3 files changed, 20 insertions, 4 deletions
diff --git a/nix/libstore/remote-store.cc b/nix/libstore/remote-store.cc
index 0539bbe127..324ef5eb30 100644
--- a/nix/libstore/remote-store.cc
+++ b/nix/libstore/remote-store.cc
@@ -462,11 +462,18 @@ Paths RemoteStore::importPaths(bool requireSignature, Source & source)
 
 void RemoteStore::buildPaths(const PathSet & drvPaths, BuildMode buildMode)
 {
-    if (buildMode != bmNormal) throw Error("repairing or checking is not supported when building through the Nix daemon");
     openConnection();
     writeInt(wopBuildPaths, to);
-    if (GET_PROTOCOL_MINOR(daemonVersion) >= 13)
+    if (GET_PROTOCOL_MINOR(daemonVersion) >= 13) {
         writeStrings(drvPaths, to);
+        if (GET_PROTOCOL_MINOR(daemonVersion) >= 15) {
+            writeInt(buildMode, to);
+        }
+        /* Old daemons did not take a 'buildMode' parameter, so we need to
+           validate it here on the client side.  */
+        else if (buildMode != bmNormal) throw Error("repairing or checking \
+is not supported when building through the Nix daemon");
+    }
     else {
         /* For backwards compatibility with old daemons, strip output
            identifiers. */
diff --git a/nix/libstore/worker-protocol.hh b/nix/libstore/worker-protocol.hh
index d037d7402e..7b7be4a8a0 100644
--- a/nix/libstore/worker-protocol.hh
+++ b/nix/libstore/worker-protocol.hh
@@ -6,7 +6,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x10e
+#define PROTOCOL_VERSION 0x10f
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
diff --git a/nix/nix-daemon/nix-daemon.cc b/nix/nix-daemon/nix-daemon.cc
index bd9eebe0a9..c1e697bcac 100644
--- a/nix/nix-daemon/nix-daemon.cc
+++ b/nix/nix-daemon/nix-daemon.cc
@@ -451,8 +451,17 @@ static void performOp(bool trusted, unsigned int clientVersion,
 
     case wopBuildPaths: {
         PathSet drvs = readStorePaths<PathSet>(from);
+        BuildMode mode = bmNormal;
+        if (GET_PROTOCOL_MINOR(clientVersion) >= 15) {
+            mode = (BuildMode)readInt(from);
+
+	    /* Repairing is not atomic, so disallowed for "untrusted"
+	       clients.  */
+            if (mode == bmRepair && !trusted)
+                throw Error("repairing is not supported when building through the Nix daemon");
+        }
         startWork();
-        store->buildPaths(drvs);
+        store->buildPaths(drvs, mode);
         stopWork();
         writeInt(1, to);
         break;