST on PREPROCESSED-HOST values to avoid pointless copying.
+  ;;
+  ;; This is just to improve readability for some property definitions and
+  ;; avoid confusing situations where hostattrs appear to be missing (for
+  ;; example, if the hostname is not set until HOSTNAME:IS); properties which
+  ;; will look up multiple hostattrs by supplying a value for HOST should call
+  ;; PREPROCESS-HOST on that value themselves.
+  (let ((host (if (and (subtypep (class-of host) 'unpreprocessed-host)
+                       (not (eql host *preprocessing-host*)))
+                  (preprocess-host host) host)))
+    (getf (slot-value host 'hostattrs) k)))
 
 (defun get-hostattrs-car (k &optional (host *host*))
   (car (get-hostattrs k host)))