store: Use the daemon's substitute URLs by default.

Partly fixes <http://bugs.gnu.org/20217>.

* guix/store.scm (set-build-options): Change #:substitute-urls to
  default to #f.  Send the 'substitute-urls' pair only if
  SUBSTITUTE-URLS is true.
* guix/scripts/build.scm (set-build-options-from-command-line): Do not
  default to %DEFAULT-SUBSTITUTE-URLS for #:substitute-urls.
* guix/scripts/size.scm (%default-options): Remove 'substitute-urls'.

3 files changed, 13 insertions, 10 deletions

diff --git a/guix/scripts/build.scm b/guix/scripts/build.scm
index ee7e5b958c5..644ffe8d6ec 100644
--- a/guix/scripts/build.scm
+++ b/guix/scripts/build.scm
@@ -185,8 +185,7 @@ options handled by 'set-build-options-from-command-line', and listed in
                      #:max-build-jobs (or (assoc-ref opts 'max-jobs) 1)
                      #:fallback? (assoc-ref opts 'fallback?)
                      #:use-substitutes? (assoc-ref opts 'substitutes?)
-                     #:substitute-urls (or (assoc-ref opts 'substitute-urls)
-                                           %default-substitute-urls)
+                     #:substitute-urls (assoc-ref opts 'substitute-urls)
                      #:use-build-hook? (assoc-ref opts 'build-hook?)
                      #:max-silent-time (assoc-ref opts 'max-silent-time)
                      #:timeout (assoc-ref opts 'timeout)
@@ -512,6 +511,8 @@ arguments with packages that use the specified source."
              (urls  (map (cut string-append <> "/log")
                          (if (assoc-ref opts 'substitutes?)
                              (or (assoc-ref opts 'substitute-urls)
+                                 ;; XXX: This does not necessarily match the
+                                 ;; daemon's substitute URLs.
                                  %default-substitute-urls)
                              '())))
              (roots (filter-map (match-lambda
diff --git a/guix/scripts/size.scm b/guix/scripts/size.scm
index 44ff92655bd..e999cce1fdd 100644
--- a/guix/scripts/size.scm
+++ b/guix/scripts/size.scm
@@ -252,8 +252,7 @@ Report the size of PACKAGE and its dependencies.\n"))
                   (show-version-and-exit "guix size")))))
 
 (define %default-options
-  `((system . ,(%current-system))
-    (substitute-urls . ,%default-substitute-urls)))
+  `((system . ,(%current-system))))
 
 
 ;;;
diff --git a/guix/store.scm b/guix/store.scm
index c4e35737114..8413d1f4523 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -501,11 +501,11 @@ encoding conversion errors."
                             (build-cores (current-processor-count))
                             (use-substitutes? #t)
 
-                            ;; Client-provided substitute URLs.  For
-                            ;; unprivileged clients, these are considered
-                            ;; "untrusted"; for "trusted" users, they override
-                            ;; the daemon's settings.
-                            (substitute-urls %default-substitute-urls))
+                            ;; Client-provided substitute URLs.  If it is #f,
+                            ;; the daemon's settings are used.  Otherwise, it
+                            ;; overrides the daemons settings; see 'guix
+                            ;; substitute'.
+                            (substitute-urls #f))
   ;; Must be called after `open-connection'.
 
   (define socket
@@ -533,7 +533,10 @@ encoding conversion errors."
       (let ((pairs `(,@(if timeout
                            `(("build-timeout" . ,(number->string timeout)))
                            '())
-                     ("substitute-urls" . ,(string-join substitute-urls)))))
+                     ,@(if substitute-urls
+                           `(("substitute-urls"
+                              . ,(string-join substitute-urls)))
+                           '()))))
         (send (string-pairs pairs))))
     (let loop ((done? (process-stderr server)))
       (or done? (process-stderr server)))))