From 0dd988d2e3653d81b7bda43e0618ce330553b7bc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Fri, 29 Apr 2016 17:33:22 +0200
Subject: [PATCH] Better error message

---
 src/libstore/binary-cache-store.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libstore/binary-cache-store.cc b/src/libstore/binary-cache-store.cc
index 90d7fa18b..ff717a5dc 100644
--- a/src/libstore/binary-cache-store.cc
+++ b/src/libstore/binary-cache-store.cc
@@ -137,7 +137,12 @@ void BinaryCacheStore::narFromPath(const Path & storePath, Sink & sink)
 
     /* Decompress the NAR. FIXME: would be nice to have the remote
        side do this. */
-    nar = decompress(info->compression, ref<std::string>(nar));
+    try {
+        nar = decompress(info->compression, ref<std::string>(nar));
+    } catch (UnknownCompressionMethod &) {
+        throw Error(format("binary cache path ‘%s’ uses unknown compression method ‘%s’")
+            % storePath % info->compression);
+    }
 
     stats.narReadBytes += nar->size();