From 9d2f48df024fab5b99f1243cdf912a926c0e1e3d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Thu, 3 Sep 2015 23:37:33 +0200
Subject: [PATCH] publish: Gracefully handle the lack of a deriver.

* guix/scripts/publish.scm (narinfo-string): Catch 'system-error' around
  'load-derivation' call; return BASE-INFO upon ENOENT.  This allows us
  to return the narinfo even if DERIVER is missing.  Before that, the
  exception would be uncaught, leading to 500 Internal Error on the
  client side.
---
 guix/scripts/publish.scm    | 23 ++++++++++++++++-------
 guix/scripts/substitute.scm |  2 +-
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/guix/scripts/publish.scm b/guix/scripts/publish.scm
index e3bcac8047..cc96355947 100644
--- a/guix/scripts/publish.scm
+++ b/guix/scripts/publish.scm
@@ -151,7 +151,7 @@ (define (narinfo-string store-path path-info key)
          (references (string-join
                       (map basename (path-info-references path-info))
                       " "))
-         (deriver (path-info-deriver path-info))
+         (deriver    (path-info-deriver path-info))
          (base-info  (format #f
                              "StorePath: ~a
 URL: ~a
@@ -162,12 +162,21 @@ (define (narinfo-string store-path path-info key)
                              store-path url hash size references))
          ;; Do not render a "Deriver" or "System" line if we are rendering
          ;; info for a derivation.
-         (info (if (string-null? deriver)
-                   base-info
-                   (let ((drv (load-derivation deriver)))
-                     (format #f "~aSystem: ~a~%Deriver: ~a~%"
-                             base-info (derivation-system drv)
-                             (basename deriver)))))
+         (info       (if (string-null? deriver)
+                         base-info
+                         (catch 'system-error
+                           (lambda ()
+                             (let ((drv (load-derivation deriver)))
+                               (format #f "~aSystem: ~a~%Deriver: ~a~%"
+                                       base-info (derivation-system drv)
+                                       (basename deriver))))
+                           (lambda args
+                             ;; DERIVER might be missing, but that's fine:
+                             ;; it's only used for <substitutable> where it's
+                             ;; optional.  'System' is currently unused.
+                             (if (= ENOENT (system-error-errno args))
+                                 base-info
+                                 (apply throw args))))))
          (signature  (base64-encode-string
                       (canonical-sexp->string (signed-string info)))))
     (format #f "~aSignature: 1;~a;~a~%" info (gethostname) signature)))
diff --git a/guix/scripts/substitute.scm b/guix/scripts/substitute.scm
index 95aae2a372..e908bc997e 100755
--- a/guix/scripts/substitute.scm
+++ b/guix/scripts/substitute.scm
@@ -703,7 +703,7 @@ (define (show-help)
 ;;;
 
 (define (display-narinfo-data narinfo)
-  "Write to the current output port the contents of NARINFO is the format
+  "Write to the current output port the contents of NARINFO in the format
 expected by the daemon."
   (format #t "~a\n~a\n~a\n"
           (narinfo-path narinfo)