From e72bd43190bd561f7d96810a93f3b30f5f741343 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Tue, 17 Mar 2015 10:19:36 -0400
Subject: [PATCH 1/2] store: Add query-path-info operation.

* guix/store.scm (<path-info>): New record type.
  (read-path-info): New procedure.
  (read-arg): Add 'path-info' syntax.
  (query-path-info): New variable.
---
 guix/store.scm | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/guix/store.scm b/guix/store.scm
index a3f3cbf..8e1a180 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -60,6 +60,7 @@
             valid-path?
             query-path-hash
             hash-part->path
+            query-path-info
             add-text-to-store
             add-to-store
             build-things
@@ -79,6 +80,13 @@
             substitutable-paths
             substitutable-path-info
 
+            path-info?
+            path-info-deriver
+            path-info-hash
+            path-info-refs
+            path-info-reg-time
+            path-info-nar-size
+
             references
             requisites
             referrers
@@ -212,6 +220,24 @@
                 (cons (substitutable path deriver refs dl-size nar-size)
                       result))))))
 
+;; Information about a store path.
+(define-record-type <path-info>
+  (path-info deriver hash refs reg-time nar-size)
+  path-info?
+  (deriver path-info-deriver)
+  (hash path-info-hash)
+  (refs path-info-refs)
+  (reg-time path-info-reg-time)
+  (nar-size path-info-nar-size))
+
+(define (read-path-info p)
+  (let ((deriver  (read-store-path p))
+        (hash     (base16-string->bytevector (read-string p)))
+        (refs     (read-store-path-list p))
+        (reg-time (read-int p))
+        (nar-size (read-long-long p)))
+    (path-info deriver hash refs reg-time nar-size)))
+
 (define-syntax write-arg
   (syntax-rules (integer boolean file string string-list string-pairs
                  store-path store-path-list base16)
@@ -236,7 +262,7 @@
 
 (define-syntax read-arg
   (syntax-rules (integer boolean string store-path store-path-list
-                 substitutable-path-list base16)
+                 substitutable-path-list path-info base16)
     ((_ integer p)
      (read-int p))
     ((_ boolean p)
@@ -249,6 +275,8 @@
      (read-store-path-list p))
     ((_ substitutable-path-list p)
      (read-substitutable-path-list p))
+    ((_ path-info p)
+     (read-path-info p))
     ((_ base16 p)
      (base16-string->bytevector (read-string p)))))
 
@@ -532,6 +560,10 @@ string).  Raise an error if no such path exists."
      ;; /HASH.narinfo.
      (query-path-from-hash-part server hash-part))))
 
+(define-operation (query-path-info (store-path path))
+  "Return the derivation store path for PATH."
+  path-info)
+
 (define add-text-to-store
   ;; A memoizing version of `add-to-store', to avoid repeated RPCs with
   ;; the very same arguments during a given session.
-- 
2.1.4