From 620e92e880f8a011c5f465ea4fee2abf857d4ab2 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Tue, 6 Nov 2012 13:44:59 +0100
Subject: [PATCH] =?UTF-8?q?Add=20an=20option=20=E2=80=98use-binary-caches?=
 =?UTF-8?q?=E2=80=99?=
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This allows disabling the use of binary caches, e.g.

  $ nix-build ... --option use-binary-caches false

Note that

  $ nix-build ... --option binary-caches ''

does not disable all binary caches, since the caches defined by
channels will still be used.
---
 doc/manual/conf-file.xml                 | 10 ++++++++++
 scripts/download-from-binary-cache.pl.in |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/doc/manual/conf-file.xml b/doc/manual/conf-file.xml
index 2dc260b35..6a575b9e3 100644
--- a/doc/manual/conf-file.xml
+++ b/doc/manual/conf-file.xml
@@ -318,6 +318,16 @@ build-use-chroot = /dev /proc /bin</programlisting>
   </varlistentry>
 
 
+  <varlistentry><term><literal>use-binary-caches</literal></term>
+
+    <listitem><para>If set to <literal>true</literal> (the default),
+    Nix will check the binary caches specified by
+    <option>binary-caches</option> and related options to obtain
+    binary substitutes.</para></listitem>
+
+  </varlistentry>
+
+
   <varlistentry><term><literal>binary-caches</literal></term>
 
     <listitem><para>A list of URLs of binary caches, separated by
diff --git a/scripts/download-from-binary-cache.pl.in b/scripts/download-from-binary-cache.pl.in
index 74df79d8f..a018b3b2a 100644
--- a/scripts/download-from-binary-cache.pl.in
+++ b/scripts/download-from-binary-cache.pl.in
@@ -177,6 +177,10 @@ sub getAvailableCaches {
     return if $gotCaches;
     $gotCaches = 1;
 
+    return if
+        ($Nix::Config::config{"use-binary-caches"} // "true") eq "false" ||
+        ($Nix::Config::config{"untrusted-use-binary-caches"} // "true") eq "false";
+
     sub strToList {
         my ($s) = @_;
         return map { s/\/+$//; $_ } split(/ /, $s);